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Ecology and salmon related articles

Pond Scum No Match for Corps

by John Stang, Herald staff writer
Tri-City Herald, September 23, 2003

Pond scum? We don't need no stinkin' pond scum.

So says the Army Corps of Engineers, which has used some high-tech gadgetry to jazz up algae-eating microbes in a formerly funky smelling pond at Pasco's Riverview Park.

The 7-acre Corps holding pond at the southern end of Pasco's 18th Avenue next to the Columbia River had accumulated an almost impenetrable 3- to 4-inch-thick layer of algae and other yucky green stuff on top.

The pond is designed to collect runoff water from yards, fields and businesses between the blue and cable bridges. A Corps pump then sends the water into the Columbia River.

The pond has been doing its job for about 50 years. But during that time, it also has collected significant amounts of phosphates and nitrates from fertilizers used in nearby yards and industry.

For decades, the algae has grown, ever wider and thicker.

The pond's entire surface had become covered with a layer of algae so thick that a flat-bottomed johnboat could not be pushed through it.

Since the sun could not penetrate, life in the 3 to 5 feet of water beneath the algae became sluggish.

Gary Snyder, head of Clean Water Research and Technology of Spokane, described the subsurface world as a can of soda that had been opened and left to sit for a long time. The carbonated bubbles fizzle away, leaving a flat liquid.

In the pond's case, oxygen bubbled away, and the pond's minnows and bluegill became lethargic. The birds that preyed on them lost interest.

And as the microbes that eat algae became almost dormant, layers of ever-thickening algae stagnated and decayed.

And stunk big time -- enough to routinely send rotting vegetation smells to the nearby ballfields, homes and businesses.

People complained to the Corps about the smell, said Jimmie Brown, environmental compliance coordinator for the Corps' Walla Walla district.

The Corps tried ways to circulate air through the pond, but nothing worked.

Finally, the Corps contracted with Clean Water Research and Technology to use a device called a water resonator.

The small solar-powered resonator -- which is mounted on a raft -- knocks loose the hydrogen atoms that were left from former water molecules. Those had latched onto water molecules, preventing any more oxygen from escaping.

The resonator enables enough oxygen to escape from the water molecules for the dormant microbes to become peppy and start munching on algae.

On Monday, after four weeks of treatment, most of the surface algae was gone. The Corps has decided to keep the resonator in place for two more weeks.

Meanwhile, the minnows and blue gill have become lively again, and river otters, pelicans and herons have returned to hunt the fish.

"The place is now teeming with wildlife," Brown said.

Related Sites:
List of 54 Pesticides under review.

John Stang
Pond Scum No Match for Corps
Tri-City Herald, September 23, 2003

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