QUANTIFYING LAND USE AND WATER QUALITY CHANGES WITHIN A SMALL RURAL WATERSHED IN SOUTHEASTERN OHIO (1961-2004)

The environmental impacts of agriculture and urbanization in the form of population dispersals from cities into more rural areas can be determined by assessing changes in water quality with respect to land use/land cover changes over a period of time. The North Crooked Creek watershed, approximately 11,400 acres, lies in the west-central portion of the larger Will Creeks watershed. The North Crooked Creek watershed is predominately rural but contains the village of New Concord which has a population of about 2700 (the population rises to approximately 4300 during the academic year). GIS analysis of topographic maps and aerial photographs spanning the years 1961-2004 allow for quantifying/determining any land use/land cover changes within the North Crooked Creek watershed. Preliminary analysis indicates that a complex interaction between deforestation, new forest growth, agricultural use, and acid-mine drainage/exposed mine spoils over the past forty years play a role in affecting water quality with respect to pH, specific conductance, bicarbonate, and sulfate concentrations.

Specific conductance and pH values were measured in tributaries just north and south of North Crooked Creek. Initial comparison of pH values collected in November 2007 to those last collected by the USGS in 1979-1980 show pH values in the range of 6.45 to 7.66 compared to the USGS values of 7.1 to 8.5. Specific conductance values are highest (1632 microsiemens) closest to the spots of acid-mine drainage/exposed mine spoils in the eastern portion and decrease downstream. In the southwestern portion of the subwatershed, two tributaries in an identified agricultural zone initially tested with pH values of 6.89 and 6.90 and the two lowest specific conductance values (465 and 391) so far. High pH, specific conductance, and sulfate concentration values (or conversely, low bicarbonate values) are often associated with surface mining and acid-mine drainage within a subwatershed. Acid-mine drainage is often the cause of poor water quality within the Wills Creek watershed, and within the North Crooked Creek subwatershed extremely localized spots of acid-mine drainage/exposed mine spoils are found in the northern and eastern portions.