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Listen to the boating meeting on April 2

Standley Lake Boating Taskforce (SLBT) 

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Trailered boats will not be permitted on Standley Lake beginning this summer due to increasing concerns of zebra and quagga mussel infestation. Although the invasive species have not been detected in Westminster’s drinking water supply, a recent review of the policies and methods used to prevent an infestation found decontamination is not fully effective for many trailered boats. Boat launch data for 2018 also found multiple instances of Standley Lake boaters deliberately bypassing protective measures.

All 2019 permits that have been issued for trailered boats have been canceled and no additional permits will be sold. Individuals who already purchased a 2019 permit are being notified and will receive a full refund. Permits can still be purchased for non-trailered watercraft such as kayaks, canoes, rafts and paddleboards. Those types of watercraft will still have to go through the city’s on-site decontamination procedure.


Zebra and quagga mussels, non-native aquatic species with a potential for significant damage, present a growing threat to Colorado water resources. Once established in a body of water they decimate local ecosystems, clog potable water infrastructure and cause algae blooms that threaten water quality.

“Standley Lake is the drinking water supply for roughly 300,000 people in Westminster, Northglenn and Thornton,” said Max Kirschbaum, Public Works and Utilities Department director. “Water comes directly from the lake into our treatment system. If these mussels establish themselves in the lake, there would be significant, on-going costs to keep our system running. Protecting our community’s water supply will always be the chief concern.”

Westminster has shared its decision with the cities of Thornton and Northglenn, along with the Colorado Department of Natural Resources. Public Works officials with those cities have indicated support for the decision. Westminster City Council has been advised of this policy decision by city staff. 


Standley Lake was the first body of water in Colorado to implement a zebra and quagga mussel protection plan. Since 2007, Westminster has utilized a system of decontamination for all watercraft, plus a quarantine program for all trailered boats.

Decontamination involves spraying all surfaces of a vessel and conducting a visual inspection to ensure zebra and quagga mussels are not present. This process will continue for non-trailered watercraft and is proven to be effective. However, there are portions of trailers and powerboats that cannot be effectively sprayed and cleaned. Most notably, ballast tanks within the hulls of powerboats cannot be sprayed, entirely drained, or visually inspected.

These boats have therefore been subject to quarantine. Quarantine periods have been extended at Standley Lake through the years as more research on the survivability of zebra and quagga mussels became available. Most recently, a 2013 study found zebra and quagga mussels could potentially survive in ballast tanks for up to 27 days. Westminster extended its quarantine to 35 days in 2013.

Unfortunately, a review of boat launch data during the 2018 season found as many as 24 boats circumvented the quarantine process. Boat owners launched the boat on other lakes, in some cases multiple times, and then launched on Standley Lake only days later. Trespassing notices are being issued to several owners.


“The Standley Lake boating community has largely been a terrific partner in helping protect these waters,” said Jason Genck, director of Westminster Parks, Recreation and Libraries – the department that manages Standley Lake recreation facilities and permits. “Until we can determine if there’s a way to ensure these types of boats won’t pose a substantial risk at the lake, we need to put these activities on hold immediately and indefinitely.”

Westminster will continue to conduct testing for zebra and quagga mussels at Standley Lake through its ongoing water quality monitoring program.

View the information item that has been sent to City Council

The decision to immediately and indefinitely cancel permits for trailered boats and restrict this type of recreation on the lake indefinitely is due to increased concerns about infestation from zebra and quagga mussels (ZQM). These invasive species   are spreading to bodies of water throughout the United States. The mussels often spread by attaching to boats or trailers. Trailered boats pose a specific concern as decontamination methods cannot be totally effective in preventing ZQM from spreading.

Many boats that are launched off a trailer are powerboats that are equipped with ballast tanks. Ballast tanks are located within the boat’s hull and fill with lakewater to keep the boat lower in the water as its speed increases. The tanks cannot be fully drained or visually inspected to confirm they’re clean. This provides an opportunity for ZQM to remain inside the tanks and enter new bodies of water. Additionally, many boat trailers allow water to enter their frames. The inside of the frames also cannot be sufficiently drained.

Preserving water quality at Standley Lake is staff’s highest priority as this is the drinking water supply for three cities and 300,000 people.  Zebra and quagga mussels are a viable threat to Standley Lake and staff needs to make sure that any ANS program is 100% effective. Multiple studies have shown that the largest threat to the transport of ZQM from one body of water to another is a trailered boat that has ballast tanks. Both trailers and ballast tanks trap water that is undetectable and can harbor ZQM larvae for extended periods making them unable to decontaminate 100% effectively. Paddle boards, canoes, kayaks, and inflatable rafts do not have internal compartments, like ballast tanks, and do not require a trailer to transport. These vessels can easily be decontaminated and inspected and do not hold water that is undetectable. Much more information about this can be found in the staff report to City Council

Yes. These types of watercraft will still be allowed provided they can be launched without a trailer and go through the mandatory decontamination spraying process just like in previous years. Decontamination of these types of watercraft has been extremely effective in removing ZQM from surfaces that can make contact with the water.

