Water Talks Underway in South Thurston Countyby Gordon White Over the past several years, citizens in south Thurston County have struggled with floods, contaminated well water and soils so saturated that lakes have emerged from the ground. Photos of water-soaked homes and of families walking over planks have been featured in the local newspaper. "It's like Minnesota out there," observed one person. "There's water everywhere." Water Issues Defy Clear-cut Solutions Residents of south county have experienced two very different kinds of flooding over the past few years: flooding from high water tables and flooding from overflowing rivers and streams. The causes and effects of these types of flooding are very different. In some areas of south county, the land is like a large flat sponge. This sponge works great in holding onto water from rainfall and slowly releasing it during the year to streams and aquifers. However, if the area receives above average rainfall two to three years in a row, this sponge becomes saturated, unable to absorb more rainfall. Water begins to pool at or above the surface causing flooding of homes, businesses, roads, and farm fields. A review of rainfall records of the past 50 years shows Thurston County gets back-to-back years of above average rainfall about every twenty years or so. These periods of above average rainfall coincide with information about high water table flooding from longtime residents of the area. Back-to-back years of heavy rains were to blame for high water-table flooding in 1971/72 and, most recently in 1996 and 1997. During the past 100 hundred years, farmers and other landowner dug ditches into this sponge to help drain off the water faster so they could get into their fields earlier in the growing season. For the most part these ditches worked to move the water off the fields earlier in the year, however they did not prevent flooding altogether. For better or worse, many of these farm fields became subdivisions over the last twenty years during periods of below normal rainfall. During this same time period the one time farm ditches became overgrown with vegetation, and in some cases filled in during home construction or road building. Other areas of south county are within the flood plains of major rivers and streams. Most residents of these areas have not been surprised by the f looding, but have been surprised by the frequency of flooding and the major streambank erosion that has taken acres and acres of land. So what should Thurston County government do about these problems? Just as water surfaces, so do people's attitudes about potential government solutions. Opinions range from property-rights advocates, who want the county to step aside entirely, to others who support an aggressive stance in regulating growth and development. Some people think the county should take a "buyer beware" stance and hold people accountable for their own decisions. Others want a more protective role to stop people from building in high water table or "big flat sponge" areas. Others want the county to drain the "big flat sponge" areas entirely. "Why Did the County Allow Us to Build Here?" Regardless of where they fall on the political spectrum, many people share a common question: "Why did Thurston County allow us to build here in the first place?" The answer, in part, is that the county lacked the legal tools to control the location of development. Many of the residential subdivisions experiencing "high water table" and river flooding were created prior to the adoption of county zoning. Another problem is that these flood-prone areas are not easily identified. Federal flood plain maps done in the early 1980's have been found to be off by 20 to 50 percent. And there are no maps which show the boundaries of the "big flat sponge". In 1981 when the county did adopt zoning, planners raised concerns of the potential for flooding problems in the "flat sponge areas", but not enough information was available to verify the specific areas of concern. It wasn't until recently, with the adoption of the growth management regulations, that the county had land use laws in place that would have prevented development in the river flood plain areas. Interestingly, federal soil surveys show in general that the "flat sponge" areas are subject to seasonally high water tables, but the surveys are not useful for site-specific building conditions, and cannot be used on their own to deny a subdivision or building permit. In order to determine the suitability of particular building sites, site-specific soil analyses are done to find evidence that the soil is subject to seasonal high water. However, the infrequent nature of flooding meant that soils in these problem areas lack tell-tale clues that they are subject to high water-table flooding. County Seeks Solutions Thurston County is working to tackle these flood problems in the south county area. Infrared photos taken this winter are providing the county with "hard" data about flood-prone areas, and the county is examining ways to improve development regulations and warn potential homeowners about potential high water table and river flooding. To guide their decisions on water problems, Thurston County commissioners have decided to apply a "litmus" test:
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