Date of this Version
Environmental Studies Undergraduate Student Thesis, University of Nebraska-Lincoln, 2021.
The relationship of land use categories and water quality was explored in three different streams in the tri-state area of Nebraska, Iowa, and Missouri. These streams included: a fourth order stream, Salt Creek, near Waverly, NE, a third order stream, Maple Creek, near Nickerson, NE, and a sixth order stream, Nodaway River, near Graham, MO. Stream order was to be kept relatively low due to the impact tributary rivers have on a given stream's nitrate concentration. Nearby land use is expected to impact nutrient concentrations to a greater extent for smaller rivers than on larger rivers with more tributaries. First, all streams' nitrate concentrations were assessed over a 20 year period. Nitrate levels were considered on a milligram per liter basis from filtered stream water. Next, land use categories were considered within a 11,500 acre area around the stream testing site. Nearby land use in each of the three sites were predominantly corn acreage (CA), Soybean Acreage (SA), and Pasture Acreage (PA). Land use was assessed from the years 2001 through 2020 in the Salt Creek and Maple Creek locations while land use was assessed from the year 2006 through the year 2020 in the Nodaway River location. Significant correlations were not found in the Salt Creek and Nodaway River locations. However, significant correlations were found between land use categories and nitrate concentrations in the Maple Creek location. CA was found to be positively correlated with nitrate levels in the Maple Creek location with a correlation factor of 0.49. PA was found to be negatively correlated with nitrate levels in the Maple Creek location with a correlation of -0.51. Stream order and proximity to a large city may have impacted the results found in the Salt Creek and Nodaway River locations. Just upstream from the Salt Creek locations is the city of Lincoln, NE, a potentially large source of urban runoff. Nodaway River was the largest stream that was examined, so the potential effects of tributary river nitrate concentrations may have impacted the magnitude of effect of nearby land use.