Several hundred people showed up on Aug. 18th for the 7th Annual Secchi Day on Beaver Lake, the source of drinking water for more than 400,000 Arkansans. In all, 33 teams of concerned citizen scientists participated, and 35 potential sampling sites were sampled, most in duplicate. Secchi depth is a measure of water transparency that involves lowering a black and white disk into the water and recording the measurement when the disk is no longer visible.
Extreme drought conditions in 2012, opposed to the heavy spring rains and flood discharge of 2011, yielded greater Secchi depths from the Horseshoe Bend area of Beaver Lake to Beaver Dam, according to Dr. Robert Morgan, Manager of Environmental Quality for Beaver Water District. The greatest Secchi depth was at Beaver Dam yielding 5.65 meters (approximately 18.5 feet), and the lowest Secchi depth was at the War Eagle arm yielding 0.35 meters (just over 1 foot). This year’s results were similar to 2007, which was one of the region’s other dry years. In addition to Secchi depth readings, water samples are analyzed by Beaver Water District’s lab technicians. The technicians measure chlorophyll a, total phosphorous, and nitrate in each of the water samples. Chlorophyll a is a pigment in algae that is used to measure the density of the algal population in water. Phosphorous and nitrate are both nutrients that promote algal growth. See a full report on results at http://www.bwdh2o.org/wp-content/uploads/2012/12/Secchi-Day-2012-Results.pdf.
Secchi Day on Beaver Lake is made possible by 11 partners including Audubon Arkansas, Beaver Water District, the U.S. Army Corps of Engineers-Beaver Lake, the U.S. Geological Survey, the University of Arkansas Cooperative Extension Service, Hobbs State Park, Arkansas Master Naturalists, the Association for Beaver Lake Environment, Beaver Watershed Alliance, Arkansas Game & Fish Commission, and Ozarks Water Watch. Secchi Day is one of the premiere water public awareness and education events in Arkansas. Next year’s event will be held on Aug. 17, 2013.