Improve Fish Passage Research Articles

Water Velocity Measurements on a Vertical Barrier Screen at the Bonneville Dam Second Powerhouse

Fish screens at hydroelectric dams help to protect rearing and migrating fish by preventing them from passing through the turbines and directing them towards the bypass channels by means of a sweeping flow parallel to the screen. However, fish screens may actually be harmful to fish if the fish become impinged on the surface of the screen or become disoriented due to poor flow conditions near the screen. Recent modifications to the vertical barrier screens (VBS) in the gate wells at the Bonneville Dam second powerhouse (B2) were intended to increase the guidance of juvenile salmonids into the juvenile bypass system but have resulted in higher mortality and descaling rates of hatchery subyearling Chinook salmon during the 2008 juvenile salmonid passage season. To investigate the potential cause of the high mortality and descaling rates, an in situ water velocity measurement study was conducted using acoustic Doppler velocimeters in the gate well slots at turbine units 12A and 14A of B2. From the measurements collected, the average approach velocity, sweep velocity, and the root mean square value of the velocity fluctuations were calculated. The approach velocities measured across the face of the VBS were variable and typically less than 0.3 m/s, but fewer than 50% were less than or equal to 0.12 m/s. There was also large variance in sweep velocities across the face of the VBS with most measurements recorded at less than 1.5 m/s. Results of this study revealed that the approach velocities in the gate wells exceeded criteria intended to improve fish passage conditions that were recommended by National Marine Fisheries Service and the Washington State Department of Fish and Wildlife. The turbulence measured in the gate well may also result in suboptimal fish passage conditions but no established guidelines to contrast those results have been published.

BINARY FISH PASSAGE MODELS FOR UNIFORM AND NONUNIFORM FLOWS

ABSTRACTBinary fish passage models are considered by many fisheries' managers to be the best available practice for culvert inventory assessments and for fishway design. Misunderstandings between different passage‐modelling approaches often arise, however, because of the absence of a formal comparison between the different approaches that include detailed derivations with consistent terminology and example applications. In this paper, one‐dimensional binary fish passage models were reviewed, and derivations from basic principles were provided for clarification. For uniform flow, a simple exhaustion‐threshold (ET) model equation was derived that predicts the flow velocity threshold in a fishway that causes exhaustion at a given maximum distance of ascent if a fish swims at the optimal ground speed. Velocities at or above the threshold predict failure to pass (exclusion). Velocities below the threshold predict passage. The ET model was therefore intuitive and easily applied to predict passage or exclusion. It was also shown to be consistent with the ascent‐distance (AD) model that shows that fish must adopt an optimal ground speed to maximize AD. The limitation of passage models to uniform flow was addressed by deriving a general model framework for passage that accounts for nonuniform flow conditions more commonly found in the field, including backwater and drawdown water‐surface profiles. Comparison of these models with experimental observations of volitional passage for top‐performing western mosquitofish Gambusia affinis indicates reasonable prediction of binary outcomes (passage or exclusion) if the flow velocity is not near the threshold flow velocity. More research is needed on fish behaviour, passage strategies under nonuniform flow regimes and stochastic methods that account for individual differences in swimming performance. Future experiments should track and measure ground speeds of ascending fish to test passage strategies and to improve model predictions. Stochastic models, such as Monte‐Carlo techniques, that account for different passage performance among individuals and allow prediction of the percentage of fish passing are needed to improve fish passage prediction. Published in 2011 by John Wiley & Sons, Ltd.

Fish Passage Assessment of an Advanced Hydropower Turbine and Conventional Turbine Using Blade-Strike Modeling

