L.S. Seigley, G.R. Hallberg, T. Wilton, M.D. Schueller, M.C. Hausler, J.O. Kennedy,
G. Wunder, R.V. Link, and S.S. Brown

Iowa Department of Natural Resources, Geological Survey Bureau,
Open File Report 92-1, 1992, 31 p.


A Nonpoint Source Monitoring Project (USEPA 319 Nonpoint Source Program) has been developed for the Sny Magill Watershed located in northeastern Clayton County, Iowa. The Sny Magill Watershed Nonpoint Source Pollution Monitoring Project, an interagency effort, is designed to monitor and assess improvements in water-quality resulting from implementation of two water-quality special projects in the watershed: the Sny Magill Hydrologic Unit Area project and the North Cedar Creek Agricultural Conservation Program-Special Water Quality Project. North Cedar Creek is a tributary to Sny Magill Creek. The project is supported, in part, by a Nonpoint Source Program (Section 319, Clean Water Act) grant from the USEPA, Region VII.

Both Sny Magill and North Cedar creeks are Class "B" coldwater streams managed for "put and take" trout fishing. The Sny Magill Watershed drains a 35.6 square mile area and is affected by water pollutants related to agricultural landuse and management, primarily sediment, animal waste, nutrients, and pesticides. A paired watershed approach is being used, with the Bloody Run Watershed (adjacent watershed to the north) serving as the control watershed. The watersheds are well suited to a paired approach; the Sny Magill Watershed drains 35.6 square miles and the Bloody Run Watershed drains 37.6 square miles. The groundwater hydrogeology and known surface water characteristics are similar; both receive groundwater baseflow from the Ordovician Galena aquifer. The watersheds share surface water and groundwater divides and their proximity to one another minimizes rainfall variation. Subbasins within the Sny Magill Watershed will also be compared, using the paired approach as well as upstream/downstream comparisons.

A primary monitoring site was established on both Sny Magill and Bloody Run and equipped with U.S. Geological Survey stream gages to measure discharge and suspended sediment. In addition, other sites on both Sny Magill and Bloody Run will be sampled for chemical and physical water-quality parameters on a weekly to monthly basis, an annual habitat assessment will be conducted along stretches of stream corridor, biomonitoring of macroinvertebrates will occur on a bi-monthly basis, and an annual fisheries survey included.