Book Description

British Columbia departments are developing instream flow guidelines for fish in order to aid in the process of setting instream flows in provincial streams. The guidelines are made up of two components: review guidelines that present a set of seasonally adjusted thresholds for alterations to natural stream flows; and assessment methods, a set of endorsed techniques for assessing flow alterations in streams. This document presents technical information used to support proposed instream flow thresholds as part of the review guidelines. The introduction explains aspects of the guidelines, including their rationale, application, development, and users. The objectives & guiding principles for developing the flow thresholds and the regulatory context for instream flow requirements are also described. This is followed by reviews of the following: stream hydrology & channel morphology in British Columbia and the use of channel geometry for habitat assessment & standard setting; the effect of streamflow on production of fish & invertebrates; the risk of entrainment of organisms & detritus when water is diverted from a stream; and the methods used to determine instream flow requirements for fish, including their characteristics, advantages, drawbacks, and recommendations for their use in British Columbia. The final sections contain recommended instream flow thresholds for British Columbia, based on a variety of analyses of historic flow data presented in the appendices, and guidance on developing an effective monitoring program (water license compliance monitoring and biotic response monitoring).