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<br />OUl527
<br />Craddock and Pears e (1938) made studies in the Boise River Bas in
<br />of Idaho and found that a bunchgrass range in good condition yieldedprac-
<br />tically no sediment and runoff which averaged only 0.4 percent of the
<br />precipitation. In contrast, an annual weed type of vegetation areas yielded
<br />approximately 7 1/2 tons of soil per acre, which was 150 times as much
<br />sediment as those growing bunchgrass. The runoff was correspondingly
<br />higher. These data indicate that the protection of the proper species of
<br />plant life on the range is highly important in the prevention of erosion.
<br />Selection of the proper location is highly important and should receive a
<br />great deal of"study. No stock pond should be located where it will create
<br />or stimulate erosion that cannot be overcome by protective measures.
<br />
<br />Reduc in/:( sedimentation
<br />
<br />Stock ponds normally may be protected from excess ive sedimenta-
<br />tion by proper management and treatment. An area of sufficient sizeand
<br />suitable for seeding to grass can often be located above a ,stock pond where
<br />it will slow down the flood waters and cause much of the sedimentation
<br />to be dropped. Grazing can be controlled within a fenced ar ea to allow
<br />for the maximum erosion control adjacent to the pond-us ing plant life
<br />(Talbot, 1943). The contributing watershed must be grazed in such a
<br />manner as to leave sufficient grass, shrubs, and forbs to slow down the
<br />flow of the water to the'extent that excessive erosion will not take place.
<br />
<br />It may be found that maintaining an adequate protective grass cover
<br />will reduce runoff so much that there will be little to supply the pond. In
<br />such a case, a decision must be reached about which conditon will be of
<br />greatest benefit, good range or water. The decision can be complex as
<br />it will involve both economics and range mangement problems.
<br />
<br />There is an ultimate limit of feasible storage in every watershed.
<br />It is only natural that the initial stock ponds should be constructed at the
<br />most favorable and economic sites and that substitute or supplementary
<br />storage facilities of the same capacity will be most costly (Eakin, 1936).
<br />It then becomes pertinent to consider relative costs of protection of devel-
<br />oped storage against depletion by sedimentation.
<br />
<br />Small detention or check dams for catching sediment are one
<br />means of preventing the sedimentation of stock ponds. The. check dams
<br />should, when poss ibl e, be built within a fenc ed area above {he impound-
<br />ment to be protected.
<br />
<br />Sometimes special conditions will allow the placing of spillways
<br />in ponds expected to overflow so as to minimize sedimentation. Off-
<br />channel stoc k ponds where properly located and constructed have an
<br />
<br />37
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