Source or sink? Quantifying beaver pond influence on non-point source pollutant transport in the Intermountain West

Non-point source (NPS) pollution remains high in many watersheds despite strategies aimed at reducing such pollution. Beaver (Castor canadensis) activity converts lotic systems to semi-lentic by impounding stream flow and trapping sediments, which have a affinity for NPS pollutants as nitrogen (N), phosphorus (P), heavy metals. This study identify environmental conditions under beaver ponds influence the fate cycling of pollutants. Dissolved particulate nutrients were sampled upstream downstream three headwater differing age character through summer season. Sedimentation rates sediment concentrations metals also determined. Results from this suggest that can attenuate rate 2 4 times greater than riffle reach (p < 0.05). Metal sequestration scaled with pond organic matter content. The oldest youngest had no significant effect on dissolved (NO3?, TDN SRP) or total P (TP). middle was TN sink (0.6–0.8 g N m?2 d?1 [p = 0.03]) influenced nutrient differently spring (21% NO3? 0.03], 61% SRP 0.05]) compared (34% source, 7% sink). little apparent TP loads during period but accumulated 146 sediments suggesting may their potential within first few years development then subsequently act weak source. We use theoretical relationship describing sediment-water interactions show biogeochemical processing is optimized intermediate levels supply residence time. If are be considered an option landscape scale restoration, useful predicting effects water chemistry, aid interpretation variable quality results inherently heterogeneous environments.