Reading Water
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At Dancing Sheep Farm, water rationing is a part of my family’s daily life. Rain, collected off roofs and stored in fourteen 3,000–gallon underground cisterns, provides for all our water needs. We use an average of 172 gallons a day in our four–person household; I know this because we meter every gallon. For us, water conservation is not just a nice idea; it’s a fact of life. Lingering in the shower in June can mean empty cisterns by September. Our watershed is the combined square footage of the barn, carport and house, totaling 4,200 square feet of catchment area. Annual rainfall averages forty–three inches, from which we could theoretically harvest 108,360 gallons (4,200 square feet x 43 inches x 600/1,000). But not all this rain reaches our cisterns; some evaporates when it hits the roof, and some is lost to spillage as it overruns the gutters. In practice, we can harvest about 92,000 gallons during an average year, or enough for 535 days. No problem, right? Not so fast. Oregon rain does not fall evenly throughout the year, as it does in Texas, where home rainwater systems are more common. Half the annual total falls during December through February, which exceeds our cistern storage capacity—we’re often unable to store all the winter’s water, losing some to overflow. The summer drought runs from June through September, during which we may enjoy as little as two inches of rain altogether. I get nervous if the tanks are not at least three–quarters full as we enter summer. During average years we make do with little hardship (well, shorter showers than I’d like after a hot day baling hay). But 2005 is no average year. At the end of April, our tanks were one–third full with only a hope and a prayer for a wet late spring. Without that, we won’t meet our summer needs. All of which puts us in the same boat as many western–state residents; the only difference is, few of them realize it. National forests are to the West what our water system is to Dancing Sheep Farm. What happens to the precipitation that falls on national forests may depend more on the underlying geology of the land than on how the forests themselves are managed. Some forestland, like the west slope of Oregon’s Cascade mountains, is like our metal roofs—water runs off the land quickly after rainfall. Rivers and streams from this type of land flood readily in the winter and dry up just as easily in the summer. Other types of geology, such as the Cascades high–elevation lava fields or the deep layers of sand and gravel left by past glaciers, store water underground like our farm’s cisterns, before releasing it more evenly throughout the year. Neighboring watersheds, like the Santiam and McKenzie Rivers in Oregon, can have dramatically different patterns of seasonal flow because of their underground rock formations. Logging and road construction can hurt water quality by eroding dirt into streams, but how forest practices affect the amount of water delivered to towns, farmers or fish is less certain. On the one hand, trees exhaust water back to the atmosphere via respiration, which can total 20 to 30 percent of the precipitation that falls on a forest. On the other hand, in some locales, especially where fog and wind combine, trees act as giant condensation towers, wringing water from low–hanging clouds. But, it is geology combined with our convoluted infrastructure of reservoirs, canals and diversions that affect streamflows more than forest management alone. With the threat of increasing droughts on the horizon throughout much of the West, water literacy will soon prove as important to the city dweller as it is to us at Dancing Sheep Farm. |