CPW continues fight against aquatic nuisance species in Colorado’s lakes and reservoirs
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This boat propeller is covered in invasive mussels. Zebra and quagga mussels attach themselves to objects like boats and docks as well as critical drinking water infrastructure such as pipes and pumps.
DENVER – Fewer boats requiring decontamination due to fouling by destructive species entered Colorado in 2022 compared to previous years with nearly 500,000 inspections performed. However, for the first time, Colorado Parks and Wildlife detected adult invasive zebra mussels at Highline Lake. The fight continues for the agency’s statewide inspection program this year as Aquatic Nuisance Species staff will work to keep invasive species from spreading in the state’s lakes and reservoirs.“The discovery at Highline Lake emphasizes the need for CPW to continue to strive to meet the challenge of protecting the state’s waters and infrastructure from aquatic nuisance species,” said Robert Walters, CPW’s ANS program manager. “And as boating season approaches we continue to ask for help from boat owners to combat invasive species in the state.”
Colorado’s ANS inspectors were busy during 2022. Staff conducted a total of 446,663 inspections and decontaminated 27,003 boats suspected of carrying mussels, other aquatic invasive species or standing water. Most concerning is the continued increase in the number of boats fouled with mussels.
In 2019, 86 boats were found to be fouled with invasive mussels. In 2020, that number jumped to 100. And in 2021 that skyrocketed to 181. In 2022, CPW found 148 boats entering the state with this highly destructive species in spite of a significant overall drop in boating at Lake Powell due to low water levels and lack of ramp access. Mussels are destructive to aquatic habitat, can seriously damage reservoir infrastructure and cause problems on boats.
Contaminated boats usually come into Colorado from neighboring states, especially Utah and Arizona because of our proximity to Lake Powell which has been mussel-infested for years. Other neighboring states with mussel infestations include Kansas, Nebraska, Oklahoma, Texas and South Dakota. Most Midwestern and East Coast states also have infested waters.
About the ANS Program
The Colorado ANS Program was authorized by the Colorado Legislature in 2008 utilizing severance tax funds and in 2018 the Colorado General Assembly provided funding to the program through SB17-259, funding the program through boating registration fees from residents and non-residents.
Since CPW’s ANS inspection program started in 2008, 6.5 million boats have been inspected and 199,465 boats have been decontaminated. The agency is aided in the program by Colorado counties, municipalities, water districts, federal agencies and private companies that also conduct inspections. CPW also works proactively looking for aquatic nuisance species by sampling waters throughout the state. In 2022, crews sampled 180 standing waters and fourteen flowing waters and the National Park Service provided 56 water samples; these intense sampling efforts resulted in the early detection at Highline and emphasize the importance of this program.
In 2021, Colorado Legislature passed House Bill 21-1226 which authorized Colorado Parks and Wildlife to implement a pilot roadside watercraft inspection and decontamination program. Year one of this pilot program was implemented in 2022 at the Loma Port of Entry. This effort was highly successful as 26 mussel fouled boats were intercepted over the course of three days. The pilot program will be expanded in 2023.
CPW has also been instrumental in establishing the Water Inspection and Decontamination (WID) protocols which are now used by states throughout the nation. Agency staff also are active with the Western Regional Panel on Aquatic Nuisance Species Watercraft Inspection and Decontamination Committee.
Walters said that CPW will always remain vigilant in the fight against mussels.
“Mussels aren’t going away. However, by continuing our preventative watercraft inspection program Colorado can continue to set an example in the West and keep our waters clear of highly destructive invasive species.”
Highline Lake
In September 2022, CPW’s Aquatic Nuisance Species Sampling & Monitoring team detected a single adult zebra mussel at the west boat ramp at Highline Lake. This was the first time an adult mussel had ever been found in a Colorado water body. In October, several more adult mussels were identified at the southeast corner of the dam, on the east boat ramp, and immediately below the reservoir. Additional sampling of the reservoir and surrounding areas throughout the fall and early winter showed no evidence of zebra mussels upstream of Highline Lake.
After careful consideration, CPW devised a two-pronged approach which included a significant drawdown of the reservoir in an effort to expose the majority of the mussels to freezing and drying conditions overwinter, and at the conclusion of the drawdown, the application of EarthTec QZ, an EPA-registered molluscicide, to the remaining water. CPW started the drawdown process in November and molluscicide application began on March 1.
The ANS Program will continue to monitor the reservoir for any evidence of zebra mussels on a routine basis throughout the boating season. Even if nothing is found in 2023, Highline Lake will be considered “Infested” for the next five years. During this time, Highline Lake State Park staff will implement a containment watercraft inspection & decontamination program, which requires all watercraft leaving the reservoir to be decontaminated, to minimize the potential for this invasion to spread into additional waters.
What can boaters do to help prevent the spread of aquatic nuisance species?
Boat owners are reminded to “clean, drain and dry” boats after every use and utilize the green-seal program when entering and leaving a body of water. Boaters should also inspect their trailers and look in hard-to-reach spots on boats and engines for evidence of mussels. Anyone who has used a boat in waters outside of Colorado is obligated to tell boat inspectors. Boat owners can also call any state park or wildlife office if they have questions, concerns or would like information on scheduling an off-water inspection/decontamination.
All ballast boats, inboard and inboard/outboard engines must have a green seal in between launches or decontamination may take place prior to launching. Boaters are encouraged to inspect their own boat between every use and make sure it is clean, drained, and dry.
The State of Colorado requires boats to be professionally inspected if:
- a boat has been in any body of water that is positive, or suspect for ANS
- a boat has been in any body of water outside of Colorado
- a boat will be entering any water body where inspections are required
Boaters are required to stop for an inspection when both entering, and exiting most bodies of water in Colorado. Stricter inspection requirements exist when taking a vessel from one body of water to another. To encourage a speedy inspection process, boaters are encouraged to:
- Keep your green exit seal attached to your vessel and trailer. This seal tells inspectors what body of water the vessel was in last.
- Have your paper exit slip (blue or white) readily available. This slip tells inspectors details from your previous exit inspection that can speed up the process.
- Open/drain all compartment hatches like: live/bait wells, bilge areas, anchor compartments, equipment compartments and any other compartments that hold items that could have come into contact with water. Have the anchor and ropes out of their compartments for inspection.
- If you know the next body of water you are going to will require a decontamination procedure, request a decontamination during the exit inspection so you can get onto your next boating adventure more quickly.
Media Kit
The Google Drive Folder below contains several items that we hope will be helpful to you in preparing stories and educating the public about keeping harmful ANS invaders from outside of our state. 2023 ANS Media Kit The folder contains the following information:
- A variety of ANS photos and video including check stations, inspection and decontamination processes and invasive species
- 2023 ANS Fact Sheet
- ANS green seal program
- State of Colorado Aquatic Nuisance Species Management Plan
- Variety of public information materials provided to boaters
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Right: Inspection process requires thorough examination of every inch of a vessel
Colorado Parks and Wildlife (CPW) is an enterprise agency, relying primarily on license sales, state parks fees and registration fees to support its operations, including: 43 state parks and more than 350 wildlife areas covering approximately 900,000 acres, management of fishing and hunting, wildlife watching, camping, motorized and non-motorized trails, boating and outdoor education. CPW's work contributes approximately $6 billion in total economic impact annually throughout Colorado.