7912

• UCREFRP Catalog Number: 7912
• Author: Tennant, D. L.
• Title: Instream Flow Regimens for Fish, Wildlife, Recreation and Related Environmental Resources.
• USFW Year: 1975.
• USFW - Doc Type: Billings, MT.
• Copyright Material: NO

Reconunend the most appropriate and reasonable flow(s) that can be
justified to provide protection and habitat for all aquatic resources.

RESULTS

Detailed field studies were conducted on 11 streams in 3 states
between 1964 and 1974 testing the Montana Method (Table 2). This
work involved physical, ch~mical, and biological analyses of 38
different flows at 58 cross-sections on 196 stream miles, affecting
both coldwater and warmwater fisheries. Reports or publications on
6 study streams are available as indicated in Table 2. Numerous
black and white photos and 35 nun. slides were taken of all the flow
stages studied at each cross-section. The studies were all planned,
conducted, and analyzed with the help of state fisheries biologists.
These studies reveal that the condition of the aquatic habitat is
remarkably similar on most streams carrying the same portion of the
average flow.

I

Width, depth, and velocity are physical instream flow parameters
vital to the well-being of aquatic organisms and their habitat.
Sixteen-hundred measurements of these parameters for 48 different
flows on 10 of the streams cited in Table 2 show that they all increase
with flow and that changes are much greater at the lower levels of flow
(fig.l). Width, depth, and velocity all changed more rapidly from no
flow to a flow of 10% of the average, than at any point thereafter.
Ten percent (10%) of the average flow covered 60% of the substrates,
depths averaged 1 foot, and velocities averaged 3/4 foot per second.
Studies show that these are critical points or the lower limits for

.

7