ACTIVITIES AND OBSERVATIONS For 1 day, May 4, normal sequence of spillway gate operations was changed to determine riverflow patterns for future power generating units. The waterflow was reduced in the right ladder from 11:00 to 11:30 a.m. and again from 1:30 to 3:40 p.m. on August 6 to repair a broken chain on an adjustable weir. On August 30, attraction water was discontinued at left ladder entrance at 10 a.m. for removal of grass and weeds from the drop gate screen. Water was restored to the attraction system at left ladder entrance on August 31 at 2:30 p.m. On September 1, the center ladder was partially dewatered from 12:45 to 2:30 p.m. to allow inspection by a diver of the diffusion gratings in the lower part of the ladder. On September 16, from 10:25 to 11:50 a.m., attraction water at the left ladder entrance was discontinued to allow a diver to clean grass and weeds from a large screen in front of the drop gate. On September 20, the center ladder was partially dewatered from 9 a.m. to 4 p.m. to repair a broken chain on an adjustable weir. An open submerged orifice was discovered at bottom of the counting station weir. Fish passing through this opening were not counted. On September 21, the right ladder counting station was out of operation from 6 to 10 a.m. owing to high water in the pools above the counting weir. This condition resulted from grass and weeds plugging the pickets at the counting station. On October 1, the center ladder was partially dewatered from 11 a.m. to 5 p.m. to repair a broken chain on an adjustable weir. On October 5, the attraction water was discontinued at the center ladder from 10:20 to 11:40 a.m. to allow a diver to clean the screen in front of the entrance drop gate. On October 15, attraction water at the left ladder was discontinued from 10:00 to 11:30 a.m. during removal of grass and weeds from the ladder entrance screen. As part of an evaluation study of effects of Wanapum Dam reservoir encroachment on the ladders at Rock Island Dam, the Bureau of Commercial Fisheries trapped and tagged fish at the left bank ladder. Chinook were taken in a floating trap at the exit, and sockeye were trapped at the counting station inside the ladder. All fish taken were tagged with numbered Petersen disks and released about 1,000 ft. (feet) below the dam in equal amounts on each bank of the river. Trapping and tagging was performed intermittently from May 16 through June 9 for chinook and July 14 through August 4 for sockeye. During this period, 311 chinook and 679 sockeye were tagged and released. Numbers of tagged fish returning through the ladders were: chinook, 288; sockeye, 626. Twelve chinook tagged by fishery agencies in the lower river were observed passing over Rock Island Dam during the counting season. During 1965, fish were observed with cuts or abrasions on their heads and bodies. Of the 85,107 salmon and steelhead seen passing over the counting boards, 3,801 fish (4.5 percent) had injuries (table 21). This was more than twice the percentage of injured fish observed in 1964. Because in both years the counters could see only the top and one side of each fish, the incidence of injury might have been greater than observed. Of the total number of injured fish observed in 1965, about 67, 22, and 11 percent were recorded in the left, middle, and right ladders, respectively. In 1964, these percentages were 56, 23, and 21. As in previous years, the greatest number of injuries was observed on the large chinook and sockeye. In the 2-wk. (week) period July 16-31, 26,691 sockeye were counted through the fishways and injuries were noted on about 8 percent. In 1964, during the same period, about 2 percent of the sockeye observed had injuries. Throughout the counting season, State and Federal fishery personnel made frequent inspections of fishway operations at Rock Island Dam. Inspections were similar to those at other main stem dams where fishways were operated. |