A variety of land uses affects water quality of streams at the Indiana Dunes National Lakeshore. Discharge from storm sewers and runoff from roads contributed lead, zinc, and chlorinated hydrocarbons (chlordane, DOT, ODD, DDE, and PCB's) to all streams except Derby ditch. In addition, the Little Calumet River received ammonia from industrial discharges, and organic materials, nitrogen, phosphorus, and fecal coliform from wastewater-treatment-plant and combinedsanitary- and storm-sewer discharges. As a result, water at some sites in the lower reaches of the Little Calumet River contained dissolved-ammonium-nitrogen concentrations exceeding 0.10 milligram per liter, dissolved-oxygen concentrations less than 3.0 milligrams per liter, and fecal coliform populations exceeding 2,000 colonies per 100 milliliters.
Seepage from two landfills may have caused the concentration of dissolved solids in the west Grand Calumet River lagoon to exceed that in the east lagoon. Ammonium concentrations in the west lagoon ranged from 13 to 16 milligrams per liter as nitrogen.
Pesticides used in agricultural areas were the major source of DOT, ODD, DDE, and dieldrin on streambed materials. Runoff from residential areas was a major source of nitrate, organic materials, and chlordane in Derby ditch and Dunes Creek.
Wetland drainage contributed significant amounts of organic materials to streams and at times increased concentrations of dissolved sulfate and iron. Dissolved-iron concentrations correlated with dissolved-organic-carbon concentrations in yellow-brown water of Kintzele and Derby ditches.
