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Sampling Strategy Community Attributes to Sample To adequately understand what factors may be limiting endangered fishes in the Upper Colorado River Basin will require monitoring a variety of ecosystem attributes. Important attributes to monitor identified by Stanford (1994) were distribution and abundance of zoobenthos communities, zooplankton, fish, some measure of the primary producer community, and physical habitat features. This proposal describes methodology to monitor the abundance and distribution of benthic macroinvertebrates, standing stock of organic matter, periphyton chlorophyll a concentration and biomass, and water temperature. Study Reach Delineation Rivers to be sampled include the Colorado River, the Green River, the Gunnison River, the White River, and the Yampa River. The sampling units in this monitoring project should be unique riverine habitat types stratified by reach (sensu strata, Osmundson et al. 1995). Sampling reaches along each river were delineated based on geology, large tributary stream confluences, the presence of endangered fish populations, and previous fish and invertebrate investigations. Sampling reaches for the Colorado River, the Green River, the Gunnison River, the White River, and the Yampa River are listed in Table 1. Reaches that contain major tributary stream confluences should be separated to include sampling locations above and below tributary streams. Initially, all reaches shown in Table I should be sampled. After preliminary data analysis, the number of reaches may be reduced. If the number of reaches is reduced, it will be important that we do not lose information on the connectivity of reaches. One of Dr. Stanford's recommendations was the need to understand invertebrate communities in a river continuum context. Within reach sampling locations should be selected based on the availability and of different habitat types (Table 2) and the ability of investigators to effectively sample them. Samples should be collected from all major habitat types within each reach. The purpose of sampling all major habitat types rather than just riffles, which is most common, is that different habitat types have different invertebrate assemblages and different responses to stream discharge events. At this time, we do not know which habitats are most productive, how habitat specific production is affected by different discharge regimes, or what organisms can be used as indicators of high quality habitat conditions (Stanford 1994). There are three strategies for collecting samples from distinct habitat types within reaches: Strategy one: Collect several samples in several examples of each habitat type within each reach. Samples from the same location and habitat type would be composited into a single sample. Samples collected from the same habitat type but in different locations within the same reach would not be composited. 2