For the Lake’s Sake : Keeping Algae Growth Down, Water Level Up Takes Delicate Balancing Act

Westlake Village resident Ben Schulman constantly tinkers with the formula for serenity on Westlake Lake.

Kill too much algae and light will cause weeds on the lake floor to sprout as much as six inches a day. Let the algae grow, and within days a green carpet will grow thick enough to virtually prevent a duck from getting its feet wet crossing the lake.

“We’ve got some very difficult problems to deal with both technically and financially,” explained Schulman, president of the Westlake Lake Property Assn. “And we’re devoting almost all of our time to solving them.”

In addition to coping with the ever-regenerating algae, Schulman said, the artificial lake’s engineers have struggled daily to keep it full while losing up to 1,000 gallons each minute to evaporation in the summer heat.

So far, Schulman said, they have been able to refill the lake fast enough to conceal the problem from the nearly 1,200 residents who gaze out at it every day.

The 150-acre lake, which straddles the border between Ventura and Los Angeles counties, remains a scene of tranquillity, where it is common to spy a blue heron in flight or a sailboat gliding along in the breeze.

Residents such as William Murphy say the beauty of the lake is a cure for the discomfort of summer swelter. “In front of my house it may be summer, but in back of my house it’s always fall,” he said, the water lapping up against his deck. “You always feel a little bit cooler when you’re looking out at the lake.”

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It has not, however, been a summer of calm for Schulman.

Normally, the lake is fed by surface runoff from the surrounding 18 square miles. In years of low rainfall, engineers compensate by tapping into two wells that collect water from an aquifer.

Heavy precipitation two years ago provided enough runoff to keep the lake full for the entire summer, and the wells didn’t operate all season.

This year, the wells began pumping during the first week in June and have not stopped.

The lake loses water in three ways. Evaporation, if unchecked, will drop the surface five feet during the hottest summer months. The neighboring Westlake Golf Course, by virtue of a 30-year-old agreement, siphons off as much as 400 gallons a minute to irrigate its greens.

Each day, a smaller amount is pushed over a 450-foot-long dam at the east end of the lake as required by the state to provide water to areas downstream.

To keep up with the water loss, Schulman and members of the lake’s water management committee have begun to talk about building a new well.

“We’re trying to improve the efficiency of the two wells we’ve got, to get it to pull more water from the aquifer,” Schulman said. “But now we have to consider a third well, which is a pretty expensive proposition.”

Money for such a project would come from the yearly dues that residents around the lake are assessed. Schulman declined to say how much residents pay, but one lakeside resident said his fee for the upkeep runs about $1,300 a year. “You get what you pay for, and this is a beautiful lake,” Schulman said.

Few realize the effort it takes to keep the lake beautiful.

“I really don’t know that much about the maintenance of the lake,” said Irving Wasserman, who lives on the island in the middle of the water. “I see them out there chopping away at the algae all the time, but that’s about all.”

Algae, Schulman’s other main concern, is a problem at many lakes.

Last year on nearby Lake Sherwood, algae grew with abandon. Dead layers of the brownish-green plant filled the air with an odor described by residents as sewage-like.

On Westlake Lake, Murphy said, the plant has at times grown so thick that residents have had a hard time maneuvering boats through it.

“Especially in the summer, it grows like crazy,” he said.

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Crosby Fentress, chairman of the property association’s water management committee, said the algae feeds on dead weeds that have accumulated at the bottom in layers as thick as two feet. Also contributing to the fast growth are nutrients from the reclaimed water frequently used to irrigate nearby neighborhoods, which drains into the lake.

“You can’t eliminate it 100%,” Fentress said. “You just have to try to keep it under control.”

To do that, the property association purchased a $45,000 harvester machine, which chops the algae and sucks it off the surface of the lake.

The caretakers also use chemicals in small doses to address the problem.

“When the lake was new, they used enough chemicals to keep it like a swimming pool,” Schulman said. “But they learned that if the lake surface was too clear, the light would speed up the growth of weeds at the bottom.

“It was a no-win situation,” he said.

Bill Hanson, who for many years worked as the lake’s engineer, called lake management a balancing act.

“Really, it’s a scientific process,” said Hanson, a chemical engineer. “If you manage it well, you end up with something really terrific.”