BATHYMETRIC AND WATER QUALITY SURVEY OF THREE LAKES IN COOK COUNTY, ILLINOIS

The U.S. Geological Survey, in cooperation with the Cook County Bureau of Technology (BOT), collected bathymetry and water-quality data from numerous lakes throughout Cook County, Illinois, in the summer of 2022. The primary objective of this study was to create a water-resources inventory of the surveyed characteristics for an initial baseline and future comparison by the Cook County BOT. Bathymetry data was collected using an acoustic Doppler current profiler (ADCP) and processed and developed into bathymetric maps using a geographic information system (GIS). Additional water-quality data collected using multi-parameter sondes include: temperature, pH, turbidity, dissolved oxygen, and specific conductance. To possibly identify similarities with bathymetry, water quality, and land usage, three lakes, Tampier Lake, Busse Woods Reservoir, and Saganashkee Slough were studied further. The pH of water from Tampier Lake and Busse Woods Reservoir were 8.1 and 8.0, respectively. Tampier Lake had a substantially higher specific conductance of 1,160 microsiemens per centimeter (µS/cm), compared to 616 µS/cm from Busse Woods Reservoir. Both lakes are relatively shallow (less than 2.0 meters deep) and lie within natural kettled wetlands, surrounded by residential development. Tampier Lake has agricultural areas within its watershed, while the watershed of Busse Woods Reservoir has highways and commercial areas. Both lakes exhibited considerable algae growth at the time of the study. In contrast to Tampier Lake and Busse Woods Reservoir, Saganashkee Slough, an artificial lake of similar depth with mostly forested and wetland areas within its watershed, had a pH of 7.6, specific conductance of 641 µS/cm, and substantially less algae. This study indicates that nutrient runoff from urban areas may have potential effects on wetlands, such as increased pH levels, causing stress to aquatic fauna, and promoting algal growth. The data from these examples do not necessarily indicate that water depth is an important factor in overall water quality and ecosystem health.