Our Water, Our World: The Mystery of the Underground RiversBy Paul Pickett One question I have heard asked many times is "how much water do we have"? The correct answer is "we don't know". The response to that answer is often interesting. Outrage. Anger. Confusion. It seems like such a simple question. Why shouldn't we know? One reason we don't know is that we don't have a Superman with x-ray vision to look under the ground. Most of the water available for people to use is ground water, which likes to keep its whereabouts a mystery. Of course there are some areas where the amount of ground water is well known. But these areas are more the exception. Why the mystery? In Thurston County we have a very complex geology. In some areas, ancient volcanoes left outcroppings of cooled lava, which give us the basalt bedrock of the Black Hills. In other areas the uplifting of the continent has lifted sedimentary deposits from the bottom of the ocean to the tops of the hills. Then came the glaciers – grinding across the landscape and leaving a wide variety of debris, from sand beds to gravel outwash to clay layers to hardpan. The result is a complex mélange of materials scattered below the landscape. Layers and lenses and pockets of the kinds of gravel that can hold water occur at various depths and locations that are difficult to predict. So the only way to know what's down there is to poke a hole in it. You can look in lots of holes and get an idea of what's down there, but sometimes what's in one hole looks very different from another one not too far away. Bottom line for all this: to answer the question about how much water is down there takes a lot of holes, and also careful scientific measurements and mathematical tools for analysis. And that takes a lot of money. The answer is always at best a SWAG (scientific wild-assed guess), but money can make the guess more likely to be true, or at least answer the question for specific locations. What's also important for ground water is not just where it is, but where it's going. Ground water often follows the lay of the land and eventually emerges in a stream or river. In the dry days of summer any flow you see in a stream is coming from ground water. So where that ground water came from may be very important to the fish in the stream. That's why the big environmental question in ground water science is "hydraulic continuity". If you drill a well in one location, are you using water that would otherwise have reached a stream? And how much are you affecting the stream? As you can gather from the discussion above, this is not an easy question to answer. For exempt wells, we don't even demand an answer, we just hope everything will be ok. For big wells that need water rights, a lot of time and money can go into answering that question. For the last several years Lacey, Olympia, Yelm, and the Nisqually Tribe have been trying to discover what the effect of tapping a regional aquifer in northeastern Thurston County will be on the springs and streams of the region. This mystery is still being explored at this time. What makes this very complicated is that ground water flows don't necessarily follow surface water boundaries. Several studies have shown that ground water from the Nisqually River basin is flowing west into the Deschutes River basin. The Deschutes River TMDL study showed that flow increases and gets cooler in the reach of the river that receives this inflow. So what are the effects of wells in the Nisqually River basin on Deschutes River flow? And how do we manage the use of this underground river with the Swiss-cheese patchwork of water planning on the ground's surface? There is no Deschutes River basin watershed planning group. The Nisqually watershed planning group doesn't look outside its boundaries and may be losing its state funding. The Department of Ecology is seeing its funding cut for water management. And hundreds of exempt wells are put in each year with no management at all. A common belief in this area in years past was that there was an underground river from Mount Rainier that provided our water in Thurston County. We now know this is not true, but many mysteries still remain about the flow of water under the earth and about how we manage it. And on these mysteries rest the future of our water environment. Paul Pickett is an environmental engineer, Public Utility District Commissioner, and regular columnist for Green Pages.
Back to Home page. |
