I’ve been thinking a lot this week about the water management issue on the west coast of the United States.

California’s are the most dire at the moment, as the state experiences a once-in-500-years drought brought on by climate change. And the most recent National Climate Assessment predicts that things will get far worse over the next 30-40 years as snowpacks shrink and waterways carry less water downstream. Plus, a few days ago a report came out showing that the groundwater in the Colorado River basin is being depleted at an alarming rate.

This isn’t just California’s problem; this is a problem for the whole United States, because much of the food that we eat is grown in California’s agricultural region. The state is the largest agricultural producer in the country by a significant margin, and is the sole U.S. producer of several crops including almonds and walnuts.  Here’s a great summary of statistics about California agriculture.

The good news is that California is right next to the Pacific ocean, and water desalination technology has advanced significantly over the last couple of decades (we have several companies to thank for that). The not-so-good news is that desalination is not without its environmental impacts: it is extremely power intensive, and you have to do something with the salt, minerals, and other pollutants that you remove from the water.

Desalination isn’t particularly new; people have done it for thousands of years in stills which boil water and then condense the steam. And the nice part about that, as a baseline, is that since it’s simply a matter of heating the water we can do that not only with any power source that can generate electricity (solar, wind, hydro, nuclear, gas…) we can even do it as part of a co-generation facility by capturing and re-directing excess heat from the power generation process. It’s still power intensive: the theoretical lower bound of how much energy you would need to desalinate a cubic meter of water is 1 kilowatt-hour, and some suggest that the practical limit is around 2 kilowatt-hours. So take a 1200-watt hair dryer and run it constantly for 2 hours; there, you’ve desalinated one cubic meter of seawater.

Fortunately, California also has an abundance of sunshine, and a fair amount of wind along its coast. It may not look pretty, but there will be fresh water for drinking and irrigation. There are currently 17 desalination plants in California in the planning stages, and it wouldn’t surprise me if governments find ways to streamline their construction. Again, there are environmental concerns, such as keeping marine life out of the seawater intake system. Hopefully that will all get sorted out.

Here in Washington State, the problem looks a little different. As Cliff Mass wrote recently, the Pacific Northwest might be an oasis from the effects of climate change, through a very lucky confluence of effects. Its geographic location means that the temperature range won’t change much, and amount of precipitation it receives also will stay about the same. Amusingly, even the rising ocean level won’t have much of an effect, because the continental plate it sits on has historically been pushed down by the weight of enormous glaciers, and the melting of those glaciers (over a long period of time) is causing the whole plate to buoy up.

But — isn’t there always a but? — there is one important change. While there will still be approximately the same amount of precipitation, it will fall primarily as rain instead of snow in the mountains.  From the National Climate Assessment report:

Snow accumulates in mountains, melting in spring to power both the region’s rivers and economy, creating enough hydropower (40% of national total) to export 2 to 6 million megawatt hours per month. Snowmelt waters crops in the dry interior, helping the region produce tree fruit (number one in the world) and almost $17 billion worth of agricultural commodities, including 55% of potato, 15% of wheat, and 11% of milk production in the United States.

Seasonal water patterns shape the life cycles of the region’s flora and fauna, including iconic salmon and steelhead, and forested ecosystems, which cover 47% of the landscape. Along more than 4,400 miles of coastline, regional economic centers are juxtaposed with diverse habitats and ecosystems that support thousands of species of fish and wildlife, including commercial fish and shellfish resources valued at $480 million in 2011.

The snowpack, and how it shapes water flows throughout the year, is a central and critical aspect of the Pacific Northwest ecosystem, and it is going to change dramatically. If we don’t address it, it will lead to spring flooding and summer droughts.

The traditional way to handle this is to dam rivers to create reservoirs. And we certainly know how to build dams: there are an estimated 75,000 of them on waterways in the United States (though many of them are for hydro power generation, not strictly for flood control or reservoir creation). We have also learned much in the past few decades about the environmental damage that these dams have wreaked on the environment, particularly on fish stocks as they have blocked migration both upriver and downriver. In fact, of late there has been a growing movement to remove dams as a first step to restoring ecosystems. One of the largest dam removal projects is right here in Washington State: the removal of two dams, both around 100 years old, on the Elwha River.

We are lining up for a major conflict: on one hand it will be critically important to capture rainfall up in the mountains, as near as possible to its source, so we can control its release throughout the year mimicking the old snowpack cycle: to maintain entire river flows for fish migrations, and to supply people with water for drinking and irrigation. On the other hand, if we dam the rivers to accomplish this, we will just be creating a different ecological problem. Or several ones, since we will also be flooding large areas behind the dams in the process.

Dams are the simplest means to create reservoirs, but they are not the only one. Just as many communities have  reservoirs to collect local precipitation which are not attached to rivers (and are often man-made lakes in their own right), there’s no reason we can’t build “side reservoirs” in the mountains that don’t impede the river flow but feed from it and to it as necessary. It won’t be easy, and it won’t be cheap, but there is a middle ground to be found here. Hopefully there will be the political will and the cooperation from stakeholders to find that solution. Because the clock is ticking — all you have to do is look at the lack of snow in much of the Cascades right now (other than Mt. Rainier and Mt. Baker) to know that trouble is brewing.

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