USGS study confirms increased sediment, nutrients throwing watershed out of balance

Steamboat Lake was closed for human and animal contact with the water for two weeks last August after harmful levels of a toxin produced by blue-green algae were found in the water. (Photo courtesy Julie Arington)
A type of blue-green algae is visible at Stagecoach Reservoir shoreline in August 2019. Park managers ask humans and pets to avoid these areas of scum in case low levels of toxins may be present. (Photo courtesy Craig Preston)
Blooms of a type of blue-green algae are present by the shoreline and in the waters at Stagecoach Reservoir in August 2019. (Photo courtesy Craig Preston)

The official release Thursday of a two-year U.S. Geological Survey technical study commissioned by the Upper Yampa River Watershed Group confirms that increased sediment and nutrients in the river watershed are throwing the aquatic system off balance.

“The study shows that the system is out of balance, and we want to know why, where and what actions we can begin to take to ensure our good water quality,” said Steamboat Springs resident Lyn Halliday, an environmental scientist for 28 years and watershed group coordinator.

The issue could lead to increased recreational closures of local reservoirs, such as Stagecoach Reservoir or Steamboat Lake, due to rising environmental stress from warmer weather and less water moving through reservoirs, which can push normal algae into overgrown toxic blooms.

“Algae is normal, and algae blooms are normal, but we are seeing trends that are signaling the system is out of balance and a proliferation of algae blooms that are not normal,” Halliday said. “Some things feed on algae, and it’s an important part of the aquatic ecosystem. But too much of anything will throw a system out of balance. It’s a signal that something is wrong.”

The grassroots, volunteer watershed group that formed in 2012 has been active in developing and gathering local, state and federal funding for studies, including the Upper Yampa River Watershed Plan in 2016. The plan outlined the need for gathering more information, such as during the recent USGS study that used existing data to characterize and identify changes in stream flow and water-quality constituents, including suspended sediment, nitrogen and phosphorus.

According to U.S. Environmental Protection Agency information on nutrient pollution, “Harmful algal blooms are a major environmental problem in all 50 states. Red tides, blue-green algae and cyanobacteria are examples of harmful algal blooms that can have severe impacts on human health, aquatic ecosystems and the economy.”

The EPA notes harmful algal blooms need sunlight, slow-moving water and nutrients, such as nitrogen and phosphorus, to proliferate, and “nutrient pollution from human activities makes the problem worse, leading to more severe blooms that occur more often.”

In the worst cases when excess growth can turn algae toxic, local recreation areas can be closed to certain uses. Steamboat Lake was closed for two weeks for swimming in mid-August 2020 due to blue-green algae blooms. Pets and people were asked to stay out of the water; paddle board rentals were closed; some guests canceled boat or campground reservations; and anglers were asked to wash their fish and hands well after fishing, Steamboat Lake State Park Manager Julie Arington said.

Arington said algae blooms have been seen in the lake in previous years but were more noticeable last summer. She said conditions this year are lining up to be conducive again to algae blooms with warmer temperatures and less water moving through the lake due to less spring precipitation and lower snowpack runoff.

“Typically, we see algae growth when little water is moving through the reservoir and with higher temps, and we already have that condition going on now,” Arington said Wednesday.

Craig Preston, Stagecoach State Park manager for 14 years, noted testing shows some toxic algal blooms have been found in Stagecoach Reservoir, typically in late summer in 2014, 2015, 2017, 2018 and 2019, but the toxins never reached a level that required any type of water closures. Colorado Parks and Wildlife is launching new educational signage for Stagecoach State Park visitors about the algae concerns.

Halliday said combined efforts can help the health of the watershed, such as low-impact development regulations to improve storm water drainage by using bioretention or rain garden capture methods that employ natural vegetation systems to filter more pollutants from urbanization. Other helpful actions include improvements to more permanent and better designed water diversion structures that do not disrupt the river as much.

Agencies, such as USDA Natural Resources Conservation Service, are working with landowners regarding nutrient management, including when to and when not to apply fertilizer by understanding soil health and performing more soil testing. Educators teach about improved grazing practices to maintain a healthy riparian area between livestock and the river, Halliday said.

Expanded collaborations among landowners and land use agencies on the county, state and federal levels are key to protecting the water quality of the Upper Yampa River Watershed along with work in data gap areas, such as more frequent sampling of post storm runoff to learn where nutrient loading originates, Halliday said.

Halliday said averting watershed impacts is a difficult problem to solve, but preventative work is less expensive than mitigation work after damage.

“In our county, Steamboat Lake’s issue last summer might have been a good wake-up call for us to pay attention,” Halliday said.

Cyanobacteria ‘present’ signs coming for Stagecoach State Park

Colorado Parks and Wildlife educators are producing new signs to post at Stagecoach State Park to help park visitors learn more about cyanobacteria, or blue-green algae, levels that can bloom and could reach toxic levels. Park Manager Craig Preston shared a preview of the signage that starts with the title “Water Recreators and Pet Owners — CYANOBACTERIA (Blue-green algae) PRESENT.”

The signage reads: “As in many bodies of water in Colorado and around the country, cyanobacteria (blue-green algae) is known to be present in Stagecoach Reservoir. The Stagecoach Reservoir algae bloom typically starts in June and lasts through September. Although many species of cyanobacteria are harmless, some can produce toxins. The production of these toxins is unpredictable.

“Although we cannot test all locations every day for all possible algal toxins, Stagecoach State Park staff does monitor cyanobacteria and test for toxins. We have been doing this since 2015. Most tests come back negative, but occasionally, areas have tested positive for low-levels of toxins. For this reason, we advise you to always use caution and follow these guidelines.

– Swim at your own risk. Unknown hazards exist.

– Avoid areas of scum whether swimming, wading or boating.

– Do not drink or allow pets to drink reservoir water.

– Clean and rinse fish well and discard guts in a trash receptacle.

“Per CDPHE (Colorado Department of Public Health & Environment) guidance and agency policy, if test results indicate toxins are above the toxin advisory level, we will post additional DANGER signs until toxin levels recede.

“Call your doctor or veterinarian if you or your animals have sudden or unexplained sickness or signs of poisoning.”

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