Tag Archives: streamflows

Rainfall and aquifers keep drought away from the Kitsap Peninsula

UPDATE: April 24, 2015
Cliff Mass, professor of atmospheric sciences at the University of Washington, says in his blog that it is too early to be predicting severe drought in Western Washington this summer because of possible late-spring rains:

“I believe the media and some local politicians have gotten a bit too worried about our ‘drought.’ We have NOT had a precipitation drought at all….we are in a snow drought due to warm temperatures. The situation is unique and I suspect we will weather this summer far better than expected.”

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The word seems to be getting around about the record-low snowpack in the mountains, which could create a shortage of drinking water and even lead to problems for salmon swimming upstream. Read about Gov. Jay Inslee’s expanded drought emergency, issued today, as well as the last update from the U.S. Department of Agriculture.

CK

Kitsap Peninsula and the islands of Puget Sound are in their own worlds, fairly insulated from what is happening in the higher elevations. In these lower elevations, the key to water supplies is rainfall, not snow, and the outlook for the year is normal so far.

As you can see from the charts on this page (click to enlarge), this year’s rainfall has been tracking closely the long-term average. If the rains are light and steady, much of the water will soak into the ground and recharge the aquifers where most area residents get their water. The aquifer levels tend to rise and fall over multiple years, depending on the rainfall.

Hansville

Casad Dam on the Union River, which supplies a majority of Bremerton’s water, filled in January, well ahead of schedule, said Kathleen Cahall, water resources manager for the city. The dam is scheduled for a normal drawdown, and Kathleen said she does not expect any water shortage.

“We filled the reservoir fairly early this year,” she said. “We are looking pretty good for the summer.”

Holly

October, the first month of the water year, was unusually wet, Kathleen said. December precipitation also was high. The other months were fairly normal for precipitation.

Precipitation in the Puget Sound region is expected to be below average for June, July and August, according to models by the NOAA’s Climate Prediction Center. Interestingly, large portions of the Central and Southwest U.S., Alaska and Florida can expect above-average precipitation. See U.S. map.

precip

Streams on the Kitsap Peninsula are fed by surface water flows and shallow aquifers. At the moment, most of the streamflows are near their historical average. That’s not the case for the larger rivers in the Northwest, which rush out of the mountains. Most are well below their normal flows, as shown by the map with the dots.

Low streamflows usually mean higher temperatures and stress for salmon. Low flows also can affect fish passage in some stretches of the rivers while also reducing spawning areas.

Streamflows

While things look fairly good on the Kitsap Peninsula now, things can change quickly. We have different vulnerabilities than elsewhere. Climate-change models predict that rains will grow more intense in the future without changing annual precipitation very much. That means more of the water will run off the land and less will soak in, potentially reducing aquifer levels over time. Managing those underground water supplies will become more and more critical.

Climate change disrupts steady streamflows, adds problems for chinook

Climate change appears to be altering the flow characteristics of Puget Sound salmon streams, and the outcome could be an increased risk of extinction for chinook salmon, according to a new study.

I’ve long been interested in how new housing and commercial development brings more impervious surfaces, such as roads, driveways and roofs. The effect is to decrease the amount of water that infiltrates into the ground and to increase surface flows into streams.

Chinook salmon Photo: Bureau of Land Management
Chinook salmon
Photo: Bureau of Land Management

Stormwater experts talk about how streams become “flashy,” as flows rise quickly when it rains then drop back to low levels, because less groundwater is available to filter into the streams.

The new study, reported in the journal “Global Change Biology,” suggests that something similar may be happening with climate change but for somewhat different reasons.

Climate models predict that rains in the Puget Sound region will become more intense, thus causing streams to rise rapidly even in areas where stormwater is not an issue. That seems to be among the recent findings by researchers with NOAA’s Northwest Fisheries Science Center and Washington Department of Fish and Wildlife:

“Over the last half century, river flows included in our analysis have become more variable — particularly in winter — and these changes are a stronger predictor of chinook population growth than changes in average winter flows or climate signals in the marine environment.

“While other impacts to this ecosystem, such as habitat degradation, may be hypothesized as responsible for these trends in flow variation, we found support for increasing flow variation in high-altitude rivers with relatively low human impacts.”

Joseph Anderson of WDFW, an author of the report, told me that chinook salmon, listed as threatened under the Endangered Species Act, may be particularly vulnerable to dramatic changes in streamflows. That’s because spawning chinook tend to show up before winter storms arrive — when the rivers at their lowest levels. The fish are forced to lay their eggs in a portion of the river that will undergo the most forceful flows once the rains begin to fall.

High flows can scour eggs out of the gravel and create serious problems for emerging fry, Joe said. Other factors may come into play, but the researchers found a strong correlation between the sudden variation in streamflows and salmon survival.

In the lower elevations, where development is focused, flow variability could result from both impervious surfaces on the land and more intense rainstorms. Efforts to infiltrate stormwater into the ground will become even more important as changes in climate bring more intense storms.

Stormwater management is an issue I’ve written about for years, including parts of last year’s series called “Taking the Pulse of Puget Sound.” See Kitsap Sun, July 16, 2014. Rain gardens, pervious pavement and infiltration ponds are all part of a growing strategy to increase groundwater while reducing the “flashiness” of streams.

Other strategies involve restoring rivers to a more natural condition by rebuilding side channels and flood plains to divert excess water when streams are running high.

According to the report’s findings, the variability of winter flows has increased for 16 of the 20 rivers studied, using data from the U.S. Geological Survey. The only rivers showing less variability were the Cedar, Duwamish, Upper Skagit and Nisqually.

The effect of this streamflow variability was shown to be a more critical factor for chinook survival and growth than peak, total or average streamflow. Also less of a factor were ocean conditions, such as the Pacific Decadal Oscillation and related ocean temperature.

Eric Ward, of Northwest Fisheries Science Center and lead author on the study, said many researchers have focused attention on how higher water temperatures will affect salmon as climate change progresses. High-temperature and drought conditions in California, for example, could damage the organs of salmon, such as their hearts.

Salmon swimming up the Columbia River and its tributaries could encounter dangerously warm waters as they move east into areas growing more arid. Some salmon species are more vulnerable to temperature, while streamflow may be more important for others. Coho salmon, for example, spend their first summer in freshwater, which makes extreme low levels a critical factor.

Eric told me that further studies are looking into how various conditions can affect each stage of a salmon’s life, conditions that vary by species. One goal is to build complex life-cycle models for threatened species, such as chinook and steelhead, to determine their needs under the more extreme conditions we can expect in the future.

Washington water rights: Will the logjam be broken?

When it comes to water rights in Washington state, it seems to me that the Legislature is trying to sell survival suits on a sinking ship.

Because of budget problems, the Legislature last year slashed 25 percent of the Department of Ecology’s staff in the program that studies water resources and issues water rights. As you can see from Ecology’s map at right (click to enlarge), more than 7,000 water rights are pending, and the backlog is growing.

The latest move is to expedite applications where groups of people are willing to pay for studies to determine if water is available. Reporter Chris Henry wrote about the approved Senate Bill 6267 in yesterday’s Kitsap Sun.

The new law allows a group of water-rights applicants to get together and pay for the studies needed to process water rights for a given area. Anyone not willing to contribute to the study must wait in line for Ecology to get around to processing their water rights. So the new law works well for water utilities, which have enough money to pay for the studies. It may or may not work well for farmers and others who have limited dollars, depending on their share of the costs.
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