_GENERAL DOCUMENTS - C1981017 (258)

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Bench Outslopes. The Outslopes vary in size from about three to eight acres in extent. Slope lengths to eight hundred feet are not uncommon. The Outslopes lie at approximately the angle of repose, are generally devoid of vegetation and are heavily gullied. These Outslopes shed large quantities of sediment each year, directly impacting the quality of Coal and Dutch Creeks. This iron rich sediment is though to contribute to the degradation of Coal Creek quality. The Division of Minerals and Geology,has successfully revegetated three of the seven Outslopes. Two were revegetated in 1997. In 1999, the Division applied for, and received a Non-Point Source Grant. Funds from the grant were used to attempt stabilization through revegetation of the remaining five Mine Bench Outslopes. Of the five outslopes, four have a southerly aspect, and one has a northerly aspect. Weather patterns in the fall of 1999 and the summer of 2000 were not conducive to wildland revegetation. As a result of sustained hot weather and droughty conditions, revegetation success on the southerly facing Outslopes was insufficient to substantially reduce sediment delivery to receiving streams. The one northerly facing slope was successfully revegetated. An examination of field data collected during the 2000 and 2001 field seasons indicates that a vegetative cover of approximately thirty percent has been established at this location. As a result of this cover establishment, modeling suggests that sediment generation from this slope has been reduced by approximately 4.33 tons per acre per year, equating to a nearly forty percent reduction in sediment generation. The amount of sediment generated from this Outslope is anticipated to decrease over time as vegetation becomes more established and matures. For comparison purposes, the less successfully vegetated southerly facing Outslopes experienced an estimated sediment generation reduction of less than one ton per acre per year. Consequently, as Mesaverde Group generated sediment delivery is reduced from the Mine Bench Outslopes as a result of establishing vegetation, the levels of iron bearing sediment found in receiving streams will be reduced. Sediment generation is directly tied to snowmelt runoff and summer thunderstorm events. Direct measurement of sediment generation is extremely difficult due to the remoteness of the Outslopes, and the flashy nature of the runoff events. Therefore indirect measurement of sediment production through the use of computer generated Models is necessary. Modeling suggests that the unvegetated Outslopes shed 10.8 tons per acre per year of Mesaverde Group derived sediment. 3.0 PROJECT DESCRIPTION 3.1 The Project has two environmental goals: (1) Reduce erosion at the four remaining Outslopes by fifty percent through the establishment of a vegetative cover of forty percent or greater; (2) Contain fifty percent of the sediment which continues to be generated from three of the Outslopes following revegetation. Programmatic goals are two fold: Involve local communities in the watershed improvement project; Disseminate high altitude revegetation and erosion control information to the scientific community, local governments and other interested organizations. 3.2 Objectives Objective 1: Reduce outslope erosion through vegetative processes.