Why a water quality monitoring plan is needed for Lake Elsinore and Lake Canyon – press enterprise

Satellite imagery is now being used to track water quality in Elsinore and Canyon Lakes and this is one of the reasons a 10-year-old plan for monitoring the two lakes has been updated.

The Santa Ana Regional Water Quality Control Board recently released the revised final quality assurance project to monitor the amount of nutrients in the two lakes. The draft is available for public review and comment until September 19.

“This reflects the latest thinking on what is appropriate (in oversight),” said administrator Mark Norton of the Lake Elsinore and San Jacinto Watersheds Authority. “We’re also including the use of satellite photography, which is something new.”

The decline in water quality in both lakes resulting from nutrients that feed the algae led to the formation in 2000 of the Authority, a coalition of agencies along the lakes and the river that feeds them.

In December 2004, the State Council established mandates requiring the reduction of nutrients in the lakes by 2015 and 2020. The monitoring plan was launched in 2006.

“Elsinore Lake and Canyon Lake have a history of high nutrient levels and algal blooms resulting in decreased water clarity, as well as occasional fish mortalities likely due to transient low oxygen conditions. dissolved, ”states the project report prepared for the board by Amec Foster Wheeler.

The problematic nutrients monitored are phosphorus, nitrogen, ammoniacal nitrogen and chlorophyll. Targets have also been set to increase dissolved oxygen levels in lakes.

Canyon Lake, a man-made drinking water reservoir located two miles upstream from Elsinore Lake, met its 2015 targets. This success was in large part due to the authority’s strategy of periodically treating the water with the substance. alum, which removes phosphorus. Applications have taken place every spring and fall since 2013. Another is scheduled for the last week of September.

Lake Elsinore, however, proved more difficult, especially due to the drought. Southern California’s largest natural freshwater body, Elsinore Lake relies on precipitation that overflows the Canyon Lake Dam. This has not happened for several years and Lake Elsinore is at its lowest level since 1993.

Measures taken to improve the quality of the lake include the installation of an aeration system and the daily filling of the lake with reclaimed water.

However, the lake is too big for alum treatments to be affordable and killing the algae with an algaecide makes the problem worse because it results in more nutrients, Norton said.

“It’s a little harder to restore something to a pristine state than it has historically been,” Norton said. “We recognize that we may not be able to restore Lake Elsinore to Lake Tahoe-like water quality due to natural conditions.”

Today, Lake Elsinore is grappling with the aftermath of a blue-green algae bloom that forced the city to close the lake for a week in late July and early August due to high toxicity levels. Signs are installed along the shore to warn visitors against any bodily contact.

Norton, however, said there was no correlation between the nutrient reduction effort and blue-green algae, which are bacteria that thrive in warm, shallow, stagnant water.

Contact the author: 951-368-9690 or michaelwilliams@pe.com

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