Canyon Lake to receive 11th alum treatment


Canyon Lake will receive another alum treatment starting Monday, Sept. 17. According to the Lake Elsinore & San Jacinto Watersheds Authority (LESJWA), this will be Canyon Lake’s 11th alum treatment.

Doses of alum will be applied to the lake in the main body, East Bay and the area north of the causeway from Sept. 17 through Sept. 21.

Being that Canyon Lake is located near the end of the watershed, it receives high levels of nutrients, such as nitrogen and phosphorus, as a result of stormwater runoff. These nutrients encourage algae growth. By adding alum to the water, it immediately binds to the phosphorus causing it to neutralize and become inactive.

Alum, the method selected to provide the best results for Canyon Lake, is a naturally occurring mineral that has a proven track record of success. According to LESJWA, alum is safe for both humans and aquatic life and does not affect drinking water quality.

The lake will remain open during the entire treatment process. Recreational users will experience little disruption during treatment application and implementation.

In order 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 using local stakeholder funding to continue alum water treatments in Canyon Lake. The TMDL Task Force evaluated several options during the CEQA process 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.

The alum schedule is as follows:

Main Body: Monday, Sept. 17, 7 a.m. to 4 p.m.

Main Body: Tuesday, Sept. 18, 7 a.m. to 4 p.m.

Main Body: Wednesday, Sept. 19, 7 a.m. to 4 p.m.

East Ramp/North Causeway: Thursday, Sept. 20, 7 a.m. to 4 p.m.

Clean-up: Friday, Sept. 21

For daily operational updates, visit For more information, contact Mark Norton at 951-354-4221 or