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Natural Areas Information
Natural Areas Information
CNAP Designated Areas Map

See the full CNAP Designated Areas map​.​

​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Designated Natural Areas contain a wide representation of Colorado’s ra​re plants and animals, unique plant communities, rich fossil locations, and geological features. Ownership of these sites include all types, such as private land, land trusts, local, state and federal lands. Visitation and recreational opportunities are at the discretion of the property owner. 

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Natural AreaLocationSizeDesignatedLandownerLand ManagerDescription
Aiken CanyonEl Paso County1,600 acres1994State Land Board/ Leased by The Nature ConservancyAiken Canyon

The Aiken Canyon Natural Area includes the largest intact foothills ecosystem known from the Front Range. The area contains one woodland and two foothills shrubland plant communities of special concern. Aiken Canyon also contains an unusual diversity and concentration of wildlife. Mountain lion, black bear, wild turkey, elk, golden eagles and an abundance of neotropical migratory birds are present in the area. The ponderosa pine and Douglas-fir along streams and on the rugged canyon walls have not been logged, unlike most of the Front Range.

To learn more about Aiken Canyon, visit, The Nature Conservancy's website.

Antero-Salt CreekPark County8,520 acres2010State Land Board
Antero-Salt Creek

The Antero-Salt Creek Natural Area is home to several rare habitat types in Colorado: perched wetlands supporting fen-like vegetation, alkaline marshes and salt springs. Together these habitats house several state and globally imperiled plant species, and provide seasonal homes for rare birds and butterflies. The following is an excellent description of the property provided by the Colorado Natural Heritage Program:

"This area was given the name 'bayou salado' by French explorers due the presence of salts. The plants and plant communities that dominate the alkaline flats are salt-tolerant species...The surrounding uplands are dominated by montane grasslands."

The Natural Area encompasses portions of multiple named and un-named creeks that flow off the eastern flanks of the Buffalo Peaks and Trout Creek Pass into the Antero Reservoir. The property has good connectivity with forested and riparian systems located on Pike National Forest to the west.

Arikaree RiverYuma County2,240 acres2012State Land Board
Arikaree River

The Arikaree River Natural Area is part of the largest and best remaining example of a naturally functioning Great Plains river system in Colorado. Several native and uncommon species of amphibians, fish and reptiles reside within the near-pristine habitat that includes high-quality native prairie and riparian plant communities. The area is also home to birds, including ferruginous hawks, burrowing owls and greater prairie chickens, and serves as a meeting ground for many bird species from the eastern and western United States.

Badger WashMesa County1,904 acres1989
Bureau of Land ManagementBadger Wash

Badger Wash consists of an entire small watershed that has been used for hydrologic research for more than 30 years. Biologic values include high-quality examples of a cold desert shrubland community (mat saltbush/saline wild rye) and populations of the rare plants Astragalus musiniensisEriogonum contortum and Cryptantha elata.

Blue MountainLarimer County292 acres 1983Private
Blue Mountain

This natural area includes an exposure of the Blue Mountain Fault, providing a clear example of drape or drag faulting and of stratigraphic pinch-out of two Permian formations (Satanka and Ingleside). The zone of mingling between the alluvial fan of the ancestral Rockies and the sand beaches of the ancestral sea is clearly visible. Physaria bellii, ​a rare, narrow endemic, is found in two places on the property.

Bonny PrairieYuma County50 acres1988Bureau of Reclamation; leased by Colorado Parks & Wildlife
Bonny Prairie

Bonny Prairie Natural Area supports a remnant of the loess prairie community, an ecosystem that may once have covered millions of acres in the central United States. Loess, the key element of this prairie, is a fine rock powder that results from the grinding of rocks beneath glaciers. When the ice sheet that covered much of North America eighteen thousand years ago melted, billions of tons of loess were exposed. Wind carried the loess to distant areas and, along with water, shaped the soft deposits into bluffs and rolling hills.

Loess deposits themselves are not rare; however, deep deposits and undisturbed areas with native vegetation are unusual. Because loess soils are fertile and easily tilled, this land was eagerly sought and cultivated as the midwest was settled. Extensive areas in Nebraska, Kansas and Iowa which formerly supported this community type are now devoted to the cultivation of corn and wheat. It is estimated that the little bluestem loess prairie community represented at Bonny Prairie now covers only about 35% or less of its former range. Although the community probably was once common in southeast Yuma and northeast Kit Carson counties, the prairie at Bonny Prairie Natural Area is one of the few fragments of remaining intact loess prairie known in Colorado today.

Upland loess prairies are typically dominated by warm-season grasses of medium height, especially little bluestem (Schizachyrium scoparium) and sideoats grama (Bouteloua curtipendula). The relatively lush and tall little bluestem prairie at Bonny stands in contrast to the sparse, sandy shortgrass prairie that dominates much of eastern Colorado.

Bonny Prairie was designated as a Colorado Natural Area in order to recognize and protect this unusual biological community and to provide a critical ecological baseline area for the loess region of the Great Plains. 

Boulder Mountain ParkBoulder County7,401 acres2009City of Boulder, Open Space & Mountain Parks
Boulder Mountain Park

Boulder Mountain Park is located along the foothills-plains interface just west of the City of Boulder. This Natural Area encompasses Green Mountain, Longs Canyon, the Boulder Flatirons, and the Western Mountain Parks Habitat Conservation Area. All of these areas represent a rich ecotonal area between the mountains and the plains, and create a large habitat for a variety of species.

These management areas support typical examples of modern foothills community types as well as plant species left over from the cooler and wetter conditions prevalent during the last ice age. Among the plant relicts are a stand of paper birch and disjunct populations of boreal and subalpine plants. The property contains a high concentration of rare plants, including one extremely rare plant. There are also several rare birds, mammals and insects that call this park home. At this site, visitors can walk through 1.5 billion years of geologic history and view the renowned Boulder Flatirons.

Brush Creek FenCuster County 9 acres2003Private
Brush Creek Fen

An unusual wetland, Brush Creek Fen is on a shallow ridge between North and South Brush creeks, yet does not receive water from either creek. Rather, underground springs slowly release water into the fen’s upper wet meadows, forming small freshets that finger through the lower meadows. The waters likely remain perched on the higher ridge due to an impermeable subsurface lens. The fen is dominated by beaked sedge (Carex utriculata), with Idaho bent grass (Agrostis idahoensis) abundant. Peat is sporadic (some quaking), mixed with thin rocky soils supporting blue and occasional Englemann spruce. Wood lily, Hypoxis hirsuta, Carex leptalea, an Alnus/Picea plant community, and nesting Lewis woodpecker can be found at this site.

California ParkRoutt County640 acres2002State Land Board
California Park

California Park provides nesting habitat for a large number of state-rare greater sandhill cranes, historic state-endangered boreal toad breeding, and is the only area in Colorado where the three native species of grouse occur together: Columbian sharp-tailed, blue and northern sage.

Castlewood CanyonDouglas County2,170 acres   1994Colorado Parks & Wildlife
Castlewood Canyon

Castlewood Canyon marks the descent of Cherry Creek from the north rim of the Palmer Divide. This natural area supports one of the best remnants of northern Black Forest plant communities, including unlogged forests of ponderosa pine and Douglas-fir, Gambel oak thickets, and grasslands of mixed prairie and foothills species. Several plant species of special concern have been found within the park boundaries, including Woodsia mexicana (Mexican woodfern), Asplenium septentrionale (grass-fern), and Smilax lasioneuron (carrion-flower). An unusual dryland heron rookery and a turkey vulture roosting site are among the zoologic features of the park.

Chalk BluffsWeld County640 acres2001State Land Board
Chalk Bluffs

This natural area is a small portion of an extensive area in northern Colorado where the barren outcrops of the Ogallala, Fox Hills and Arikaree Formations known as the Chalk Bluffs dominate the landscape. The western site is on the Wyoming border north of Greeley and east of I-25. The eastern site is in northwestern Logan and northeastern Weld counties. Lesser outcrops extend between the two sites and also form the northern bluffs of the S. Platte River valley in eastern Logan County.

The cliffs are protected from fire by their barrenness, and thus support outlying populations of foothills plant species such as ponderosa pine, Rocky Mountain juniper, limber pine, and mountain mahogany. These montane plants combine with prairie grasses to form communities unique to the escarpment. Clay lenses within the sandstone layers support a different type of barrens community, one dominated by hard cushion plants such as Stenotus armerioides and Tetraneuris acaulis and the rare plants Cryptantha cana and Parthenium (Bolophyta) alpinum. The rocks are rich in Miocene, Eocene and Paleocene vertebrate fossils, and the bluffs support a high concentration of nesting raptors.

Colorado Tallgrass PrairieBoulder County269 acres1984City of Boulder, Open Space & Mountain Parks
Colorado Tallgrass Prairie

The Colorado Tallgrass Prairie Natural Area consists of eight small parcels located along the broad floodplain of South Boulder Creek. The properties contain the largest known area of the once-extensive xeric and mesic native tallgrass prairies in Colorado. These tallgrass prairie remnants support flora similar to the prairies of South Dakota, Kansas, and the Midwest, including big bluestem (Andropogon gerardii), switchgrass (Panicum virgatum), and yellow Indiangrass (Sorgastrum nutans). The grassland also supports a wide variety of wildlife from spirited songbirds to elusive mountain lions.