Please remove any Westminster tag you may currently have on your boat. All tags are invalid until further notice. Should a boating program resume in the future, instructions regarding boat permitting will be provided.

Allowed: Car top boats and paddle craft (car top vessels are those that can be lifted onto and taken from the top of a passenger vehicle or from the bed of a truck), multi-chambered inflatable devices and electric trolling motors. Maintenance, rescue and patrol boats operated by City personnel will also continue to be allowed on the water but are subject to decontamination and if necessary, quarantine protocols.

Prohibited:Trailer-hitched boats, motorized gas-powered boats and engines, sailboats, belly boats, single-chambered flotation devices (including inflatable rafts, inner tubes and inflatable mattresses, pool toys or any floating device not designed for open water use).

In addition to decontamination, trailered boats have been subject to a 35-day quarantine before being allowed to launch at Standley Lake. The length of the quarantine is based on a 2013 study that found ZQM can potentially survive up to 27 days in ballast tanks. Westminster staff reviewed boat launch data for trailered boats with a 2018 Standley Lake permit and found as many as 24 boats had circumvented the quarantine and decontamination program. In most cases, this was a result of a small number of permit-holders tampering with quarantine measures. Trespassing notices are being issued.

Once ZQM are established in a body of water, they will begin to attach to every hard surface. This includes drinking water infrastructure. Standley Lake is Westminster’s sole source for drinking water. Water from the lake enters Westminster’s treatment system directly, so an infestation of ZQM in the lake would threaten to clog intake pipes and spread inside other pipes. ZQM can also create algae blooms that can cause taste and odor issues in drinking water, or more seriously, allow for toxic algae blooms that can render a water supply unusable.

Westminster Public Works and Utilities Department tests for the presence of zebra and quagga mussels in Standley Lake throughout the year. So far, testing has not detected these species in Standley Lake. Testing will continue throughout this year and into the future.

Since 2007 when ZQM were identified as a threat to Colorado waters, Westminster has been a leader in developing a protection plan to substantially reduce the threat of these species entering Standley Lake. As more information about the survivability of ZQM has become available, the requirements of the protection plan have become stricter. As many as 24 instances of boaters deliberately skirting the city’s tag and quarantine system were discovered this winter.

Westminster is a leader in adopting decontamination spraying routines and imposing quarantines on boats. These measures have been adopted at other lakes to prevent zebra and quagga mussel larvae from getting established. In addition to staff experts, the city has brought in outside experts to verify the risk of acquiring zebra mussels as well as determine the impact of an infestation. The immediate conclusion is that the threat is just too great to move forward with the policies that are in place.

The National Marine Manufacturers Association (NMMA) has made ANS a top priority and recently came to Colorado, visited several Watercraft Inspection and Decontamination (WID) sites, and created a digital essay, titled "Keeping Colorado Waterways Clean and Sustainable." View the essay, watch a mini-documentary on the efforts out west and a view a walk-through of the decontamination process.

A ZQM infestation in Standley Lake would require new systems to be developed to prevent the mussels from clogging essential water infrastructure. City staff estimate these systems would cost approximately $10 million to install and $3 million to operate each year. These costs would impact rates for Westminster water customers. Westminster, Northglenn and Thornton have all committed, through an intergovernmental agreement, to mutually protect the drinking water supplies that all three cities rely on. ZQM infestation could translate to a meaningful increase in monthly water rates for Westminster residents.

The lake’s ecosystem would also be severely impacted. ZQM populations can filter massive amounts of water, but in doing so would eliminate the microscopic organisms that form the base of the food chain. This would cause a chain reaction up the food chain resulting in destruction of the now healthy ecosystem in Standley Lake. Additionally, changes in water chemistry would cause the existing invasive aquatic plant, Eurasian milfoil, to increase in density as the beneficial milfoil weevils population declines.

Standley Lake Regional Park and Wildlife Refuge is a valued recreation destination for thousands of local residents. Since ZQM was first identified as a threat to Colorado waters in 2007, Westminster has had a ZQM protection plan in place for the lake. This protection plan was the first of its kind in Colorado, and Westminster has been a leader in its approach. However, as more information has become available over the years, and key information came to light over the winter about ZQM, staff has identified that even this robust program is not capable of being fully protective of the lake. The risk is too large to accept.

As zebra and quagga mussels spread to more bodies of water in Colorado and the west, the level of risk increases, and that makes the prospect of returning trailered boats to Standley Lake increasingly unlikely.

Westminster collected approximately $480,000 in revenue from trailered boat permits in 2018. This revenue will not be available this year. However, Westminster has increasingly worked to develop expanded recreational programs at Standley Lake which continue to grow and thrive. 

