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III. Data Collection Methods A. Cross Section Surveys. A total .of 23 cross sections were established and monitored in this reach of the Green River during the spring and summer of 1993. This included eight cross sections around the spawning bar (two were added by the National Park Service after the initial site selection), nine cross sections in the intervening reach between the spawning bar and the wetlands reach, and seven cross sections in the immediate vicinity of the wetlands. Cross sections were tightly spaced in both the spawning bar and wetland reaches and widely spaced apart in the intervening reach,. Cross section location was selected using several criteria. At least one cross section was located both upstream and downstream of the desired reach to be monitored. Cross sections were located at hydraulic controls (such as constrictions), areas of interest (spawning sites, wetland channel entrance, wetland channel exit), and at appropriate intervals between the two study reaches. Endpoints were chosen so that the cross section would be perpendicular to the river thalweg at high flows. These endpoints consisted of a 3 ft - 5/8" dia. rebar (bar) and cap and a 5 ft T-fence post which served as a tagline post. A total station was used to establish endpoint bar and caps coordinates surveyed from USGS benchmark geodetic coordinates. In August, the final cross section endpoint. elevations were established with a level loop using the Dinosaur Quarry benchmark (el. 4865.896). Initially in April, a level loop was completed on the downstream nine cross section;;. A second level loop was completed on the eight upstream cross sections in June. The remainder of the cross sections and the entire system were tied together in August running one level loop from the Quarry benchmark upstream to the first group of cross sections and a second level loop to the downstream group of cross sections. The last two level loops were closed within 0.05 ft. Starting with the left bank bar and cap as a zero station reference, overbank areas and water surface elevations were surveyed to the nearest 0.01 ft. Specific survey points included topographic changes in elevation of 0.5' or greater, a break in slope, specific topographic or geologic features and every 10' station. Flow depths were recorded to the nearest 0.1' and bed elevations were assigned by subtracting the depth from the water surface elevation. If opposite edge of water surface elevations were different by more than 0.1', intermediate water surface elevation were surveyed. River substrate, vegetation, and other descriptive information were recorded and photographed. 7