Both surface and groundwater quality affect Catholic Creek’s biological communities. Fractures in the basalt underlying the watershed allow for shallow groundwater upwelling, which can convey added nutrients to the stream. Drain tiles installed in the wet areas of farm fields also convey excess nutrients directly to the stream. Nutrient enrichment can lead to aquatic plant and algal growth, which in turn can lead to dissolved oxygen sags when the plants respire. Fish species and the macroinvertebrates that sustain them are negatively affected by dissolved oxygen sags. Algal growth can also cause a loss of instream habitat.
Riparian plantings, wetland restoration, better nutrient management on croplands, off-site watering and riparian fencing for cattle, and septic system upgrades can all benefit the water quality of Catholic Creek. These treatments and BMPs can have a positive impact on several limiting factors simultaneously, as part of a holistic watershed restoration approach.