Hydropower is the largest renewable energy source in the world. However, in the Columbia and Snake River basins, several species of Pacific salmon and steelhead have been listed for protection under the Endangered Species Act due to significant declines of fish population. Dam operators and design engineers are thus faced with the task of making hydroelectric facilities more fish friendly through changes in hydro-turbine design and operation. Public Utility District No. 2 of Grant County, Washington, applied for relicensing from the U.S. Federal Energy Regulatory Commission to replace the 10 turbines at Wanapum Dam with advanced hydropower turbines that were designed to increase power generation and improve fish passage conditions. We applied both deterministic and stochastic blade-strike models to compare fish passage performance of the newly installed advanced turbine to an existing turbine. Modeled probabilities were compared to the results of a large-scale live-fish survival study and a Sensor Fish study under the same operational parameters. Overall, injury rates predicted by the deterministic model were higher than experimental rates of injury, while those predicted by the stochastic model were in close agreement with experimental results. Fish orientation at the time of entry into the plane of the leading edges of the turbine runner blades was an important factor contributing to uncertainty in modeled results. The advanced design turbine had slightly higher modeled injury rates than the existing turbine design; however, no statistical evidence suggested significant differences in blade-strike injuries between the two turbines, thus the hypothesis that direct fish survival rate through the advanced hydropower turbine is equal to or higher than that for fish passing through the conventional turbine could not be rejected.

The Penobscot River, Maine, USA: a Basin-Scale Approach to Balancing Power Generation and Ecosystem Restoration

Although hydropower is a source of low-carbon energy, without careful consideration and management, dams have the potential to degrade river ecosystems and the goods and services they provide to society. Today, a broad range of hydropower interests and stakeholders are seeking approaches to hydropower development and operation that are more environmentally and socially sustainable. The Penobscot River Restoration Project ('the Project') illustrates that basin-scale approaches can provide a broader set of solutions for balancing energy and riverine environmental resources than can be achieved at the scale of individual projects. The Penobscot basin is the largest in Maine and historically supported culturally and economically significant populations of migratory fish. These migratory fish populations declined dramatically following the construction of a series of hydropower dams on the main stem river and major tributaries in the early 20th century. The Project, negotiated between a power company (PPL Corporation) and a coalition including the Penobscot Indian Nation, resource agencies, and nongovernmental conservation organizations, features the removal of two main stem dams on the lower Penobscot and improved fish passage at the dams that remain. Because of various capacity and/or operational changes, power production will be increased at the remaining dams and total hydropower energy production from the basin will be maintained or increase slightly. The Project is expected to expand considerably the proportion of the basin accessible to migratory fish and contribute to significant increases in fish populations. The Project illustrates that a basin-scale approach can potentially yield more comprehensive solutions for sustainable hydropower than can be achieved at the project scale, and we recommend that such large-scale planning processes can improve the sustainability of both regulatory licensing of existing dams as well as the planning of future dams in regions undergoing the expansion of water-management infrastructure.

Optical Fish Trajectory Measurement in Fishways through Computer Vision and Artificial Neural Networks

Vertical slot fishways are hydraulic structures that allow the upstream migration of fish through obstructions in rivers. The appropriate design of a vertical slot fishway depends on the interplay between hydraulic and biological variables because the hydrodynamic properties of the fishway must match the requirements of the fish species for which it is intended. One of the primary difficulties associated with studies of real fish behavior in fishway models is that the existing mechanisms to measure the behavior of the fish in these assays, such as direct observation or placement of sensors on the specimens, are impractical or unduly affect the animal behavior. This paper proposes a new procedure for measuring the behavior of the fish. The proposed technique uses artificial neural networks and computer vision techniques to analyze images obtained from the assays by means of a camera system designed for fishway integration. It is expected that this technique will provide detailed information about the fish behavior, and it will help to improve fish passage devices, which is currently a subject of interest in the area of civil engineering. A series of assays has been performed to validate this new approach in a full-scale fishway model with living fish. We have obtained very promising results that allow accurate reconstruction of the movements of the fish within the fishway.

Using spatial, seasonal, and diel drift patterns of larval Lost River suckers Deltistes luxatus (Cypriniformes: Catostomidae) and shortnose suckers Chasmistes brevirostris (Cypriniformes: Catostomidae) to help identify a site for a water withdrawal structure on the Williamson River, Oregon

