Right now, early summer 2019, half the rivers in Washington State are in the bottom 10 percent of average flows measured for this time of year. Five percent of rivers show record low flows. Many of these waterways bear spawning salmon and steelhead, including those listed under the federal Endangered Species Act.
Some good rain events at the right time will help but the die is cast. Low water and heat are going to be hard on salmon and steelhead this summer in many streams, likely reducing survival.
That’s the reality of climate change for both hatchery and ESA salmon and steelhead in the Columbia River basin. It’s going to get worse.
We know the basics. Pacific Northwest climate assessments say:
— The region has warmed 2 degrees F since 1900, and will warm another 4 to 9 degrees by 2100, depending in part on whether global emissions takes a lower or higher path.
— Warmer temperatures will result in more precipitation falling as rain rather than snow
— Snowpack will diminish, particularly in lower-elevation watersheds, and stream flow timing will be altered
— Peak river flows will likely shift to earlier in the spring
— Water temperatures will continue to rise
This, of course, is the worst possible prediction for Columbia River basin salmonids. Too much heat and not enough water will kill these fish. Winter rains and earlier spring snowmelt diminish salmon reproduction. Indeed, stream flow at The Dalles Dam will peak as much as a month earlier by mid-century.
Scientists say about one-third of the Northwest’s current habitat for salmonids will be unsuitable for coldwater fish by the end of the century.
The year 2015 gave us a glimpse into the future. In the Northwest, 2015 temperatures were 3.4°F above normal (as compared to the 1970–1999 average), with winter temperatures 6.2°F above normal. These temperatures are what’s expected for the mid-century. Winter, spring and summer precipitation was below normal by 25 percent, 35 percent and 14 percent, respectively. June, 2015 precipitation was 4.6 inches below the 20th Century average.
In July, 2015 water temperatures in the lower Columbia River and its tributaries were higher than in any other year on record, leading to a high rate of mortality for sockeye and chinook.
The warm, dry weather also led to irrigation shortages, agricultural losses, limited snow- and water-based recreation, drinking water quality concerns, and hydropower shortages.
When 2015 conditions become the new normal for basin salmonids, the region will be at risk of losing hundreds of millions of public dollars in past and ongoing investments in habitat improvements in the Columbia River basin.
So what are we going to do about it?
Good ideas have been out there for awhile. Tweaking Columbia River basin mainstem reservoir management to better reflect the new runoff normal has been getting plenty of attention by federal agencies managing the river. Identifying, protecting and improving existing cold water refuges is crucial. Investing in technology that moves colder, deeper reservoir water downstream at the right time for the fish. Continue water efficiency efforts. Intensify funding for habitat projects that shade and cool streamsides.
And then there is the interesting issue of building more reservoir storage. Peak flows are shifting to early spring. More small reservoirs in certain locations would capture that spring water for later in the summer/fall for fish and possibly other uses. Such efforts would require much collaboration in determining the right sites and getting new water storage facilities built. If such an approach is feasible, waiting another couple of decades might be too late for many salmonid populations.
Fortunately, in the works now are crucial guiding documents for Columbia Basin salmon and steelhead recovery. The Northwest Power and Conservation Council is in the midst of writing a new basin fish and wildlife program intended to guide for five years over $250 million a year in Bonneville Power Administration fish and wildlife spending. And NOAA Fisheries is writing a new Biological Opinion that will give direction to actions and funding for the recovery of ESA-listed salmon and steelhead.
No doubt these documents will give heavy emphasis to mitigating impacts of regional climate warming.
The science is clear. Forecasting, modeling and research have given us the basics. Now come the practical, on-the-ground efforts to ensure basin salmon and steelhead have enough cool water in the rivers to survive.
— Bill Crampton, [email protected], 541-312-8860
Also see:
— CBB, Nov. 30, 2018, FEDERAL CLIMATE REPORT SUGGESTS MORE WARM YEARS SUCH AS 2015 WILL BE A REALITY FOR COLUMBIA BASIN https://www.www.www.cbbulletin.com/federal-climate-report-suggests-more-warm-years-such-as-2015-will-be-a-reality-for-columbia-basin/
— CBB, April 8, 2016, STUDY: COLD HEADWATER STREAMS APPEAR LEAST VULNERABLE TO CLIMATE CHANGE, OFFER REFUGE FOR COLD WATER SPECIES https://www.www.www.cbbulletin.com/study-cold-headwater-streams-appear-least-vulnerable-to-climate-change-offer-refuge-for-cold-water/