Austin Lake, Kalamazoo County, MI

austin_lake_kalamazooAustin Lake is a 1,132-acre natural, glacial origin lake with nearly 6.5 miles of shoreline, a maximum water depth of 8.0 feet and an average depth of approximately 5.0 feet. The lake is located sections 23, 24, 25, 26, 35, and 36 in the City of Portage (T.3S, R.11W), in Kalamazoo County, Michigan. The sediments in the South Basin of the lake are very thick, high in ammonia, low in oxygen, and are an imminent threat to the health of the Austin Lake ecosystem. Additionally, the South Basin sediment negatively impact recreation and property values as a result of these undesirable characteristics.
Water quality parameters such as water temperature, dissolved oxygen, pH, conductivity, turbidity, Secchi transparency, total dissolved solids, sediment reduction, algal community composition, and relative abundance of submersed aquatic vegetation were assessed at all 64 sites in July “pre-aeration” and in October “post-aeration” in 2012. The overall results indicate that an approximate loss of 0.9 feet of sediment occurred in diffuser sampling locations and an approximate loss of 0.5 feet occurred in control sampling locations. The lake water level only differed by 0.4” on the two sampling dates.
Additionally, a reduction of Eurasian Watermilfoil from 86% to 23% was noted throughout the South Basin after the 4 month operational period of the laminar flow aeration system. This indicates that the system has caused a decline in the abundance of the aquatic plant. A smaller decline in the submersed aquatic plant, Sago Pondweed was also noted. However, there were no measured declines in the other native aquatic plant species, Yellow Water lily and Southern Naiad.