Location: Northwest Irrigation and Soils Research
Project Number: 2054-13000-009-12-I
Project Type: Interagency Reimbursable Agreement
Start Date: Aug 1, 2019
End Date: Sep 30, 2021
Evaluate the effects of conservation practices in the USR watershed in southern Idaho.
Water samples will be collected weekly during the irrigation season and biweekly during the winter from 10 sites (8 return flow and 2 inflow sites) in the Twin Falls irrigation tract to calculate sediment and nutrient balances for the watershed. We will cooperate with Idaho Department of Water Resources (IDWR) to continue measuring return flow at eight sites that we have cooperatively maintained since 2005. Return flow data from all sites will be used to calculate annual water, sediment and nutrient balances for the watershed. These balances will be used to determine if the quantity and quality of return flow is changing as more land has converted from furrow to sprinkler irrigation. Additional 500 mL samples will be collected monthly in 2019 from irrigation return flow sites and analyzed for culturable bacteria and antibiotic resistance genes. This information will be used to identify spatial and temporal trends of bacteria and antibiotic resistance genes in the irrigation return flow streams. Sediment and nutrient losses will continue to be measured at the outlet of a 200 ha subwatershed to determine water quality impacts after the cropland that contributed substantial sediment loads was converted from furrow irrigation to sprinkler irrigation in 2018. Irrigation runoff from the remaining furrow irrigated fields in the subwatershed flows through a sediment pond or filter strip to remove sediment.