Comanche Grassland Lesser Prairie ChickenBaca County9,210 acres1987
U.S. Forest ServiceComanche Grassland Lesser Prairie Chicken

This Comanche National Grassland site historically contained prime habitat for the Lesser Prairie Chicken as well as the largest concentration of leks (mating display grounds) for the Lesser Prairie Chicken in Colorado. The dense sandsage community on the site provided critical habitat for this state-listed threatened species. This species has not been observed on the Natural Area for several years.  

Copeland Willow CarrBoulder County 80 acres2005City of Longmont
Copeland Willow Carr

This wetland is the largest and highest quality lower montane willow carr on the Front Range. Major wetland functions provided by the willow carr are wildlife habitat, shoreline stabilization, sediment trapping, production export, and floodwater storage. On-site censuses indicate that this riparian community has one of the most diverse assemblages of breeding bird species in Colorado. The area also provides habitat for beaver, the endangered boreal toad, and the threatened greenback cutthroat trout (state fish of Colorado). Potential exists for these animals to be reintroduced.

Cross Mountain CanyonMoffat County2,160 acres1997Bureau of Land ManagementCross Mountain Canyon

Cross Mountain Canyon is a classic example of an "exhumed horst" cut by a superimposed stream. This block of ancient sedimentary rock was folded, broken, and uplifted during the formation of the Uintah Mountains in the early Tertiary period. These mountains were eventually worn down and buried in their own debris, then were again uncovered or exhumed by erosion as a new round of uplift began about 10 million years ago. In the meantime, the Yampa river had established its modern course, and as the land rose, the river cut a deep canyon and exposed the structure of the mountain. Vertical cliffs of Mississippian Madison Limestone rise to over 200 feet in height in the canyon, which is bounded on the west by a well-exposed fault zone. Two rare plant species and four endangered fish species occur in the canyon of the Yampa at this site. Peregrine falcons may nest on the cliffs.

Dakota Hogback / Dinosaur RidgeJefferson County2,168 acres2002Jefferson County Open Space
Dakota Hogback / Dinosaur Ridge

The prominent ridge which forms the primary feature of the Natural Area provides excellent illustrations of the geology of the Dakota Hogback, including exposures of the Dakota, Lyons and Lykins formations. Dinosaur Ridge, a National Natural Landmark paleontological site is included in the Natural Area. Here dinosaur tracks, bones, plants and trace fossils are well-exposed in this hogback of Morrison shales capped by Dakota Sandstone.

Dinosaur Ridge tracksThe hogback south of Dinosaur Ridge supports good examples of mixed foothills shrublands, pinyon-juniper woodlands and mixed grasslands. The hogback as a whole acts as a raptor migration corridor. The area also provides a scenic western backdrop for the Denver metropolitan area. Click here​ to visit the Friends of Dinosaur Ridge website for more information.

Deer GulchRio Blanco County1,809 acres1988Bureau of Land ManagementDeer Gulch

This site in Deer Gulch provides habitat for two rare plant species endemic to Green River shales, Physaria parviflora (Piceance bladderpod) and Argillochloa dasyclada (Utah fescue). Good quality remnants of Great Basin grassland, mixed mountain shrubland and lower montane Douglas-fir forest communities also occur within the boundaries. This area is also a BLM Area of Critical Environmental Concern. 

Dome RockTeller County640 acres1986Colorado Parks & Wildlife
Dome Rock
This scenic area is dominated by massive exfoliating outcrops of Pikes Peak granite. Dome Rock, among the most spectacular of the formations, rises 800 feet from the canyon floor. The site also contains good-quality examples of ponderosa pine, limber pine, Douglas-fir and Montane grassland plant communities. The area provides winter browse and lambing grounds for a herd of bighorn sheep.
Droney GulchChaffee County3,726 acres1999State Land Board; Bureau of Land ManagementDroney Gulch
Sparsely vegetated light brown hills with highly erosive steep slopes characterize the landscape of Droney Gulch Natural Area. On many hillsides, loose soils of the Dry Union Formation are exposed. These soils support one of the largest and best-known occurrences of the rare Brandegee's wild buckwheat (Eriogonum brandegeei), a small shrub less than six inches high. This Colorado endemic is one of the rarest plant species in North America.

Brandegee's wild buckwheat is known only from nine occurrences along the Arkansas River in Chaffee and Fremont counties in central Colorado. The plant has been found only on the Dry Union Formation and lower members of the Morrison Formation. Where it occurs, numbers of individuals are high, but the species appears to be restricted to a very limited habitat type within a narrow global range.
Dudley BluffsRio Blanco County1,620 acres1988
Bureau of Land ManagementDudley Bluffs

Dudley Bluffs is an outcrop of the thirteen mile Tongue of the Green River Formation, which supports populations of two threatened plant species, Physaria obcordata (Piceance twinpod) and Lesquerella congesta (Dudley Bluffs bladderpod). Remnants of high quality pinion pine - Utah juniper woodlands and cold desert shrublands also occur at Dudley Bluffs.

East Sand DunesJackson County 3,534 acres1982, 2002State Land BoardState Forest State ParkEast Sand Dunes

The East Sand Dunes are the only undisturbed example of an active cold-climate dune system in Colorado. There are only two such dune formations in the state; the other is North Sand Dunes, eight miles to the north, which has been heavily used by off road vehicles. Freeze-thaw and snow-melt processes form sedimentary structures that distunguish the East Sand Dunes from those found at Great Sand Dunes National Monument in southern Colorado. These cold-climate dunes are the only major active area in a predominantly dormant dune field which covers approximately 25 square miles. The relatively high precipitation, short summers and cold climate combine to greatly reduce sand movement, even on the active dunes. Because the dunes are active, the area is in a fragile state of soil and vegetative development and is an example of an ecosystem which is extremely rare in Colorado.

Elephant RocksRio Grande County378 acres1994
Bureau of Land ManagementElephant Rocks

Elephant Rocks are a weathered remnant of the Fish Canyon tuff, dating from the late Oligocene period roughly 28 million years ago. The rocks themselves support an occurrence of the rare parsley Neoparrya lithophila (rock-loving neoparrya). This member of the parsley family favors igneous outcrops or sedimentary rocks derived from volcanic eruptions. An interesting mixture of short grass prairie and foothill shrub land vegetation occurs on the site.

Escalante CanyonDelta & Montrose Counties2,290 acres1992
Bureau of Land ManagmentEscalante Canyon

Escalante Creek has cut a 1300-foot deep canyon revealing a geologic cross section representing over 600 million years of deposition and erosion (from the Precambrian to the Cretaceous). A federally threatned plant species and Astragalus linifolius (Grand Junction milkvetch) are found at this site. Hanging gardens in the canyon walls harbor Mancos columbine (Aquilegia micrantha) and Eastwood monkeyflower (Mimulus eastwoodiae). High-quality plant communities, including Great Basin grasslands, saltbush barrens, pinyon pine - Utah juniper woodlands and a saltgrass meadow occur throughout the canyon.

FairviewMontrose County377 acres1992
Bureau of Land ManagementFairview

The site contains significant populations of rare species, Eriogonum pelinophilum (clay-loving buckwheat), which is listed as federally endangered, and Penstemon retrorsus (adobe beardtongue). These species grow on otherwise barren adobe badlands.

Fourmile CreekPark County960 acres2010State Land Board
Fourmile Creek

The Fourmile Creek Natural Area was designated due to its unique wetland communities and rare plants. This area is recognized for having very high biological diversity due to a rare wetland type referred to as an "extreme rich fen", which is known only from South Park, Colorado and a few other locations in the world. Additionally, the area is critical passage for migrating wildlife between the Mosquito Range and South Park. The grasslands of this property may also be suitable for the mountain plover, a declining species throughout Colorado and the Great Plains.

Fruita Paleontological LocalityMesa County280 acres1987
Bureau of Land ManagementFruita Paleontological Locality

Jurassic outcrops, deposited about 140 million years ago, are the most fossil-rich formations within the Grand Valley and are protected within these acres at Fruita. The quality of preservation, completeness, and abundance of the fossil specimens make the Fruita Paleontological Locality unique. Some of the oldest mammal fossils found in the Western Hemisphere occur here. Fossil specimens found at the Fruita site include species of primitive mammals, a new genus of crocodilia, two carnivorous and several herbivorous dinosaurs.

Please be aware that this site contains features of state-wide significance. Collection is prohibited at all times with out proper permits.

Garden Park Fossil LocalityFremont County2,668 acres 1991
Bureau of Land ManagementGarden Park Fossil Locality

Garden Park - Colorado's Jurassic Park
"Garden Park." It s​​​​​​ounds like an idyllic suburb, but it may be the greatest Jurassic dinosaur graveyard in the world. Located eight miles north of Cañon City in south central Colorado, Garden Park's fossils helped to fuel the dinosaur craze that began in the 1890s and continues today. If you are looking for an explanation for why children who can't yet tie their own shoes have mastered words like "Diplodocus" and "Apatosaurus," look no further than Garden Park.

