Nine years. That’s how long citizen scientists and others have collected water quality data on Beaver Lake during the annual Secchi Day event. So, is Beaver Lake water quality staying constant, or is it improving or degrading? Dr. Bob Morgan, Manager of Environmental Quality for Beaver Water District, shared some comments with regard to this year’s data collection, which took place on Aug. 16th. Beaver Water District supplies drinking water, sourced from Beaver Lake in Northwest Arkansas, to more than 300,000 people.
“We had eight new volunteer sampling teams join us this year for our 9th annual Secchi Day,” he said. “Overall, 27 teams covered 35 sample sites throughout Beaver Lake. We’re especially pleased that many of our dedicated teams have been participants every year since this event started in 2006.”
Morgan explained that teams collect water samples and take Secchi disk readings to determine water clarity. Secchi depth is a measure of water transparency that involves lowering a black and white disk into the water and recording when the disk is no longer visible.
This year, the greatest Secchi depth of 3.61 meters, or approximately 11.84 feet, occurred at Hall Spring Branch near Starkey. The lowest depth of .58 meters, a bit less than 2 feet, was measured at the confluence of the White River and Richland Creek.
Technicians in the District’s lab analyzed each of the water samples. Morgan said one laboratory test is to determine levels of chlorophyll a, a pigment in algae that is used to measure the density of the algal population in water. Samples also are tested for phosphorous and nitrate, also referred to as “nutrients” that promote algal growth.
“Secchi Day results were mixed this year. Overall, Secchi readings across the entire lake were less than average, 2.44 meters versus the long term average of 2.68 meters,” Dr. Morgan said. “However, the results depended upon where in the lake measurements were taken. In the upstream reaches of the lake (those areas furthest from the dam), the readings were just slightly deeper than average at 1.36 meters compared to 1.29 meters as the long-term average. The mid-reaches of Beaver, roughly from Hickory Creek to Highway 12, were also better than average. But north of Highway 12, practically all of the readings were lower than average.”
Morgan said this was unexpected, since 2014 has been a low-rainfall year. However, the chlorophyll data were more as expected for a dry year, with all but two sites having less chlorophyll than average.
“Secchi results may have been skewed by the choppy conditions on the lake and the broken sunshine, making readings hard to obtain,” he said. “It is still hard to say if the quality of water in the lake is constant, improving or degrading. It is likely safe to say that water quality is not constant. But, making a determination of an improving or degrading trend will require more data. What we have now is a real good baseline of where Beaver Lake was in the early 2000s.”
Secchi Day on Beaver Lake is made possible by 10 partners including 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. 15, 2015. To read this year’s Secchi report, link to the District’s website at bwdh2o.org.
About Beaver Water District
Beaver Water District’s mission is to serve our customers’ needs by providing high quality drinking water that meets or exceeds all regulatory requirements and is economically priced consistent with our quality standards. For more information, visit www.bwdh2o.org.