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Longview fights Lake Sacajawea algae blooms after pandemic pause on treatment

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Lake Sacajawea algae

Algae sits on top of Lake Sacajawea on Wednesday, June 22, in Longview. Staff says the scum was partly created by the pause in invasive species prevention during the pandemic. 

There are a lot of visitors to Lake Sacajawea Park this summer, including plants the city doesn’t want there.

Longview Parks and Recreation is ramping up efforts to combat algae blooms, waterlilies and other noxious species that grow in and around the lake.

The work to eliminate the unwanted weeds preserves the health of native vegetation and, in combination with the recently-begun pumping of water from the Cowlitz River into the lake, helps to improve the lake’s appearance.

“It might be a slow change, and it might not be noticeable right away, but we’re definitely going to be tackling it as much as we can,” said Joanna Martin, Longview’s parks and urban forestry manager.

Invasive plants

Currently, no parks and recreation employees are permitted to treat invasive species.

Martin said the city fell behind on controlling the spread of invasive plants in 2020 because treating the plants was not an essential city service during the COVID-19 lockdowns. The only parks employee who had a permit to apply aquatic pesticides left the same year. Other parks employees are now in the process of testing to receive a permit.

Last year the parks department brought in a city employee from Mint Valley Golf Course who was certified to apply aquatic pesticides. Martin said the city will likely bring in the same employee this summer or find an outside agency with the right licenses.

“What we’ve been doing is trying to find experts in the field... to come and step in for a year or two, to help bring it back up to where it was,” Martin said.

The department has applied for permits from the Washington Department of Ecology to treat the algae blooms on the lake’s surface and four other species: fragrant waterlily, yellow flag iris, Eurasian water milfoil and Himalayan blackberry.

The Cowlitz County Noxious Weed Control Board maintains a list of dozens of noxious and invasive species that local governments and private landowners need to control or eliminate, including the ones Longview is focusing on at the lake.

Milfoil is considered a different class of noxious weed than the other three because of a state requirement to contain its spread. The other species were a local priority set by the county board.

Pumping water

Monday saw another measure to improve water quality in Lake Sacajawea as the city began pumping water into it. Water from the Cowlitz River comes in through the north end of the lake and flows out the south end to refresh and circulate water in the lake.

The lake pumping usually begins around May 15. Longview’s stormwater manager Steve Haubner said the start of the pumping was delayed by roughly a month because the high volume of spring rain left the Cowlitz River with too many particulates, which would work against the goal of improving the lake’s water quality.


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