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Atascadero Lake, freshly dredged, now waits for rain to fill it up

The dredging project at Atascadero Lake has come to a close. This photo taken Oct. 29 shows the difference between the dredged portion, left, and undredged portion of the lake.
The dredging project at Atascadero Lake has come to a close. This photo taken Oct. 29 shows the difference between the dredged portion, left, and undredged portion of the lake. jjohnston@thetribunenews.com

The darkened rows of freshly tilled muck scraped from the dry bed of Atascadero Lake serve as a visible end to a dredging project that wrapped last week.

“We removed enough sediment to cover a football field 10-and-a-half-feet deep,” city public works deputy director Dave Athey said Friday.

Overall, the city has spent almost half a million dollars to haul out years of built-up bird feces and dead plant life in two rounds of dredging work to make the lake cleaner and deeper for when the rains return.

The Atascadero City Council made a big push to get the work done because city leaders said it was rare for the lake to completely dry up and would help solve years of repeated challenges that have plagued it in previous years, including dead fish, bird feces and odor as numerous algae blooms grew and decreased the water's oxygen in the hot months, killing fish and plants every few years.

At capacity, the city-owned lake, connected to Atascadero Creek, can hold up to 68 million gallons of water over about 27 acres. When it's full, its deepest point is 13 feet.

The two-phase dredging project scraped over 22 acres atop the lakebed, extending its capacity by 6 million gallons and making the lake deeper by an average of 1.5 feet, Athey said.

About five acres remain untouched near the dam and lake’s west side, Athey said, which workers weren’t able to dredge because “the consistency of the sediment was that of frosting.”

“It was just too wet, and the contractor just kept getting stuck,” he said.

The latest round of dredging removed 22,500 cubic yards of sediment.

“I can say that the sediment is a net accumulation over the last 90-plus years,” he added. “By scraping all that top layer off, we were able to get a lot of that old plant material out of there which has been causing a lot of those water quality problems we’ve been having.”

The council made dredging one of its main goals for improving the lake as residents complained about the water disappearing.

As the lake’s last drops of water disappeared, the dredging project picked up earlier this month where the city left off last fall, when it spent $70,000 on emergency dredging at the lake's south end.

The city had been waiting on permits from several government agencies that have jurisdiction over the watershed to begin the second phase.

The latest permit allowed for dredging during the month of October. Friday was the deadline to complete the second phase.

Overall, the contractor was able to get more done than planned. Original plans called for the second phase of dredging to remove 15,000 cubic yards, and the project ended up removing an additional 7,500 cubic yards. Thick piles of sediment were then transported and dumped on a Templeton Road property owned by the Atascadero Mutual Water Co., Athey said, noting that the city tested the soil and it's not hazardous. The water utility leases the property to a dry farmer in town who will use the soil to fertilize his hay fields.

Going forward, city staff says they’re looking to Mother Nature to fill the lake with water once again, which could begin this weekend with the first rain in months.

The newly formed Friends of Atascadero Lake group, separate from the city, also has plans to beautify the lake. They hosted a cleanup with the city in early October that included trimming trees around the lake’s perimeter, weeding and cutting back bushes, Athey said.

The project is now out of the dredging phase and into cleanup, which is expected to end next week. Cleanup involves restoring access on the lake perimeter path and surrounding roads and removing fencing and equipment.

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