This essay highlights the necessity for the establishment of new instream flow standards, as well as the revision of existing standards. This presents a problem since the standards themselves cannot be defined scientifically. The authors recommend the implementation of an adaptive management program involving three elements; setting conservative interim standards; establishment of an adequate monitoring program involving active manipulation flows; and establishment of effective procedure to revise the interim standards. The program details should vary from case to case, especially for species like salmon, where adult populations depend on a myriad of factors, not simply instream flows. Examples of current and previous uses of these standards are given.

River regulation imposes primary changes on flow and sediment transfer, the principal factors governing the alluvial channel regime. In this study, the effect of flow regulation is isolated from sediment delivery. Peace River was regulated in 1967 for hydropower. The gravel-bed reach immediately downstream from the dam has become stable. Gravel accumulates at major tributary junctions, so the river profile is becoming stepped. Further downstream, the river has a sand bed. It can still transport sand, so morphological changes along the channel include both aggradation and channel narrowing by lateral aggradation. In the gravel-bed Kemano River, the addition of water by diversion from another river caused degradation when additional bed material was entrained below the inflow point. However, the effect became evident only after many years, when a competent flood occurred. The short-term response was channel widening. The time-scale for the response depends on the size of the river and the nature and severity of regulation. In both rivers, significant adjustment will require centuries and will intimately involve the riparian forest.

Hydrologic alteration is indisputably the most cited cause of species decline in aquatic systems. Most studies focus on the longitudinal impacts of dam construction and operation, but few examine the impact of flow alteration on tributaries. Consequently, tributary habitat and fauna are often overlooked in management processes involving mainstem projects. Most tributary impacts fall into two categories described by the National Environmental Policy Act (NEPA): direct effects and cumulative impacts. This review summarizes the issues that are most pervasive in the literature, provides specific examples of known effects, and integrates complex ecological aspects relecant to the hydropower relicensing process.

We studied the role of technical clarity in successful multi-party negotiations. Our investigations involved in-depth interviews with individuals who were the principal participants in six consultations conducted under the Federal Energy Regulatory Commission's (FERC) hydroelectric power project licensing process. Technical clarity was especially important in the cases we studied because they concerned questions that were science-based. The principal issues in the six cases were fish passage, instream flow for fish habitat, and entrainment of fish in hydropower turbines. We concluded that technical clarity was one of the most critical elements in these conflicts. The most successful negotiations were marked by a shared understanding of technical issues among the parties.

Utility companies release water to mitigate the effects of hydroelectric projects on fish habitats. Utility companies, government agencies, and research communities in Canada, the United States, Europe, New Zealand, and Australia were surveyed as part of a Canadian Electrical Association study to evaluate the effectiveness of water release as a mitigation. Respondents identified only 28 projects in which water was released specifically to protect fish habitats. Fewer than half of these projects (12) were judged as being effective. Six case histories with preimpact assessment and postimpact monitoring were reviewed. In four cases fish habitat or fish populations or both were maintained; in two cases they were not. The effectiveness of water release differed among rivers and fish species, and was greatest when designed to meet the habitat requirements of each life-history stage. A review of the literature did not support the theory that a particular fraction of the mean annual flow provides the best fish habitat. Although smaller changes in the flow regime had smaller effects, increasing minimum flows above those historically observed did not necessarily increase fish production.

The economic value of water that flows over a scenic waterfall was measured using the contingent valuation method. Allowing both the value per day and trips to vary with flow resulted in values per cubic feet per second (cfs) of flow ranging from $1000 for the first 100 cfs to $300 for additional flow at 550cfs. Accounting for the value of foregone hydropower, the economically optimum flow just considering aesthetics of the falls was about 235-240 cfs during the main recreation season. Monthly analysis during the recreation season suggested that optimum flows varied from 165-175 cfs during the early and later recreation season to 500-600 cfs during the four prime recreation months. These flows were three to ten times greater than current minimum flows. Recommendations are made that the Federal Energy Regulatory Commission should use non-market valuation techniques such as contingent valuation surveys to ensure that environmental values are given equal consideration with power values in dam licensing and relicensing decisions.

