Beaver Water District’s (BWD) professional laboratory staff have completed the analysis of collected water samples from BWD’s 16th Annual Secchi Day on Beaver Lake. The event was held Aug. 21, 2021, with the help of dedicated volunteers. “This year, we had 25 sampling teams collecting data and water samples at 31 of our normal 35 sites,” said Dr. James McCarty, Manager of Environmental Quality. “Poor weather conditions hampered efforts to collect data in the areas near Indian Creek and Beaver Dam.” Secchi Day is named for the Secchi Disk, a black and white device lowered into the water to measure transparency.
The task of sampling teams is to take Secchi depth readings to determine water transparency. Teams also collect water samples at each site that are analyzed for chlorophyll-a, total phosphorus, and total nitrogen to determine algal density and nutrient concentration. Secchi depth is the maximum depth at which the alternating black and white pattern can be distinguished from above the water’s surface. Matthew Rich, Environmental Specialist with BWD, spoke about results and data from Secchi Day with the BWD’s Board of Directors at their monthly meeting held on Oct. 21. “Secchi depth is not only affected by the amount of nutrients and sediment within the lake, but also weather conditions above the surface of the lake,” Rich said.
“Windy and rainy conditions will reduce the ability to see the Secchi disk because of wave action generated by rough weather. In addition, clouds that produce the rainstorms will block incoming sunlight, further reducing Secchi depths. While we did see some reduction in water transparency as compared to last year’s data, the change was minimal and well within the range that we ordinarily see. This type of result really highlights the importance of understanding year-to-year variability of these water quality parameters.” After 16 years of data collection, Dr. McCarty said despite the less-thanideal weather for Secchi Day 2021, long-term averages of Secchi Day data show the high level of water quality in Beaver Lake is being maintained.