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C. Discharge Measurement. Three discharge measurements were taken during 1993; one in April and two in June (Appendix B). The purpose of the discharge measurements was to estimate the flow split around the spawning bar. On April 19, approximately 1,450 cfs was measured for entire cross section E-4; 26% in the right channel and 74% in the left channel. The discharge was measured for cross section E-4 on June 4 and E-5 on June 5. A limited number of velocity intervals were measured to estimate the discharge in June. During these two days the estimated discharge at the Jensen USGS gage was about 19,000 cfs. The measured discharge was 17,300 cfs at E-4 and 20,300 at E-5. On June 4, the flow split at E-4 was 21 % in the right channel and 79% in the left channel. This was slightly less flow in the right channel than during the April measurement. D. Water Surface Prediction. The Corps of Engineers HEC-2 water surface profile program was applied to predict water surface elevations for cross sections E-1 through E-18. The cross section locations and distances between cross sections were established to appropriately model this river reach with the HEC-2 model. Initially, the HEC-2 data files were created using the cross section data first from April and then from June. This cross section data was assigned elevations according to a preliminary survey using an unverified benchmark. In August, all the cross section end points were correctly assigned elevations with a level loop survey to a confirmed USGS benchmark. This necessitated revisions in the bed elevations in the original HEC-2 data file. The HEC-2 analysis was then finalized using the cross survey data collected in August because all of the cross sections were surveyed on that trip. The cross section revisions did not significantly effect the n-value calibration. The HEC-2 n-value calibration was performed using an initial Manning's n estimate of 0.025, 0.030 and 0.040. The program then generated n-values at each cross section to match the water surface elevations. The results shown in Table 3 indicate the variability in the n- values. There are several factors which can effect the n-value estimates. These include: poor surveys of the water surface elevation, local controls such as flow constrictions, variable discharge during the survey, and changes in the cross section due to scour or deposition. Local flow controls cause the greatest variability in n-values although it should be noted that the water surface elevations surveyed in June were influenced by wind-induced waves. In Table 3, the average n-value was computed to be 0.029 based on a starting n-value of 0.030. 20