Study Reach.--Section 1 is about 1.8 miles upstream from gage.
Gage Location.--Lat 45°55', long 116°01', in SE1/4 NW1/4 sec.30, T.30N., R.4E., on right bank just downstream from powerhouse of Washington Water Power Co., 6 miles east of Grangeville.
Drainage Area.--865 sq mi.
Gage Datum and Elevations of Reference Points.--Not available.
Stage, Discharge Measurements and Computed n-Values.--Gage heights were 12.50 ft at gage; 30.85 ft at section 1. Peak discharges was 12,600 cfs. on May 29, 1948.
Date of Observation | Discharge (ft3/s) | Average Cross Section Area (ft2) | Hydraulic Radius (ft) | Mean Velocity (ft/s) | Slope | Coefficient of Roughness n |
---|---|---|---|---|---|---|
5/29/1948 | 12625.3 | 1334.3 | 8.51 | 9.46 | 0.006284 | 0.051 |
Description of Channel.--Bed consists of rock and boulders; d50 = 250 mm, d84 = 440 mm. Banks are mostly boulders and have trees and brush along tops.