Water Stewardship Information Sources

Citation Hatfield, T, Lewis, A, Ohlson, D and Bradford, M. 2003. Development of instream flow thresholds as guidelines for reviewing proposed water uses. Prepared for BC Ministry of Environment.
Organization Ministry of Environment
URL http://www.env.gov.bc.ca/wld/documents/bmp/phase2_instreamflow_thresholds_guidelines.pdf
Abstract/Description or Keywords The Ministry of Water, Land and Air Protection and the Ministry of Sustainable Resource
Management are developing Review Guidelines and Assessment Methods to aid in the process
of setting instream flows that will protect fish and fish habitat in British Columbia streams. The
Review Guidelines support a two-tiered review process for proposed water uses on BC streams.
The first level is a scoping level process that sets instream flow reference points—seasonallyadjusted
thresholds for alterations to natural stream flows that are expected to result in low risk
to fish, fish habitat, and productive capacity. These thresholds are meant to act as a “coarse
filter” during the review of proposed water uses; they are general reference flows to be used on
BC streams when there is limited biologically or physically relevant data available. Good
quality physical and biological data may indicate that it is safe to undertake water diversions in
excess of the thresholds. In the absence of such information however, it cannot be assumed that
exceeding the thresholds will be without risk. Projects that propose to exceed these flow
thresholds must therefore collect additional data, which will be reviewed and used during a
more detailed project review. The Assessment Methods are a set of endorsed techniques for
assessing flow alterations on British Columbia streams, and ultimately for studying their
ecological effects. The Assessment Methods include techniques for collecting data used in
screening level reviews as well as data used during more intensive project reviews. This
document presents technical information used to support proposed instream flow thresholds as
part of the Review Guidelines.
Based on a variety of formal and informal evaluations we pursued the possibility of adapting an
historic flow method for reviewing water license applications on British Columbia streams. Our
recommendations for a standard-setting technique using historic flow data are presented in this
report. The recommendations are based on a variety of analyses of historic flow data from
around BC. The final recommendations should be subjected to a formal peer-review process.
The recommended flow thresholds are based on fish-bearing status and historic flow data,
which create two specific data requirements. The first is an adequate assessment of fish
presence and absence; the second is an adequate time series of mean daily flows. low flow, environmental flow needs, EFN, aquatic habitat, fisheries, salmonids
Information Type report
Regional Watershed Province
Sub-watershed if known
Aquifer #
Project status complete
Contact Name
Contact Email