A review and reanalysis of the published literature show that several assumptions are violated in the application of the Instream Flow Incremental Methodology (IFIM) without consideration of the implications of so doing. The fundamental assumption of a positive linear relationship between "potential available habitat" (WUA) and biomass of fish has neither been documented nor validated, particularly in warmwater streams. Absence of correlation precludes prediction of changes in fish populations. In some studies the test of this assumption appears to be equivalent to a calibration operation. The other assumption violated includes independent selection of habitat variables by fish. The presence of significant interaction among habitat variables can affect the stream flow recommendations. Another problem exists in application of Physical Habitat Simulation (PHABSIM): one WUA unit should not be interpreted as being equal to another in biological production or habitat value unless shown to be an exact replica. Several combinations of physical variables could give rise to the same amount of WUA, none of which may be correlated to the biomass of fish. The utilization, suitability, or preference curves should not be treated as probability functions; a rating of 1.0 is not equivalent to probability of 1.0. Care should be taken to distinguish between real behavioral preferences of fishes based on distributional occurrence from abundance (relative or absolute size) in a stream.

Efforts by a citizen's group, Putah Creek Council, to improve the flow regime of a California stream for ecosystem, aesthetic, recreational, educational, and research purposes led to a successful court trial in which fish conservation played a key role. A major issue around which the trial revolved was the proper interoperation of section (5937) of the California Fish and game Code, which states that fish must be maintained in "good condition" below a dam. We defined good condition to mean there had to be healthy individual fish in healthy populations that were part of healthy biotic communities. This definition resulted in a conceptual model for instream flows for the creek that favored native resident and anadromous fishes. The stream flow recommendations from this model had four components: living space flows for the entire creek, resident native fish spawning and rearing flows, anadromous fish flows, and habitat maintenance flows. The trial judge, in attempting to balance competing demands for the water, ordered the implementation of only the first two recommendations. The order has been appealed by the water interests, but regardless of the final outcome, the court's decision reflects the growing public interest in protecting streams, the need for innovative use of existing legal tools to try and protect aquatic resources, and the importance of biological information in developing flow recommendations for complex fish assemblages.

This paper examines the effects of dam construction and operation in the Columbia River Basin on salmon populations. While the hydrograph of the Columbia River has been significantly impacted by dams, the seasonality of regulated flow on the Snake River has been less affected. The Snake River storage has been used for agricultural diversion while the Columbia has been for electrical generation. The reservoir system has effects on flow velocities, water chemistry (nitrogen supersaturation), habitat availability and reliability, and stream temperatures. Dams block about one third of the Columbia River watershed to access by anadromous fish.
Effects of Dams on Salmon;
Fish kills occur as a result of several characteristics of dams. Bruising, descailing, and stress caused by by-pass facilities; susceptibility to prey following delivery from by-pass to outfall; estuary damage; effects on the homing ability of fish; limited success in fish use of by-pass facilities. The effect of migration speed on smolt survival is uncertain but assumed to have an impact. More research is necessary.
Mitigation of Dam's Effects on Salmon:
Seven measures for mitigation of dams' effects on salmon are discussed
1. Fish passage facilities 2. Predator control 3. Transportation 4. Spill 5. Flow augmentation 6. Reservoir drawdown 7. Dam removal.

1. This paper introduces a new approach for setting streamflow-based river ecosystem management targets and this method is called the 'Range of Variability Approach' (RVA). The proposed approach derives from aquatic ecology theory concerning the critical role of hydrological variabliity, and associated characteristics of timing, frequency, duration, and rates of change, in sustaining aquatic ecosystems. The method is intended for application on rivers wherein the conservation of native aquatic biodiversity and protection of natural ecosystem functions are primary river management objectives.
2. The RVA uses as its starting point either measured or synthesized daily streamflow values from a period during which human pertubations to the hydrological regime were negligible. This streamflow record is then characterized using thirty-two different hydrological parameters, using methods defined in Richter et al. (1996). Using the RVA range of variation in each of the thirty-two parameters, e.g. the values at +/- 1 standard deviation from the mean or the twenty-fifth to seventy-fifth percentile range, are selected as initial flow management targets.
3. The RVA targets are intended to guide the design of river management strategies (e.g. reservoir operations rules, catchment restoration) that will lead to attainment of these targets on an annual basis. The RVA will enable reiver manageres to define and adopt readily interim management targets before conclusive, long-term ecosystem reesearch results are available. The RVA targets and mangement strategies should be adaptively refined as suggested by research results and as needed to sustain native aquatic ecosystem biodiversity and integrity.