The Columbian | Serving Clark County, Washington

A new $750,000 study will examine the plumbing of Vancouver Lake.

The study, jointly funded by the U.S. Geological Survey and local agencies, marks the latest effort to understand the lake before trying to clean it up. By better understanding how the lake functions, local authorities hope to reduce the toxic blooms of blue-green algae that routinely prompts summertime health warnings against swimming or water contact.

The lake, which is checked regularly for toxic blooms, currently is open for swimming.

“I know nobody wants to study the lake forever,” said Ron Wierenga, director of Clark County’s Clean Water Program. “We feel that this USGS study is going to fill the most significant data gap, to at least send us in a direction to come up with reasonable management alternatives.”

Those alternatives could include targeted programs to retrofit stormwater drainage systems, inspect septic systems, or otherwise curtail precursor chemicals such as nitrogen or phosphorus used in fertilizers.

“Those are expensive,” Wierenga said. “You need to be as sure as you can be that it’s going to get you the outcome you want.”

The three-year study will begin this summer with the commission of three new water gauges on Lake River, Burnt Bridge Creek and the flushing channel.

Sophisticated gauges will be able to measure the volume and velocity of water as it flows both in and out of the flushing channel and Lake River. A more traditional stream gauge will be placed in Burnt Bridge Creek, which flows into the shallow lake. Researchers also will look for smaller sources, such as irrigation ditches and storm drains.

In the years ahead, researchers will survey groundwater discharge, analyze lake-bottom sediments and estimate the level of potential pollutants falling into the 2,300-acre lake from rainwater.

“It’s not a simple bathtub system, where it’s water in and water out,” Wierenga said.

Vancouver Lake is fed by Lake River, Burnt Bridge Creek and a flushing channel created by the Army Corps of Engineers in 1983 to mimic the natural flushing action provided by the Columbia River before settlement. Lake River itself collects runoff from a series of streams coursing through a wide swath of west Clark County, most notably Salmon Creek. Although Lake River typically flows out of the lake, it backs up when the Columbia is swollen with high water flowing out or tides pushing in.

Much of the phosphorus, for instance, could be embedded in the lake sediment. In that case, it would be relatively easy for wind to stir up material from the lake bottom that’s only 3 to 5 feet below the water surface.

The county, city of Vancouver and Port of Vancouver are splitting the $405,500 local share of the study, with the USGS contributing $346,100 through the agency’s cooperative water program. The local agencies are part of the Vancouver Lake Watershed Partnership, a coalition of local government agencies and citizens that formed in 2004 to address chronic water quality problems.

Erik Robinson: 360-735-4551, or erik.robinson@columbian.com.

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