HYDROGEOLOGIC INVESTIGATIONS OF THE SILVER LAKE WETLAND, MIAMI COUNTY, OHIO

A water quality study was conducted to determine the quality of surface and ground water at the Silver Lake wetland site, located in western Miami County, Ohio. The study area consists of a constructed wetland, which is undergoing environmental monitoring to assess whether or not the site is meeting the criteria to be designated as a wetland. This site is located on weathered glacial till and lacustrine deposits which overlie thick deposits of outwash sand and gravel. The site was originally part of an extensive wetland area, prior to being drained and extensively farmed. To assess the water quality and functionality of the wetland, water samples were collected from ten sites: Seven shallow monitoring wells, two streams which flow into the wetland site, and the discharge point of a pond at the end of the wetland. These ten sites were sampled four times during 2011to document seasonal changes in water quality. The pH, temperature, specific conductance, oxidation reduction potential (ORP), and total dissolved solids (TDS) of the samples were determined in the field using a Myron Multimeter. The concentrations of nitrate, ammonia, and phosphorus from the ten sites were analyzed at the Ohio State University’s Star Lab. The water samples collected in September were analyzed for a full suite of water quality parameters, to determine the water quality of the surface and ground water flowing into and out of the wetland site. This data was also used to construct a Piper Diagram to characterize the general water quality of the surface and ground water. In addition, this study assesses the effectiveness of the constructed wetland site in treating nutrients, such as nitrate, which flow into the wetland from adjacent farms and residences. By the time the water flows out of the wetland site, significant quantities of nitrate are removed from the surface water. Our study found that nitrate removal ranged from 98.4% in the spring, to 39.1% in the fall, and is likely a result of the combined natural processes of denitrification, ammonification, mineralization, filtration and plant up-take (Reinhardt 2006, Chemistry Daily 2010).