Habitat Assessments

pb survey 

Surveys are conducted to document the amount and quality of stream habitat available to aquatic organisms, specifically native fishes. Surveys are limited to where we can gain access to the stream channel and get permission from private landowners. Since 2001, the RCD has surveyed all salmonid streams in the Napa River watershed. California Department of Fish and Game contributes most of the funding for the project.


Napa RCD Stream Habitat Typing Protocol (pdf)

The RCD uses methodology described in the California Salmonid Stream Habitat Restoration Manual (Flosi and Reynolds, 1994). A two-person crew walks the channel and samples approximately 10% of the habitat units for:

  • Flow: Measured with USGS flow meters or visually estimated
  • Channel Type: Measured according to Rosgen system
  • Temperatures: Water and air temperature taken every tenth habitat unit
  • Habitat Type: Determined according to DFG categories 
  • Cobble Embeddedness: Visually assessed at potential spawning locations
  • Shelter Rating: Assigned to each unit based on amount of structure and cover
  • Substrate Composition: Dominant and subdominant particle class visually assessed
  • Canopy: Measured with a spherical densitometer and broken into evergreen/deciduous components
  • Bank Composition and Vegetation: Material and vegetation class on both banks
  • Large Wood: Count of the number of pieces of wood larger than 12” diameter
  • Bank Full Width: Measured to nearest foot every tenth habitat unit 

View recent Habitat Assessment Reports