Patrons can leave their boats in storage through the end of April if they have already paid for the winter season. If you want to keep your boat in storage for the summer, you will need to purchase summer boat storage, which is $200 from May-September.

Barr Lake State Park 
Directions: Take I-76 northeast from Denver, exit on Bromley Lane. Go east to Picadilly Road, then south to the park entrance. 
Fee: Please see Barr Lake State Park Fee Information for additional information. 
Boating: Only sailboats, hand-propelled craft and boats with electric trolling motors or gasoline motors of 10 horsepower or less are permitted on Barr Lake. A boat ramp is located adjacent to the north parking lot. |
Fish: Channel catfish, smallmouth and largemouth bass, rainbow trout, walleye, bluegill, wiper and tiger muskie are among the species that have been stocked at Barr Lake by the Colorado Colorado Parks & Wildlife. 
Water Acres: 1,918 
Elevation: 5,100 feet 
Managing Agency: Colorado Parks & Wildlife. For more information, call 303-659-6005. 

Bear Creek Lake 
Directions: 1/8 mile east of Highway C-470 on Morrison Road. 
Fee: $10 per vehicle 
Boating: 10 horsepower maximum 
Fish: Tiger muskie, rainbow trout, smallmouth bass and saugeye. 
Water Acres: 110 
Elevation: Lake: 5,558 feet; Mt. Craven: 5,779 feet 
Managing Agency: City of Lakewood. For more information, call 303-697-6159. 

Boulder Reservoir
Directions: From Highway 36, go north to the Longmont Diagonal (Highway 119) and turn northeast. At Jay Road turn west and then north almost immediately onto 51st street. 
Fee: See Boulder Reservoir Fees
Boating: All watercraft require permit, must launch from south shore after going through inspection
Fish: Walleye, channel catfish, black crappie, bluegill, largemouth bass, yellow perch and rainbow trout 
Water Acres: 540 
Elevation: 5,173 feet 
Managing Agency: City of Boulder Parks and Recreation. For more information, call 303-441-3461.

Boyd Lake State Park 
Directions: Exit I-25 west at U.S. 34 near Loveland, turn north onto Madison Avenue, then follow the signs. 
Fees: Please see Boyd Lake State Park  fees.
Boating: Two paved launch ramps. A six-lane ramp is located north of the swim beach, while a two-lane ramp is located just north of the group picnic area. The entire lake is open to boating and sailing. Only the south end of the lake is open to water-skiing. The ski pattern is counterclockwise. 
Fish: Bass, catfish, crappie, perch, rainbow trout and walleye 
Water Acres: 1,750 
Elevation: 4,958 feet 
Managing Agency: Colorado Parks & Wildlife. For more information, call 970-669-1739. 

Carter Lake 
Directions: I-25 north to Colorado Highway 56 (Berthoud exit) west, follow the signs to Carter Lake. 
Fee: $6 daily fee; $6 daily boat fee; $7 camping 
Boating: No restrictions 
Fish: Kokanee salmon 
Water Acres: 1,140 
Elevation: 5,760 feet 
Managing Agency: Larimer County. For more information, call 970-679-4570.

Chatfield State Park 
Directions: From Denver, take Wadsworth Blvd. (Colorado Highway 121) south past C-470, and turn left into the Park at the Deer Creek entrance. As an alternate route, take Santa Fe Blvd. south to Titan Road, turn west on Titan Road to Roxborough Park Road, and turn north to the Plum Creek entrance. 
Fees: Please see Chatfield State Park Fees. 
Boating: Three boat ramps, water-skiing, sailboarding and personal watercraft 
Fish: Trout and bass, channel catfish, yellow perch, crappie, bluegill, sunfish and carp. The lake is periodically stocked with rainbow trout and other fish by the Colorado Parks & Wildlife.  
Water Acres: 1,550 
Elevation: 5,430 feet 
Managing Agency: Colorado Parks & Wildlife. For more information, call 303-791-7275. 

Cherry Creek State Park 
Directions: One mile south of I-225 on Parker Road, adjacent to south Denver.
Fees: Please see Cherry Creek State Park Fees. 
Boating: Two boat ramps, water-skiing, personal watercraft and sailboarding 
Fish: Trout, walleye, bass, crappie, pike, carp and catfish, state record walleye have been caught at the reservoir 
Water Acres: 880 
Elevation: 5,550 feet 
Managing Agency: Colorado Parks & Wildlife. For more information, call 303-699-3860.

Horsetooth Reservoir
Directions: Take I-25 to the Fort Collins exit (Harmony-Tinmath), go west on Harmony, then north on Taft Hill Road about 1 mile to County Road 38E, take County road 38E west to the reservoir. 
Fee: $7 daily 
Boating: No restrictions 
Fish: Largemouth and smallmouth bass, walleye, saugeye, white bass and wiper 
Water Acres: 2,000 
Elevation: 5,400 feet 
Managing Agency: Larimer County. For more information, call 970-679-4570.

