Water officials in northern El Paso County are attributing unusual tastes and odors in tap water to a seasonal algae bloom in Lake Woodmoor.
Residents and businesses served by the Woodmoor Water and Sanitation District serving the unincorporated Tri-Lakes community east of Monument across Interstate 25 have raised concerns in recent weeks about an earthy, musty and sometimes “swampy” taste and odor coming from their taps, prompting district officials to reassure customers the water remains safe while taking additional steps to address the problem.
District Manager Jessie Shaffer said the taste and odor are being caused by naturally occurring organic compounds associated with algae and aquatic vegetation in Lake Woodmoor, rather than contaminants that pose a health risk.
“First and foremost, please don’t be alarmed regarding the safety of the water,” Shaffer said in a statement, noting that the water is compliant with federal- and state-mandated contaminant levels.
Shaffer said the water is perfectly safe to drink, cook with and bathe in.
According to the district, the primary culprits are geosmin and 2-methylisoborneol, commonly known as MIB. The compounds can be produced as algae reproduce and die and are naturally present in lake ecosystems. Aquatic weeds can also contribute to taste and odor-producing compounds.
Although harmless at the concentrations found in drinking water, the compounds can be detected by people at extraordinarily low levels. Most people can begin detecting them at concentrations of about 5 parts per trillion, while particularly sensitive people may notice concentrations as low as 1-2 parts per trillion, Shaffer said.
Woodmoor isn’t the first community to face issues with unusual taste and odor with its water in the past month. Cañon City residents packed council chambers recently seeking answers about what several described as a swampy turn in the water coming out of their taps.
The Woodmoor district issued an updated notice Aug. 12 describing the problem as a natural, seasonal algae bloom fueled by warm, sunlit water. The compounds do not easily break down through standard water treatment processes and can create perceptions of mud, damp soil or mold when drinking or heating the water.
The issue has been particularly noticeable this summer because of hot and dry conditions favorable to rapid algae growth, Shaffer said.
Woodmoor has used several measures over the years to control algae in Lake Woodmoor, including diffusers installed on the lake bottom to aerate and mix the water, increase dissolved oxygen and reduce temperature differences within the water column. Chemical treatments have also been used to suppress phosphorus and control algae.
Aeration began in 2016, followed by annual spring chemical treatments beginning in 2019. Shaffer said the district had not previously needed to conduct a second chemical treatment during the same year since implementing those practices.
This changed Aug. 10, when a contractor applied an additional treatment to Lake Woodmoor in response to this summer’s conditions.
“We believe this will reduce the taste and odor compounds, but it will also take some time,” Shaffer said. “We anticipate that the unpleasant taste and odor of tap water should begin to improve in a week or two and we apologize for the inconvenience this has caused anyone.”
Operations Superintendent Dan LaFontaine said the district is also optimizing treatment processes, continuously monitoring water quality and flushing fire hydrants throughout the distribution system to replace older water with newer water as conditions improve.
The district has suggested that residents who find the taste objectionable should chill their drinking water, add lemon or other fruit or use an activated-carbon pitcher filter. Those suggestions have not satisfied everyone.
Mia Montgomery, a resident of the Woodmoor Park Homeowners Association, said she first noticed the problem in early to mid-July.
“It smelled and tasted swampy,” Montgomery said. “It’s crazy we’re paying for what smells like pond sludge.”
She said the problem affects more than drinking water, with the smell noticeable while showering and doing laundry.