Managing The Lake

Preserving, Protecting and Maintaining
Lake Mission Viejo’s Water Quality
Third in a series of articles on the fascinating and challenging job of managing our beautiful Lake Mission Viejo.
The Association is dedicated to providing a premier freshwater lake by protecting and maintaining the lake’s water quality. As the lake ages and faces new external threats from Quagga mussels and Golden algae, the work of maintaining lake water quality has transformed from the relatively simple task of sampling and testing lake water into a challenging and multi-faceted campaign to ensure Lake Mission Viejo continues to be a valued recreational asset.
Quagga mussels provide a good example of how commitment and hard work can pay off. These tiny mussels, native to the Ukraine, are thought to have migrated to the East Coast of the United States in ship ballast water. They quickly crossed the continent by clinging to the hulls of pleasure boats, reaching California in 2007 or 2008.
Because the mussels quickly gather on any hard surface, like boat hulls, docks and inlet and outflow pipes, they pose a serious threat to the lake. In 2008, just as the threat became known, the Association began inspecting and tagging all watercraft before they were allowed to enter the lake, and in the 11 years since the program began, we have inspected and tagged more than 27,000 watercraft.
LMVA continues to test our waters for Quagga mussels and equally troubling Zebra mussels, sending water samples to the Scripps Institute of Technology for testing. The test results are encouraging, showing that our efforts have paid off and the Lake remains free of the mussels. Our Compliance Department, Dock Staff and boat inspection team are committed to keeping it that way.
Golden Algae
In 2014, the lake suffered its first Golden algae bloom, and nearly all the fish in the lake died, as he golden algae toxin prohibited their gills from processing oxygen. (Golden algae affects only gill breathing organisms)
Since then, we have invested thousands of hours of staff time and more than $100,000 in scientific studies to find a way to limit Golden algae’s damage. It’s a huge challenge because Golden algae affects lakes around the world, and no one has yet found a way to control, let alone eliminate, this threat.
After the initial Golden algae assault on the lake, the Association commissioned a study by Dr. David Caron to determine possible strategies to manage Golden algae blooms. Dr. Caron is an award-winning researcher into harmful bloom-forming species of microalgae.
That study looked at multiple factors, including pH, TDS (salts) and minerals. The study was encouraging, indicating that reducing the lake’s pH could, at a minimum, limit the damage caused by future algae blooms. Dr. Caron called the lowering of pH “highly significant” because Golden algae in Lake Mission Viejo appears to be more toxic to fish than Golden algae in other lakes, adding, “Our experimental results at low pH indicated that an approach that focuses on reducing toxicity by altering the pH of the lake might be an effective way of reducing the threat of fish kills due to Golden algae.”
To develop a plan based on these findings, the Board recently approved new studies by Dr. Caron that include extensive in-lake testing of the use of alum, a chemical commonly used to treat drinking water, to reduce lakewater pH levels. The tests will be conducted within confined enclosures in the lake and the application of alum will be guided by data developed through new laboratory tests he will conduct into Golden algae’s response to various pH and salt levels.
We are hopeful that periodic alum application will help us to reduce the frequency and impact of Golden algae blooms, and that Dr. Caron’s new studies will aid us in designing the most cost-effective methods for applying the alum.
A positive step towards reducing minerals and salts in the lake’s waters has been made with LMVA’s $5.5 million investment in the Advanced Purified Water (APW) plant that is now providing lake refill water. While the decision to switch to APW water was driven by new state water conservation requirements that precluded the purchase drinking water from SMWD for lake refill, water quality is benefitting because APW water contains a fraction of the mineral and salt content of the SMWD water we previously used.
We are now closer than ever to developing actionable plans to address Golden algae’s toxicity, and while progress will be incremental, it will be progress – and that will enable the Association to meet its commitment to provide our Members with a premier freshwater lake.