Sny
Magill Watershed Project: Clayton County, Iowa
Nonpoint source pollution originates from diffuse areas, such as urban streets, lawns, and farm fields, and is considered to be the major impediment to improved water quality in the U.S. In an agricultural state such as Iowa, nonpoint pollution affects most of Iowa’s streams and water bodies. Since 1991, the Sny Magill Creek Watershed has been the focus of an interagency effort to bring about voluntary changes in farm management practices that reduce nonpoint source pollution, and to monitor and measure the resulting improvements in water quality.
Water Quality Concerns
Sny Magill Creek, located in northeast Iowa, is one of 25 coldwater streams identified by the state of Iowa as a priority concern. Impairment of its water quality is primarily a result of nonpoint agricultural sources, particularly sediment, animal waste, nutrients, and pesticides.
Sny Magill Creek is one of the more widely used streams for recreational trout fishing in Iowa. It drains a 22,780-acre agricultural watershed consisting of row crops, pasture, forest and forested pasture, and farmsteads. There are approximately 140 dairy, beef, and swine producers in the watershed.
The watershed is characterized by narrow, gently sloping uplands that break into steep slopes with abundant rock outcrops. Up to 550 feet of relief occurs across the watershed. The stream bottom of Sny Magill and its tributaries is primarily bedrock and gravel with frequent riffle areas. Along the lower reach of the creek where the gradient is less steep, the stream bottom is generally silty. Sny Magill Creek empties into the backwater wetlands of the Upper Mississippi River Wildlife and Fish Refuge and part of Effigy Mounds National Monument.
Improvements in water quality from the implementation of extensive Best Management Practice (BMP) methods have been observed in two recently completed, smaller scale projects in Clayton County: Ensign Hollow and North Cedar Creek (a tributary to Sny Magill Creek). BMPs are designed to reduce the amount of pollutants -such as sediment, nitrogen, phosphorus, and animal wastes - that enter surface water or groundwater. Increased rates of natural reproduction of brown trout have been documented in Ensign Hollow and are attributed to BMP implementation. Sedimentation and fecal coliform rates have been lowered in North Cedar Creek, increasing the creek's ability to support brook trout reproduction.
Project Development
Building on successes at Ensign Hollow and North Cedar Creek, the Sny Magill Watershed Project began in 1991 as an interagency effort to encourage landowner adoption of a wide variety of BMPs, as well as to monitor and quantify improvements in water quality.
Project Objectives
Current BMP implementation objectives and their progress to date include:
* Achieve a 50% reduction in sediment delivery to Sny Magill Creek.
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Figure 1. Contour terraces and contour stripcropping are best management practices (BMPs) designed to reduce soil erosion. Photo by Dwight Stapher, Clayton County Soil and Water Conservation District. |
Estimates based on the Universal Soil Loss Equation suggest that as a result of implemented BMPs, sediment delivery to Sny Magill Creek has decreased over 33% since 1991. The BMPs preferred by landowners are contour terraces, water and sediment control basins, contour stripcropping, and conservation tillage (Figure 1).
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Figure 2. Soil bioengineering techniques (use of living plant materials) were adapted to stabilize part of the Sny Magill Creek streambank. Photo by Charles Wittman. |
Streambank erosion is a major source of sediment. Demonstrations
that utilize multiple bank-stabilization techniques, ranging from
willow posts to rock rip-rap, have been initiated (Figure 2).
* Reduce manure runoff to Sny Magill Creek through development of 30 animal manure management systems.
Many landowners have adopted proper manure management and utilization practices because of their low cost and the economic benefit of proper nitrogen and phosphorus crediting in an overall nutrient program.
* Accelerate the adoption of refined crop and manure management practices that reduce agricultural pollution potential in the watershed.
Integrated Crop Management (ICM) methods are being used to assist producers with the adoption of refined crop-management practices. A project coordinator served as a crop consultant and hired a crop scout to make field observations. This activity resulted in 39,450 pounds less nitrogen, 33,625 pounds less phosphate, 128 pounds less alachlor (herbicide) and 1,450 pounds less corn rootworm insecticide being applied annually in the watershed. The cost savings to the producers involved with the ICM activity is averaging $13.85 per acre per year.
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Figure 3. Education plays a vital role in meeting the nutrient and pest management needs of area farmers. Photo by Charles Wittman. |
An education-based Nutrient and Pest Management Program was
developed to help smaller producers refine crop-management
practices on their own. Workshop sessions are used to instruct
producers on proper soil-sampling techniques, soil-test
interpretation, manure nutrient management, fertility planning,
and pest management (Figure 3). Producers then develop and
implement their own crop management plan.
* Develop a series of demonstrations to educate the watershed's producers and the public at-large about water quality issues.
Several field demonstration sites in the watershed focus on proper nutrient and pest management, tree plantings and other forestry practices, and pasture and manure management practices. A packet of information for current Conservation Reserve Program (CRP) landowners is being developed that identifies alternative land-use practices that have an economic potential similar to the option of returning land to row-crop production. In addition, these landowners are being invited to attend various field days and workshops to discuss these alternative land-use practices.
A survey is being conducted to document changes in landowner attitudes before, during, and after completion of this project. This survey will evaluate social and educational impacts of the project activities on participating landowners.
The ultimate test of the success of land treatment changes in reducing nonpoint source pollution is improved water quality. Current water-quality monitoring objectives and progress to date include:
* To document water-quality improvements that result from implementation of land treatment projects in the Sny Magill Watershed.
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Figure 4. Monitoring of fish species. Photo by Charles Wittman |
The Sny Magill Watershed is part of the U.S. Environmental Protection Agency's Section 319 National Monitoring Program to address nonpoint source pollution. Changes in water quality are being measured using a paired watershed approach. Sny Magill is being compared with the adjacent Bloody Run watershed to the north. Improved water quality will be documented through information from fish surveys (Figure 4), assessments of habitat conditions along the stream corridor, inventories of bottom-dwelling organisms (Figure 5), and monitoring the stream flow, sediment concentrations, and chemical quality of water.
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Figure 5. Sampling of bottom-dwelling organisms in Sny Magill Creek. Photo by Kathie Bentley. |
* Refine monitoring techniques to determine the effectiveness of specific management practices on water quality.
A monitoring procedure to measure the outflow from two similar watersheds has been developed. Additional sites have been established on tributary watersheds, and implementation of land treatment measures is being tracked.
* To increase Iowa's capacity to utilize habitat and biologic monitoring elsewhere across the state.
Sampling procedures for habitat assessment and biologic monitoring of bottom-dwelling organisms were pilot tested and refined. They are now in use elsewhere across Iowa as part of a statewide bioassessment monitoring effort.
* To use water quality and habitat monitoring data interactively with public education programs to expand awareness of the need for nonpoint source pollution prevention by farmers.
*To supply Iowa and the U.S. Environmental Protection Agency with measures of success of nonpoint source pollution control measures on a watershed scale.
Prepared by Iowa Department of Natural Resources, Geological
Survey Bureau
September 1995
Supported, in part, through grants from the U.S. Environmental
Protection Agency
Region VII, Nonpoint Source Program.
Agencies/Contacts