Semi-Annual alum treatment coming next month

Doses of alum will be applied to Canyon Lake’s Main Lake, East Bay and North Ski Area the week of April 10 by the Lake Elsinore & San Jacinto Watersheds Authority. The authority last applied the alum in October and April of last year. This will be the 19th time over the years that it has overseen the alum application in Canyon 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.

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, Mark Norton, Authority Administrator of the LESJWA, said. Drinking water quality will not be affected by any of the treatment options. Canyon Lake will remain open during the entire treatment process.

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

“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,” Mark said. “This dose reflects a continuance of alum application to Canyon Lake, typically applied twice a year, similar to previous years.”

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 and 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, Mark said.

The planned schedule of the alum application will take place 7:00 a.m. to 4:00 p.m. each day. The week’s schedule will be boats applying the alum to the Main Lake, April 10 and 11, the Main Boat Ramp, April 12, the East Bay, April 13 and the North Ski Area and Clean-up, April 14.