Why save water in the PNW?

Why save water in the PNW?

Written By Ethan Duvall

“It rains so much in the Pacific Northwest, so why do we need to worry about conserving water?”

This is something I get asked a lot – and before I started working in the water supply industry – I asked myself the same question.

It makes sense to go the extra mile in saving water if you live somewhere arid and hot (I’m sure many of us are aware of the water scarcity issues that haunt hotter states such as Arizona and California). But does saving water in rainy western Washington really matter?

The short answer is yes. After learning more about the hydrology of western Washington, I found that it’s not about how much water we get, it’s about when we get it, and frankly, who gets to use it.

Western Washington receives the majority of its precipitation during the winter – roughly 6x more precipitation compared to the summer. On average, Seattle experiences over 10 inches of precipitation in December and January alone, and only 1.37 inches during July and August. These late summer months are when stream, reservoir, and groundwater levels begin to run low, temperatures rise, and water becomes most important.

Although high-mountain snowmelt helps supplement freshwater availability in the late summer, a changing climate has unfortunately weakened this natural form of drought mitigation. Rising average temperatures have resulted in less snowpack during the winter, decreasing the amount of snowmelt throughout the summer and spring. Under a moderate emissions modeling scenario, spring snowpack levels across Washington are projected to decrease 44 percent by 2040, and 65 percent by 2080 (compared to the 1971-2000 average). Rising temperatures have also resulted in drier summers, intensifying drought stress on native ecosystems, increasing the risk of wildfires, and decreasing freshwater availability.

Demand for water is also the highest during the late summer. Residential water use increases significantly due to spikes in outdoor irrigation, showering, drinking water, and recreation. The average Washingtonian family uses more than 300 gallons of water per day This water comes directly from our streams, reservoirs, and groundwater, limiting the amount of water that returns to natural waterways. As populations continue to grow, human demand for water continues to increase while water continues to become less and less available.

Humans are not the only ones who need water during the summer; many native plants and animals depend on sufficient water supplies during these hotter summer months for their survival. The same water that we use indoors and outdoors to drink, cook, clean, wash and landscape is the water that salmon and other species need in rivers and streams to survive. Conserving water helps maintain sufficient water levels and temperatures for freshwater fish, increases water quality, and helps mitigate drought stress for native plants and animals.

Does this mean we only need to worry about conserving water in the summer? Not necessarily. Although water is most scarce in the summer, surface water reservoirs and groundwater aquifers recharge in the winter when precipitation increases and temperatures cool. We rely on these storage reservoirs for water in the summer, which makes saving water during the winter just as important. Winter salmon runs also face the same issues of rising water temperatures and decreased flows as spring salmon runs, meaning the less water we use to fill reservoirs, the more we can provide for salmon and other freshwater species.

Overall, the message is simple: Saving water in the Pacific Northwest is just as important as anywhere else, and is the fastest, easiest, and most economical way to stretch our limited water supplies. Conserving water supports fish populations and native ecosystems, provides freshwater year round, and can help mitigate impacts of climate change and increased water demand on humans and wildlife alike. We are lucky to call the Pacific Northwest home, so let’s do our part to conserve its natural beauty.

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