BOARD00970

• Board Meeting Date: 7/22/1993
• Description: Agenda or Table of Contents, Minutes, Memos. Partial.
• Board Meetings - Doc Type: Meeting

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INSTREAM FLOW QUANTIFICATION - LITTLE DRY CREEK
April 5, 1993
PAGE 5

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the riparian vegetation is directly related to the surface water flows in Little Dry Creek. In
other words, if some level of the base flow of the creek is protected by an instream flow water
right, then that aspect of the natural environment will be protected. Dr. Cooper's conclusions
are that: 1) the base flows are important to the long term stability of the riparian community,
2) that 40 - 60 % of the base flow could be diverted without harm to the riparian vegetation, and
3) that the peak flows are also important to the long term health of the riparian vegetation.

The DOW requests that the CWCB keep these conclusions in mind when reviewing the
results of the instream flow quantification based on the fishery present in Little Dry Creek.

Terrestrial Wildlife Resources

The Little Dry Creek corridor, due to its level of development and its natural state, is
habitat to numerous species of birds which depend to some degree upon the presence of a
flowing stream. Over 60 species of birds can be observed in the Little Dry Creek corridor on
a fairly regular basis. Numerous species of mammals, amphibians, and reptiles also depend on
the water, and the life forms it supports, to survive in the Little Dry Creek corridor.
Documentation of these occurrences and observations are available from a number of sources.
Since the needs of these species is not a large part of the instream flow quantification contained
herein, documentation is not attached.

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METHODS AND APPROACH

The DOW employed the Instream Flow Incremental Methodology (lF1M) and the
Physical Habitat Simulation System (pHABSIM) developed by the US Fish and Wildlife Service
to quantify the instream flow needs of the existing fish population of Little Dry Creek. Two
IFIM sites were selected using a representative reach approach. In this approach, the entire
creek corridor was surveyed as to the habitat features and two representative reaches were
selected for study. Transects were laid out in the two reaches, the cross sections were surveyed,
and tied together by elevation for hydraulic modeling purposes. Due to the steady nature of the
flows in Little Dry Creek (see both APPENDIX C and APPENDIX D), water surface elevations
for only two flows were used in the modeling. Three flows and water surface elevations were
measured as per the IFIM methodology, two of the flows were so close together that no
additional accuracy to the hydraulic modelling was gained by using all three flows. While this
is not the ideal situation, the DOW is of the opinion that the results are reliable and the
recommendations contained in this report are sufficient for the CWCB to move forward with an
instream flow appropriation for Little Dry Creek.

_ . The locations of the two IFIM sites on Little Dry Creek are noted on the map in Figure .-
_ 1. One site was located in CRY and one in CGY. Each of the sites contain the habitat types _