Michael J. Sale

Modification of fluvial gravel size by spawning salmonids

Salmonids (salmon and trout) winnow fine sediment from streambed gravels during construction of the nest or [open quotes]redd[close quotes] used for spawning and incubation of fertilized eggs. The gravels and interstitial fine sediments excavated during this process are exposed to currents and differently transported: Gravels move a short distance, while the fine sediments are swept further downstream from the redd. To quantify the resultant modification of particle size distributions in redds, the authors sampled redds and adjacent undisturbed gravels to document changes in size distributions. These data were compiled with previously published observations to analyze the general nature of size modification during spawning. The final percentage finer than 1 mm in the gravels, P1[sub f], is related to the initial percentage finer than 1 mm, P1[sub i], by the equation P1[sub f] = 0.63 P1[sub i]. Hydraulic variables (water surface slope, mean column velocity, depth, shear stress, unit stream power) explained little of the variance and did not appear in the optimal models. Because fisheries biologists are called upon to evaluate gravels as potential spawning sites, these findings should prove useful in such evaluations. 44 refs., 5 figs., 4 tabs.

Potential Impacts of Hydrokinetic and Wave Energy Conversion Technologies on Aquatic Environments

Abstract A new generation of hydropower technologies, the kinetic hydro and wave energy conversion devices, offers the possibility of generating electricity from the movements of water, without the need for dams and diversions. The Energy Policy Act of 2005 encouraged the development of these sources of renewable energy in the United States, and there is growing interest in deploying them globally. The technologies that would extract electricity from free-flowing streams, estuaries, and oceans have not been widely tested. Consequently, the U.S. Department of Energy convened a workshop to (1) identify the varieties of hydrokinetic energy and wave energy conversion devices and their stages of development, (2) identify where these technologies can best operate, (3) identify the potential environmental issues associated with these technologies and possible mitigation measures, and (4) develop a list of research needs and/or practical solutions to address unresolved environmental issues. We review the results ...

The effects of acidic deposition on streams in the Appalachian Mountain and Piedmont Region of the Mid‐Atlantic United States

Streams in the Appalachian Mountain area of the mid-Atlantic receive some of the largest acidic deposition loadings of any region of the United States. A synthesis of the survey data from the mid-Appalachians yields a consistent picture of the acid base status of streams. Acidic streams, and streams with very low acid neutralizing capacity (ANC), are almost all located in small (<20 km2), upland, forested catchments in areas of base-poor bedrock. In the subpopulation of upland forested systems, which comprises about half the total stream population in the mid-Appalachian area, data from various local surveys show that 6–27% of the streams are acidic, and about 25–50% have ANC less than 50 μeq L−1. After excluding streams with acid mine drainage, National Stream Survey estimates for the whole region show that there are 2330 km of acidic streams and 7500 km of streams with ANC less than 50 μeq L−1. Many of the streams with base flow ANC less than 50 μeq L−1 become acidic during storm or snowmelt episodes. Sulfate from atmospheric deposition is the dominant source of strong acid anions in acidic mid-Appalachian streams. Their low pH (median, 4.9) and high levels of inorganic monomeric aluminum (median, 129 μg L−1) leached through soils by acidic deposition are causing damage to aquatic biota. Quantification of the extent of biological effects, however, is not possible with available data. Localized studies have shown that stream water ANC is closely related to bedrock mineralogy. Attempts to quantify this relationship across the mid-Appalachians, however, were frustrated by the lack of adequate scale geologic mapping throughout the region. Sulfate mass balance analyses indicate that soils and surface waters of the region have not yet realized the full effects of elevated sulfur deposition due to watershed sulfate retention. Sulfur retention is likely to decrease in the future, resulting in further losses of stream ANC.

Evidence of Food Limitation of Rainbow and Brown Trout in Southern Appalachian Soft‐Water Streams

Abstract Seasonal patterns of age-specific growth rates and condition factors of rainbow trout Salmo gairdneri and brown trout S. trutta were studied in relation to the available food resources in five streams of the southern Appalachian mountains. Standing crops of benthic invertebrates were low relative to streams of similar size in other geographic areas. Although terrestrial organisms contributed substantially to the invertebrate drift, total drift rates were also relatively low. Numbers of prey items per trout stomach were small and were directly related to drift rate. These results reflected the limited food base. Condition factors (weight˙length-3) of age- 1 trout declined during summer, and growth rates among age-1 and older trout were generally lower in summer than in winter, despite favorable summer water temperatures. This “inverted” seasonal pattern of growth was likely due to an inadequate food base. We believe that growth rates were relatively low in summer because much of the limited energy...

Distribution and Stability of Potential Salmonid Spawning Gravels in Steep Boulder-Bed Streams of the Eastern Sierra Nevada

Abstract High-gradient boulder-bed streams have been the sites of relatively few studies of salmonid spawning habitat, although they have geomorphic and hydraulic characteristics—and therefore gravel distributions—that are quite different from the more commonly described lowergradient channels. We documented gravel distribution in seven high-gradient stream reaches in the eastern Sierra Nevada. Gravels occurred only in locations characterized by relatively low shear stress; they formed small pockets in sites of flow divergence and larger deposits upstream of natural hydraulic controls. In 1986 (a wet year), all tracer gravels placed in gravel pockets at nine sites on four streams were completely swept away, and substantial scour, fill, and other channel changes occurred at many sites. In 1987 (a dry year), tracer gravels and the channel cross sections were generally stable. Periodic mobility of gravel may explain why brown trout Salmo trutta are more abundant than rainbow trout Oncorhynchus mykiss in the ...

