09 ‎(3)‎

• Board Meeting Date: 11/18/2007
• Description: ISF Section - Increases to ISF Rights, C.R.S. 37-92-102‎(4)‎‎(a)‎
• Board Meetings - Doc Type: Memo

Over the years, DOW biologists observed that self-sustaining fish populations require more than
a single "minimum" flow during months when they are actively moving through the channel and
spawning. "Research has shown that single year-round minimum flows, when maintained as a
long-term condition, cannot he expected to sustain the same fish populations or aquatic life as a
natural flow regime, where low flow conditions occur infrequently and for shorter periods
(Stalnecker and Wick 2000). "1 Because of these and similar observations and studies, the DOW
re-evaluated its procedure for linking R2Cross hydraulic variables with biologic requirements.
As a result, DOW adopted new standards for creating the instream flow recommendations it
submits to the Board, including a higher "minimum" flow during the summer months. The
DOW will provide a memo under separate cover which further discusses the history of increases
and biological analyses.
Most instream flow recommendations considered by the Board today include at least two flow
periods. However, most of the Board's early decrees were based upon the earlier R2Cross
interpretation and provide only a single year-round instream flow to preserve the natural
environment. Based upon observations and experience, biologists have concluded there is a need
for seasonal high flows on certain streams. Consequently, they have recommended that the
Board increase the decreed amount on some streams during the spring/summer season to ensure
preservation of the natural environment to a reasonable degree. As discussed in the preceding
overview of C.R.S. 37-92-102(4)(a), the increased water right appropriations are junior to and
"stacked" on top of the existing decreed instream flow water right. To date, the Board has
appropriated 21 increases to decreed instream flow water rights (See Attachment A).
Historically, the Board has appropriated increases to existing instream flow water rights 1) when
additional water is made available to a stream, 2) to provide additional water for critical
biological activities (spawning), and/or 3) to refine original calculations of the amount of water
required to preserve the natural environment. Attachment B provides several examples of past
increases appropriated by the Board.
3) The Process for Appropriating an Increase
As previously mentioned, staff follows the statutory guidance outlined in C.R.S. 37-92-102(4)(a)
and processes proposed increases to appropriations as it would any other ne~v appropriation for
ISF purposes. The process for appropriating new instream flow water rights is outlined in ISF
Rule 5.
During its analysis of the data provided by a recommending entity, staff evaluates the
recommendation based on the documented presence of a natural environment and the specific
needs of that natural environment to ensure its reasonable preservation. A key component of this
evaluation is the review of the recommending entity's scientific rationale explaining and
justifying the requested increase over the existing appropriation. It is important to note that the
natural environment that is being evaluated may be the same natural environment that the Board
sought to protect under the original appropriation. However, it could be a natural environment
that differs from the original due to changes in water availability analyses, water quality factors,
geomorphology, water temperature and/or other factors. Use of the R2Cross or any other
methodology to quantify the amount of water needed is based on the current interpretation and
application of the science by the State's DOW biologists. In either case, staff evaluates a request
for an increase that is based on changed circumstances. For example, there has been a change in
the natural environment or water availability, or there has been a change in the understanding
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