THE IMPACT OF LAKE STRATIFICATION ON BIOGEOCHEMICAL CYCLING AND DOWNSTREAM WATER QUALITY: CASE STUDY OF WALKER AND FAYLOR LAKES IN SNYDER COUNTY, PA

In recent years, dams have received extensive scrutiny for their effects on stream and river systems throughout the United States. Dams vary greatly in size and scale, but investigations often focus on large-scale dams because of their visibility in the public eye and pronounced impact. This can result in smaller and less impactful impoundments being overlooked, despite the cumulative impacts these dams can have on higher order water systems. Two small water impoundments; Walker and Faylor Lakes located respectively on the north and west branches of Middle Creek in Snyder County, Pennsylvania have demonstrated an impact on Middle Creek. This study focused on using onsite physical properties and grab samples for chemical analysis in the laboratory to determine the effects of the two impoundments on their streams. To further correlate the physicochemical results, kick sampling for benthic macroinvertebrates were also used to build a comprehensive understanding of the impact of the two impoundments on their respective stream system. Both upstream and downstream sites from the dams were sampled. All sites were checked for T^o, pH, Ke, DO, TDS, ORP, COD, BOD₅, F, Cl, NO₂^-, SO₄^2-, NO₃^-, P, K, NH₄⁺, K, Mg²⁺, and Ca²⁺. All parameters; were positively correlated. Data show that the physical and chemical changes to the streams, are caused by the dams and are affecting the biological communities in the downstream water course. Walker Lake was found to have a much greater negative impact on the north branch of Middle Creek and significantly degraded the water in relation to certain parameters due to seasonal thermal stratification and the geomorphology of the reservoir. BOD₅ and NH₄⁺ concentrations were found to be significantly higher downstream of Walker Lake with respect to upstream of both branches and downstream of Faylor lake. An increase in Hillsenhoff Index scores, and pollution-tolerant taxa as well as a decrease in Shannon Diversity Index numbers, were also observed downstream of Walker Lake when compared to upstream of both branches and downstream of Faylor Lake. Faylor Lake Dam did not have a significant impact on the west branch of Middle Creek.