Bones of the great dinosaurs lie in a set of Jurassic rocks known as the Morrison Formation, exposed throughout much of the western US. The formation is a series of claystones, limestones and sandstones deposited by meandering rivers on a broad, rich alluvial plain between 145 and 155 million years ago. What makes Garden Park unique is that fossils are found throughout the 350-foot-thick formation, in contrast with the better-known quarry at Dinosaur National Monument, which is restricted to a single sandstone bed.

Dinosaur bones were first found in Garden Park by local residents in the 1870s. Word got back to the museums of the eastern U.S. and two of the greatest figures of American paleontology were soon involved. Edward Cope and Othniel Marsh played out a major chapter in their intense personal and professional rivalry in the quarries at Garden Park (see "Dinosaur Wars" article from the Smithsonian). Marsh was an amateur paleontologist who owed his professorship at Yale to a rich uncle. Cope was a professional associated with the Philadelphia Academy of Sciences. Former friends, their relationship ended in decades of slander, bribery and outright destruction of one another's fossil finds. However, because of the public nature of Marsh and Cope's dispute, and the tremendous collecting efforts that arose from it, the rest of the country became aware of the fascinating world of the Late Jurassic and its mighty dinosaurs.

The intense drive to publish first caused both scientists to commit careless mistakes, such as mixing up the bones of different species when naming a new animal. Marsh didn't even do most of his own fieldwork, instead hiring a local rancher, M.P. Felch, to do his excavating for him. Fortunately for science, Felch, although lacking formal training in paleontology, was a careful worker and a thorough observer. The type specimen of Stegosaurus stenops, Colorado's State Fossil, was recovered intact by Felch. It is now on display at the Smithsonian.

In addition to the Marsh and Cope quarries, at least four other fossil quarries pock Garden Park. Fossil dinosaur skeletons from Garden Park can be found in most of the natural history museums in the U.S. Researchers from the Denver Museum of Natural History and the University of Colorado continue to work the area. The quarries at Garden Park produced the type specimens of Camarasaurus, Allosaurus, Ceratosaurus, Diplodocus and Haplocanthosaurus, as well as at least 16 species of freshwater invertebrates. The skeletons of dozens of species of Jurassic mammals, fish, crocodiles and turtles have also been recovered.

Almost forgotten in the hullabaloo over fossils is the fact that Garden Park contains significant populations of three of Colorado's rare plants – Mentzelia chrysantha, Asclepias uncialis, and Eriogonum brandegeei. Perhaps the most interesting thing about the plant populations is that they are isolated by many miles from other populations. Garden Park is also the site of the first oil well in the western U.S. (1862).

Once Cope and Marsh abandoned their quarries in the 1880s, Garden Park fell into relative obscurity. Small expeditions would arrive every few decades, quarry bone for a season or two, and carry away their findings. Nonetheless, Garden Park is one of the most important late Jurassic vertebrate localities in North America, because of the quality of its specimens and the breadth of time covered. The Garden Park Fossil Area was designated a National Natural Landmark in the early 1970s. In the 1980s, a group of amateur paleontologists formed the Garden Park Paleontology Society and began pushing for increased protection and recognition of the area's scientific and historic significance. Their efforts paid off. In 1990 Garden Park was designated a Research Natural Area by the Bureau of Land Management and a Colorado Natural Area by the state. The Society itself has blossomed and now boasts a small but high-quality museum, the Dinosaur Depot, in the heart of Cañon City.

Please be aware that this site contains features of state-wide significance. Collection is prohibited at all times without proper permits.

Gateway PalisadeMesa County2,569 acres1987
Bureau of Land ManagementGateway Palisade

The Gateway Palisade is an outstanding scenic feature consisting of a 2000 foot monolithic fin of dark red Wingate sandstone. The stratigraphic sequence displayed at this site helps to interpret the geologic history of the Uncompahgre Uplift during the Permian period (225 million years ago).

There have also recently been several rare plant species discovered on the property, making this Natural Area even more interesting.

Geneva Basin Iron FensClear Creek County102 acres2004Clear Creek County
Geneva Basin Iron Fens

This site contains several iron fens which support the first (and currently only) known population of Sphagnum girgensohnii (a sphagnum moss) in Colorado. The iron fen differs from many others in having large expanses of unvegetated limonite. It also illustrates the effects of groundwater pH on vegetation; spring flow from the south is circumneutral and supports moderately-rich fen vegetation (Salix planifolia, Carex aquatilis); groundwater from the west and north is extremely acidic and supports limonite, sphagnum, bog birch and dwarfed Engelmann spruce. 

GothicGunnison County1,190 acres1980
U.S. Forest ServiceGothic

Gothic Natural Area contains virgin stands of Engelmann spruce - subalpine fir forest, typical of the upper montane ecosystem of western Colorado. The area ranges in elevation from 10,000 feet at the East River to 12,809 feet at the summit of Mt. Baldy and includes high elevation features such as glacial cirques, moraines, talus slopes and high alpine lakes.

This area also provides an outstanding resource for research and education. Researchers from the nearby Rocky Mountain Biological Laboratory use the Gothic Research Natural Area for a variety of projects.

Gunnison GravelsMesa County5 acres1987
Bureau of Land ManagementGunnison Gravels

The Gunnison Gravels ACEC protects unique gravel deposits which prove that the Gunnison River flowed through this site during prehistoric times. Cactus park was part of the ancestral channel of the Gunnison river from 1 to 5 million years ago. The Gunnison River and possibly the Colorado River once flowed through this area and carved Unaweep canyon to the west. Over time tributaries cutting into the soft Mancos shale to the north coupled with the rapid uplift of the harder Precambrian rocks in Unaweep Canyon caused the Colorado and Gunnison Rivers to flow around the Uncompahgre Plateau.

The gently rolling former stream valley floor is cut along the Cactus Park Fault by the eroded channel of an intermittent branch of Gibler Creek. The small residual sandstone bedrock outcrops form low cliffs along the gulch and small ridges and hills in the proposed area. The valley floor is sagebrush and grass covered with isolated stands of piñon-juniper woodland community.

Haviland LakeLa Plata County125 acres2012Colorado Parks and Wildlife
Haviland Lake

Haviland Lake Natural Area in La Plata County comprises much of the Haviland Lake State Wildlife Area. The riparian shrub lands and wet meadows provide habitat for sensitive wildlife species such as the osprey and the northern leopard frog. The natural peat lands and robust wetland vegetation also make the site significant for rare plants and other ecological features.

High Creek FenPark County 1,147 acres1994The Nature Conservancy; State Land Board
High Creek Fen

High Creek Fen is a calcareous (rich in calcium carbonate) spring-fed wetland supporting a large number of rare plants that are calcareophilous (calcium-loving) and/or arctic disjuncts. Arctic disjuncts are isolated populations of species whose normal range is now much further north. The calcareous conditions at High Creek are due to the fact that the wetland's springs seep through limestone-rich glacial outwash from the high elevations of the Mosquito Range to the west. The wetland community at High Creek Fen is a relict of the much colder and wetter conditions that prevailed in South Park during the last ice age. Primula egaliksensis (Greenland primrose), Salix candida (silver willow), Sisyrinchium pallidum (pale blue-eyed grass), Eriophorum gracile (slender cotton grass), Ptilagrostis porteri (Porter feathergrass), Carex microglochin (few-seeded bog sedge), Salix myrtillifolia (low blueberry willow), and Packera pauciflora (alpine groundsel) are all found at High Creek Fen. Click here​ to visit The Nature Conservancy's site about the Preserve.

High Mesa GrasslandFremont County1,100 acres1982
Bureau of Land ManagementHigh Mesa Grassland

"Good grass"

That comment was made in 1881 by E. B. Sopris, the government surveyor who laid out the townships containing High Mesa Grassland. It is still probably the best description of this 1100-acre Natural Area managed by the Bureau of Land Management (BLM).

While most areas in Colorado containing "good grass" simply became "good grazing" for domestic livestock, High Mesa Grassland took a different route. Located on the north rim of the Arkansas River Valley, high above Cañon City, High Mesa (known locally as Somerville Table or Table Mountain) had good grass but no water. Small numbers of cattle grazed the area sporadically, but the area could never support either large numbers of livestock or for very long without a water source. Therefore, unlike many montane grasslands in Colorado, the species composition at High Mesa has changed little since the late 1800s. Parry oatgrass, mountain muhly, junegrass, western wheatgrass, slender wheatgrass, blue grama, and others form the grassy matrix of the Natural Area. Penstemon, cinquefoil, groundsel, goldenaster and lupine provide splashes of color through the summer. Where the soils are thin and rocky or the volcanic bedrock is exposed, dense shrublands of oak and mountain mahogany form islands in the sea of grass.

The "High Mesa" part of this Natural Area's name comes from the underlying geology. A cap of dense volcanic rock protects the underlying granite, sedimentary rocks, and volcanic ash flows from the erosion that cut the Arkansas River canyon half a mile deep next door. The cap is part of the Thirtynine-Mile Volcanic Field, which was active periodically between 35 and 27 million years ago and spewed out thousands of feet of ash and lava. A final burst of volcanic activity about 19 million years ago produced the protective cap of andesite that forms Table Mountain.

