Search

Nepal is rich with inland water resources and has great potential for electricity power generation. Hydropower is one of the most sustainable national income sources to increase the nation’s GNP. Relatively few water resources are under utilization, however, although some lakes in Pokhara valley and the Kulekhani storage type hydropower reservoir are successful in supporting multipurpose usage, combining electric power generation, irrigation and aquaculture. The Kaligandaki hydropower system is run of river, thus not feasible for cage fisheries; instead, it produces fingerlings of indigenous riverine fish for release into the river. The impoundments after damming the rivers adversely impact both fish biodiversity and local fishing communities. Ecosystem change destroys feeding as well as breeding grounds, with a resultant loss of fish species. Where the movement of migratory fish up and down river is affected by hydropower development, fish hatcheries near the dam sites or fish ladders for fish movement should be considered as mitigation options. Local user groups and other stakeholders should be involved in decision-making, to keep good relations concerning peoples’ livelihoods and the sustainability of aquatic resources. River systems should be thoroughly studied jointly with concerned agencies (e.g., electricity, irrigation and fisheries authorities; and local authorities) during formulation and application stages of hydroelectric power development projects. Hydro Nepal: Journal of Water, Energy and Environment Vol. 1, No. 2(2008) pp. 22-25

The development of the fish passage and fish spawning facilities for the Wells Hydroelectric Project is described. Because the spillway and powerhouse are combined into a single structure in the unique Hydrocombine concept conceived for the Wells Project, the conventional fish passage facilities could not be directly used at the Wells Project. A fish attraction system was developed by using submerged high velocity water jets at each end of the Hydrocombine to provide an attraction flow across the downstream face of the Hydrocombine. The jet locations and jet flow were developed from hydraulic model tests of the Hydrocombine structure. Two staircase type fish ladders are provided for passage of fish over the Hydrocombine, one ladder located at each end of the Hydrocombine. An extensive fish spawning facility was constructed immediately downstream from the west embankment of the dam. Located in the west fish ladder is a sorting facility for diverting selected fish to the spawning channel. A 150-acre artificial pond for rearing steelhead trout is constructed in the Wells Reservoir.

Description of 3 major fishway installations operated by Corps of Engineers, 2 more under construction, and several in planning stage; results of studies to determine most efficient solutions; laboratory studies on scale models and also on full scale models of fish ladders; details of fishways at McNary dam and Ice Harbor dam.

A series of tests were conducted to investigate the sense of smell in migrating coho (Oncorhynchus kisutch) and spring salmon (O. tshawytscha). By pouring dilute solutions of each of 54 substances into the path of the salmon moving up a fish ladder at Stamp Falls, B.C., positive responses were noted by recording changes in the rate of migration. Representative samples of alcohols, aldehydes, ketones, esters, organic acids and oils, as well as shark repellent and a pulp-mill effluent caused no significant change in the migration. However, dilute water rinses of mammalian skins had distinct repellent action. An acute olfactory sense enabling adult Pacific salmon to detect predators from a downstream position was considered to have survival value. The use of mammalian predator skins to repel salmon from destructive river locations is suggested.

4800 ft long dam consists of 450 ft gravity section on west bank, 1100 ft powerhouse section, 375 ft arch section, and 750 ft spillway section in river bed, and 120 ft gravity section and 2000 ft earth dam section on east bank; river diversion, 5,000,0000 cu yd excavations, and 1,000,000 cu yd concreting work; fish ladder at west bank and fish passage along entire river bed section; plant will produce 1.215 Mw by 11 units.

A device that can be used for rapid detection and separation of migrating adult coho salmon marked as juveniles with magnetized wire tags was tested in November and December 1967 at the Minter Creek Hatchery of the Washington Department of Fisheries. About two-thirds of the test fish in the holding pond entered the structure; the device correctly separated 89% of the fish with tags and 99% of the untagged fish. Placement of this equipment in streams, fish ladders at dams, and in hatcheries, would facilitate removal of tagged specimens from the general population of fish.

Passage of upstream migrant sockeye salmon (Oncorhynchus nerka) and chinook salmon (O. tshawytscha) through the three pool-and-weir type fish ladders at Rock Island Dam on the Columbia River was controlled to a large extent by the proportion of the total flow discharged through the turbines and also by the location of the open spillway gates with respect to the ladders. At intermediate river discharges (140,000 through 300,000 ft3/sec) it was demonstrated conclusively that the fish's preference for either the right or center ladders could be controlled by spilling adjacent to these ladders. Response to the attraction spill was rapid. Attraction of sockeye was dependent not only upon spill position but also upon the tailwater elevation at the ladder entrance. The statistical analysis of fish behavior in an experimental choice situation is discussed in some detail, particularly the use of Chi-square and analysis of variance methods.

