Location: Northwest Irrigation and Soils Research
Project Number: 2054-13000-010-003-I
Project Type: Interagency Reimbursable Agreement
Start Date: Jul 31, 2021
End Date: Sep 30, 2024
Evaluate the effects of conservation practices in the Upper Snake Rock watershed in southern Idaho.
Water sampling will be expanded in cooperation with the Twin Falls Canal Company to include seven additional irrigation return flow sites that were sampled from 2005 to 2008. Additionally, inflow and outflow will be sampled from four water quality ponds that have been constructed with support from EPA 319 funding. Samples will be collected weekly from 30 sites during the irrigation season and biweekly from 15 sites that continue to flow during the winter. 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 and the canal company continues to install water quality ponds. Sediment and nutrient losses will continue to be measured from a 200 ha subwatershed where fields have been converted from furrow irrigation to sprinkler irrigation. Approximately 10% of the cropland was sprinkler irrigated in 2005, an additional 50 ha will be converted to sprinkler irrigation in 2021, making the subwatershed almost 80% sprinkler irrigated. Advanced pattern recognition and machine learning processes will be used on publicly available remote sensing data to identify and map irrigation systems used on agricultural fields across the watershed. With this new methodology, changes in irrigation systems can be mapped and related to water quality dynamics in irrigation return flow streams. This technique could also be used in other watersheds where irrigation systems are being added or changed.