Dam! Impacts of Beaver Dams on Surface and Groundwater Quality
Beaver (Castor canadensis) activity (i.e., damming of streamflow) holds significant potential to impact in-stream nutrient processing, through reduction of streamflow velocity and increase of water residence time within pools, trapping of sediment and organic material, raising of riparian groundwater tables and restoration of channel-floodplain connectivity. Thus, dams may represent a “no-cost in-stream conservation practice” that provides compound benefits beyond water quality and quantity, such as enhanced wildlife habitat and increased riparian vegetation diversity. Few studies have focused exclusively on beaver dam impacts to in-stream nutrient processing and watershed-scale nutrient loading, especially in the agricultural Midwest, where watersheds frequently exhibit elevated nutrient loads, flashy hydrology and stream channel incision.
The overall goals of this project are to identify and quantify key nutrient-removal processes associated with beaver dams and estimate the potential impact of dams on watershed-scale nutrient loading within the agricultural Midwest. To achieve project goals, we will pursue three main objectives:
- quantify hydrologic impacts of beaver dams at the stream reach-scale in select Iowa watersheds;
- quantify in-stream and shallow groundwater nutrient processing impacts of beaver dams at the stream reach-scale in select Iowa watersheds; and
- expand stream reach-scale results to estimate watershed-scale hydrologic and nutrient loading impacts of beaver dams.
Project objectives will be achieved through two years of field data collection and modeling, focused on six beaver dam complexes located within six central Iowa watersheds in the Central Iowa and Minnesota Till Prairies Major Land Resource Area, i.e., Des Moines Lobe.