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Table 1: RSRA indicator variables and the reasons for including them in the protocol. <br />CATEGORY AND <br /> <br />VARIABLE JUSTIFICATION FOR INCLUS101V IN RSRA ASSESSMENT <br />Water Quality: llense algal growth may indicate nutrient enrichment and other types of pollution which <br />Algal growth may result in decreased dissolved oxygen in the water column and affect invertebrates and <br /> the ability of fish to spawn. <br />Water Quality: Solar exposure affects stream temperature and productivity. Decreased streambank <br />Channel shading and solar vegetation cover, increased channel width, and reduced stream depth increases exposure, <br />exposure raises water temperatures and impacts aquatic life. Native trout usually require cool stream <br /> temperatures. <br />Hydrogeomorphology: Channels that are deeply downcut or incised result in a reduced frequency of overbank <br />Floodplain connection and flooding into the adjacent flood plain during peak runoff or stream flows. The absence of <br />inundation frequency flooding lowers water tables, reduces nutrient availability in the floodplain, decreases plant <br /> germination, growth and survivorship, and may lead to the loss of riparian vegetation and <br /> the invasion of upland species. <br />Hydrogeomorphology: Steep and unstable vertical banks dominate many southwestenr streams, limiting the <br />Vertical bank stability physical dynamics of aquatic ecosystems and increasing erosion and sediment loads <br /> through sloughing off of soils during high flow events. Steep ba~iks may limit «°ildlife <br /> access to water. <br />Hydrogeomorphology: Fish and aquatic invertebrate diversity and population health is related to habitat diversity. <br />Hydraulic habitat diversity Features such as oxbows, side channels, sand bars, gaveUcobble bars, riffles.. and pools <br /> can provide habitat for different species or for the different life stages of a single species. <br />Hydrogeomorphology: Riparian soils reflect existing stream flow dynamics (e.g., flooding), management practices, <br />Riparian area soil integrity and vegetation. It affects potential vegetation dynamics and species composition, as well as <br /> wildlife habitat distribution and quality. <br />Hydrogeomorphology: Beavers are keystone species in riparian systems because they modify geomorphology and <br />Beaver activity vegetation, and reduce variance in water flows and the frequency of floods. Beaver dams <br /> and adjacent wet meadows provide important fish and plant nursery habitat. <br />FishlAquatic Habitat Qualifier: Fish and most aquatic invertebrates require perennial or constant flows to survive. Streams <br />Loss of perennial flows that were originally perennial but are now ephemeral no longer provide habitat for these <br /> species unless there are refuges that never dry out (e.g., permanent pools). <br />Fis1L'Aquatic Habitat: Fish use pools, with reduced current velocity and deep water, to rest, feed and hide from <br />Pool distribution predators. Many species use gravel-bottomed riffles to lay their eggs. The number, size, <br /> distribution, and quality of pools, and pool to riffle ratios indicate the quality of fish <br /> habitat. 1:1 pools to riffle ratios are generally considered to be optimum. <br />Fish'Aquatic Habitat: Underbank cover is an important component of good fish habitat, used for resting and <br />U nderbank cover protection from predators. A number of aquatic invertebrates also use these areas. <br /> Undcrbank covcr usually occurs with vigorous vcgctativc riparian growth, dcnsc root <br /> masses, and stable soil conditions. <br />Fish/Aquatic Habitat: Low levels of gavel and boulder embeddedness on the channel bottom increase benthic <br />Cobble embeddedness productivity and fish production. The filling of interstitial spaces betwean rocks with silt. <br /> sand, and organic material reduces habitat suitability for feeding, nursery cover, and <br /> spawning (egg to fry survival) by limiting space and macroinvertebrateproductIon. <br /> Increased embeddedness often reflects increased sediment loads and altered water flow <br /> patterns. <br />Fish~'Aquatic Habitat: The density and composition of aquatic invertebrates are strong indicators of stream health, <br />Diversity of aquatic macro including temperature stresses, oxygen levels, nutrients, pollutants, and sediment loads. <br />invertebrates Larvae and adult macroinvertebrates provide critical food for fish and other invertebrate <br /> and vertebrate species in sneam-riparian ecosystems. <br />