[Water_news] 4. DWR'S CALIFORNIA WATER NEWS: WATER QUALITY - 5/31/07

Department of Water Resources

California Water News

A daily compilation of significant news articles and comment

 

May 31, 2007

 

4. Water Quality

 

Aeration system gives life to Lake Elsinore - Riverside Press Enterprise

 

Local officials unveil lake aeration system - North County Times

 

 

Aeration system gives life to Lake Elsinore

Riverside Press Enterprise – 5/30/07

By Mary Bender, staff writer

 

LAKE ELSINORE - Tiny bubbles ripple to the surface of this recreational lake, a sign that 12 new pipelines are infusing the water with oxygen, which experts say will significantly improve the quality of the lake.

 

Today city officials will dedicate Lake Elsinore's new diffused aeration system, which pumps air into the lake through 4,000-foot-long polyvinyl chloride pipelines that radiate from opposite shores. The lake's caretakers say that less algae will grow and fewer fish will spontaneously die in the aerated, oxygenated water -- problems that have plagued the lake for much of its history.

 

On Wednesday, members of the State Water Resources Control Board and the Elsinore Valley Municipal Water District got an up-close look at the long, snaking pipes during a tour with Pat Kilroy, the city's director of lake and aquatic resources.

 

Dennis Waite, who handles lake maintenance operations for the city, steered a 35-foot barge from the dock at Lake Elsinore's Seaport Boat Launch. He took the passengers to several spots on the lake, where they could see the pipelines that Water District crews floated to the surface.

 

Deputies from the Riverside County Sheriff's Department escorted the vessel in their patrol boat to make sure other lake users didn't collide with the pipelines.

 

Each black pipe, measuring 1 ½ inches in diameter, is perforated for its final 2,500 feet so the air is released not just at its mouth but at numerous points along the way, said Andrew Komor, project manager from Pacific Advanced Civil Engineering, the Fountain Valley firm that designed the aeration system.

 

The holes are small -- just .04 inches -- and are spaced about 5 feet apart, Komor said. A series of concrete blocks weigh down the pipelines to keep them on the lake floor, and each pipe is lashed to a slightly bigger, 2-inch-diameter companion that maintenance crews employ to float the pipes to the lake surface when necessary, he said.

 

"Eighty percent of man-made lakes have a form of diffused aeration," Komor said, adding far fewer natural lakes are similarly equipped.

 

Lake Elsinore is a natural lake.

 

Four air compressors, each with a 200-horsepower engine, pump air into the lake through the pipelines that fan out like fingers.

 

Two air compressors are housed together on the south side of the lake, near Grand Avenue, and the other pair is on the north side, near Lakeshore Drive.

 

Each compressor can pump 1,000 cubic feet of air per minute along the bottom of the lake, which gets to about 27 feet at its deepest points.

 

"We don't want to churn up the bottom sediments," said Mark Norton, administrator of the Lake Elsinore & San Jacinto Watersheds Authority, explaining that carp, a non-native fish, thrive on those nutrients. "We have this huge overpopulation of carp."

 

With a surface area of more than 3,000 acres, the lake is the largest freshwater body in Southern California. But its shallow depth leads to problems with an overgrowth of algae, which depletes the amount of oxygen in the water beyond the level that fish can survive.

 

Further, the lake typically loses about 4 ½ feet of its depth per year due to evaporation, which makes its harder for the water to stave off a swampy smell or murky appearance.

 

"We've seen the lake get pea-soup green," Norton said. "One of the biggest factors of a healthy lake is having a full lake."

The watersheds authority teamed with the Elsinore Valley Municipal Water District to administer state grants from water bonds approved by California voters in recent years.

 

Lake Elsinore received $15 million from Prop. 13, which passed in 2000. Those funds paid the $2.2 million construction cost of the diffused aeration system, along with related water quality projects on the lake, such as the annual removal of carp -- 1.5 million pounds of the fish since 2002 -- and the stocking of lake with hybrid striped bass, which feed on baby carp. #

http://www.pe.com/localnews/inland/stories/PE_News_Local_C_lake31.3e99d3c.html

 

 

Local officials unveil lake aeration system

North County Times – 5/31/07

By Jose Carvajal, staff writer

 

LAKE ELSINORE -- Tiny bubbles in the lake had local officials feeling fine Wednesday as they unveiled a $2.2 million aeration system they say will improve water quality in the lake and reduce fish die-offs.

Consisting of six 4,000-foot-long pipelines strung along the bottom of the lake, the system will circulate oxygen throughout the water and thus prevent algae blooms near the surface from choking off the air supply and leading to the die-offs, officials with the Lake Elsinore-San Jacinto Watersheds Authority said.

 

When it formed in 2000, the authority received $15 million in bond money from the state to improve water quality and protect wildlife habitats in a 770-square-mile area that reaches from the San Jacinto Mountains to Lake Elsinore. The city of Lake Elsinore and the Elsinore Valley Municipal Water District, who share responsibility for the lake, are among the authority's member agencies.

 

While the authority kicked in $1.5 million from the bond for installation of the system, the city, county and water district split the remaining $700,000 evenly. The water district will operate and maintain the system, with the three agencies also expecting to split the expected $150,000 annual bill.

The installation of the system is the second phase of a two-part plan to improve the quality of the lake's water, which has traditionally suffered because of the odorous fish die-offs. The first phase called for the installation of 20 underwater fans that mix the lake's water and circulate oxygen.

Those fans, which were installed in 2004, can only do so much, said Phil Williams, president of the watershed authority's board and an Elsinore Valley Municipal Water District board member. The fans only mix water near the surface, he said, and the pipelines will help get oxygen moving farther down.

"It's basically like the bubblers people put in their aquariums to keep their fish alive," Williams said. "In essence, we're doing the same thing. It's just on a much grander scale."

The pipelines, which total nearly 9 miles of 1 1/2-inch-wide plastic pipes, are perforated every five feet with holes 1/4 of an inch in diameter. Williams said the authority spent $10,000 for the rights to use such a pattern because it had previously been patented.

The pipes are attached to 2-inch-wide pipes that can be filled with air so they can be floated to the surface for maintenance. Both sets of pipes are connected to one of two sets of compressors on opposite shores of the lake.

The compressors run automatically and are triggered by a computer that receives information from two sensors near the middle of the lake. The sensors measure the lake's temperature, salt content, pH levels and oxygen amounts. When the water reaches certain benchmarks in those categories, the compressors will come on.

On Wednesday, authority officials turned on one of the air pipelines during a media tour.

At about every 5 feet along the length of the line, bubbles could be seen rushing to the lake's surface.

Andy Komor, an engineer for the Fountain Valley-based company that designed the system, said it is not all that different from systems installed at other lakes. About 80 percent of man-made lakes have aeration systems, he said, while only about 20 percent natural lakes, including Lake Elsinore, use them.

At Lake Elsinore, Southern California's largest naturally occurring lake, the changes to the water will likely be subtle, Komor said.

"It won't turn the water from pea soup green to Aquafina, but it'll turn it from pea soup green to light green," he said.

Mark Norton, administrator for the watershed authority, said the system should help meet the ultimate goal of reducing fish die-offs.

"We want to prevent fish kills," Norton said. "That's a big part of what we do here." #

http://www.nctimes.com/articles/2007/05/31/news/californian/4_02_505_30_07.txt

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