HR: 0800h
AN: H31B-1298    [Abstracts]
TI: Natural Wetlands Mediate Non-point Source Water Pollution From Irrigated Pastures
AU: * Knox, K
EM: akknox@ucdavis.edu
AF: UC Davis, Dept of Land, Air and Water Resources 1 Shields Ave, Davis, CA 95616 United States
AU: Dahlgren, R A
EM: radahlgren@ucdavis.edu
AF: UC Davis, Dept of Land, Air and Water Resources 1 Shields Ave, Davis, CA 95616 United States
AU: Tate, K W
EM: kwtate@ucdavis.edu
AF: UC Davis, Plant Sciences Department 1 Shields Ave, Davis, CA 95616 United States
AB: Non-point source discharge from grazed pastures may be high in nutrients, sediment, and pathogens, three major contributors to water quality impairment in California. Intercepting pollution at its source and managing water quality within the landscape are essential to maintaining healthy downstream waters. We investigated the efficacy of flow-through wetlands interspersed throughout the agricultural landscape to reduce non-point source pollution of tailwater from cattle-grazed, irrigated pastures in the Sierra Nevada Foothills of California. Wetlands are known to positively impact water quality through ecological processes such as filtration, sedimentation, microbial transformations and plant uptake of nutrients. Influent and effluent water of small (0.25 ha), natural wetlands located downstream from flood irrigated pastures was analyzed for Escherichia coli, NO3-N, total N, total suspended solids (TSS), total P, and dissolved organic carbon (DOC) throughout two summer irrigation seasons (June to October). We compared reductions of sediment, nutrients and E. coli provided by a healthy, non-degraded wetland with reductions from flow through a channelized, degraded wetland. Large reductions in E. coli (>75%) and TSS (>50%) were observed in water exiting the healthy wetland while nutrient and DOC (~ 20%) concentrations were less affected by flow through the wetland. The channelized wetland provided smaller reductions in all constituents than did the non-degraded wetland. Results from this study demonstrate that small flow-through wetlands can improve water quality through the attenuation of E. coli and suspended sediments, and to a lesser degree DOC and nutrients.
DE: 0496 Water quality
DE: 0497 Wetlands (1890)
DE: 1871 Surface water quality
DE: 1880 Water management (6334)
SC: Hydrology [H]
MN: Fall Meeting 2005