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Monitoring the Variability of Surface Water Sites

Three surface water sites in eastern Iowa (see map below) were monitored on a daily basis in order to evaluate the variability of selected parameters through time in Iowa streams.  The variability of pesticides, nitrogen, phosphorus and bacteria was evaluated through a 90-day period including part or all of May, June, July, and August, 2000.  Sites that were monitored include Old Man's Creek near Sharon Center (Johnson County), the English River at Riverside (Washington County), and the Iowa River at Marengo (Iowa County).  In addition to sampling for common herbicides, water samples were collected and sent to Aventis CropScience, where isoxaflutole (Balance™) were analyzed and reported to the Iowa Department of Natural Resources.  Samples are analyzed for the parent compound of Balance and its two degradates.

In addition to these three sites, the 60 monthly surface water sites were sampled for Balance during May, June, and July 2000.

Red dots represent the three intensive monitoring sites for the Old Mans Creek watershed (yellow), the English River watershed (gray), and the Iowa River watershed (green). Blue represents the rivers in Iowa.

Watershed Characteristics

  Old Mans Creek
 (Johnson Co.)
English River 
(Washington Co.)
 

Iowa River 
(Iowa Co.)

 

Drainage Area (mi2) 201 627 2787
Basin Length (mi) 34.3 63.8 146.2
Average Basin Slope (%) 6.0 5.7 3.6
Main Channel Length (mi) 42.0 100.1 269.7
(including East and West Branch Iowa River)
Landuse Percentages (%)      
Artificial 0.8 0.5 0.9
Barren 0.3 0.4 0.5
Grass 38.0 39.0 23.1
Row Crop 56.1 54.6 70.9
Water 0.1 0.1 0.4
Forest 4.7 5.4 4.2

For more information, contact Mary Skopec at (319) 335-1579 or mary.skopec@dnr.iowa.gov.