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? <br />United States <br />Department of <br />4PAgriculture <br />File Code: 2500 <br />Route To: <br />subject: Drought Conditions and Conservation Measures <br />To: Forest Supervisors <br />Date: March 14, 2002 <br />As spring and summer approach we appear to be heading into our third consecutive year of <br />below average snowfall. I want to update you on our concerns with the drought situation, as well <br />as the extent of our ability to address it. <br />The Forest Service has a long history of managing for "favorable conditions of flow." The <br />enabling legislation that created the first National Forests, "The Organic Act," stated the purpose <br />of the National Forests was to "provide for favorable conditions of flow and a continuous supply <br />of timber." In the late 1800's extensive timber harvest lead to higher spring flooding, and was <br />depriving ranchers and farmers of valuable late summer water for irrigation. People of the day <br />were worried that continued over harvest of timber in the western mountains would ruin ranching <br />and farming, as well as deplete timber supply. Thus, for over 100 years the Forest Service has <br />recognized the link between healthy forest and healthy watersheds. <br />Research has shown that it takes extensive vegetation manipulation to realize any increases in <br />water yield, and that the predominant time of year in which water yield can be increased is <br />during flood events (Enclosure A, from Larry Schmidt - RMRS). Consequently landslide <br />activity can increase, erosion can increase, and stream channels can become destabilized. As the <br />unstable stream channels erode, the water table drops, and riparian zones are lost. Healthy <br />riparian zones act as nature's reservoirs, and meter out water yield for late season flows. It was <br />precisely this type of stream damage that likely was occurring in the late 1800's, triggering the <br />Organic Act and the formation of the National Forests. <br />Current research treatments designed to generate water yield have been necessarily limited to a <br />few very small basins (mostly less than one square mile) in elevations and aspects most <br />conducive to water yield increases. Our ability to increase water yield on a larger watershed <br />basis is limited by many constraints, including land ownership, vegetation type, fish and wildlife <br />needs, legal water quality requirements, elevation and terrain. Larger watersheds have more <br />constraints, both physical and legal, that limit our ability to fully apply a research prescription. <br />The number one driver that affects water yield is precipitation, and precipitation is relatively <br />constant over the long term. As human population continues to grow, particularly in the arid <br />Intermountain Region, we expect to see increasing pressures placed on the demand for water. <br />That demand will continue to come from both consumptive (irrigation, drinking water, etc) and <br />non-consumptive (fishing, rafting, etc) sources. Our ability to appreciably change the amount <br />and timing of water is limited by many constraints, and the practical physical reality is, we are <br />not able to make significant changes on a large scale. Consequently, the most effective <br />management of National Forest System Lands will emphasize "optimal" water yield rather than <br />Forest Intermountain Region 324 25th Street <br />Service Ogden, UT 84401 <br />801-625-5605 <br />ow_ <br />4v <br />? Caring for the Land and Serving People Printed on Recycled Paper `d