Use of a Water Temperature Forecasting Model to Curtail Irrigation Withdrawals from Fifteenmile Creek, Near the Dalles, Oregon, for the Benefit of ESA Listed Mid-Columbia Steelhead Oncorhynchus mykiss

We developed a water temperature forecasting tool to diminish loss of ESA listed “threatened” steelhead during periods of high water temperatures in Fifteenmile Creek, near The Dalles, Oregon.  In the summer of 2009, a temperature induced fish-kill was noted on irrigated portions of Fifteenmile Creek, prompting an investigation by NOAA fisheries. In response, the Fifteenmile Watershed Council ratified the development of the FAST program (Fifteenmile Action to Stabilize Temperatures).  The program used funds to compensate irrigators so instream flow was maximized during periods of high water temperatures.  We used a mixed-model to forecast water temperatures at five sites throughout the watershed using historic water temperature and climate data.  Then, using the local 7-day forecast, we projected the daily water temperature at each site.  If water temperature was forecast to exceed temperatures lethal to steelhead (22^o C), an alert was issued so irrigators could curtail water-use.  In 2013 a voluntary program was initiated, and in 2014 a fully-developed compensation-based approach was implemented.   In 2014 approximately 0.125 m³/s was restored into the creek which was running at 0.133 m³/s, essentially doubling the instream flow.  This resulted in average temperature reduction (modeled) of 0.9 C (1.6^o F) during the 2014 alert.