Stream Habitat Reach Summary - San Francisco Bay, Central Coast [ds159]

This database helps identify and describe instream habitat available to anadromous salmonids within the surveyed streams. The database is designed for use in conjunction with biological inventories and adult salmonid escapement surveys conducted later in the same year. The data were collected by Department of Fish and Game primarily to: 1) provide a useful source of information for evaluating, designing and monitoring stream habitat improvements for salmonids based on critical fish habitat needs and 2) aid in internal management decisions regarding stream restoration projects and potential. DATA LIMITATIONS AND ASSUMPTIONS For analytical purposes, users should assume that data collection methods were similar enough between streams, years, and observers to allow comparison of relative values. Observer bias is presumed to be low to non-existent. Reach-level in-stream habitat data are designed for suitability assessment of salmonid habitat at local levels. They should not be used for large watershed-level assessment tasks as assessment at this level would require either complete stream sampling or a statistically derived sample design providing for assignment of measured parameters, within acceptable error limits, on a watershed-wide basis. In addition, the shapefile comprising these data is a visual representation of the data and have not been calibrated to existing stream data from U.S. Geological Survey quadrangle maps. Therefore, spatial errors should be expected. KNOWN CAVEATS OF THE DATA: A significant scaling error often occurs in these data. Some of this error could be from mapping fine-scale ground measurements to a coarser map scale. The average in-stream habitat unit is approximately 55 feet (17 m) long while 1:24,000 scale maps may be accurate to the nearest 90 feet (30 m). In most cases, distances measured at a fine scale will exceed measurements at a course scale (Mandelbrot, 1982). Due to this and other error sources, habitat units for some streams may not be accurately placed on the map. Uncertainty of this mapped habitat unit precision increases with distance upstream. In many cases, the scaling error caused the length of the stream as measured during surveys to exceed the apparent stream length mapped on 1:24,000 scale digital hydrography. In these instances, a scaling factor was applied automatically by the NCNCR 'Stream Habitat' application (contact Karen Wilson, KLWilson@dfg.ca.gov, for information on this program). Even after application of the scaling factor, instances of the length discrepancy exceeding 1000 feet were found in the data where the surveys covered several miles. During processing of the files in the application, a "log file" is created that records errors or problems in each file. The folder containing the log files can be searched using the term "A scaling factor is needed" to rapidly locate these files. Habitat conditions can change drastically both from year to year and within a season. Factors to consider when comparing between years or seasons include variable stream flows (especially flood events), temperatures and silt loads. Use caution when analyzing these data with other time-dependent data such as stream biological inventories and salmon carcass surveys.

The Stream Habitat - San Francisco Bay, Central Coast_[ds159] shapefile contains two years of in-stream salmonid habitat data at the reach level. The data have been summarized from habitat unit level data collected by DFG from June 1996 into September of 1997. The South Coast portion of the original dataset could not be represented at the stream reach level, so is not included here. The remaining 49 streams/stream surveys represent 180 miles of streams surveyed in the San Francisco Bay and Central Coast hydrologic regions of California. The database helps identify and describe in-stream habitat available to anadromous salmonids within watersheds of the California San Francisco Bay and Central Coast Hydrologic Regions. Data were collected using standardized survey techniques according to the version of the "California Stream Habitat Restoration Manual" (see Flosi et al.) that was current in the year of survey. Field survey teams measured up to 60 parameters for selected habitat units. Stream surveys typically started at the downstream confluence and proceeded upstream to the "limit of anadromy" as assessed by the survey crew. WHAT EACH RECORD REPRESENTS Each of the 100 records in this dataset represents in-stream habitat unit level data summarized at the stream reach level. A habitat unit is the base level for the stream habitat surveys and is generally determined by the occurrence of riffle, run and pool sections along the stream. Stream reaches are determined by changes in stream channel type as described by Rosgen (1994).

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Use in accordance with the California Salmonid Stream Habitat Restoration Manual.