Alum treatments continue at Canyon Lake

CANYON LAKE – Another alum application was applied in Canyon Lake Feb. last week, following final testing and recommendation from scientists.

The Lake Elsinore & San Jacinto Watersheds Authority (LESJWA) is responsible for managing the alum applications. LESJWA, a joint powers authority, exists to improve water quality in Canyon Lake and Lake Elsinore within the watershed. Canyon Lake has a history of receiving high levels of nitrogen and phosphorus that enter the lake through water runoff. By reducing nutrients in the lake, the severity of algae blooms decreases, as algae feeds on phosphorus.

“Historically, Canyon Lake receives high loads of nutrients, especially following heavy storm events, such as those which taken place over the past two months,” shares Mark Norton, LESJWA Administrator. “Since early 2016, alum treatment of Canyon Lake has expanded to include sections of Canyon Lake north of the causeway; an area plagued with repeated concerns over algae blooms.

The alum treatments have been proven effective in reducing the phosphorus concentrations in the lake water and thereby minimize the prevalence of algae blooms.”

Our historic drought created a thirsty region for Southern Californians. In the southwest portion of Riverside County, Lake Elsinore reached low lake levels suffering algae blooms over the hot 2016 summer months. Recent storms hit hard, bringing much needed rain and snow. In the San Jacinto and Lake Elsinore Watersheds, snowmelt and rain flow downward and end up in Canyon Lake and eventually Lake Elsinore. As water enters Canyon Lake, along with it comes an increase in excess nutrients and sedimentation. Alum treatments to Canyon Lake have been effective in reducing nutrients and sediment concentrations related to flows of nutrients that enter the lake.

Alum application to Canyon Lake are applied at levels that are safe for humans and marine life. It has continued as the preferred treatment to improve water quality in Canyon Lake. Minimal disruption will take place for lake recreation, said Norton. Before alum applications, water samples are always tested for dissolved oxygen, pH and temperature to confirm appropriate water quality conditions, a procedure that is always followed before beginning the treatment process. During the application, sections of the lake being sprayed were by necessity blocked off, however access was to be open immediately following. To view the project updates, residents can visit

To comply with water quality regulations, enforced by the State through the local Santa Ana Regional Water Quality Control Board, the Lake Elsinore & Canyon Lake Nutrient Total Maximum Daily Load (TMDL) Task Force continues to conduct alum water treatments in Canyon Lake. The TMDL Task Force evaluated several options and determined that alum application provides the best option as a step to effectively treat the entire lake in a timely manner with minimal impact to Canyon Lake residents.

Funding for the alum applications is being provided by the Lake Elsinore and Canyon Lake Total Maximum Daily Load (TMDL) Task Force, which consists of cities, the County of Riverside, agriculture and dairy coalitions and other organizations in the San Jacinto River watershed. Implementation of the alum project is being coordinated by the City of Canyon Lake, the Elsinore Valley Municipal Water District, LESJWA, the TMDL Task Force and the Canyon Lake Property Owners.

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