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decrease in flow; the question is whether or not the change can be detected <br />at an off -site streamgage. <br />b <br />i <br />Cd <br />3 <br />x <br />L <br />U <br />C <br />3 <br />O <br />Gq <br />a> <br />t� <br />7 <br />E <br />7 <br />U <br />600 - <br />500- <br />400- <br />300. <br />200. <br />100• <br />0 <br />0 <br />GGG Pre- harvest(1951 60) <br />Pred Pre - harvest <br />O <br />OCO Post -harves t(1961 -80) <br />" Pred Post - harvest <br />y <br />57.092 +1.914' <br />A' <br />.tY <br />0, A' <br />y= 1.540+1.242 <br />x <br />i i i I I - 1 1 <br />50 100 150 200 250 300 350 <br />Cumulative North Fork Water Yield (in) <br />Figure 10: Cumulative annual water yield for Brownie Creek plotted over that for North Fork <br />of Dry Creek. The Brownie Creek streamgage was relocated in 1960. Harvest <br />occurred on Brownie Creek from 1960 -1972 and effect is not evident. <br />As noted earlier, the primary objective of this effort is to address the <br />application of existing water yield augmentation technology to the "suitable <br />and treatable" NFS land in the North Platte River Basin and quantify the <br />potential for augmentation through timber harvest. At the outset, it should be <br />noted that even Coon Creek, where water yield augmentation was the <br />primary focus and dedicated use of the land, less than 24 percent of the total <br />watershed area could be impacted. The initial intent was to harvest one -third <br />of the watershed area in order to mimic the experimental watershed <br />treatments. Even though the Coon Creek project was minimally constrained <br />by concern over other resources, operational constraints -in the forest plan <br />limited the harvested area to less than 24 percent of the watershed area. <br />In managing public lands, the USFS must address the potential impact of <br />any proposed alternative on numerous resources. Figure 11 represents a <br />simple schematic showing the relative impact of various harvesting practices <br />on the value of various resources, including water. There are tradeoffs, and <br />as can be inferred from Figure 11, not all resource needs can be met on a <br />given site. Patch clear cutting (PC), for example, appears to maximize water <br />yield, per acre hanzested, but it is very detrimental to several other resources <br />currently considered important. Patch clear cutting cannot be applied to all <br />20 <br />1 <br />r <br />[7 <br />rJ <br />