Dredging to start in Atascadero Lake to clear out dead plants

The island no longer has water around it at Atascadero Lake.
The island no longer has water around it at Atascadero Lake. dmiddlecamp@thetribunenews.com

Dead plants and gunk that have settled in the bottom of Atascadero Lake over the years will be dredged, starting Monday, to help improve the health of the drought-plagued waterway.

The move comes two months after a massive fish die-off when the lake’s murky mix of hydrogen and oxygen, warmed by soaring summer temperatures, killed the perch and carp that live there.

The issue is a reoccurring problem for the city-owned lake, which is connected to Atascadero Creek and is dependent on rain.

Its hot-weather problems crop up when algae blooms grow and decrease the water’s oxygen levels, producing a stinky, low-level environment. Hundreds of fish died in 2001, and about 30 more died in 2008.

But this year’s dead fish catastrophe was the worst the city has ever seen. An initial city estimate that hundreds of fish had died has now ballooned to 2,000 to 3,000 dead fish, Public Works Director Russ Thompson said.

After residents complained about the lake’s low water levels, the City Council said Atascadero couldn’t afford to fill it with water because of the estimated cost of at least $500,000. Instead, the council opted to focus on the lake’s long-term health over quick fixes and authorized spending $70,000 to dredge the lake to make it deeper and cleaner when the rains return.

But the city first had to obtain state permits, which Atascadero recently received, to start the work. In the summer, the city also installed three floating fountains designed to produce more oxygen in the water.

The dredging process will take about a week and involve an agricultural tractor pulling a scraping box, Thompson said.

“The scraper lifts the sediment into a large boxlike device that will then move the dirt to a stockpile along the side of the lake,” and then be hauled away, he explained.

Viborg Sand & Gravel Inc. of Paso Robles was contracted for the work. Paso Robles-based biological consultant Althouse & Meade Inc. was also hired to monitor the lake’s inhabitants such as birds, fish and plants during the dredging process.