The answer to that semi-rhetorical question is: YES! While much of the nation is in severe water crisis at this point (USA Today June 7, 2007), much of the coastal Pacific Northwest seems immune to the vagaries of drought. We should not let our good hydrologic fortune lull us into a sense of complacency, however. Drought is an important topic for the North Coast. Let’s take a quick tour of our local hydrologic situation.The casual observer of the North Coast would assume that we have abundant water resources. After all, average annual rainfall ranges from 50 to 150 inches. Beaches may receive the low end of that range, while the majority will fall on the crest of the Coast Range. Yet just because we get a lot of precipitation, it doesn’t mean that the water falls consistently all year. Generally by early July, a ridge of high pressure sets up over the eastern Pacific, and sends storms towards the north. This weather pattern will usually stay in place through late September, and the consistent rains don’t usually start until November. Check out our climate patterns by visiting the Oregon Climate Service website.
The summer dry-season is also the time of year when our population peaks as tourist destinations swell with visitors, and part-time residents return to enjoy the best of the county. Of course, the summer and early fall is also the peak production period for farmers and gardeners alike. So water use is also at its peak. When water demand collides with water scarcity, we have drought. When it is driven primarily by population growth, we call that a “social drought.” In some increasingly popular coastal areas such as the South Coast, it is possible to have a social drought most summers. Given trends in second and vacation home growth on the North Coast, these water crises might not be far behind for us either.
Water is also scarce in the summer because of our geology. From northern to southern tip, the area’s mountainous terrain has created many relatively short watersheds. These funnel water through steep, rocky, narrow canyons into relatively short, shallow floodplains—the Tillamook Valley and Clatsop Plainss being the exceptions—and into the Pacific Ocean. This means that water transits quickly through our communities. Our subsurface geology is particularly complex here too. Much our groundwater seeps into shallow aquifers beneath our narrow floodplains. Depending upon the slope, the groundwater may seep towards lower points. This is the explanation for some springs at the beaches, where groundwater hits its lowest possible point and surfaces. Other springs are formed in mountain slope areas as water trickles through fissures in the rock. Once on the surface, spring water rejoins streams on their journey to the sea. Most surface and groundwater has little place else to go but towards the ocean.
A significant portion of groundwater is also tied to summertime water in our rivers. While wintertime rains fill our streams to overflow, how is it that they continue to flow without rain into early September? The reason is that groundwater recharged by precipitation into the surrounding watersheds feeds them with a steady supply from springs and underground seepage during the dry season. The effect is a delayed release of water that lasts from the last springtime soaking rain through the dry season. Take away that water and we would see our rivers slow to a trickle, while smaller streams may dry completely. In drought years this is often the expected outcome. Our summertime droughts are just one drier-than-normal winter away.
All of this mixture of geography, geology, population, and climate means that despite seemingly abundant rains, water conservation is important for maintaining healthy communities and watersheds upon which we depend. After all, North Coast residents have been working diligently to help salmon populations with habitat enhancement, but what if we–even temporarily during summertime drought periods–drained their rivers dry for ourselves? Where I come from in the U.S. Southwest, this is the all too typical and ultimately tragic story: river bottoms were settled, people tapped them as well as their surrounding aquifers for cities and agriculture, draining aquifers that fed streams, and the result was that rivers ran dry by the end of the 20th century. Fortunately, the Pacific Northwest is not in that position unless our climate becomes dramatically drier. However, given the word from recent global warming models published by the Intergovernmental Panel on Climate Change, this is a possibility.
Global patterns aside, the North Coast climate can produce unpredictable dry periods. Its communities are also experiencing some rapid growth in primary and second homes in selected areas. Placed in context with shallow aquifers and short watersheds, drought is not a distant possibility. To address drought, water conservation should be common practice, especially during the summer when demand is peaking and water is scarce. For just one start on that path, check out Water – Use it Wisely. For information on water conservation techniques, contact Oregon State University Extension Service – Tillamook County, 2204 Fourth Street, Tillamook, OR 97141; (503) 842-3433.