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"'::l" f'- C"j Relationship of the Silt Project to National Forest Lands The Silt project features and project lands are all outside the exterior boundary of the White River National Foresto As far as can be foreseen, the project will not impair or affect any existing facility or service on national forest lands. Relationship of Watershed Conditions to the Sll t Pro,iect The watershed area of the Sll t project comprises about 175 square miles. It consists of the East, Middle and West Rifle Creek drainages, plus the drainage area of the lands lying south of the Grand Hogback and the west portion of Dry Elk Valley north of HaJ'nc>y Gap Reservoir. Sixty-three per- cent of the lands in the watershed are owned by the Federal Government, wIth the remaining 37 percent being in private and State ownership. Watershed problems consist largely of: (1) silt and sedIment production from the Mancos shale areas above the Rifle Gap Reservoir; (2) denuded watershed lands due to improper grazing practices and loss of protective cover by fire; (3) abandoned beaver dams, which break and contribute sedi- ment to stream flows; and (4) local flood water and sediment damage to irri- gation canals and systems foltcwhg thunderstorms and rapid snow"'filelt runoff on erosive type soils and steep and sparsely vegetated slopes. No large flood control structures are recommended. The high and intermediate elevation zones pose no flood problems to the project. Flood control struc- tures will be ineffectual in the lower elevation zones due to steep slopes, raw soils and sparse vegetation. Critical areas do exist and their harmful effects can be lessened by improved management such as fencing, revegetation and restricted grazing. Canal or ditch designs should provide protection for runoff from these lower elevation areas. Individual floods will be small due to short slopes and low rainfall but the cumulative effects of these events creates a need for corrective measures. Sediment production can be reduced by the application of land treatment measures to watershed lands. Improved watershed conditions wlll r.educe ditch and canal operation and maintenance cost. Establishment of land treatment measures on problem areas will also reduce sediment carried by streams and extend the useful life of the reservoirs. Needed watershed treatment can be accomplished and would be justified under programs of Federal land administering agencies and by private land owners with assistance normally furnished by Federal and State agencies through Soil Conservation Districts and otherwise. vi