Rogers-Lowell Area News

Beaver Lake “Secchi Day” Data Released; Citizen Scientists Helped Beaver Water District Collect Samples

On Aug. 19 for the 12th year in a row, volunteer citizen scientists collected water quality data on Beaver Lake near Rogers in Northwest Arkansas during the annual Secchi Day event, always held on the third Saturday each August. Beaver Water District (BWD) staff then analyzed data and produced a report that helps answer this question: How is the water quality in Beaver Lake doing?

Matthew Rich, Environmental Specialist with Beaver Water District (BWD), spoke about results and data from Secchi Day with attendees at the regularly scheduled meeting of the Northwest District of the Arkansas Water Works & Water Environment Association (AWW&WEA) meeting held Wednesday (Oct. 11, 2017) in Eureka Springs.

During Secchi Day, sampling teams take Secchi disk readings to determine water clarity, and collect water samples which are tested for chlorophyll-a, total phosphorus, and nitrate, to determine algal density and nutrient concentration. Secchi depth is a measure of water transparency that involves lowering a black and white disk into the water and recording the maximum depth in which the black and white pattern can be distinguished from above the water’s surface.

“After 12 years of collecting data, we are finally getting a picture of the variability in water quality at the different sites,” Rich said. “On Beaver Lake, as you travel from Hwy. 412 bridge to the dam, chlorophyll-a decreases and Secchi transparency increases. This is because as water moves through the lake, nutrients are used up and suspended particles like sediment and algae fall to the bottom, making the northern part of the lake less productive.”

This year’s data shows that most water quality parameters were fairly close to the 12-year average. The average lake Secchi depth this year was around 9 feet, which is slightly higher than the long-term average of 8.8 feet. The average lake chlorophyll-a this year was 6.39 parts per billion (ppb) which was slightly lower than the longer term average of 7.32 ppb. Both of these values point to 2017 as being a year with better than average water quality. However, there are a lot of factors that play into those numbers and the amount and timing of rainfall is one of the largest contributors.

“Secchi Day started as a way to engage citizen scientists but has given us some really good data. We are committed to the long haul on this data and will likely only start to see trends play out on timescales of multiple decades. As the watershed around the lake changes, Secchi Day is there as a measure of how the lake will respond to that change,” Rich said.

James McCarty, BWD’s Manager of Environmental Quality, added that “Secchi Day is only one example of the work we do. In fact, all year-round BWD, the United States Geological Survey, the Arkansas Department of Environmental Quality and the Arkansas Water Resources Center collect data on Beaver Lake and its tributaries. Nutrient loads to Beaver Lake are a major driver of algae production so we work with many different partners to encourage programs that monitor for and help to reduce sources of nutrients. For example, just this last year, BWD and partners assembled an $8.6 million multi-year grant to reduce sources of nutrients in the West Fork of the White River, a major tributary to Beaver Lake.”

To read this year’s Secchi report, link to BWD’s website at bwdh2o.org then go to the Secchi Day page here (https://www.bwdh2o.org/education-outreach/secchi-day/) and the report will be on the bottom left. Next year’s event will be held on Aug. 18, 2018. Secchi Day on Beaver Lake is made possible by 12 partners including BWD, the U.S. Army Corps of Engineers-Beaver Lake, the U.S. Geological Survey, the University of Arkansas Cooperative Extension Service, Northwest Arkansas Stormwater, Hobbs State Park, Northwest Arkansas Master Naturalists, Beaver Watershed Alliance, Arkansas Game & Fish Commission, Ozarks Water Watch, One Community, and Girl Scouts Diamonds of Arkansas, Oklahoma and Texas. Secchi Day is one of the premiere water public awareness and education events in Arkansas.