Colorado Parks and Wildlife begins the process to fill Highline Lake

Rachael Gonzales
Northwest Region Public Information Officer
970-773-8587 / [email protected]
Twitter: @CPW_NW Colorado Parks and Wildlife begins the process to fill Highline Lake

GRAND JUNCTION, Colo. — Colorado Parks and Wildlife (CPW) is happy to announce that the process to refill Highline Lake at Highline Lake State Park has begun. On Monday, March 31, staff at Highline Lake State Park, in collaboration with the Grand Valley Water Users Association, opened the headgate, allowing water to flow into Highline Lake.

In the coming weeks, Highline Lake will gradually fill using water from the Government Highline Canal. Although an official opening date has not been determined, Highline Lake is expected to open for all surface activities this year. 

“We are grateful for the support and understanding of our boating and angling community,” said Alan Martinez, Highline Lake State Park Manager. “It’s great to see water flowing into Highline Lake again, and we look forward to welcoming our water recreationists back for the 2025 boating season.” 

In anticipation of welcoming boats back to Highline and taking advantage of low lake levels, the boat ramp located on the west side of the park received much-needed repairs, including a new concrete pad. Upgrades to the Aquatic Nuisance Species (ANS) inspection and decontamination stations were also made in early 2025 in anticipation of a busy boating season.

Recreational boaters and anglers can expect similar boating protocols as they did in 2023 for the upcoming 2025 boating season.

What to expect for the 2025 boating season: 

• Boats launching​ at Highline Lake will be subject to inspection and decontamination protocols before launching. 

• All boats must be clean, drained and dry before launching at Highline Lake, or they will be decontaminated.

• Upon exiting the lake, all boats will be inspected and decontaminated, and boaters will be issued a green seal and a blue receipt​ indicating the boat was last used on a body of water with a known aquatic nuisance species. 

“We are continuing our efforts to fight the zebra mussel infestation at Highline Lake,” said Robert Walters, Invasive Species Program Manager.  “We remain hopeful that draining the lake has eradicated zebra mussels; however, Highline Lake will be considered infested until we have five consecutive years of negative results. During this time, boats leaving Highline Lake will require decontamination as part of our ongoing efforts to stop zebra mussels from spreading further within our state.”

Boaters are reminded that Wakeless Wednesdays will be in effect every Wednesday through Sept. 30 once the lake opens to boating for the season.

Those planning to visit Highline Lake State Park are encouraged to stay updated on the status of the lake by following the park's social media pages on Facebook and Instagram or by visiting the Highline Lake State Park section on our website.

Repairing the drain
In addition to the work completed on the boat ramp and the ANS inspection building, repairs were made to the outlet drain in preparation for filling the lake. To address the significant accumulation of silt that has built up over the past 60 years and to prevent clogging of the outlet — which could potentially lead to spillover into Mack Wash below the dam — dredging was conducted near the outlet and spillway on the south side of the park. Dredging also occurred in the inlet channel to help clear the sediment that had built up at the east boat ramp.

“This is the first time in over 60 years that there has been no water in Highline Lake, and the entire lake bed has been exposed. Over that time, large amounts of silt, sediment and debris have settled on the dam face and built up along the lake bed,” said Martinez. “It was important to prevent damage to the dam infrastructure as well as being able to do underwater inspections on the outlet structure in the future that we took advantage of the situation and removed the significant buildup near the outlet.”

Removing silt from these areas will help rebuild the warmwater fishery by promoting the growth of natural aquatic vegetation on the lake bed, creating a healthier habitat and overall lake ecosystem.

“Our goal is to rebuild a robust and diverse fishery that offers fishing opportunities for a variety of desirable warmwater fish as well as seasonal fishing opportunities for coldwater rainbow trout. Rebuilding this renowned fishery will take time, but we are committed to rebuilding this so that it is once again a destination fishery,” Martinez said. 

Creating habitat
In February,  a team of CPW aquatic biologists, Highline Lake staff, volunteers and local district wildlife managers installed new fish habitat in various locations on the lake bed. Using recycled Christmas trees and wreaths, the team constructed new fish structures in the northern part of the lake. These new structures, in addition to previous structures installed over the last 60 years, will provide suitable habitat for shelter and food, encouraging fish recruitment while the naturally occurring aquatic plant life regenerates.

​Following the return of normal water levels, CPW will begin restocking Highline Lake. Initially, catchable trout will be harvestable for anglers. 

CPW will continue to monitor and sample Highline Lake weekly for the presence of zebra mussels. This will involve shoreline, substrate and plankton tow sampling. It is important to understand that even if no evidence of zebra mussels is found in the first year, Highline Lake will be classified as "infested" for five years. If no zebra mussels or other aquatic nuisance species are detected during this time, the lake will revert to a negative prevention status.

Be a pain in the ANS: Clean, Drain and Dry your vessels and fishing gear
Everyone has a part to play in preventing the introduction and spread of invasive species in Colorado. Simple actions, like cleaning, draining and drying your motorized and hand-launched vessels — including paddleboards and kayaks — can significantly protect Colorado's waters. These steps are crucial in helping to prevent situations similar to the recent one at Highline Lake.

“Eradicating an invasive species once it is established can be difficult, which is why we focus so heavily on preventing their introduction,” said Maddie Baker, Invasive Species Specialist. “Preventing the spread of aquatic nuisance species starts with you. By taking the extra time to complete a few simple steps, you can help prevent zebra mussels, or any other invasive species, from spreading to other bodies of water throughout Colorado.”  

Anglers are also encouraged to keep their angling gear free of mud and plants between each and every use. By cleaning, draining and drying your angling gear, you can prevent unknowingly moving a species from one body of water to another, even within different stretches of the same river, causing a domino effect of invasion with irreversible ecological damage.

Learn more about how you can prevent the spread of aquatic nuisance species and tips to properly clean, drain and dry your boating and fishing gear by visiting our website. Tips for anglers and a map of CPW’s new gear and watercraft cleaning stations is available here.

Highline Lake Media Kit

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Background
On Sept. 14, 2022, a single adult zebra mussel was found on an artificial PVC substrate in the lake during routine invasive species sampling. Following this initial discovery, additional zebra mussels were located on docks and boats, leading to increased sampling efforts. As a result, CPW updated the status of Highline Lake from “Suspect” to “Infested.” This marked the first time a body of water in Colorado had been classified as infested with zebra mussels.

In November 2022, CPW began lowering the water level at Highline Lake in preparation for a two-phase strategy aimed at eradicating the zebra mussels while conserving the warm-water fishery. In March 2023, CPW applied three separate treatments of EarthTech QZ, an EPA-registered copper-based molluscicide, to the lake.

In October 2023, Highline Lake State Park and ANS Sampling crews discovered more adult zebra mussels during routine work to remove buoys from the water in preparation for winter. While efforts in early 2023 did not achieve the ultimate goal of eradicating zebra mussels, CPW believes it helped to keep population numbers at a manageable level, given that a single female zebra mussel can produce more than 30,000 eggs per reproductive cycle. CPW conducted an additional round of molluscicide applications in November of 2023 and doubled the molluscicide concentration (compared to the spring treatment) to further suppress zebra mussels.

In early 2024, after the additional discovery of adult zebra mussels in 2023, CPW lowered Highline Lake as part of a more aggressive approach to eradicating zebra mussels and ultimately emptied the lake. With the lower water levels, CPW closed Highline Lake to all motorized boating for the 2024 boating season for the first time since 1967. On Monday, Nov. 18, 2024, CPW completed the draining of Highline Lake, marking the first time in 60 years that the lake has been fully emptied.