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Fall rains have begun. What does that mean for salmon and drinking water providers?

It's officially autumn and for water managers around the Pacific Northwest, the onset of fall rains brings with it the first wave of seasonal treatment challenges.

Intense storms and damaged watershed habitat are a recipe for water quality disaster for native salmon and hundreds of town’s public water supplies.

Many small and rural communities in Oregon and Washington rely upon rivers and streams for their drinking water, but there is often degraded habitat upstream, which causes water quality issues that water providers must address to deliver clean drinking water. For example, older logging roads in forested lands, particularly those built before the 1980s, were poorly designed and can deliver massive amounts of sediment into streams, especially during storm events.

With climate change we are seeing more frequent and bigger storms. Plus, snow pack has been decreasing for decades in the West. As a result, with more of our total precipitation coming in large and irregular rain events, we anticipate seeing more sediment in our rivers than either people or fish are accustomed to.

Intense rains and rain-on-snow events can oversaturate soils, compromise legacy forest roads, and otherwise exacerbate erosion and landslides. Soil and organic matter end up in our streams and rivers at rates beyond what fish adapted to over millennia and what towns built their water treatment plants to handle. Elevated levels of turbidity and suspended sediments in creeks can smother salmon eggs and force drinking water treatment systems to shut down. To bring highly turbid water to safe drinking water standards also requires increased use of disinfection products. Toxic and potentially carcinogenic chemicals, such as bromate and trihalomethanes, are created as byproducts of the disinfection process.

Moreover, climate change brings with it a lot of unpredictability. While the total amount of suspended sediment in a stream makes a big difference for spawning salmon, the variability over time can be even more problematic for water treatment operators. Constant vigilance is required when the clarity of water can change by orders of magnitude within a matter of hours. Uncertainty at this temporal scale has very practical consequences for operations, maintenance, and costs borne by the public.

Fortunately, watershed restoration is a cost-effective strategy for helping to keep drinking water treatment costs down while ensuring the protection of community public health and improving fish and wildlife habitat. That’s why we help to lead the Drinking Water Providers Partnership. Our group of federal and state agencies and nonprofits directs money and technical assistance to community groups for projects that will enhance water quality for native salmon and steelhead, and people.

map dwpp funded 2018

The most common restoration projects that the Partnership has supported are those designed to reduce the risk of erosion and recover in-stream habitat complexity. As a result of these habitat improvements, flood waters can slow down, groundwater supplies can recharge, and sediment can settle out which means that drinking water treatment plant operators get a more reliably clean supply of water. In turn, they need less chemicals and energy to make the water safe for public consumption, plus there’s higher quality habitat in-stream for native fish, ensuring future generations can enjoy salmon returning year-after-year.

In its three years of operations, the Drinking Water Providers Partnership has invested $1.3 million dollars in nearly three dozen projects that are improving more than 750 acres and 60 river miles in watersheds that provide habitat for native salmon and steelhead as well as drinking water to over 1 million Oregonians and Washingtonians.

Check out this map to see where all this good work is happening and look for the Drinking Water Providers Partnership’s 2019 Request for Proposals at the end of this month. Applications will be due January 29, 2019. Stay tuned!

Learn more about the Partnership here: https://workingwatersgeos.org/our-work/drinking-water-providers-partnership

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Geos Institute