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10 In 1982 nine hydraulic measurements and sediment samples were collected at Mathers Hole in the months May through July. The seasonal hydrograph was composed of two peaks; the first of which occurred on May 5 and was the highest. All the sediment samples were collected on the recessional limb. The highest measured discharge for which samples were collected was approximately 11,000 cfs. The sampling program for 1983 was greatly expanded over that from the previous year. Forty-three daily sets of sediment data were collected at Mathers Hole, with the highest sampling discharge being 19,300 cfs. Measurements were made on both the rising and recession limbs; 28 sets of sediment data were collected on the rising limb and 15 on the falling limb. The sediment samples were supplemented with measurements of water surface slope, river width, cross section profiles and velocity. Suspended sediment samples were collected at ten foot verticals with a USGS D-74 depth integrating suspended sediment sampler using the ETR (Equal Transit Rate) method. The D-74 sampler is lowered from the surface to bed and raised to the surface at the same rate at each vertical. This rate should not exceed that which would fill the bottle approximately three quarters full at the deepest vertical. The transit rate is established by volume of sampler container, nozzle size, velocity profile of the stream, and the flow angle. A type B-56 USGS reel was used to raise and lower the D-74 sampler. In 1982, a sample bottle was collected at each vertical and returned to the laboratory for analysis. An improved and simplified method was implemented for 1983 field season. After the bottle was removed from the suspended sampler, the contents were poured through a 0.0625 mm sieve into a graduated cylinder and the volume recorded. The fluid contents plus the fine sediment (silts and clays) were then poured into a 32 liter churn. This process was repeated at each ten foot vertical for two crossings of the entire river. At the completion of each crossing the sand size sediment in the sieve was washed into a container and sealed. Following the completion of the second crossing, the churn was pumped and three supernatant samples were drawn off from the nozzle of the churn into three separate 250 ml bottles. These bottles together with the two sand containers were returned to the laboratory to determine suspended sediment concentration. The field assistants were trained by USGS personnel in Denver to apply this new method. The Helley-Smith sampler was employed to collect unmeasured sediment zone samples near the bed. The Helley-Smith sampler was operated at each vertical in conjunction with the D-74 sampler. At each vertical, the Helley-Smith sampler was lowered to the bed and left there for 30 seconds. For each crossing a separate bag of sediment was collected, sealed and returned to the lab. The Helley-Smith sampler is not sanctioned by the USGS but represents the best available technology for bedload and unmeasured suspended zone sampling. Discharge measurements were facilitated in 1983 by erecting a staff gage. A stage-discharge relationship was calibrated with 24 measure- ments over the two field seasons. The Mathers Hole cross section