7922

• UCREFRP Catalog Number: 7922
• Author: Bovee, K. D.
• Title: A Guide To Stream Habitat Analysis Using The Instream Flow Incremental Methodology, Instream Flow Information Paper No. 12.
• USFW Year: 1982.
• USFW - Doc Type: \
• Copyright Material: NO

does require that two or more parties agree on what the status quo is, The
methodology described here is designed to define a starting condition, and
then provide data on incremental changes so that professionals can evaluate
new conditions. It is quite possible that a solution arrived at through
incrementalism would have been considered radical had it been proposed at the
outset.
The Instream Flow Incremental Methodology (IFIM) adheres to the principle
of incrementalism. In one sense, the IFIM can be thought of as a collection
of computer models and analytical procedures designed to predict changes in
fish habitat due to increments of flow change. Indeed, this methodology does
enable such predictions. It can also be used to evaluate such diverse impacts
as changes in channel structure or alterations in waste loading from a pollu-
tion source. In fact, it can be used to translate changes in land use to
changes in the stream environment, if the user follows it that far. However,
the IFIM is much more than a collection of computer models. It is, in fact, a
thought process that begins with the structuring of the study design and
carries through to the final negotiation of a problem solution. Several of
the underlying principles of the methodology are presented and discussed
below.
The first, and probably most important principle, is that implementation
of an instream flow regime is inseparable from water management. Therefore,
the IFIM should be thought of as a water management tool. It is not intended
to be an ecosystem model. However, it is designed to have environmental and
ecological applications. The IFIM will not ensure against ecological blunders,
as is true with other decision systems, including ecosystem models. Ecological
blunders can be prevented only insofar as we are able to foresee the conse-
quences of our actions and adapt our management accordingly. The IFIM does
allow a systematic evaluation of different management options, providing
quantitative estimates of fish habitat available under each option.
The second principle is that the method is not intended to generate a
single solution, but to predict the impacts of different alternatives. Users
seeking a mechanistic solution to a problem may find this methodology difficult
to understand. The methodology has been specifically designed to provide
multiple solutions. Therefore, the user must embrace the philosophy of incre-
mentalism and iterative problem solving before the methodology can be used to
its full advantage. Following this philosophy, the methodology best lends
itself to a systems approach. Such an approach opens a wider variety of
options and water management alternatives to an application of the methodology.
The third principle is that the objectives of any application must be
rigorously defined. It is quite possible for two identical applications of
the methodology to result in vastly different solutions, due solely to the
objectives of the analysts. For example, two groups may have as their
objective, "the design of a flow regime to maintain a fishery at a minimally
acceptable level." To one group this really means, "To maximize fish habitat
within the constraints of the available water supply." To the other group,
the same objective means, "To maximize out-of-channel water use without elimin-
ating the fishery."
2