Eight Years Not Enough to Determine Beaver Lake Quality

After eight years of testing for water quality, it’s still too soon to determine if Beaver Lake is improving or not. That’s the latest word from Beaver Water District, the public utility that supplies drinking water to more than 300,000 customers in Northwest Arkansas.

Each August, the district measures water quality during its event called Secchi Day. During the event, black and white Secchi disks are lowered at different points throughout the lake. The depth at which the disk is no longer visible is called the Secchi depth.

This year, the greatest depth, and thus, the greatest water clarity, was 18.04 feet at Quarry Cove. The lowest depth of .98 feet was recorded at the confluence of the White River and Richland Creek.

Volunteers are an important factor during Secchi Day, as is a partnership of private, state and federal agencies.

The district also tests for Chlorophyll a, total phosphorous and nitrate. Chlorophyll a is a pigment in algae used to measure the density of the algal population in water. Phosphorous and nitrate are both nutrients that promote algal growth.

What’s for certain is that water transparency is higher during drought years than in flood years, said Dr. Bob Morgan, the district’s manager of environmental quality.

Morgan also said that water transparency is negatively affected by the level of algae in the water: the higher the level of algae, the lower the Secchi depth.

“These data are consistent with the scientific literature on reservoirs and a confirmation that our citizen science is working,” Morgan said.