Dissertations and Theses @ UNI


Open Access Thesis


Nonpoint source pollution--Cedar River Watershed (Minn. and Iowa); Land use--Cedar River Watershed (Minn. and Iowa); Land use.; Nonpoint source pollution.; United States--Cedar River Watershed.; Academic theses;


A comparative water analysis on major Cedar River tributaries was conducted to determine nutrient and sediment concentration, nutrient loads, and watershed land use during the spring and summer of 2002. The Cedar River watershed is located on a primarily agricultural land, and has a drainage area of20,242 km2. The watershed extends from southern Minnesota to southeastern Iowa, where it joins the Iowa River which subsequently flows into the Mississippi River. Past studies have concluded that the Cedar River contributes much of the nutrients entering the Mississippi River and the Gulf of Mexico. These nutrients then contribute to the zone of hypoxia in the Gulf.

From April 28, 2002 until September 28, 2002, weekly samples were taken from six of the eight major tributaries that contribute flow to the Cedar River. Discharge data were obtained from continuously monitoring U.S. Geological Survey stations. Measured water quality parameters were those found in highly agricultural watersheds, including nitrate-N, total dissolved phosphorus (TDP) and suspended sediments in the water column, and sediment phosphorus in the bedload. Watershed land use data were obtained from 2002 Landsat satellite photography.

The results of this study indicate that of the six tributaries studied, Black Hawk Creek had the highest average nitrate-N (8.2 mg/L), sediment P (355.1 µgig), and suspended sediment (438.1 mg/L) concentrations. Black Hawk Creek also had the highest percentage of row crop agriculture (82%). Beaver Creek had the highest average total dissolved P concentrations (136.5 µg/L). This study concluded that the most impaired water body entering the Cedar River during this investigation was Black Hawk Creek. Regression analysis between water quality variables and land use indicates that water quality is dependent on certain watershed characteristics. The most statistically significant relationship was the negative correlation between nitrate-N concentrations and watershed areas (p value = 0.0078). The other highly significant relationship was the negative correlation between suspended sediment concentration and Conservation Reserve Protection (CRP) acreage (p value= 0.0151).

Future studies of water quality and watershed land uses should take into consideration more than row crop percentages. Also, suspended sediment load should be quantitatively investigated.

Year of Submission


Degree Name

Master of Science


Department of Earth and Environmental Sciences


Department of Earth Science

First Advisor

Mohammad Z. Iqbal


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Date Original




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