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I I I I I I I I I I I I I I I I I I I TABLE 5.2 WATER SURFACE ELEVATIONS (FT) FOR RANGE OF FLOWS UNDER EXISTING CONDITIONS Flow rate XS 1500 XS 1400 XS 1300* XS 1200** XS 1100 XS 1000 (cfs) us of dam ds of dam 350 4953.39 4953.38 4953.28 4950.12 4950.10 4947.78 650 4953.70 4953.69 4953.54 4950.61 4950.58 4948.50 1200 4954.13 4954.11 4953.91 4951.19 4951.14 4949.40 3000 4955.15 4955.12 4954.81 4952.52 4952.41 4951.27 3460 4955.37 4955.33 4955.01 4952.84 4952.73 4951.65 6470 4956.55 4956.51 4956.12 4954.67 4954.54 4953.66 11600 4958.13 4958.10 4957.63 4956.87 4956.72 4955.90 13500 4958.61 4958.59 4958.10 4957.46 4957.31 4956.48 18700 4959.84 4959.83 4959.30 4958.82 4958.65 4957.75 21200 4960.37 4960.36 4959.83 4959.37 4959.20 4958.27 * Cross Section 1300 is located immediately upstream of the diversion dam ** Cross Section 1200 is located immediately downstream of the diversion structure at the toe of the dam 5.3 Ditch Hydraulics for Fish Screen Design The survey of the Hartland Ditch was conducted on May 12, 2000. At the time of the survey the staff gage in the ditch reading was 1.78 ft corresponding to 31.2 cfs on the gage rating table (Appendix F). Flow entering the spill channel is estimated to be 12.7 cfs based on weir flow over the existing flashboards. Thus flow in the upstream portion of Hartland Ditch is estimated to be 43.9 cfs. These flows and water surface elevations are used to calibrate the hydraulic parameters for modeling proposed conditions. The results of the calibration analysis are presented in Appendix F. Based on the calibration model, a Manning's n value for the channel is set at 0.038 for the channel and 0.04 along the banks. Depths of water for the range of flows analyzed (60 to 80 cfs) vary between 4 and 5 feet with velocities ranging between 1 to 1.5 fps. 22