(Photo above Tumalo creek from the web)
Flows in the headwaters of Tumalo Creek will be severely reduced in the coming decades, according to a new study released today. The study indicates that by the year 2039, the average June baseflow for Tumalo Creek will decline by 61 percent compared to a 2008 baseline. The study, Climate Change Impacts on Stream Flows, Upper Deschutes Basin, indicates that a warming climate will impact groundwater discharge to streams, decreasing the flows that currently contribute to Bend’s water supply.
The study was commissioned by Central Oregon LandWatch (COLW) and conducted by the hydrogeologic consulting firm Mark Yinger and Associates. They used modeling tools to simulate climate change, aquifer recharge, and groundwater flux to and from streams in the basin. The models indicate that by mid-century, there will be a significant reduction in the volume of water in Tumalo Creek above Tumalo Falls during summer and fall months, and that in the future there may be little or no water for the City of Bend to divert in warmer months.
“The study concludes that, “because of the significant impacts of climate change on the upper portion of Tumalo Creek, from which the City of Bend gets its surface water, the City’s planned water withdrawals from Tumalo Creek may not be sustainable if flows over Tumalo Falls are to be protected.”
“Fish, wildlife, municipal water providers, irrigators and recreationists all rely on these stream flows,” said Paul Dewey, executive director of COLW. “The findings from this study confirm that the upper reaches of the Tumalo basin will be profoundly affected by climate change and reinforce the importance of working to conserve water now.”
The model shows that reductions in stream flow will occur primarily in the higher elevation reaches of tributaries to the Deschutes River. They indicate that by the year 2039, the average June baseflow for Tumalo Creek will decline by 61 percent compared to a 2008 baseline. The flows will decline further by the year 2060, to 86 percent less than current flows. The study also modeled future impacts to Whychus Creek, whose headwaters are at a lower elevation than Tumalo Creek.
Results show a consistent five to ten percent reduction of flow throughout the year, not just the warmer months.
While the results of the study show the long-term impacts of climate change on Central Oregon’s water resources, its effects are being felt now. Scientists say this year’s warmer weather and reduced snowpack are a precursor of what’s to come, including water shortage problems, drought and more frequent wildfires.
“While we can’t make it snow, we can take steps that will mitigate the risk to our critical water resources,” said Dewey.
“It is imperative that we make the right decisions today to make sure there is an adequate water supply in the future.
” Those decisions would include moving the City to more of a reliance on groundwater and less on Tumalo Creek water, moving Tumalo Irrigation District to more of a reliance on Deschutes River water instead of Tumalo Crrek water, and reducing consumption by City conservation measures and by improving on field efficiencies by TID and Three Sisters Irrigation District (because of reduced flows on Whychus Creek).”
Paul Dewey, COLW Executive Director: 541-420-8455 paul@centraloregonlandwatch.org.
