Reduced Snow Pack and Earlier Runoff

Receding glaciers

Warmer temperatures mean more precipitation will fall as rain, not snow, and more snow will melt earlier in the spring.

Much of Washington’s water supply is stored in snow pack and glaciers that melt into rivers. As this stored snow recedes to higher elevations, less will be available to feed rivers. Too much water runoff (melted snow) through early spring when it's not needed will not help in summer when it is needed. Less snow means that glaciers are not replenished. Downstream effects include changes in

Facts about Washington's retreating glaciers and declining snow pack - (pdf) April 2007, Department of Ecology

Learn more about glaciers and snowpack from the U.S. Geologic Survey (USGS) Washington Water Science Center.

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Lower summer stream flows

Current and Seasonal Drought Information and Maps

Climate change from global warming affects the Northwest with recurring drought seasons. Multiple droughts since 1971 resulted in dry streams, withered and abandoned crops, dead fish, record low rivers and declining ground water levels. Between 2000 and 2005, Washington experienced two drought emergencies, resulting in drought declarations by Governors Locke and Gregoire.

The winter of ’04-’05 was one of the warmest, driest winters on record for Washington State. By early March the mountain snow pack was just 26% of normal. Many rivers and creeks across the state flowed at or near record-low levels. Much depends on abundant stream flows in the summer, including agricultural irrigation, drinking water supply, fish and wildlife, and hydropower production.

Sources: Managing our Water Successfully, Issue up close, pg 1 – Washington Department of Ecology #06-11-023

2005 Drought Response Report to the Legislature – Washington Department of Ecology, pp iii, 1 #06-11-001

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Salmon declines

Salmon and many other fish rely on timely, abundant, cold, clean water to spawn and rear young. Projected climate change would increase fall and winter flooding. As peak river flows shift to earlier in the spring, salmon rearing, migration and spawning are negatively affected.

Low flows in spring and summer result in warmer water which holds less oxygen and stresses fish. Increased summer stream temperatures may exceed tolerable limits for coldwater fish. Changing temperatures in lakes, Puget Sound, and the coastal ocean could decrease food for fish.

During the drought of 2001, hundreds of thousands of juvenile salmon were stranded by low flows in the Columbia River and were unable to travel to the Pacific Ocean. In spring 2005, above-average ocean temperatures and reduced ocean movement resulted in a 20-30 percent drop in juvenile marine salmon populations.

A 50-year warming trend in Lake Washington has reduced the food available for fish and caused algae blooms.

High stream temperatures in 2004 were implicated in major sockeye salmon die-offs in the Fraser River.

When fish are stressed by one process, they are less able to deal with other environmental stressors. One study describes how salmon already stressed by high water temperature are less able to deal with a toxic pollutant, or pathogen. A 2001 study indicates warmer temperatures can increase the infection rate or susceptibility of fish to illness. Loss of streamside tree cover and/or water withdrawals can change water temperatures, particularly critical during peak summer temperatures.

Sources: Fish & Shellfish - King Co. Climate Conference 2005 (University of Washington – Climate Impacts Group)

Climate Impacts on Washington's Hydropower, Water Supply, Forests, Fish and Agriculture (University of Washington – Climate Impacts Group) pg 35

Impacts of Climate Change on Washington's Economy (University of Oregon) pg 76

Maximum Temperature: Upper Optimal Temperature Limits for Salmonids in the Williamette and Lower Columbia Rivers (University of Portland)

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Lower groundwater tables

Early snowmelt and reduced late-summer stream flows affect aquifer recharge for underground water supplies. More rain in winter could cause more stormwater runoff instead of slow recharge. Higher summer temperatures with less summer rainfall could dry out the soil through evaporation and plant transpiration. As ground water levels drop, some wells will go dry. As people deepen their wells, pumping costs go up. Conflicts over water needed in streams, demands for senior water rights and new water rights could escalate.

Ground water, water located under the ground, is stored in aquifers. Aquifers are underground geological water systems that store and/or transmit ground water, such as to wells, springs and streams. Aquifer recharge is the process of adding water to an aquifer, either naturally or artificially.


Source: Chris Peter, Golder Associates, King County Climate Conference 2005

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Hydropower loss

Higher, earlier winter peak-flows would increase electricity production during the winter/spring. But lower summer stream flows would decrease energy production in the summer when it is most needed.

Dams generate 72% of the state's electricity (compared to the national average of 7% from dams). Higher temperatures will directly affect power demand by reducing demand for heating in winter (when Northwest hydropower is cheap) and increasing demand in summer for air conditioning (when Northwest hydropower is more expensive).

Sources: Hydropower – King Co. Climate Conference 2005 – (University of Washington - Climate Impacts Group)

Impacts of Climate Change on Washington's Economy (University of Oregon) pg 36

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Recreational loss

As temperatures rise, winter precipitation will include more rain and less snow. Over 40% of the winter recreation in Washington over the last 10 years occurred at low elevation ski areas (Snoqualmie Summit, Mt. Baker, Mt. Spokane, & 49 Degrees North are most likely to be affected by climate change). The Summit at Snoqualmie experienced “warm winters” in 27% of the years from 1971 to 2000, and may experience over 50% of “warm winters” by 2040.

Total visits to Washington's ski areas over the last decade averaged 1.65 million visits per year. Annual revenue from Washington's ski areas falls within a range of $50 million – $150 million for ski passes, tickets, lessons, rentals. This does not include secondary revenues from skier’s food, retail sales, accommodations, etc.

Source: Impacts of Climate Change on Washington's Economy (University of Oregon) pp 70-73

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More water pollution

In a warmer climate, rain could increase fall and winter flooding in susceptible river basins. Rain, running quickly off the land, especially over paved or open areas, is referred to as “runoff.” Runoff carries with it pollutants left on the ground or flowing off paved areas (car oils, antifreeze, brake lining dust, pet and farm waste, fertilizers and pesticides, etc). (Learn more about Ground and Surface water and Stormwater.)