Stream Habitat - San Francisco Bay, Central and South Coast [ds126]

The database is designed for use in conjunction with biological inventories. The data were collected by CDFG 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 low to non-existent. Unit-level in-stream habitat data are designed for suitability assessment of salmonid habitat at fine scales (stream segment). 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 these 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 (30m). 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, this scaling error caused the length of the stream as measured during surveys to exceed the apparent stream length mapped on 1:100,000 scale digital hydrography. For 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). 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.

The StreamHabitat - San Francisco Bay, Central and South Coasts [ds126] shapefile contains in-stream habitat unit-level files collected on 57 streams of the San Francisco Bay and California Central and South Coasts Hydrologic Regions from 1993 to 1997. Approximately 221 miles of streams were surveyed. The database helps identify and describe in-stream habitat available to anadromous salmonids within surveyed watersheds. The data were collected by the California Department of Fish and Game (CDFG) using standardized survey techniques according to the version of the "California Stream Habitat Restoration Manual" that was current in the year of survey (see all Flosi, et al. references). 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. Habitat typing follows a modified version of the system described in Bisson et al. (1982). Stream channel typing follows Rosgen (1994), beginning with the 1995 field season. WHAT EACH RECORD REPRESENTS: Each record represents in-stream habitat attributes measured at the habitat unit 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.

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In accordance with the California Salmonid Stream Habitat Restoration Manual,