Some scientists think that High Mesa Grassland is similar to what the floor of South Park, located 30 miles north of the Natural Area at nearly the same elevation, looked like before 1850. Beginning in the late 1860s, South Park became a center for hay and livestock production. Numbers of livestock grazed in South Park peaked at nearly 40,000 sheep and more than 100,000 cows in the late 1920s. This intense, long-term use took its toll on the grasslands of South Park, removing virtually all of the palatable grasses and leaving a relatively sparse plant community consisting primarily of junegrass, blue grama, and fringed sage. If the scientists are correct, then High Mesa Grassland could serve as a model for restoration of the original plant community of South Park.

Table Mountain has been much honored over the years. The Somerville Table Research Natural Area was established by the BLM in 1965 (its 680 acres form the core of the modern High Mesa Grassland Natural Area). Somerville Table was recommended for National Natural Landmark status in 1968, although it was never given that status. The High Mesa Grassland Area of Critical Environmental Concern and Colorado Natural Area was established by the BLM and the Colorado Natural Areas Program in 1987.

Hoosier RidgePark County373 acres2015U.S. Forest ServiceHoosier Ridge

Hoosier Ridge consists of a broad alpine ridge that is an east-west oriented portion of the Continental Divide. The western half of the area is underlain by upper Cretaceous and lower Tertiary rocks while the eastern portion is underlain by Minturn Formation of the Pennsylvanian age. The east-west orientation of the ridge and the uncommon geology of the area have combined to produce a habitat that is one of the top botanical hotspots in Colorado. The USFS reports that at least seven vegetation communities in excellent condition are found within the Hoosier Ridge area, including dry and wet alpine tundra, grassland, krummholz forest and alpine fen.

The high quality vegetation communities and the unique set of environmental conditions found at Hoosier Ridge support an incredible number of rare plant species. Hoosier Ridge is home to at least 16 rare or imperiled plant species, including three species only found in Colorado, two USFS sensitive species and a federally-listed species. Particularly significant rare plant species include: Penland alpine fen mustard (Eutrema penlandii):, Globe gilia (Ipomopsis globularis), Gray’s Peak whitlow grass (Draba grayana), and Sea pink (Armeria scabra ssp. sibirica). Because of its remarkable botanic diversity, Hoosier Ridge has been included in the Mosquito Range Potential Conservation Area that is of the highest ranking of Biodiversity Significance (B1) in Colorado, as ranked by the Colorado Natural Heritage Program.

Hurricane CanyonEl Paso County520 acres1980
U.S. Forest ServiceHurricane Canyon

The site includes two primary canyons, cut by the North and South Forks of French Creek, and several secondary canyons. This tract is characterized by steep slopes and canyon bottoms covered with boulders or loose rocky soil produced by erosion. The virgin stands of Douglas fir and ponderosa pine are rare undisturbed examples of lower montane forest. Oak brush cloaks the lower slopes, while Engelmann and blue spruce occur along streams at higher elevations.

Indian SpringSaguache County640 acres1987National Park ServiceIndian Spring

Indian Spring is the largest of the natural cold springs in the San Luis Valley. It lies in the midst of an active, warm climate dune field adjacent to Great Sand Dunes National Monument. The drainage has been separated from the Rio Grande River for several thousand years, isolating the aquatic fauna. A rare species of tiger beetle and an unusual diversity of wasps, bees and butterflies occur nearby.

Indian Springs Trace FossilFremont County40 acres1980Private
Indian Springs Trace Fossil

The Indian Springs Trace Fossil Natural Area includes an outcrop of the Harding Formation which is unusually rich in markings or traces of animals which lived 450 million years ago in the Ordovician Period. Twenty-five types of trace fossils illustrate the behavior of creatures living in the mudflats of an ancient tidal lagoon. Tracks and burrow patterns of jawless armor-plated fish, horseshoe crab, brachiopods and trilobites have been recorded. This site is considered the best location in North America to study trace fossils during this period, due to the excellent preservation and wide variety of the types of trace fossils.

Please be aware that this site contains features of state-wide significance. Collection is prohibited at all times with out proper permits. Visitation is allowed at the discretion of the private land​​owner. For visitation information contact the Indian Springs Ranch and Campground​

Irish CanyonMoffat County12,960 acres1990
Bureau of Land ManagementIrish Canyon

Irish Canyon is an excellent example of a beheaded stream valley; the stream in Irish Canyon was pirated by Vermillion Creek in early Pleistocene time, leaving a 1000-foot deep dry gorge. The canyon supports populations of several plant species of special concern including Bolophyta ligulata, Cryptantha caespitosa, and Eriogonum tumulosum. High-quality examples of northwestern Colorado plant communities are found on the floor and canyon walls, and Irish Lakes represent one of the few natural playa lakes in this part of the state. Rock art and other archaeological sites abound in the canyon. Stream piracy occurs when headword erosion enables one stream to capture the water flow from another stream.

For more information, visit the BLM's Irish Canyon web page​​.

Jimmy CreekLarimer County640 acres2002State Land Board
Jimmy Creek

The area includes a sedge wetland basin, surrounded by hills of sage and grasslands. The sedge meadows contained within serve as habitat for plant species of special concern, including the rare pale blue-eyed grass (Sisyrinchium pallidum) and the larch-leaf beardtongue (Penstemon laricifolius spp. exilifolius).

Ken-Caryl RanchJefferson County1,602 acres2000Private
Ken-Caryl Ranch

The Ken-Caryl Ranch Natural Area contains a textbook example of the geologic formation known as a "hogback." The highest ridge of the hogback is composed of Dakota sandstone (approximately 75 million years old), with a lower ridge to the west composed of Glennon Limestone (about 250 million years old). The Niobrara shale on the east face of the main hogback supports a population of a hybrid between two rare species of twinpods, Physaria vitulifera x Physaria bellii. The area is also an important topographic feature for migrating raptors. The Ken-Caryl hogback is vegetated with a mosaic of plant communities representative of the rocky scarps and shallow valleys of hogbacks along the east face of the Front Range. There are examples of foothills mixed grass prairie, oneseed juniper woodland, and Gambel oak thicket.

Kremmling Cretaceous Ammonite LocalityGrand County1,037 acres1986State Land Board; Bureau of Land ManagementKremmling Cretaceous Ammonite Locality

This site has exceptionally large and well-preserved fossils of giant ammonites (Placenticeras spp.) and many other groups of marine invertebrate fossils, including nautiloids, bivalves and gastropods which lived about 70 million years ago. The fossil ammonites found here are the largest specimens of this Cretaceous group known in North America. The area's exceptionally diverse fossil biota, including rare tropical and subtropical forms, represents an unusual fossil assemblage in North America.

Please be aware that this site contains features of state-wide significance. Collection is prohibited at all times with out proper permits.

Limestone RidgeMoffat County1,350 acres1990
Bureau of Land ManagementLimestone Ridge

Limestone Ridge supports a cross-section of Great Basin vegetation types in excellent condition, including three high quality native plant communities which are now rare in Colorado: curlleaf mountain mahogany woodlands, pinyon pine - Utah juniper woodlands with native bunchgrass understory, and limestone barrens communities. The limestone barrens contain cushion plants that are more typical of alpine environments, here occurring at lower elevations on rocky barrens of limestone substrate. A rare plant is also found here. The ridge itself crowns the eastern end of Cold Spring Mountain, a large, relatively flat-topped ridge which is an erosional remnant of the northeast limb of the Uinta anticline. The Mississippian limestone capping the ridge is more than 300 million years old.

Lookout MountainMoffat County6,500 acres1990
Bureau of Land ManagementLookout Mountain

Lookout Mountain is an excellent example of an isolated, flat-topped erosional remnant of a once-extensive Tertiary alluvial plain. Some 26 million years ago, much of Colorado was a relatively flat plain, the surface of which is preserved in these types of remnants. The mountain is capped by the Bishop Conglomerate, made up of flood and mudflow deposits derived from the Uinta Mountains to the northwest. The site contains high-quality cold desert shrublands and pinion-juniper woodlands.

Populations of three plant species of special concern are also found in the alluvial gravels that cap the mountain: Astragalus detritalis (debris milkvetch), Cryptantha caespitosa (tufted catseye), and Sphaeromeria capitata (rock tansy). The site provides a panoramic vista of much of northwestern Colorado, as well as of the colorful badlands formed of Green River and Wasatch shales at Vermillion Bluffs.

Lower Greasewood CreekRio Blanco200 acres1998
Bureau of Land ManagementLower Greasewood Creek

Lower Greaswood Creek Natural Area includes a relatively undisturbed example of piñon-juniper woodland. The area also supports significant populations of the Uinta gilia (Gilia stenothyrsa), which is endemic to the soils formed from the Green River and Uinta formations. Endemic species are those which are restricted to a particular area or narrow habitat type. Shale formations such as the Green River often support plant species which are uniquely adapted to the particular chemistry of the shale derived soils.

McElmoMontezuma County443 acres1986
Bureau of Land ManagementMcElmo

It’s about as far as you can get from Denver and still be in Colorado - about 8 ½ hours of driving and a high clearance vehicle will get you there. Needless to say, it is one of Colorado’s least-visited Natural Areas, but its isolation is a great part of its value. McElmo’s inhabitants thrive on being left alone.

