ScholarWorks at University of Montana

Nutrient Levels of Storm Drain Water Flowing into Ashley Creek

Water quality in the Flathead Lake drainage is of great concern. The potential of wetlands to reduce pollution has been established for certain aquatic pollution parameters, especially nitrates and phosphates. This study investigated the levels of nutrients that entered a storm drainage ditch approximately 100 meters long that empties into Ashley Creek. The source of water was a storm sewer that services most of east Kalispell, Montana. Nitrate and phosphate levels were determined at both ends of the ditch to see if nutrient levels were reduced as runoff passed through the vegetation in the ditch. Phosphates were reduced 54% while nitrates were reduced 90%. While I hypothesize Ceratophyllum demersum was responsible for most of the nutrient trapping, lab studies found Hippuris vulgaris to be the most efficient nutrient trapper of the native plants tested. Planting additional vegetation or meandering the ditch may be a viable option to increase the pollution filtering process.