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ARS Home » Pacific West Area » Kimberly, Idaho » Northwest Irrigation and Soils Research » Research » Publications at this Location » Publication #310629

Research Project: Soil and Water Conservation for Northwestern Irrigated Agriculture

Location: Northwest Irrigation and Soils Research

Title: Water temperature in irrigation return flow from the Upper Snake Rock watershed

Author
item Bjorneberg, David - Dave

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2015
Publication Date: 5/10/2015
Publication URL: http://handle.nal.usda.gov/10113/61107
Citation: Bjorneberg, D.L. 2015. Water temperature in irrigation return flow from the Upper Snake Rock watershed. Agricultural Water Management. 158:209-212.

Interpretive Summary: Water returning to a river from an irrigated watershed could increase the water temperature in the river. The objective of this study was to compare the temperature of irrigation return flow water with the temperature of the diverted irrigation water. Water temperature was measured weekly in the main irrigation canal, 24 return flow streams and one ephemeral stream from 2005 to 2008 in the Upper Snake Rock (USR) watershed. The USR is an 82,000 ha watershed in southern Idaho, USA, that has about 60% of the farm land furrow irrigated and the remaining 40% sprinkler irrigated. Median annual water temperatures in irrigation return flow streams were not greater than the water diverted from the river, suggesting that water flowing through the canal system and furrow irrigated fields does increase temperature. Water in seven of the 14 return flow streams that received flow from subsurface drains had significantly lower temperatures than the main canal in at least two years of the four years. Results of this study indicate that water can be diverted from a river for surface irrigation without increasing the temperature of the irrigation return flow.

Technical Abstract: Water returning to a river from an irrigated watershed could increase the water temperature in the river. The objective of this study was to compare the temperature of irrigation return flow water with the temperature of the diverted irrigation water. Water temperature was measured weekly in the main irrigation canal, 24 return flow streams and one ephemeral stream from 2005 to 2008 in the Upper Snake Rock (USR) watershed. The USR is an 82,000 ha watershed in southern Idaho, USA with about 60% of the area surface irrigated and the remaining area sprinkler irrigated. Median annual water temperatures in irrigation return flow streams were not greater than the water diverted from the river, suggesting that water flowing through the canal system and furrow irrigated fields does increase temperature. Water in seven of the 14 return flow streams that received flow from subsurface drains had significantly lower temperatures than the main canal in at least two years of the four years. Significant differences were generally only two to three degrees Celsius. Results of this study indicate that water can be diverted from a river for surface irrigation without increasing the temperature of the irrigation return flow.