Boats that did not return to Standley Lake were not included in the 24 boats mentioned. Boat launch data from the state indicates 312 launches by 84 different permit holders on other lakes. Only the 24 that returned and launched without going through the proper decontamination and quarantine were listed. Regarding the violations, the permit holders that were verified to have violated the program were given trespass from Standley Lake, with a 30-day review process (which is standard with the trespass program).

Composite samples are taken at 5-6 locations across the lake. This is done twice every month as long as there isn’t ice on the water, which prevents sampling. There is also an annual shoreline survey that looks for adult mussels that have adhered to hard structures. Generally a quarter of the shoreline is surveyed annually.
No. There has never been a positive test result for zebra or quagga mussels (either veliger or adults).

Green Mountain Reservoir (in Summit County) tested positive for quagga mussels on Aug. 18, 2017 and is currently listed as a “containment” reservoir. Lake Pueblo tested positive for mussel larvae, know as veligers, in 2007, 2008, 2009 and 2011, but, after several years of clean reports, it was delisted from so-called containment protocol in January. Blue Mesa, Granby, Shadow Mountain, Willow Creek, Tarryall and Jumbo reservoirs and Grand Lake tested positive for zebra or quagga veligers in 2008, but all were delisted in 2014 and are now considered free of the invasive species. There are several important factors to consider with these positive test results. Testing does not determine how many veligers were present in the lake.  It is possible that there were not enough veligers to establish a sustained population.  It is also possible that the veligers were not living. Also, despite significant work with multiple experts, there is always the possibility that there is something else at play. That said, based on best available information from multiple sources, Standley Lake is well within the habitable limits of zebra/quagga mussels.

There is no way to treat for zebra/quagga mussels once they are introduced, and the impact to water infrastructure would be significant. The most feasible way to limit infrastructure impacts is by introducing chlorine at the infrastructure. This would cause an increase in disinfection byproducts (which are regulated carcinogenic compounds) into our drinking water supply. We also know that the current ANS program has shortcomings. Standley Lake is a water supply for 300,000.  Westminster water rate payers, specifically, bare all of the financial risk of ANS introduction (specifically $10 million in capital costs plus $3 million annually in perpetuity), and the water delivered to those 300,000 people would be impacted if zebra/quagga mussels were to establish.  Colorado has, to date, not had a sustained infestation. This is true, but the risk to the water supply remains very real.
The Standley Lake Recreation IGA was agreed to by the cities of Westminster, Thornton and Northglenn 25 years ago and is set to expire in 2019. This agreement is between the cities that use Standley Lake water for their drinking water supply and it regulates the recreational uses at Standley Lake.  The three cities have equal input in how/what recreational activities take place at Standley Lake.  Preliminary communication regarding the new IGA has begun between the three cities. No decisions have been made about the future of boating at Standley Lake as part of this process.
All full-time staff at the lake hold state certifications as Stage II Inspectors and Decontaminators and have been certified annually since the inception of the state program (2008). Being a certified WID (watercraft inspection and decontamination) site provides access to the state’s mobile WID application. This application has been utilized by Standley Lake staff for the last four years to verify other agency tags that were placed on a boat previous to coming to Standley Lake. This allowed boats entering Standley Lake to bypass the decontamination and quarantine requirements because staff was able to verify that the boat had not launched on another water body since the previous season (staff would not allow the bypass of the quarantine and decontamination if the boat had launched on any water body after the winter season had ended). Staff did not utilize the WID application at the boat ramp because the application did not provide data in “real-time” when logging the information into the application.

Based on conversations with the state over the past two months, staff was notified by the state that the application was recently updated and would now be able to deliver search results in “real-time” as the boat information was logged. Standley Lake staff was already committed to utilizing the State WID mobile application at the boat ramp for the 2019 season.
Staff shares the concern that the type of vessels mentioned can more easily be launched in remote areas outside of the boat launch. This is an issue that staff at Standley Lake will continue to diligently monitor and control. Staff is in agreement, it is not acceptable to be able to launch vessels anywhere on the lake. The ANS program is intended to regulate all types of boats, not just some.         

The information that staff requested from the Colorado ANS Specialist regarding the 2018 Standley Lake boat permit holders was received by staff on Jan. 31, 2019. This was the first time that staff requested this information from the State of Colorado ANS Program. The intent of gathering this information was to verify that the current ANS program in place at Standley Lake was working and effective. Staff did not expect the information that 24 boats had violated the ANS program at Standley Lake. The violators will go through the city’s due process of being issued a trespass notice with a 30 day window to dispute the charges. After that process, final decisions will be made on trespass.