Located on the Utah-Colorado border about 25 miles west of Cortez, the 433-acre McElmo Natural Area occupies Bridge Canyon, a tributary of McElmo Canyon. The setting is typical of the region - a broad, dry, rocky canyon with sparse pinyon-juniper and salt-desert shrub vegetation. Two things set this area apart from its surroundings: the reptiles and the Bridge.

Bridge and McElmo canyons have long been recognized as hotspots of animal biodiversity in Colorado. According to a 1977 report by Bruce Bury and later work by Geoff Hammerson, the McElmo Natural Area and its immediate surroundings contain 13 species of snakes, lizards and amphibians, with at least another six species possible. This makes it one of the richest areas in the state for these animals. This fact alone would make the site significant. An added bonus is that several of the species are rare in Colorado, including the common kingsnake (Lampropeltis getula), the desert spiny lizard (Sceloporus magister) and the long-nosed leopard lizard (Gambelia wislizenii).

The common kingsnake is widespread through the U.S. In Colorado it is known only from the Four Corners area and parts of the lower Arkansas River drainage. The snake's skin has white bands or stripes on a black body. Adults are usually two feet long. The kingsnake is an aggressive predator, preying on rodents, birds, eggs and other reptiles, including lizards, rattlesnakes and bull snakes.

The desert spiny lizard is known in Colorado only from the Four Corners. Otherwise it occurs throughout northern Mexico and the southwestern U.S. This lizard prefers semi-arid shrublands or grassy plains near drainages. This diurnal lizard is very wary and will flee into hiding when threatened. It forages for insects, smaller lizards, and tender vegetation.

The long-nosed leopard lizard is also found throughout the western U.S. In Colorado, this large, distinctively patterned lizard is known only in the Four Corners and from the floor of the Grand Valley near Grand Junction. The long-nosed leopard lizard’s natural habitat has sparse plant cover that offers plenty of running room. When fleeing predators, this lizard tucks its front legs against its body and runs upright. According to Geoff Hammerson, this species’ habitat has probably been significantly restricted in Colorado. This is due to conversion of its preferred valley floor habitats to agriculture or to dense stands of cheatgrass, which interferes with the animal’s movement.

The Bridge is Bridge Canyon’s other, and more conspicuous, natural feature. The Morrison Formation is a series of alternating hard sandstone and softer shale rock layers, into which Bridge Canyon is cut. One especially hard layer of sandstone resisted erosion as the valley deepened, and was left exposed as a "bridge" spanning the valley floor. The center of the bridge has collapsed, as have its downstream edges.

McElmo was brought to the CNAP’s attention early on and was one of the first sites considered for designation. It was registered in 1979 and designated in 1986. The site was on the BLM’s radar as early as 1964 thanks to the efforts of members of Fort Lewis College’s biology department, who had been taking students there for decades. It was recognized as a significant biological area by the International Biological Programs in 1970 and was designated as the McElmo Rare Lizard and Snake Research Natural Area by the BLM in 1973.

McElmo, despite its isolation, is far from pristine. Heavy sheep grazing prior to the establishment of the natural area converted much of the understory in the salt desert and greasewood shrublands from native bunchgrasses and desert forbs to cheatgrass. The area was fenced to exclude unauthorized domestic livestock in 1986 and the vegetation has recovered somewhat. A complete restoration of the native vegetation would require a concentrated investment of resources, although techniques to replace cheatgrass with native bunch grasses continue to advance. Without question, restoration of native vegetation on the floor of the canyon would improve the habitat for the many lizards and snakes of the McElmo Natural Area.

Reptiles and amphibians known to occur within the McElmo Natural Area:
Tiger salamander
New Mexico spadefoot toad
Red-spotted toad
Woodhouse’s toad
Collared lizard
Long-nosed leopard lizard
Side-blotched lizard
Desert spiny lizard
Northern plateau lizard
Tree lizard
Western whiptail
Western rattlesnake

Reptiles known to occur near the Natural Area and likely to occur there:
Lesser earless lizard
Sagebrush lizard
Plateau striped whiptail
Short-horned lizard
Common kingsnake
Striped whipsnake

Mexican CutGunnison County420 acres1978The Nature ConservancyRocky Mountain Biological LaboratoryMexican Cut

The first natural area to be designated in Colorado, Mexican Cut is a spectacular glacially carved hanging valley located high in the Elk Mountains. Alternating layers of limestone and quartzite which have been folded 90° from horizontal and worn differentially by glacial action form a series of shelves, each holding several ponds. This pond complex is the most important component of the Mexican Cut ecosystem. The numerous interconnected glacial lakes (tarns) are fed by snowmelt and rainfall. Although the ponds appear to be subject to similar climatic processes, they often contain distinctly different flora and fauna. The reproductive biology of populations of the tiger salamander (Ambystoma tigrinum) varies from pond to pond. Individuals in some populations reproduce while still in a larval form; others reproduce as adults.

Access to this site is strictly controlled, due to the fragility of the ecosystem. The area is a study site for scientists from the Rocky Mountain Biological Laboratory. In addition to numerous studies of salamander biology and behavior, other investigations have focused on a variety of aquatic insects and zooplankton, as well as the impact of atmospheric deposition, particularly acid rain.

Mini-Wheeler (Stirrup Ranch)Fremont County449 acres2001State Land Board
Mini-Wheeler (Stirrup Ranch)

The unusual "Devil's Dunce Cap" formations are the eroded remnants of a 1200-square-mile volcanic ash flow. This Gribbles Park Tuff was deposited 29 million years ago during the Oligocene. Although located within the Thirtynine Mountain Volcanic Field, the tuff's source is thought to be outside of the field to the west. The exact source is unknown, and research on this may be useful in determining the timing of the opening of the upper Arkansas valley. The more well-known Wheeler Geologic site in Mineral County has higher formations (and is from a different volcanic source), but this site covers a larger area than Wheeler.

MiramonteSan Miguel County2,529 acres2012Colorado Parks & Wildlife

Miramonte Natural Area is located within the Dan Noble State Wildlife Area at Miramonte Reservoir in San Miguel County. The area is renowned for its excellent recreational opportunities and remarkably biologically diverse habitats. The area includes several exposures of Mancos shale around the edges of the reservoir, as well as sage upland habitat and a series of seeps that occur on the western edge of the property. Physaria pulvinata is found on several of the Mancos shale exposures and Puccinellia parrishii is associated with the seeps that occur on the property. Given that this population of Physaria pulvinata is one of only three currently known in the world, it is of essential importance for the preservation of this new species, only just discovered in 2006. Miramonte also contains some of the best habitat for Gunnison sage grouse outside of the Gunnison Basin, and is a known lekking site. This state candidate species is an indicator of both healthy wetland and sagebrush communities.

Mishak LakesSaguache County2,040 acres1997The Nature Conservancy
Mishak Lakes

Mishak Lakes Natural Area is part of a series of natural playa lakes on the floor of the San Luis Valley in southern Colorado. To the casual traveler, the basin of the valley appears continuously flat. However, the northern end of the valley is in fact a closed basin; streams which descend to the floor of the valley in the northern end never reach the Rio Grande River, which drains the southern portion of the valley. As a result, the area contains numerous playas - broad flat desert basins which often contain ephemeral lakes. These lakes are seasonally filled by snowmelt runoff, but ordinarily dry up by summer’s end.

The shallow, seasonal wetlands support unusually high-quality plant communities which vary in composition according to the magnitude and duration of flooding. Extensive marshlands of spikerush (Eleocharis palustris) and three-square bulrush (Scirpus pungens) are found at lake margins. The area also supports populations of the rare slender spiderflower (Cleome multicaulis). Nearby flats and dunes support greasewood (Sarcobatus vermiculatus) and rabbitbrush (Chrysothamnus spp.) communities.

Most of the playa systems in the San Luis Valley have been greatly affected by water use patterns in the valley, as has the Mishak Lakes complex. The site is currently managed for conservation, and is not open for public access at this time.

Mount CallahanGarfield County762 acres1987, updated 2008, 2015Private
Mount Callahan

The Mount Callahan, Mount Callahan Saddle, and Logan Wash Mine Natural Areas contains high quality remnants of Great Basin grasslands and barren communities and supports populations of rare plant species including Roan Cliffs blazing star (Mentzelia rhizomata) and sun-loving meadowrue (Thalictrum heliophilum). The property also provides excellent examples of a number of rare native plant communities. 

Owned by Occidental Petroleum Company (Oxy), this natural area is a great example of how a state agency and a private petroleum company can work cooperatively toward the protection and preservation of the Parachute penstemon. Oxy has engaged in voluntary efforts to protect this rare plant including buffer zones, weed control, motorized travel limits, and funding of annual population studies.

Mount Emmons Iron FenGunnison County75 acres1999
U.S. Forest ServiceMount Emmons Iron Fen

The Iron Fen is a wetland complex consisting of forested wetland, sedge fen, and a pond, all underlain by peat enriched with iron oxide (limonite). Although commonly referred to as a bog, the wetland is actually a fen. Bogs are wetlands which are disconnected from the water table and receive substantially all their moisture from rain and snow. Fens are fed primarily by ground water, and vary along a chemical gradient ranging from "rich" (enriched by mineral ions) to "poor" (poor in mineral ions). Rich fens usually have a high pH, poor fens a low pH. Mount Emmons and a very few other iron fens in the southern Rocky Mountains are the exception – they are rich in mineral ions (especially iron and sulfur) but have a very low pH. The wetland and its unusual ecology are the primary feature of the Natural Area.