A comparison of geographical information systems-based algorithms for computing the TOPMODEL topographic index

[1] The performance of six geographical information systems (GIS)-based topographic index algorithms is evaluated by computing root-mean-square errors of the computed and the theoretical topographic indices of three idealized hillslopes: planar, convergent, and divergent. In addition to these three idealized cases, two divergent hillslopes with varying slopes, i.e., concave (slopes decrease from top to bottom) and convex (slopes increase from top to bottom) are also tested. The six GIS-based topographic index algorithms are combinations of flow direction and slope algorithms: i.e., single flow direction (SFD), biflow direction (BFD), and multiple flow direction (MFD) plus methods that determine slope values in flat areas, e.g., W-M method [Wolock and McCabe, 1995] and tracking flow direction (TFD) method. Two combinations of horizontal resolution and vertical resolution of the idealized terrain data are used to evaluate those methods. Among those algorithms the MFD algorithm is the most accurate followed by the BFD algorithm and the SFD algorithm. As the vertical resolution increases, the errors in the computed topographic index for all algorithms decrease. We found that the orientation of the contour lines of planar hillslopes significantly influences the SFD’s computed topographic index. If the contour lines are not parallel to one of eight possible flow directions, the errors in the SFD’s computed topographic index are significant. If mean slope is small, TFD becomes more accurate because slope values in flat areas are better estimated. INDEX TERMS: 1899 Hydrology: General or miscellaneous; 1824 Hydrology: Geomorphology (1625); 1832 Hydrology: Groundwater transport; KEYWORDS: GIS, TOPMODEL, topographic index, single flow direction algorithm, biflow direction algorithm, multiple flow direction algorithm

Modelling the linkages between flow management and salmon recruitment in rivers

Abstract We developed a simulation model to predict instream flow effects on smolt production for fall chinook salmon ( Oncorhynchus tshawytscha ) in regulated rivers. The principal purpose of this model is to serve as a management tool to evaluate effects on salmon of instream releases from upstream reservoirs. The dramatic decline in chinook salmon in California rivers suggests a need for such a tool. We developed an individual-based and spatially explicit model to simulate the influences of riverine habitat on each lifestage leading to successful outmigration of chinook salmon. Model predictions of development, growth and survival showed good agreement with four years of field data collected on the Tuolumne River, California. Our analysis of parameter sensitivities identified flow-related redd mortality and temperature-related juvenile mortality as limitations on smolt production.

Basic hydrologic studies for assessing impacts of flow diversions on riparian vegetation: Examples from streams of the eastern Sierra Nevada, California, USA

As the number of proposals to divert streamflow for power production has increased in recent years, interest has grown in predicting the impacts of flow reductions on riparian vegetation. Because the extent and density of riparian vegetation depend largely on local geomorphic and hydrologic setting, site-specific geomorphic and hydrologic information is needed. This article describes methods for collecting relevant hydrologic data, and reports the results of such studies on seven stream reaches proposed for hydroelectric development in the eastern Sierra Nevada, California, USA. The methods described are: (a) preparing geomorphic maps from aerial photographs, (b) using well level records to evaluate the influence of streamflow on the riparian water table, (c) taking synoptic flow measurements to identify gaining and losing reaches, and (d) analyzing flow records from an upstream-downstream pair of gages to document seasonal variations in downstream flow losses. In the eastern Sierra Nevada, the geomorphic influences on hydrology and riparian vegetation were pronounced. For example, in a large, U-shaped glacial valley, the width of the riparian strip was highly variable along the study reach and was related to geomorphic controls, whereas the study reaches on alluvial fan deposits had relatively uniform geomorphology and riparian strip width. Flow losses of 20% were typical over reaches on alluvial fans. In a mountain valley, however, one stream gained up to 275% from geomorphically controlled groundwater contributions.

Status of Fish Passage Facilities at Nonfederal Hydropower Projects

Abstract The status of direct mitigation practices for fish passage was assessed as part of an ongoing, multi-year study of the costs and benefits of environmental mitigation measures at nonfederal hydroelectric power plants. Information was obtained from the Federal Energy Regulatory Commission, hydropower developers and state and federal resource agencies involved in hydropower regulation. Fish ladders were found to be the most common means of passing fish upstream; elevators/lifts were less common, but their use appears to be increasing. A wide variety of mitigative measures, including spill flows, narrow-mesh intake screens, angled bar racks and light- or sound-based guidance measures, is employed to prevent fish from being drawn into turbine intakes. Performance monitoring and detailed, quantifiable performance criteria were frequently lacking. Fifty-two of the 66 projects (82%) with operating downstream fish passage measures had no performance monitoring requirements; 50 of 71 project operators (70%...

Analysis of Environmental Issues Related to Small-Scale Hydroelectric Development V: Instream Flow Needs for Fishery Resources

The growing recognition nationwide of the importance of protecting these instream uses of water has coincided with the recent emphasis on the development of small-scale hydropower resources. The issue of instream flow maintenance in hydropower development is essentially a problem of evaluating the effects of planned modifications in hydrologic patterns. Because hydroelectric projects can alter natural flow regimes on both spatial and temporal scales, downstream water users and the aquatic ecosystem and primarily fish, can be adversely affected. Numerous methods which differ in their use of hydrologic records, hydraulic simulation techniques, and habitat rating criteria have been developed to assess the effects of stream flow regulation on aquatic biota and to provide instream flow recommendations. Consequently, guidance is needed to ensure that the most appropriate methods are selected for instream flow assessments at small-scale hydroelectric sites.