T238 Geochemistry of Urban Environments (Posters)

Wednesday, 7 November 2012
9:00 AM - 6:00 PM
Hall B

SEGMENT ANALYSIS OF CASTLE CREEK, A SMALL, URBAN & AGRICULTURAL WATERSHED, GENEVA, NEW YORK

Paper number: T238-8
Program: Technical Sessions
Time: 9:00 AM – 6:00 PM

Authors

Abstract

Streams naturally change from the headwaters to the terminus and between event and base flow conditions. Anthropogenic modifications to the landscape also impact the characteristics of the stream and its water quality. Here, we present preliminary water quality analyses of Castle Creek, a small (17 km2) watershed within the Seneca Lake watershed in central New York State to investigate how its water quality changes between event and base flow conditions, and from agricultural to urban environments. Four sites along the creek were sampled on June 12 and 14. The first date sampled a precipitation/runoff event, whereas the second date sampled base flow conditions. On each date, a four site segment analysis investigated point and nonpoint sources along the stream course. Three sites were located in Geneva, the creek terminus, upstream of the subterranean portion of the creek, and farther upstream. The farthest upstream site was at the boundary between the urban and the agricultural-rich headwaters. At each site, discharge, temperature, conductivity, dissolved oxygen, pH, and alkalinity were measured onsite, and water samples were brought back to the lab to measure total suspended solids, total phosphate, soluble reactive phosphate, nitrate, dissolved silica, and major ions following standard limnological techniques.

The stream changed dramatically between event and base flow conditions. Discharge, temperature and total suspended solids decreased; alkalinity, nitrates, dissolved silica and conductivity increased; and, dissolved oxygen and phosphates remained the same from event to base flow conditions. It suggests that the warmer precipitation diluted the input of major ions, nitrates, silica and other groundwater-fed parameters, and increased the input of suspended sediment from runoff. The flux of each parameter was larger during the event than base flow. Stream discharge, temperature, phosphates and suspended sediments increased, whereas alkalinity, conductivity and pH decreased downstream from the agricultural landscape and through the urban environment during the precipitation/runoff event. Minimal change was noted along the stream course during base flow. The data indicate that water quality in this small watershed change primarily in response to events but require additional study.