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3 <br />Section 3.0 <br />Section 3.1 (continued) <br />Temporary drainage reconstruction was accomplished on a 1300 foot segment <br />immediately above the brush crimped area in Johnson Gulch. <br />Additional erosion control work in Johnson Gulch included seeding of rills and <br />small gullies on the reclaim areas of Enfield and Ashmore pits. Livestock ponds <br />were constructed on reclaim areas in Enfield and Ashmore pits and will assist in <br />reducing flows to the major drainage. <br />Major drainageway reconstruction concluded in September of 1987 with incidental <br />activities occurring in Oct - Nov 1987. <br />Section 3.2: Flow <br />Discharge readings in Coyote drainage were recorded from a 10 year-24 hour <br />parshall flume located at the north end of the treated drainage. The peak flow <br />for Coyote drainage in 1987 was 9,982 gpm (22.24 cfs) and occurred on June 7, <br />1987 (.74" ppt event). <br />Actual flow information for other treated drainage segments is not available. <br />However, peak flow data were collected at some downstream NPDES locations <br />during discharges from the sediment control structures. <br />Section 3. 3: Results <br />No results are available evaluating the success of Trapper's erosion control plan <br />for permanenC postmine drainageways in 1987. Surveyed profiles (Fig 3-1., <br />Drainage Profile Points) of reconstructed channels were performed to assist <br />Trapper and CMLRD in monitoring the future success of these erosion control <br />treatments. In the event the drainage fails or any portion fails and is <br />reshaped, those reshaped sections will be resurveyed and submitted to the <br />Division. <br />Section 3.4: Conclusion <br />The initial success or failure of this project has yet to be demonstrated. <br />Excessive gully erosion will recur if structures were improperly placed, or if <br />unforeseen high intensity thunderstorms or snow melt drastically influence the <br />watersheds. The success of woody vegetation establishment will be key in the <br />long term channel stabilization. Without a combined effort to ensure vegetation <br />establishment and proper physical barriers to eliminate the gully network, it is <br />possible for downstream cutting to move upstream and erode the drainageways. <br />Regardless of Trappers efforts to stabilize postmine drainageways the long term <br />stability of treated drainages and of undisturbed pre-mine drainages is subject <br />to the affect of catastrophic weather patterns. <br />WA/ rb <br />