A comparison of the rates of passage of alewives (Alosa pseudoharengus) into a pool and weir fish way throughout the peak of the alewife run (22 May-6 June) in a Nova Scotia river revealed that one entrance weir, built at an elevation 0.21 m (8.0 in) lower than the existing conventional weir, passed alewives at a significantly greater mean rate (56.25/min) than the conventional weir (23.25/min). The mean rate of passage of alewives from pool to pool within the fishway (37.59/min) was not significantly greater or less than the mean rate for either of the entrance weirs. Density tests at two intermediate fishway pools revealed that the relationship between alewife density and exit rate may be described by a curve that rises to a peak exit rate of 80/min at a density of 75/m3 and then levels off to 70/min at higher densities. It is concluded that crowding and delay is not likely to occur within the fishway at the peak of the alewife run. Values for substitution in the formula of Clay (1961) for calc...

Studies of the chinook salmon runs which will be blocked by Shasta Dam on the Sacramento River, California, indicate that a total annual run of about 27,000 fish will be blocked sometime in 1942. There are two relatively distinct spawning runs, one in the spring and one in the fall. The number of eggs per female is calculated to be nearly 7,000. There are also two distinct downstream migrations, one in the spring and one in the fall. Most of the young salmon go to sea during their first spring. It is not considered practicable to install fish ladders over Shasta Dam because of the height of the structure and because young downstream migrants could not pass it safely. Therefore, consideration is being given to salvage plans similar to those used for the salmon runs blocked by Grand Coulee Dam in the upper Columbia River. All tributaries of the Sacramento River below Shasta Dam have been examined as to their suitability for transfer of the run now passing Redding. Of 17 drainages examined, 9 are dr...

Columbia River fish ladders were surveyed as a possible ecological niche for Chondrococcus columnaris, the causative agent for columnaris disease of fishes. Water samples from Bonneville, McNary, Priest Rapids, and Rocky Reach fish ladders during periods of warm-water temperature and high population density of fishes showed C. columnaris levels of from 0.06 to 4.1 organisms/ml. Samples taken upstream or downstream from the ladders were consistently negative. Average agglutinating titers and incidence of C. columnaris infection in largescale suckers were higher at the Bonneville ladder than at a site several miles downstream Coho salmon from an upper-river fish ladder (Rocky Reach) showed a higher incidence of infection and greater antibody production than at the downriver Bonneville ladder. It is concluded that fish-ladder facilities on the Columbia River are important sites for repetitive exposure of anadromous salmonids to C. columnaris.

The facilities used for river diversion, log passage, and migratory fish passage are described with respect to hydraulic problems and design criteria. Diversion was accomplished by use of a 40-ft diameter horse shoe-shaped tunnel, in conjunction with upstream and downstream cofferdams. The design of the tunnel entrance and exit channels and the concrete tunnel lining allow passage of the annual log drive. Tunnel closure involves a temporary gate at the upstream portal and a permanent concrete plug in the tunnel. Upstream migrating fish are prevented from directly entering the tunnel by a concrete sill across the exit channel. A fish trapping and loading structure to facilitate fish hauling is designed to operate alternately with a by-pass fish ladder to provide fish passage during construction.

The low rock elevation was used to advantage by the development of a nonconventional design where the turbines were deeply submerged such that spillway openings could be located above the turbine water passages and between the generators. By locating fish attraction facilities and fish ladders into the end walls and locating the specially designed switchyard on the top deck, all requirements of a hydroelectric development on the Columbia River were provided in a single structure. Extensive hydraulic model tests were necessary to verify the proposed design especially the effect on turbine operation of the spillway discharging directly above the draft tube outlets. The single concrete structure, located in a flood plain, required minimum cofferdam construction and resulted in a number of advantages, in addition to less cost, as compared to a conventional arrangement. Detailed descriptions of the structural design, fish facilities, earth embankments and construction are contained in companion papers.

Blood lactic acid concentration of anadromous alewives (Alosa pseudoharengus) sampled during their upstream migration through a pool and weir fishway was not extremely high (46.7 mg/100 ml) and the degree of exercise exhibited during ascent was judged to be moderate. For fish that were subjected experimentally to severe exercise, the concentration (108.7 mg/100 ml) was more than five times that for rested fish (18.9 mg/100 ml). Of the three groups of fish sampled directly from the fishway pools, only one had an average concentration that differed significantly from that for the rested state.

Facilities, functional design, and construction and operation problems; possibilities for further design improvements.