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04-22-2007, 04:01 PM
The Press-Enterprise
When you're trying to stay fresh as rain while being undermined by algae and carp, a breath of fresh air could be just the recipe for keeping the green water and the swampy stink at bay.
That's the plan behind a $2.4 million network of air compressors and underwater pipelines being installed at Lake Elsinore, where the infusion of oxygen will control the growth of algae and stunt environmental chain reactions that affect everything from the color of the water, to the type of fish that thrive there, to the amount of plankton that fish eat.
This "diffused aeration system" will go into operation late next month. To mark the occasion, the Lake Elsinore & San Jacinto Watersheds Authority will hold a dedication ceremony on May 31 at the city marina.
Silvia Flores / The Press-Enterprise
Leo Solorzano, the city of Lake Elsinore's lake and aquatic resources supervisor, looks over Lake Elsinore from one of two buildings that each house two air compressors that will pump air into the lake through pipelines. The purpose is to control algae growth in the lake.
"This is ... just like the diffuser in your aquarium," said Mark Norton, administrator of the Lake Elsinore & San Jacinto Watersheds Authority.
"It's not going to be like a Jacuzzi," added Pat Kilroy, the city's director of lake and aquatic resources. The aeration system will create "gently rolling bubbles coming up from the bottom of the lake," he said. "This will probably be one of the largest lake aeration systems in the U.S."
Four air compressors, each with a 200-horsepower engine, will pump air into the lake through 4,000-foot-long pipelines that fan out from the machines like fingers.
Two air compressors are housed together on the north side of the lake, near Lakeshore Drive, and the other pair is being installed on the south side of the lake, near Grand Avenue. Each compressor can pump 1,000 cubic feet of air per minute into the lake. The 12 pipelines, made of polyvinyl chloride -- commonly known as PVC -- are perforated for the last 2,500 feet, so the air will be injected into the water in a long stream, not just at the mouth of the pipeline, Norton said.
"We really want to get the air toward the deepest parts of the lake," said Kilroy, noting the water is about 27 feet at its deepest point.
The amount of oxygen in the water is vital to the aquatic health of Lake Elsinore because it affects the delicate balance of the lake's plant and marine life.
"The oxygen wasn't getting down to the deeper levels where the fish are," Norton said.
Every spring, the authority removes carp, a nonnative fish, from the lake. "They're sent out to the Coachella Valley, where there's a processing plant that turns them into fertilizer," Norton said.
Since 2002, the authority -- under a contract with the city -- has removed about 1.5 million pounds of carp from the lake, he said.
"Carp are an undesirable fish," Norton said. "There aren't many people who like to eat them. They're not considered 'game fish.' "
More importantly, the bottom-dwelling carp stir up silt and nutrients on the lake floor, and that spurs the growth of algae. Too much algae in the lake lowers the oxygen levels in the water, sometimes beyond the level that fish can survive.
As a result, under those conditions the carp and other fish die off on their own.
Such "fish kills," coupled with the mossy tint and marshy smell that too much algae can cause, make the lake undesirable to boaters and recreational users.
Pipelines such as these are part of a $2.4 million network of air compressors and underwater pipelines being installed at the lake.
"People don't like to use the lake when it's really green. Plus, it gives off odors when (algae) starts to die off," Norton said. "Sometimes on hot days, it can get particularly pungent."
Along with removing excess carp, the city and the authority turn to Mother Nature's food chain -- and a local fish farm -- to help keep the lake in balance.
"We put 4,000 pounds of hybrid striped bass into the lake. These bass feed on the 'fingerling' of the carp -- the small baby carp," Norton said.
The bass also eat a fish called threadfin shad. The shad are a villain in the lake's ecology because they consume a microscopic organism called zooplankton -- and zooplankton's favorite meal is algae, Norton explained.
Too many shad equals too little zooplankton. Too little zooplankton equals too much algae.
Another reason the authority stocks the lake with hybrid striped bass is because they serve their carnivorous duty and are a desired catch for anglers, but they do not breed, Norton said.
"You can still eat them. They just don't have the capability to reproduce," Norton said.
The hybrid also are preferred because of concerns by the California Department of Fish and Game that, in the event of a heavy rainstorm, the carnivorous bass could be swept downstream and wind up in other lakes and rivers, where they would eat the native vegetation and marine life.
Meanwhile, normal evaporation makes the lake's depth level fluctuate throughout the year. On average, Kilroy said, "we lose 9,000 gallons a minute. So every two minutes, you lose a good-size swimming pool," he said.
"Typically, we lose about 4 ½ feet per year due to evaporation," Kilroy said.
The 3,000-acre lake is fed by runoff from mountain streams and the San Jacinto River.
To offset the evaporation loss, the Elsinore Valley Municipal Water District is working on a project to bring recycled water from its treatment plant through a pipeline that will empty into the lake, Kilroy said.
The treated water "is highly filtered," Kilroy said, noting it meets state sanitation standards and is probably cleaner than ocean water.
As for the diffused aeration system, the cost of building it -- and other lake improvement projects -- was covered by $15 million that Lake Elsinore received from a state water bond approved by voters in 2000. The city, Riverside County and the Elsinore Valley Municipal Water District will share its annual operation and maintenance costs, each contributing $100,000 per year, Kilroy said.
