Author: Maria Sol Lisboa

Publisher:

Published: 2019

Total Pages: 52

ISBN-13:

Non-point source pollution (NPS), especially from agricultural runoff, is a leading contributor to water quality impairments in the U.S. Lately, attention to nutrient pollution, specially to phosphorus, has arisen due to disturbing increases in seasonal toxic blue-green algal blooms. To improve our understanding of how land use and seasonal weather patterns impact runoff and nutrient loading in temperate areas, we investigated the effect of different land uses on P inputs into Owasco Lake, in central NY. In addition, the inputs were evaluated in the context of a prolonged drought that affected the northeastern U.S. during 2016. Monitoring of base and high flow conditions was conducted between December 2015 and November 2016 at sites located along twelve tributaries to the lake, representing the dominating land uses in the watershed (i.e.: agriculture and forest). Small watersheds were chosen to be able to isolate impacts of particular land uses. The results show a strong interaction of seasonal and land use effects, with the drought event masking the effect of agricultural and mixed land use on P loads; and with the highest loads registering during the first rain event after the drought, exacerbating the agricultural impact on water quality. These findings are an important contribution from a management perspective, as projections for the Northeast US suggest that, although total precipitation will remain relatively stable, summer rains are likely to become concentrated in fewer events of higher intensities, interspaced with more prolonged dry periods. We consider it absolutely critical to incorporate detailed timing management practices for fertilizer and/or manure application relative to runoff producing storm events, in order to mitigate climate extremes impact on water quality.