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Data and Interpretive Tools

Consolidated Standard Operating Procedures (SOP) for Calculating Bioassessment Indices and other Tools for Evaluating Wadeable Stream in California

This document describes steps in calculating three different ecological indices used to quantity stream conditions in California based on biological and physical data. The instructions herein are provided as support for analysts requiring scores for the California Stream Condition Index (CSCI), Algal Stream Condition Index (ASCI), and the Index of Physical Integrity (IPI).

Additionally, these instructions will help analysts calculate landscape-scale measures of human activity, which are used to determine if stream quality as reference sites.

California Stream Condition Index

The California Stream Condition Index (CSCI) is a biological index used to score the condition of BMI communities in perennial wadeable rivers and streams. Developed in 2013 to include a broader reference data set and to ensure better statewide applicability than previous regional indices, the CSCI combines two unique types of index that have traditionally been used separately: an observed-to-expected (O/E) index and a multimetric index (MMI). The CSCI is the first index to provide a consistent statewide standard for interpreting bioassessment data and is the basis of the new statewide Biological Integrity Assessment Implementation Plan.

Physical Habitat Integrity (IPI)

Indices of Biological Integrity - Archived

For most assessment applications, the CSCI should be used instead of these IBIs. The documents provided below are for informational purposes only.

Prior to the CSCI, several regional indices of biological integrity (IBIs) were developed for different portions of the state. An IBI uses multiple metrics to describe the biological condition of a stream or river. Included metrics vary by biogeographical region and benchmark values are based on reference sites considered to be relatively undisturbed by human activity.