A small irrigation diversion dam near Chiloquin, Oregon, was removed and replaced with a pump station to improve fish passage for Lost River suckers (Deltistes luxatus) and shortnose suckers (Chasmistes brevirostris) entering the Sprague River on their spawning migrations. During the developmental phase of the pump station, a need was identified to better understand the larval drift characteristics of these endangered catostomids in order to reduce entrainment into the irrigation system. The spatial, seasonal, and diel distribution of drifting larvae was measured during the 2004 spawning season at two proposed sites on the Williamson River where the pump station could be located. Larval drift for both species coincided with the irrigation season making them subject to entrainment into the irrigation system. Drift occurred almost exclusively at night with larvae entering the drift at sunset and exiting the drift at sunrise. Nighttime larval densities were concentrated near the surface and at midchannel at both sites. Densities were generally greater on the side of mid-channel with greater flow. During early morning sampling we detected a general shift in larval drift from surface to subsurface drift. We also observed an increase in larval densities towards the shore opposite from the proposed pump station at the upper site whereas larval densities remained high at midchannel at the lower site. During daytime sampling, the few larvae that were collected were distributed throughout the water column at both pump sites. This study found that larvae drifting during all time periods were generally distributed further across the cross section, deeper in the water column, and closer to where the proposed water withdrawal structure would be built at the downstream site when compared to the upstream site. Recommendations were provided to locate the withdrawal facility at the upstream site and operate it in a manner such that larval entrainment would likely be minimized.

Bypass System Modification at Bonneville Dam on the Columbia River Improved the Survival of Juvenile Salmon

AbstractFrom 1987 to 1992, we evaluated a fish bypass system at Bonneville Dam Powerhouse 2 on the Columbia River. The survival of subyearling Chinook salmon Oncorhynchus tshawytscha released into the system ranged from 0.774 to 0.911 and was significantly lower than the survival of test fish released into turbines and the area immediately below the powerhouse where bypass system flow reentered the river. Yearling and subyearling Chinook salmon and yearling coho salmon O. kisutch released into the bypass system were injured or descaled. Also, levels of blood plasma cortisol and lactate were significantly higher in yearling and subyearling Chinook salmon that passed through the bypass system than in fish released directly into a net located over the bypass exit. This original system was then extensively modified using updated design criteria, and the site where juvenile fish reentered the river was relocated 2.8 km further downstream to reduce predation on bypassed fish by northern pikeminnow Ptychocheilus oregonensis. Based on studies conducted from 1999 to 2001, the new bypass system resulted in high fish survival, virtually no injuries to fish, fish passage times that were generally similar to water travel times, and mild stress responses from which fish recovered quickly. The mean estimated survival of subyearling Chinook salmon passing through the new bypass system was 0.946 in 2001, which was an usually low‐flow year. Survival, physical condition, passage timing, and blood physiological indicators of stress were all useful metrics for assessing the performance of both bypass systems and are discussed. The engineering and hydraulic criteria used to design the new bypass system that resulted in improved fish passage conditions are described.

Prototype measurements of pressure fluctuations in The Dalles Dam stilling basin

At The Dalles Dam on the Columbia River, fish are believed to sustain injury from exposure to turbulence and from collisions with baffle blocks and end sills in the stilling basin at high spillway discharges. Because taking velocity measurements would be exceedingly difficult in this environment, a system of pressure transducers was installed to record high-frequency pressure data for a range of spillway discharges. The sensors were mounted below two of the spillbays on the tops, faces, and sides of baffle blocks; in the gaps between baffle blocks; and on the top and face of the end sill. Statistical analyses on results from three sensors below one of the two spillways showed that mean pressure increased during head-on flow, decreased in flow separation zones, and was proportional to water depth. Power spectra indicate increased low-frequency spectral power with increased discharge, typical spectral decay rates, and the existence of spectral peaks of possible hydraulic origin. The high-frequency pressure data collected at full scale in extremely turbulent environments will contribute to efforts to improve fish passage and to develop and validate three-dimensional computational fluid dynamics models.

Is fish passage technology saving fish resources in the lower La Plata River basin?