When you're trying to stay fresh as rain while being undermined by algae and carp, a breath of fresh air could be just the recipe for keeping the green water and the swampy stink at bay.
That's the plan behind a $2.4 million network of air compressors and underwater pipelines being installed at Lake Elsinore, where the infusion of oxygen will control the growth of algae and stunt environmental chain reactions that affect everything from the color of the water, to the type of fish that thrive there, to the amount of plankton that fish eat.
This "diffused aeration system" will go into operation late next month. To mark the occasion, the Lake Elsinore & San Jacinto Watersheds Authority will hold a dedication ceremony on May 31 at the city marina.
Silvia Flores / The Press-Enterprise
Leo Solorzano, the city of Lake Elsinore's lake and aquatic resources supervisor, looks over Lake Elsinore from one of two buildings that each house two air compressors that will pump air into the lake through pipelines. The purpose is to control algae growth in the lake.
"This is ... just like the diffuser in your aquarium," said Mark Norton, administrator of the Lake Elsinore & San Jacinto Watersheds Authority.
"It's not going to be like a Jacuzzi," added Pat Kilroy, the city's director of lake and aquatic resources. The aeration system will create "gently rolling bubbles coming up from the bottom of the lake," he said. "This will probably be one of the largest lake aeration systems in the U.S."
Four air compressors, each with a 200-horsepower engine, will pump air into the lake through 4,000-foot-long pipelines that fan out from the machines like fingers.
Two air compressors are housed together on the north side of the lake, near Lakeshore Drive, and the other pair is being installed on the south side of the lake, near Grand Avenue. Each compressor can pump 1,000 cubic feet of air per minute into the lake. The 12 pipelines, made of polyvinyl chloride -- commonly known as PVC -- are perforated for the last 2,500 feet, so the air will be injected into the water in a long stream, not just at the mouth of the pipeline, Norton said.
"We really want to get the air toward the deepest parts of the lake," said Kilroy, noting the water is about 27 feet at its deepest point.
The amount of oxygen in the water is vital to the aquatic health of Lake Elsinore because it affects the delicate balance of the lake's plant and marine life.
"The oxygen wasn't getting down to the deeper levels where the fish are," Norton said.
Every spring, the authority removes carp, a nonnative fish, from the lake. "They're sent out to the Coachella Valley, where there's a processing plant that turns them into fertilizer," Norton said.
Since 2002, the authority -- under a contract with the city -- has removed about 1.5 million pounds of carp from the lake, he said.
"Carp are an undesirable fish," Norton said. "There aren't many people who like to eat them. They're not considered 'game fish.' "
More importantly, the bottom-dwelling carp stir up silt and nutrients on the lake floor, and that spurs the growth of algae. Too much algae in the lake lowers the oxygen levels in the water, sometimes beyond the level that fish can survive.
As a result, under those conditions the carp and other fish die off on their own.
Such "fish kills," coupled with the mossy tint and marshy smell that too much algae can cause, make the lake undesirable to boaters and recreational users.
Pipelines such as these are part of a $2.4 million network of air compressors and underwater pipelines being installed at the lake.
"People don't like to use the lake when it's really green. Plus, it gives off odors when (algae) starts to die off," Norton said. "Sometimes on hot days, it can get particularly pungent."
Along with removing excess carp, the city and the authority turn to Mother Nature's food chain -- and a local fish farm -- to help keep the lake in balance.
"We put 4,000 pounds of hybrid striped bass into the lake. These bass feed on the 'fingerling' of the carp -- the small baby carp," Norton said.
The bass also eat a fish called threadfin shad. The shad are a villain in the lake's ecology because they consume a microscopic organism called zooplankton -- and zooplankton's favorite meal is algae, Norton explained.
Too many shad equals too little zooplankton. Too little zooplankton equals too much algae.
Another reason the authority stocks the lake with hybrid striped bass is because they serve their carnivorous duty and are a desired catch for anglers, but they do not breed, Norton said.
"You can still eat them. They just don't have the capability to reproduce," Norton said.
The hybrid also are preferred because of concerns by the California Department of Fish and Game that, in the event of a heavy rainstorm, the carnivorous bass could be swept downstream and wind up in other lakes and rivers, where they would eat the native vegetation and marine life.
Meanwhile, normal evaporation makes the lake's depth level fluctuate throughout the year. On average, Kilroy said, "we lose 9,000 gallons a minute. So every two minutes, you lose a good-size swimming pool," he said.
"Typically, we lose about 4 ½ feet per year due to evaporation," Kilroy said.
The 3,000-acre lake is fed by runoff from mountain streams and the San Jacinto River.
To offset the evaporation loss, the Elsinore Valley Municipal Water District is working on a project to bring recycled water from its treatment plant through a pipeline that will empty into the lake, Kilroy said.
The treated water "is highly filtered," Kilroy said, noting it meets state sanitation standards and is probably cleaner than ocean water.
As for the diffused aeration system, the cost of building it -- and other lake improvement projects -- was covered by $15 million that Lake Elsinore received from a state water bond approved by voters in 2000. The city, Riverside County and the Elsinore Valley Municipal Water District will share its annual operation and maintenance costs, each contributing $100,000 per year, Kilroy said.