The unusual chemistry results in an unusual flora, similar to that of nutrient-poor "true bogs". Sphagnum mosses and small orchids are common throughout forested and open parts of the Mount Emmons wetland, and the margins of the pond support one of only four populations of the roundleaf sundew (Drosera rotundifolia) known from Colorado. Two unusual species of dragonfly (Leucorhinea hudsonica and Sematochlora semicircularis) frequent the wetland.

Mount GoliathClear Creek County160 acres1980
U.S. Forest ServiceMount Goliath

Large virgin stands of bristlecone pine (Pinus aristata) intersperse with Engelmann spruce forest and alpine grassland on this 160-acre natural area located at timberline on the flank of Mount Evans. The gnarled and twisted pines on windswept granite ridges represent the northernmost occurrence of bristlecone in Colorado. One of the oldest known bristlecone pines in Colorado (more than 1,500 years old) is found here.

NarraguinnepDolores County1,928 acres1980
U.S. Forest ServiceNarraguinnep

This natural area encompasses Narraguinnep Canyon. Cliffs of Dakota, McElmo, and La Plata sandstones frame this scenic canyon. Uncut forests of ponderosa pine, pinyon pine and Utah juniper dominate the area and are interspersed with oak thickets and a rich diversity of other shrublands.

Needle RockDelta County80 acres1992
Bureau of Land ManagementNeedle Rock

Needle Rock towers 800 feet above the floor of the Smith Fork of the Gunnison River valley. It originated as the throat of a large volcano about 28 million years ago (Miocene epoch) when molten rock intruded between existing sedimentary formations. As the surrounding country rocks eroded over millions of years, the resistant igneous core was exposed.

North ParkJackson County310 acres1986
Bureau of Land ManagementNorth Park

The North Park RNA contains a large portion of the endangered Phacelia formosula (North Park phacelia). This rare plant species is restricted to sandstone bluffs of the Coalmont Formation; its only known occurrences are in Jackson County. The designation of this site as a Colorado Natural Area helps to protect this rare species and its habitat, and facilitates research and monitoring efforts.

Orient MineSaguache County329 acres2004Private
Orient Mine

Orient Mine Natural Area contains an abandoned iron mine that is now is a summer roosting site for 250,000-300,000 Brazilian free-tailed bats; the largest population in Colorado. It is the largest all-male “bachelor” colony in the United States. Also on the site is an excellent occurrence of xeric Western Slope pinyon-juniper woodland/needle-and-thread grass plant community. The site is owned and managed by the Orient Land Trust, an organization dedicated to the preservation of the northern San Luis Valley’s natural heritage and biological resources.

Owl CanyonLarimer county658 acres1978, 1979, and 1985Private; Colorado Parks & Wildlife; State Land Board
Owl Canyon

Owl Canyon supports a disjunct, dense population of Pinyon pine (Pinus edulis) which is at the northeastern extremity of its range in North America. The closest other pinyon pine community is about 100 miles distant. Individual trees in the grove are from 200 to 500 years old. The area serves as a study site for the biology of pinyon and its associated biotic community. It also contains populations of other plant species of special interest such as the uncommon dry-site fern, Pellaea atropurpurea (purple cliff-brake).

Paradise ParkGrand County6,032 acres1983
National Park ServiceParadise Park

Paradise Park Natural Area includes 6800 acres of the upper Paradise Creek Basin. Numerous alpine and subalpine lakes fill glacially carved depressions along the creek. Pure populations of the rare Colorado River cutthroat trout inhabit the creek. Virgin forests of Engelmann spruce-subalpine fir blanket lower elevations, while scenic alpine meadows occur above treeline. This site is adjacent to the Hell Canyon Research Natural Area on the Arapaho-Roosevelt National Forest.

Park Creek HogbackLarimer County279 acres2002State Land Board
Park Creek Hogback

This property contains one of the largest populations of the rare Bell’s twinpod (Physaria bellii) in Colorado. An important foothills shrubland community, Cercocarpus montanus/Stipa neomexicana, is also present.

Pyramid RockMesa County515 acres1987
Bureau of Land ManagementPyramid Rock

Pyramid Rock is a local landmark formed of colorful clays and sandstones of the Wasatch Formation. This area supports large populations of three rare plant species: including Phacelia submutica (Debeque phacelia), and Astragalus debequaeus (Debeque milkvetch). 

Rabbit ValleyMesa County280 acres 1987
Bureau of Land ManagementRabbit Valley

Rabbit Valley is located north of the Colorado River along the northwest flank of the Uncompahgre Uplift. The quarry has produced large specimens of several dinosaurs including Camarasaurus, Allosaurus, and Camptosaurus. The Bureau of Land Management and the Museum of Western Colorado have developed the site for interpretive use, and the Museum of Western Colorado directs ongoing fossil digs. The recent discovery of an Iguanodon skull marks the earliest known record of this species. High quality pinion pine - Utah juniper woodlands occur on the site north of the fossil locality.

Please be aware that this site contains features of state-wide significance. Collection is prohibited at all times with out proper permits.

Rajadero CanyonConejos County4,305 acres1996State Land Board; Bureau of Land Management
Rajadero Canyon

This area in the eastern ridges and canyons of the San Juan Mountains protects part of the largest known Colorado population of a rare plant species, the Ripley milkvetch (Astragalus ripleyi). The name "Rajadero" possibly derives from the Spanish "rajador" – wood splitter, or "rajadura" – cleft, fissue, or crack.

Ripley milkvetch is a member of the pea family (Fabaceae), and has characteristic pod-like fruits. The plants grow up to four feet tall, with numerous stems that are a distinctive reddish purple at the base. It blooms from late June through late July, with pale yellow flowers that hang down from the stem. The global range of this species is less than 600 square miles between Terrace Reservoir, Colorado and Tres Piedras, New Mexico. Within that range, the plant is restricted to a narrow belt of volcanic soils less than ten miles wide.

Ripley milkvetch was at one time considered a potential candidate for listing under the federal Endangered Species Act, because where we find it now suggests that it may have been eliminated from much of its historic range. Ripley milkvetch populations are maintained by a delicate balance of natural processes, including fire, deer, and harvester ants. Most of the Ripley milkvetch’s preferred habitat of bunchgrass grassland with scattered shrubs, ponderosa pine, fir and aspen trees has been altered through a combination of historic heavy grazing (conversion to grass-poor shrubland), fire suppression (conversion to dense forest), and exotic species introduction (roadside plantings of smooth brome and yellow sweet clover which have spread).

This Natural Area provides high quality habitat for Ripley milkvetch, and is an outstanding example of relict montane grassland and ponderosa pine savanna plant communities in its own right.

Raven RidgeRio Blanco County4,980 acres1986
Bureau of Land ManagementRaven Ridge

Raven Ridge is an exposure of the Evacuation Creek member of the Green River Formation. The site provides habitat for eight endemic plant species including two which were recently petitioned for listing under the Endangered Species Act, and Astragalus lutosus (Dragon milkvetch), Cryptantha rollinsii (Rollin's catseye), Parthenium ligulata (Colorado feverfew), Eriogonum ephedroides (ephedra buckwheat), and Phacelia incana (hoary phacelia). Raven Ridge is unique in Colorado for its diverse rare plant assemblage. In addition, the shales contain one of the richest North American assemblages of insect fossils from the Eocene Period (approximately 37-57 million years before the present).

Please be aware that this site contains features of state-wide significance. Collection is prohibited at all times with out proper permits.

Redcloud PeakHinsdale County5,947 acres1993
Bureau of Land ManagementRedcloud Peak

The Redcloud Peak Natural Area is a largely alpine site which includes extensive hiqh-quality wetlands dominated by snow willow (Salix nivalis).

This extensive area provides habitat for an endangered butterfly.

Rough CanyonMesa County2,695 acres1989
Bureau of Land ManagementRough Canyon

Rough Canyon cuts across the flank of a large faulted monocline, and the structural complexity exposed in the canyon provides clues to the history of the Uncompahgre Uplift. The canyon also supports populations of the rare plants Astragalus linifolius (Grand Junction milkvetch) and Lomatium eastwoodiae (Eastwood's desertparsley). Pools sheltered under the vertical canyon walls contain populations of the canyon tree frog (Hyla arenicolor).

RoxboroughDouglas County967 acres1979Colorado Parks & Wildlife; State Land Board

Massive erosional remnants of Fountain Formation sandstone dominate the landscape of Roxborough State Park. The park encompasses a geologic span of 500 million years in an east-west distance of less than a mile. Exposed geology dates from Precambrian to Late Mesozoic, including hogbacks of Cretaceous, Permian and Pennsylvanian age. The vegetation of Roxborough is representative of the foothills region. Ponderosa pine and Douglas fir dominate higher elevation forests, and oak thickets cloak the lower elevations. Mixed grass prairie is characteristic of the areas between hogbacks where landslide debris has accumulated.

Saddle MountainPark County1,120 acres1980, 2002State Land Board; U.S. Forest Service
Saddle Mountain

Saddle Mountain Natural Area supports a variety of pristine plant communities. Included in the natural area are dense stands of Engelmann spruce and subalpine fir, aspen, and bristlecone pine. Extensive meadows of Danthonia parryi (Parry oatgrass) occur on shallower soils derived from basalt.