Over 450 dams have been constructed in the upper Paraná River basin in Brazil during the past 40 years. River regulation by these dams is considered a primary factor in the reduction of fish diversity and depletion of migratory species. In contrast to the upper Paraná Basin, only two large dams (both with upstream fish passage) have been constructed in the lower La Plata River basin. Fishery managers in the lower basin are concerned that existing and planned dams will further deplete populations of migratory fish species that constitute important recreational and commercial fisheries as has occurred in the upper basin. We assessed the sustainability of fisheries in the lower basin in the face of increased river regulation by using literature information to describe the efficiency of the fish passage systems used to mitigate river regulation impacts on fisheries. Our analysis shows that fish passage systems at both lower basin dams, Yacyreta and Salto Grande, fail to transfer sufficient numbers of upstream migrants to sustain populations of migratory species. Fish passage efficiency of target species in the fish elevators at Yacyreta is less than 2%. Fish diversity in the fish elevators is low because about 85% of the fish belong to only three non-migratory species (Pimelodus maculatus, Oxydoras kneri and Rhinodoras dorbignyi). Large migratory species targeted for passage rarely comprise even 5 % of the fish number in the passage system. The two Borland locks at Salto Grande Dam cannot dependably pass large numbers of migratory species because passage efficiency is dependent upon interactions of powerhouse and spillway operation with tailrace elevations. Most species in the Borland system were either a small catfish (Parapimelodus valenciennis) or a engraulid (Lycengraulis grossidens). Again, the targeted migratory species were not abundant in the passage system. We conclude that existing fish passage technology in the lower basin is inadequate and that improved fish passage designs are required to conserve migratory species. These designs must be based on integrated information from geomorphology (habitat), natural fish behavior, fish swimming capabilities, and detailed population studies.

A COMPARISON OF SINGLE-CELL AND MULTICELL CULVERTS FOR STREAM CROSSINGS

ABSTRACT: Single-barrel culverts are a common means of roadway crossings for smaller streams. While this culvert design provides an economical solution for a crossing, the adverse effects of conveying the stream through a single opening can be far reaching. The single-barrel culvert is typically sized for a design storm much greater than the channel forming discharge. This oversizing causes an interruption of the normal flow patterns and sediment transport for the system. Shallow depths at low flow in the pipe and perching at the outlet can impede fish passage. Multicell culverts (where the main culvert at the channel invert is sized for bankfull discharge, and additional pipes are placed at the floodplain elevation to convey overbank flow up to the design discharge) have been recommended as a best management practice to minimize erosion and improve fish passage. This flume study scaled a prototype single-barrel culvert to both a single-cell model, and a multicell design to compare outlet scour and flow depths within the culvert. The results provide designers and planners with evidence of the benefits of multicell culverts to justify the higher cost of installation compared to single-barrel culverts.

Efforts to Reduce Mortality to Hydroelectric Turbine-Passed Fish: Locating and Quantifying Damaging Shear Stresses

Severe fluid forces are believed to be a source of injury and mortality to fish that pass through hydroelectric turbines. A process is described by which laboratory bioassays, computational fluid dynamics models, and field studies can be integrated to evaluate the significance of fluid shear stresses that occur in a turbine. Areas containing potentially lethal shear stresses were identified near the stay vanes and wicket gates, runner, and in the draft tube of a large Kaplan turbine. However, under typical operating conditions, computational models estimated that these dangerous areas comprise less than 2% of the flow path through the modeled turbine. The predicted volumes of the damaging shear stress zones did not correlate well with observed fish mortality at a field installation of this turbine, which ranged from less than 1% to nearly 12%. Possible reasons for the poor correlation are discussed. Computational modeling is necessary to develop an understanding of the role of particular fish injury mechanisms, to compare their effects with those of other sources of injury, and to minimize the trial and error previously needed to mitigate those effects. The process we describe is being used to modify the design of hydroelectric turbines to improve fish passage survival.

