Alum treatment scheduled next week

Doses of alum will be applied to Canyon Lake’s Main Lake, East Bay and North Ski Area beginning Monday and will continue every day until finishing on Friday by the Lake Elsinore & San Jacinto Watersheds Authority (LESJWA).

Alum binds with phosphorus in the lake water, drops the nutrient to the lake bottom and thereby reduces algae growth in the lake.

The water authority will be spraying the treatment from its boat as it covers the predetermined areas of the lake, which will remain open during the entire treatment process. Recreational users will experience little disruption during treatment application and implementation.

The authority last applied the alum in May. This will be the 20th time over the years that it has overseen the alum application in Canyon Lake.

The spraying schedule is subject to change, but it is anticipated the Main Lake will be treated on Monday and Tuesday, the Main Boat Ramp area and the west end of East Bay on Wednesday, the rest of East Bay on Thursday and the North Ski Area on Friday. The boats will be out each day applying alum from 7:00 a.m. to 4:00 p.m.

Alum, the method selected to provide the best results for Canyon Lake, has a proven track record of success and is safe to both humans and aquatic life, LESJWA’s Rachel Gray said. Drinking water quality will not be affected by any of the treatment options.

Canyon Lake water mostly comes from stormwater runoff from the upper watershed each year that has high levels of nutrients that hurt water quality and threaten aquatic life.

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, a coalition of cities, the county, and several other organizations led by LESJWA, provides 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.