INFLUENCE OF BEDROCK GEOLOGY AND LAND USE ON HABITAT AND WATER QUALITY IN TWO BLUE RIVER WATERSHEDS WITH DIFFERING MANAGEMENT PLANS

A stream’s habitat and water quality are heavily influenced by the land use and geology within its watershed. Pollutants and sediment loading from watershed drainage can make streams less habitable for certain species, reducing biodiversity. Watershed management strategies, such as the promotion of best management practices in agriculture, can help to combat stream degradation from watershed inputs. The upper Blue River in southern Indiana is a biodiversity hotspot but is experiencing degradation and biodiversity loss due to watershed inputs. This is exemplified by the disappearance of the eastern hellbender salamander, an indicator species, from this area. Fine sediment loading has a particularly harmful impact on the hellbender because it causes embeddedness, decreasing habitat space within the substrate.

Two watersheds of the upper Blue River, the Salem and South watersheds, differ significantly in land use and bedrock geology and have different watershed management strategies. The Salem watershed has higher percentages of urban and agricultural land, has predominantly limestone bedrock, and has a watershed management plan in place. Conversely, the South fork has a higher percentage of forested land and siltstone bedrock and does not have a watershed management plan in place.

To determine how these watershed factors impact stream quality, five sites in the Salem fork and five sites in the South fork were tested for water chemistry, macroinvertebrate assemblage, and sediment distribution in the summer of 2017. Preliminary results suggest that the South fork showed better ecological condition than the Salem fork and that high amounts of cultivated crops and developed land negatively impacted stream quality. These results will be used by The Nature Conservancy, an organization that protects ecologically valuable areas, for developing watershed management strategies and furthering conservation within the South and Salem fork watersheds.