Introduction
In-stream habitat data include measurements of a variety of physical and aquatic stream attributes that collectivley reveal a great deal about stream condition for salmonids and trout. Characterizing and inventorying the physical conditions that define stream habitat for salmonids is an important part of the habitat restoration process. The Department of Fish and Game (DFG) collects data on a number of physical attributes of streams and classifies these streams by one of several habitat types.

They are a critical part of determining restoration priorities and identifying salmonid refugia. The California Salmonid Stream Habitat Restoration Manual, published by the DFG, describes the process of using in-stream habitat data and other data and information for identifying streams with restoration potential and working through the stream restoration process.

One important parameter measured during the in-stream habitat assessment process is shelter value rating. This aggregate measurement is intended as an index of the quality and quantity of in-stream shelter for salmonids. Other important measurements include degree of embeddedness, canopy cover, and pool depth and frequency.

The in-stream habitat data included in CalFish consist primarily of those collected by the DFG beginning in the early 1990’s and extending through most of Humboldt and parts of Mendocino counties (see below). Other departments and organizations actively collect these data and as they become available, will be included in CalFish. In addition, historical in-stream data collected by the DFG will posted to this site as funding for quality control and spatial treatment of the data become available.