Flow restoration and protection in Australian rivers

AbstractSince 1857 new Australians have constructed many thousands of weirs (3600 in the Murray–Darling Basin alone) and floodplain levee banks, 446 large dams (>10 m crest height) and over 50 intra‐ and inter‐basin water transfer schemes to secure water supplies for human use. Flow regulation has changed the hydrology of major rivers on three temporal sales–the flood pulse (days to weeks), flow history (weeks to years) and the long‐term statistical pattern of flows, or flow regime (decades or longer). The regulation of river flows is widely acknowledged as a major cause of deteriorating conditions in many Australian river and floodplain ecosystems. In response to mounting environmental concerns, all states, territories and the Commonwealth Government have committed the nation to the principles of ecologically sustainable development and a process of national water reform. Rivers and wetlands are now recognized as legitimate ‘users’ of water, and jurisdictions must provide water allocations to sustain and where necessary restore ecological processes and the biodiversity of water‐dependent ecosystems. Progress in the protection and restoration of river and wetland water regimes has been significant, with over half of mainland aquatic systems designated to receive water allocations of some sort. However, exactly how much water they will receive or retain is unclear from the data available. Moreover, the ecological outcomes and benefits of water allocations are not yet apparent in most aquatic ecosystems, with the exception of certain waterbird breeding events, the disruption of algal blooms in weirs and improved fish passage. After reviewing these issues, this paper addresses two vital questions: How much water does a river need? and How can this water be clawed back from other users? Studies conducted to date in Queensland rivers suggest that around 80–92% of natural mean annual flow (and other ecologically relevant hydrological indicators) may be needed to maintain a low risk of environmental degradation. In the Top End of the Northern Territory, some rivers are maintained at 80% of their natural flow, whereas two‐thirds of various flow indicators has been proposed as the restoration target for the River Murray, and 28% of natural mean annual flow has been negotiated for the Snowy River in Victoria. To validate these estimates, ecologists are seeking opportunities to turn river restoration projects into long‐term hypothesis‐driven experiments in ecological restoration, and the funding, time and institutional support to do so. The paper ends with some suggestions to advance the water reforms and achieve higher levels of water allocation for the environment. Copyright © 2003 John Wiley & Sons, Ltd.

NOTE TO READERS

The reaction of our readers encouraged us to alternate between traditional issues covering a variety of subjects and issues addressing a particular topic. This document is somewhat different in that it is the translation of a French issue (326/327) published in 1992 on how to improve fish passage (upstream and downstream) at obstructions. The issue included clearly illustrated complementary papers which could be consulted separately. This translation was initiated a few years ago by our colleagues from the Environment Agency (formerly the National River Authority) and, recognising the worth of such an action, we wished to be part of it.

The Development of Advanced Hydroelectric Turbines to Improve Fish Passage Survival

Recent efforts to improve the survival of hydroelectric turbine-passed juvenile fish have explored modifications to both operation and design of the turbines. Much of this research is being carried out by power producers in the Columbia River basin (U.S. Army Corps of Engineers and the public utility districts), while the development of low-impact turbines is being pursued on a national scale by the U.S. Department of Energy. Fisheries managers are involved in all aspects of these efforts. Advanced versions of conventional Kaplan turbines are being installed and tested in the Columbia River basin, and a pilot scale version of a novel turbine concept is undergoing laboratory testing. Field studies in the last few years have shown that improvements in the design of conventional turbines have increased the survival of juvenile fish. There is still much to be learned about the causes and extent of injuries in the turbine system (including the draft tube and tailrace), as well as the significance of indirect mortality and the effects of turbine passage on adult fish. However, improvements in turbine design and operation, as well as new field, laboratory, and modeling techniques to assess turbine-passage survival, are contributing toward resolution of the downstream fish passage issue at hydroelectric power plants.

Limitations on the Use of Gabions to Improve Fish Passage

Abstract Gabions are used frequently to improve aquatic habitat and rehabilitate damaged fish habitat in low-gradient streams. However, gabions should not be installed perpendicular to the stream flow if water velocities are expected to exceed 5 ft/s. This recommendation would preclude the use of gabions to improve fish passage at waterfalls. Also, gabions installed below culverts should be placed well downstream of the culvert. Weirs constructed of reinforced concrete and/or large boulders could be used as alternatives to gabions to provide for fish passage.

Connecticut River Fishways: Model Studies

The fishways at the Vernon and Turners Falls Dams were optimized by use of hydraulic model studies. In both cases, slotted weirs were modified so that a better head loss distribution was obtained. In addition, the diffusers were modified to produce acceptable exit face velocity distributions. At Turners Falls, the fish entrance was modified to produce velocity conditions known to be acceptable to the two migrating species of fish. At Vernon Dam, flow conditions were optimized at the fish exit and attraction water intake. Modeling of these fishways has resulted in design changes that should improve fish passage and minimize water consumption.