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Show PART III CURRENT WATERSHED CONDITIONS AND PROBLEMS, AND EFFECTS OF PROBLEMS There are nine million acres of public domain land considered to be in critical watershed conditions. They are in such poor condition that land treatments in addition to resource use management restrictions will be required to control accelerated soil erosion. These greatly depleted lands are widely distributed over the public domain, but tend to be concentrated in the same general areas as the areas described above An additional fifteen and one-half million acres of public domain land are moderately eroded. There are at least three areas within the public domain that merit special mention. One is the Bookcliffs area extending from Cameo, Colorado, westward to Elmo, Utah, and then southward into the heart of Garfield County, Utah. This is an extremely high sediment yield area. It is subjected to periodic severe storms and the shallow upland soils formed over Mancos shale support sparse vegetation. Deep soils formed in alluvium and colluvium from the shale are subject to piping and often are saline or gypsiferous. Another is the Paria River Basin, 1,570 square miles of predominately steep, rugged and highly erodible terrain in south-central Utah. The entire watershed is made up of sedimentary formations and, with the exception of small areas of gypsum and hard limestone, these formations are moderately to highly erodible. Undesir- able vegetal cover and previous management have contributed to the formation of a continuous gully system from mouth to headwaters of every major tributary. A third area is the San Juan River at Shiprock contri- buting 2,370 tons of sediment per square mile per year. Much of this sediment arises from public lands in San Juan, Rio Arriba, and McKinley counties in New Mexico. Many other small washes and basins with severe sheet and gully erosion exist within the public domain. They vary in size from a few hundred acres up to the size of a township and are too numerous to be discussed individually. Private Lands Accelerated water erosion damage on privately owned forest land varies greatly with the type of forest cover and the soils. For the most part, there is more damage at elevations below 7,000-7,500 feet because of thinner stands and a sparser understory in pinyon-juniper as compared to pine or fir forest. Erosion is chiefly in the form of gullying of deep, friable soils along drainageways; however, there is some rill erosion on exposed upper slopes. Nearly all of the water erosion is due to a concentration of runoff or destruction of cover by grazing, logging or fire. South and west facing slopes are more susceptible to water erosion because of greater temperature fluctuations and poorer cover. 27 |