Algae less of a problem thanks to more river water in Moses Lake

MOSES LAKE — Blue-green algae and a toxin associated with it has been much less of a problem this year in Moses Lake, in large part thanks to higher flows of Columbia River water through the lake.

“There have been lower levels of toxin,” said Stephanie Shopbell, an environmental health manager with Grant County Health District. “Algae blooms have not been as widespread.”

The toxin microcystin can be dangerous to animals and fish, and is created when cyanobacteria die. Large green algae blooms have been common on parts of Moses Lake in the last few years, prompting the health district to post warning signs telling people not to have contact with the lake water.

Both Shopbell and Harold Crose, a resource conservationist with Grant County Conservation District, attributed the better conditions in Moses Lake to more Columbia River water flowing into and through the lake.

“We’ve seen an increase in clean Columbia River water this year,” Crose said. “We’ve also had a cooler spring, so the algae blooms were later in the season.”

“The Bureau of Reclamation ran more water through this year, and that has helped,” Shopbell said.

According to Chris Overland, executive director of the Moses Lake Irrigation and Rehabilitation District, the U.S. Bureau of Reclamation — which oversees the operation of the Columbia Basin Project — has run nearly 74,000 acre-feet of water more through Moses Lake so far this than it did last year.

Overland said the Bureau has run about 187,000 acre-feet of water from the East Low Canal through the Rocky Coulee Wasteway and into Moses Lake, an increase from last year’s 113,000 acre-feet and the most since 2016, when the Bureau ran nearly 190,000 acre-feet of water through the lake.

Especially helpful has been the 30,000 acre-feet the Bureau has flowed through the lake since the beginning of August, Overland added.

The U.S. Bureau of Reclamation uses Moses Lake to deliver water to Potholes Reservoir, which in turn is delivered to customers of the South Columbia Basin Irrigation District in Grant, Adams and Franklin counties.

Typically, the Bureau has used Rocky Coulee Wasteway to deliver water to Moses Lake from the East Low Canal. However, as more smaller canals and pipe systems are being built to deliver irrigation water to farmers in the eastern portion of the project as a replacement for aquifer water, the Bureau has been testing the ability of Crab Creek to deliver water through Moses Lake to South District irrigators.

The algae blooms are attributed to high levels of phosphorous — an essential nutrient for the algae, which are a type of bacterium — in both the lake water and sediments on the bottom of the lake. One side effect of using the lake to deliver river water to irrigators is that it lowers the phosphorus levels in parts of the lake.

“It just continues to reaffirm that the main part of the lake is heavily influenced by the Bureau of Reclamation,” Crose said.

Shopbell said that with the health district busy dealing with the COVID-19 pandemic, the district has reduced testing to two sites once each week, varying the testing among a southern point near Sand Dunes, Cascade Park, Blue Heron Park, Peninsula Park, Montlake Park and Neppel Landing.

Charles H. Featherstone can be reached at cfeatherstone@columbiabasinherald.com.