Potential nonpoint-source contamination of the Spring Mill Lake drainage basin
|Status||Start Date||End Date||Locations|
|completed||Aug 25, 2002||Lawrence, Orange|
|Other Researchers:||Tracy Branam, John Comer, Richard Powell, Carl Rexroad, Noel C. Krothe, Mark A. Buehler.|
|Issue:||The drainage basin of Spring Mill Lake, a minimum of 10,000 acres, is characterized by thousands of sinkholes and a sinking stream, which is typical of the Mitchell Plain. Most precipitation falling in the basin travels underground into solution-enlarged conduits that discharge as springs in Spring Mill State Park. The water then flows a short distance in surface streams to recharge the lake. The chemical composition, biologic condition, and sediment load of these spring-generated streams dictate the water quality and sedimentation characteristics of the lake. Nitrogen enrichment and siltation of the lake have been recognized as problems, and past complications indicated the excessive presence of pesticides. Two highways, a railroad line, and many county roads lie within the drainage area of Spring Mill Lake, so that chemical spills and roadway deicing substances may quickly and drastically degrade the quality of water reaching the lake. Failed or inadequate septic systems in an area of expanding population and agricultural practices affect water quality, and erosion from tillage and construction potentially increase sedimentation rates in the lake. Because the park is used by 650,000 people each year and is part of the very limited habitat of blind cave fish in Indiana, it is imperative that deleterious effects are reduced.|
|Objective:||Determine the sources of contaminants that pollute Spring Mill Lake.|
|Approach:||To determine best land management practices and to recognize danger to the lake from chemical spills and highway construction, the drainage area of Spring Mill Lake is being better defined through injecting organic dyes at very low concentrations into the sinkholes that lead into the underlying cavernous bedrock. The dye makes it possible to delimit the boundaries of the drainage of the lake and to learn the general direction of flow of subsurface water in the bedrock. To formulate a plan to provide information on best management practices to landowners, chemical and biological contaminants are being identified and quantified and volume of sediment entering the lake is being measured. Major variations in water quality are to be expected between low-flow regimes and storm events and with seasonal events such as tillage, application of fertilizers to crop land and of pesticides to highway and railroad right of way as well as to crop land, and use of agents to deice roads in winter. Preliminary sampling and data collecting during low flow and storm events prior to specific seasonal activities will provide parameters for future sampling. Later sampling will include, but not be limited to, low flow and storm events after tillage, application of fertilizers, pesticides, and road chemicals, and a midsummer follow-up. Multiple data collecting sites will be required within the several sub-basins of Spring Mill Lake. Imagery and digital topography will be used to show land use and to estimate input of chemicals by sub-basins.|
|Products:||(1) Potential nonpoint-source contamination of the Spring Mill Lake drainage basin with emphasis on the Donaldson/Bronson/Twin Cave System: Indiana Geological Survey Open-File Study 00-13, 28 p.
(2) Amendment to the Quality Assurance Project Plan for nonpoint source contamination of the Spring Mill Lake drainage basin: Indiana Geological Survey Open-File Study 01-7, 20 p.
(3) Escherichia coli monitoring in the Spring Mill Lake watershed in south-central Indiana, in Beck, B.F., ed., Sinkholes and the Engineering and Environmental Impacts of Karst, Proceedings of the Ninth Multidisciplinary Conference: American Society of Civil Engineers, Geotechnical Special Publication No. 122, p. 309-320.
(4) Karst geology and hydrology of the Spring Mill Lake and Lost River drainage basins in southern Indiana: Indiana Geological Survey Guidebook 15, 30 p.
(5) Water quality characteristics and contaminants in the rural karst-dominated Spring Mill Lake watershed, southern Indiana, in Harmon, R.S., and Wicks, C.M., eds., Perspectives on karst geomorphology, hydrology, and geochemistry–a tribute volume to Derek C. Ford and William B. White: Geological Society of America Special Paper 404, p. 153-168.
|Benefits:||Better delineation of the Spring Mill Lake drainage sub-basins will help in assessing the impact of major changes in usage (for example, a feed lot operation or a factory) in the immediate vicinity on the ground water quality and on the fragile biota. Delineation of the sub-basins will also make it possible to assess the areas better that are most vulnerable in case of chemical spills on the highways or railroads. Project information will help to educate the public better and make individuals more aware of the effects of living on a karst terrain. Although this project is designed specifically for Spring Mill State Park, it is also important as a model for understanding environmental impacts throughout the karst region of south-central Indiana.|