Sand CreekLarimer County259 acres2002State Land Board
Sand Creek

Sand Creek Natural Area contains unique geologic formations with a montane riparian willow thicket community in good condition. The area also includes pillars and monuments of Paleozoic (Fountain Formation) cross-bedded sandstone (dune origin) and "topple blocks". There is a clear exposure of an unconformity between the top of the Sherman granite (1.7 byo) and the bottom of the Fountain Fm (270 myo). Sandhill cranes use the area for nesting. 

San Miguel River at TabeguacheMontrose County259 acres1997The Nature ConservancySan Miguel River at Tabeguache

The site encompasses a highly scenic free-flowing portion of the San Miguel River, one of the few remaining naturally functioning rivers in the West. Sand bars along the San Miguel River support high-quality Rio Grande cottonwood/coyote willow and Rio Grande cottonwood/skunkbrush plant communities. TNC has completed extensive removal of non-native tamarisk and Russian olive. Click here​ to visit The Nature Conservancy's webpage about the preserve.

Shell Duck CreekRio Blanco County504 acres2009PrivateShell Duck Creek

The areas in and around Duck Creek and Shell Duck Creek house the largest and best populations of Dudley Bluffs bladderpod (Physaria congesta) in the world. This species is listed as federally threatened under the Endangered Species Act. The Duc​​k Creek area primarily contains these unique biological resources due to the fact that the dip of the rock layers is the same as the grade of the stream, resulting in exposures of the Thirteen Mile Tongue of the Green River Formation that extend for miles along either side of the valley. Owned by Shell Frontier Oil and Gas, this natural area is a great example of how a state agency and a private petroleum company can work cooperatively toward the protection and preservation of Colorado's natural heritage.

Shell RockBaca County640 acres2002State Land Board
Shell Rock

Shell Rock Natural Area contains one of the largest known Colorado populations of Frasera coloradensis (Colorado green gentian). This site also contains a wonderful example of shortgrass prairie in good condition. The area is part of the Greenhorn Limestone Outcrops cluster of conservation sites identified in 1998 by The Nature Conservancy in "Ecoregion-Based Conservation in the Central Shortgrass Prairie." These sites were delineated based primarily on rare plant occurrences.

Slumgullion EarthflowHinsdale County1,291 acres1983Bureau of Land Management; U.S. Forest ServiceSlumgullion Earthflow

Two major earthflows included in this natural area illustrate a striking example of mass wasting (the movement of large masses of earth material). Slumgullion earthflow is over four miles long and 2000 feet wide. A huge mass of volcanic rock slumped down the valley about 700 years ago, damming Lake San Cristobal. This flow is gradually being covered by a younger flow which began 300 years ago. Trees on the earthflow are being pushed over by the forward advance of the younger flow.

South Beaver CreekGunnison County4,000 acres1997
Bureau of Land ManagementSouth Beaver Creek

This site contains a significant population of skiff milkvetch (Astragalus microcymbus), a candidate for formal listing under the Endangered Species Act. This occurrence of skiff milkvetch contains the majority of all known individuals in the world; this species is only known to occur in Gunnison County, CO.

South Boulder CreekBoulder County1,193 acres2000City of Boulder, Open Space & Mountain Parks
South Boulder Creek

South Boulder Creek Natural Area features a mosaic of high quality wetlands, wet meadows and mesic grasslands, including plains riparian forests and tallgrass prairie ecosystems.

A remnant of the plains cottonwood riparian ecosystem occurs in good condition along South Boulder Creek. This riparian community provides essential wildlife habitat and contributes to the biological diversity of floodplains along the Colorado's western plains.

In combination with riparian and grassland communities, wetlands found along South Boulder Creek are considered to be among the best preserved and most ecologically significant in the Boulder Valley.

The floodplain in the area includes habitat for three species of concern: a rare plant, Preble's meadow jumping mouse (Zapus hudsonius preblei); and Bobolink (Dolichonix oryzivorous), a locally rare bird on the edge of its range. In addition, the area serves as a research site for on-going floristic and wildlife investigations.

South Cathedral BluffsRio Blanco County1,330 acres1988
Bureau of Land ManagementSouth Cathedral Bluffs

Spectacular Green River shale bluffs in this natural area provide habitat for three rare plant species: Thalictrum heliophilum (sun-loving meadowrue), Physaria parviflora (Picence bladderpod), and Gentianella tortuosa (Utah gentian). The site is the type locality or area considered to be characteristic for Physaria parviflora. The 2000-foot high bluffs provide a wide view to the south, east and north.

Specimen MountainGrand & Larimer Counties9,056 acres1983National Park ServiceSpecimen Mountain

Specimen Mountain Research Natural Area straddles the Continental Divide in Rocky Mountain National Park and includes Specimen and Shipler Mountains. This natural area is capped with volcanic material from a nearby volcano that erupted approximately 28 million years ago and now supports virgin stands of Engelmann spruce-subalpine fir and pristine alpine meadows. The area is important calving grounds for Rocky Mountain bighorn sheep. Natural salt licks in the "crater" attract elk, deer, and bighorn sheep.

Tamarack RanchLogan County470 acres1986Colorado Parks & Wildlife
Tamarack Ranch

This natural area includes examples of plains cottonwood riparian forest and sandhills prairie. The cottonwood riparian site encompasses a portion of the broad, meandering South Platte River, providing habitat for migrating waterfowl and eastern species near the edge of their range that have migrated to Colorado from the east along river corridors, such as the opossum, white-tailed deer and red-headed woodpecker. The sandhills community provides critical habitat for the greater prairie chicken.

Treasurevault MountainLake & Park Counties320 acres2002State Land Board
Treasurevault Mountain

Treasurevault Mountain is part of the Mosquito Pass area, which supports a unique flora, including the federally threatened Penland alpine fen mustard (Eutrema penlandii), and a number of state-rare plants: Braya glabella, Braya humilis, Saussurea weberi & Papaver kluanense. The site also supports alpine communities typical of the Mosquito and Sawatch ranges.

Trinidad K-TLas Animas County180 acres2004Colorado Parks & Wildlife
Trinidad K-T

The Trinidad K-T Boundary Natural Area contains significant evidence of an asteroid impact that caused mass extinction of dinosaurs and other life forms at the end of the Cretaceous Period 65 million years ago. It contains the best surface exposure of Cretaceous-Paleogene (K-Pg) (formerly known as the Cretaceous-Tertiary (K-T)) boundary in Colorado and possibly the world.

Unaweep SeepMesa County36 acres1983
Bureau of Land ManagementUnaweep Seep

Unaweep Seep Research Natural Area is an unusual hillside spring ecosystem of wet sedge marshes and seeps. The springs are not affected by flooding or fluctuations in surface water flow. One of three Colorado populations of the rare butterfly Speyeria nokomis (Nokomis fritillary), occurs on Unaweep seep. Also, a large population of a rare wetland plant is found on the lower part of the slope.

Wacker RanchMontrose County43 acres2008Colorado Natural Areas Program/Colorado Parks & Wildlife
Wacker Ranch

Wacker Ranch Natural Area contains the federally-endangered Eriogonum pelinophilum (clay-loving wild buckwheat), which is known from only 16 populations globally and is ranked as globally and state imperiled by th​e Colorado Natural Heritage Program. The Wacker Ranch population of the clay-loving wild buckwheat is contiguous with the Fairview population on the Bureau of Land Management Area of Critical Environmental Concern. The Wacker Ranch and Fairview population is one of the largest and most viable populations of this globally imperiled plant in the world.

Wacker Ranch Natural Area is one of the few remaining undeveloped privately-owned Adobe Hills habitats found in western Colorado, and supports a relatively undisturbed black sage community. The exposure of Mancos shale that forms the substrate for the habitat is highly expansive bentonite clay that forms relatively unique ‘popcorn’ soil formations.

Wacker Ranch Natural Area contains a rich diversity of lichen and soil crust communities, including Aspicilia fruticulosa, which is a fruticose lichen ranked as critically imperiled in Colorado by the Colorado Natural Heritage Program.

West CreekLarimer County9,043 acres1983
National Park ServiceWest Creek

West Creek Natural Area includes part of West Creek and Fox Creek in the Big Thompson River Basin. These creeks support high-quality examples of montane and lower subalpine riparian systems. The plant communities occurring along the streams and their tributaries include elements of eastern deciduous forest communities found only in low-elevation Front Range riparian systems in Colorado. These species include balsam poplar (Populus balsamifera) and wild sarsaparilla (Aralia nudicaulis). Logdepole and limber pine forests cover much of the site. The area also provides habitat for elk and bighorn sheep, as well as populations of the threatened greenback cutthroat trout (Onorhychus clarki stomias).

Wheeler GeologicMineral County640 acres1983
U.S. Forest ServiceWheeler Geologic

Wheeler Geologic Natural Area is a mass of pinnacles and domes, some more than several hundred feet high. Erosive forces have sculpted these forms in white, beige and lavender layers of lava and ash. The geologic features occur within virgin forests of Engelmann spruce, which has been heavily impacted by the spruce beetle epidemic, and subalpine fir.

