IDENTIFICATION OF NUTRIENT SOURCES IN TWO OWASCO LAKE TRIBUTARIES

Owasco Lake is critical to the agricultural and tourism-based economy, and it supplies drinking water to ~44,000 people; however its water quality was consistently ranked as one of worst Finger Lakes over the past decade. Its residence time of 1-3 years indicates that it is quick to pollute but also quick to cleanup if proper remediation efforts were employed. Two streams, Dutch Hollow Brook and Owasco Inlet which collectively drain 70% of the watershed, were sampled to delineate point and non-point sources and other factors affecting delivery of nutrients to the lake. Identification of pollutant sources would dictate mitigation and remediation efforts to improve water quality in the lake.

We sampled eight sites along Dutch Hollow Brook and ten sites along Owasco Inlet every two weeks starting in March. Stream water was analyzed on-site for temperature, pH, conductivity, alkalinity, dissolved oxygen and stream discharge. Additional water was collected and analyzed in the lab for total phosphates, total suspended solids, silica, nitrates, and soluble reactive phosphate following standard limnological techniques. A companion study presents results from an autonomous sampler and stage recorder at Dutch Hollow Brook.

The 2011 data compared to earlier years, revealed larger flow, concentrations and fluxes, especially in Owasco Inlet. The trend parallels increased amounts of precipitation during the spring of 2011. Nutrient concentrations and fluxes (SRP, TP, TSS, and conductivity) were larger at the Benson trib. and South sites, both drain agricultural-rich land, and at Moravia and County Line sites. In contrast, concentrations and fluxes were lowest at Mill and Fillmore Creeks, which are buffered by forested land. Thus, runoff from agricultural land is a major non point source in the Owasco watershed.

The Benson tributary drains a large CAFO operation. We recommend the installation of buffer strips along this tributary, which could reduce nutrient-rich runoff. County line is probably affected by an aging waste water treatment plant, though to a lesser degree than in the past. It recently installed technologies to reduce phosphate from the effluent.

We suggest that Owasco Lake residents support mitigation and remediation within this tributary’s watershed to see if nutrient loading is reduced in the future.