White RocksBoulder County105 acres1979CIty of Boulder, Open Space and Mountain Parks
White Rocks

The White Rocks Natural Area takes its name from the outcroppings of light-colored Fox Hills sandstone exposed by the undercutting action of Boulder Creek. About 65 million years ago, as the Rocky Mountains were being uplifted, a large inland sea covered the central portion of what is now the United States. Large sediment-rich rivers emptied into this sea, creating deltas. The striking and beautiful sandstone cliffs at the Natural Area are a portion of one of these ancient deltas. The surface of the sandstone displays interesting patterns referred to as turtlebacks. Researchers relate these patterns to fractures caused by the regular wetting and drying of the rocks.

Fairy shrimp dwell in pools that form when rainwater accumulates in the shallow depressions among the turtlebacks. These crustaceans are uncommon in Colorado. They complete their life cycle in a few short weeks, laying drought-resistant, encysted eggs which dry into the dirt at the bottom of the pools. The eggs hatch the following spring when temperature and moisture conditions are right. Several other interesting invertebrates occur at White Rocks, include the mining bee (Perdita opuntiae), which feeds upon the pollen of prickly pear cactus (Opuntia spp.) and builds its nests in holes which it excavates in the sandstone. One early naturalist described this insect as "the bee who works in stone". In addition, the area is home to several rare ant species, including one (Aphaenogaster fulva) that is rarely found west of the Mississippi River.

White Rocks is also home to the only known population of the Black Spleenwort fern (Asplenium adiantum-nigurm) in Colorado. Although quite rare in North America, this plant is also known from Hawaii, Europe, Asia and Africa! One explanation for this wide distribution is that the fern’s microscopic spores may be carried high into the atmosphere where the jet stream distributes them around the world. Several eastern deciduous forest relicts can be found in a moist alcove below the black spleenwort, including American groundnut (Apios americana) and Joe Pye weed (Eupatorium maculatum). The rare grass, fork-tipped three awn (Aristida basiramea) also grows in cracks on top of the cliffs. This species is known from a very few sites in Colorado.

While the cliffs themselves have many interesting features, the context of this Natural Area is also important. The cliffs are situated along Boulder Creek near many acres of riparian forest and gravel pits which have been reclaimed specifically for wildlife value. A​ccess to this area is allowed only on guided tours, offered by the City of Boulder, Open Space and Mountain Parks. The variety of habitats coupled with very low levels of human activity has produced a place with an abundance and diversity of life.

Yanks Gulch/Upper Greasewood CreekRio Blanco County2,687 acres1988
Bureau of Land ManagementYanks Gulch/Upper Greasewood Creek

The Yank's Gulch/Upper Greasewood Creek Natural Area supports high-quality examples of three types of Great Basin plant communities: Mesic pinion-juniper woodland, mesic sagebrush shrubland, and western slope grasslands. Significant populations of rare plant species endemic to Green River shale are also found on the site: Physaria obcordata (listed Threatened), and Astragalus lutosus.

Zapata FallsAlamosa County619 acres2002State Land Board
Zapata Falls

Zapata Falls is located south of Great Sand Dunes National Monument. The falls themselves are an impressive geologic feature, where snowmelt from the peaks of the Sangre de Cristo Range has carved a dramatic narrow gorge. The area offers breathtaking vistas of the San Luis Valley and the Great Sand Dunes.

The falls area is one of a few known Colorado breeding sites for the rare and elusive black swift, a bird that nests exclusively in the dark recesses and spray of large waterfalls. The area also contains good to excellent quality grassland, woodland, shrubland, and forest communities.

Blacks GulchRio Blanco County800 acres2009Bureau of Land ManagementBlacks Gulch

Blacks Gulch opens into the valley of the White River at Rio Blanco Lake west of Meeker, and the site is three miles up the gulch. Blacks Gulch is the best fossil vertebrate locality of Lysite (middle early Eocene) age in Colorado. Twenty-four known paletonological specimens have been identified at Blacks Gulch. Erosion of the clays from the Wasatch Formation constantly produces new specimens of scientific merit.

The primary vegetation of the area is big sagebrush in the northwest lowlands habitat type, which was identified as a gap in protected area coverage through CNAP's Natural Areas System Review.  In addition, the area encompasses potentially suitable habitat for up to 33 animal species identified as imperiled by CNAP's Natural Areas System Review. ​

Please be aware that this site contains features of state-wide significance. Collection is prohibited at all times without proper permits. 

Duck CreekRio Blanco County3,420 acres2009Bureau of Land ManagementDuck Creek

Duck Creek is the prime location of one of the rarest plants in Colorado, the Dudley Bluffs bladderpod (Physaria congesta). This property contains two outstanding, A-ranked occurrences of this rare species that has been federally threatened under the Endangered Species Act since 1996. The large area covered by the population is due to the fact that the dip of the rock layers is the same as the grade of the stream, resulting in exposures of the Thirteen Mile Tongue of the Green River Formation that extend for miles along either side of the valley. This geologic exposure also supports an endemic thistle, Cirsium barnebyi.  Because of the occurrence of these two rare species, Duck Creek is included in the ‘Dudley Bluffs Potential Conservation Area’, a Potential Conservation Area of Outstanding Biodiversity Significance (B1), as ranked by the Colorado Natural Heritage Program.

Additionally, Duck Creek contains an example of Sagebrush Bottomland Shrublands (Artemisia tridentata ssp. tridentata/Leymus cinereus Shrubland) that is in good condition. This community type is rare in Colorado and its protection is important for the natural heritage of the state.  ​

Ryan GulchRio Blanco County1,440 acres2009Bureau of Land ManagementRyan Gulch

Ryan Gulch has a high concentration of some of the rarest and most imperiled plants in Colorado.  There are three occurrences of Physaria obcordata (Piceance Twinpod), which is federally threatened under the Endangered Species Act, and one population of Physaria (Lesquerella) congesta (Dudley Bluffs bladderpod), which is also federally threatened.  All four of these occurrences are ranked as being in good to excellent condition. A population a rare, endemic thistle, Cirsium barnebyi (Barneby’s thistle), is also found in the area.  Because of the occurrence of these three rare species, Ryan Gulch is included in the ‘Dudley Bluffs Potential Conservation Area’, a Potential Conservation Area of Outstanding Biodivirsity Significance (B1), as ranked by the Colorado Natural Heritage Program.

Most of the area is Wasatch Formation sandstones and shales and has better vegetative cover than the bands of the Green River Formation. The vegetation is a mixture of open pinyon-juniper woodland and sagebrush shrubland.

Two ButtesBaca & Prowers Counties2,960 acres2009
Two Buttes
The Two Buttes represent the top of an arching dome of sedimentary rocks uplifted by an unexposed laccolith approximately 10 miles across. The site was recommended for National Natural Landmark status for this feature alone. Hybridization between the southern plains woodrat (Neotoma micropus) and the white-throated woodrat (N. albigula) has been reported from Two Buttes. The Mexican woodrat (N. mexicana) also occurs there. The reservoir supports wintering bands of geese, including Canada, Ross', and Snow geese. A population of Colorado green gentian (Frasera coloradensis) was discovered on state lands south of the buttes in 1990.
East Lost ParkPark County6,200 acres2015
U.S. Forest Service
East Lost Park
The East Lost Park Natural Area hosts an excellent population of the globally and state imperiled Ptilagrostis porteri (Porter feathergrass), which is endemic to the South Park region of Colorado. Along with this highly rare and imperiled plant, at least three other rare plant species are found in East Lost Park: Eriophorum gracile (slender cottongrass), Carex livida (livid sedge), and Carex tenuiflora (slender-flower sedge​)​. The concentration of multiple rare grasses and sedges is in part due to the fact that East Lost Park supports an extensive high quality fen. This wetland is an uncommon feature throughout South Park and around Colorado that includes floating mats of peat. The wetland also supports a disjunct population of the star reindeer lichen (Cladina stellaris), ranked as critically imperiled in Colorado.
Staunton Park and Jefferson Counties656 Acres2015Colorado Parks & Wildlife; State Land BoardColorado Parks & WildlifeStaunton

The Staunton Natural Area encompasses two parcels within Staunton State Park: Black Mountain and Elk Falls Parcels. These parcels contain populations of the globally critically-imperiled budding monkeyflower (Mimulus gemmiparus), a plant endemic to Colorado and known from only eight locations, and James’ telesonix (Telesonix jamesii), a beautiful, globally imperiled, cliff-dwelling saxifrage with large pink flowers. 

This property also provides excellent examples of native plant communities, including a montane riparian woodland, and is home to Peregrine Falcon nesting sites. There are excellent scenic values including the Elk Falls, steep cliffs with Precambrian granite exposures, and vistas of mountains to the west and south.

Pagosa SkyrocketArchuleta County88 acres2017Colorado Parks & Wildlife

​This natural area is home to over half of the world's known population of the federally endangered Pagosa skyrocket (Ipomopsis polyantha). It also includes valuable wetland habitat and other tracked species.​

Corral BluffsEl Paso County589 acres2017City of Colorado Springs

​Corral Bluffs boasts world class paleontological resources and includes one of our state's finest fossil forests. Twelve fossil taxa from the Age of Mammals have been found here.