7046 ‎(2)‎

• UCREFRP Catalog Number: 7046
• Author: Valdez, R. A., W. J. Masslich and A. Wasowicz.
• Title: Final Report\
• USFW Year: 1992.
• Copyright Material: NO

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7. The percentage of Dative fish species in the Dolores River was relatively high when compared
to other upper basin systems; 13% in 1990, 32% in 1991, 19% for the study.

8. Native fish species including flaooelmouth sucker, bluehead sucker, roundtail chub and
speckled dace were found with evidence of successful reproduction in the Dolores River.

~ORECO~NDATIONS

1. The operation of McPhee Dam should consider enhancing the suitability of the Dolores River
for Colorado squawfish and protecting existing native fisheries. Flows observed in the Dolores
River during this study indicate that the operation of McPhee Dam has the potential to adversely
or beneficially impact native fisheries by altering timing and magnitude of flows. Extremely low
flows (20-50 cfs) released on a year round basis are potentially devastating to aquatic resources
as well as other aspects of the rivers corridor (i.e. productive cobble riffles, riparian vegetation).
Potential impacts include: 1) reduced survival and recruitment of early year classes caused by
unnatural temperature regimes, 2) winter kills due to inadequate water volume, 3) lack of access
and disruption of fish movement because of inadequate water volume, and 4) increased stress
associated with water quality problems at extremely low flow. Specific flow recommendations
include:

a Increase minimum base flows to 78 cfs during wet and normal years and 50 cfs (or equal to
reservoir inflow in less than 50 cfs) during dry years.

b. Spring and summer flows should simulate the shape of the natural hydrograph. Peak flow
should approximate peak inflow to McPhee Reservoir. Ramping up should commence as
soon reservoir inflow increases to avoid early warming in the Dolores River below McPhee
Dam. Following peak flow, a period of at least 30 days should be utilized for gradual down
ramping to a base flow. Ideally ramping of flows to base conditions should be done in a
manner to approximate relative magnitude of decreasing inflow into the reservoir.

c. Downstream flow releases should prioritize maintaining aquatic systems. The release of large
volumes of water to provide short term downstream benefits should not be allowed if it
results in loss of flexibility in managing flows for the system during the course of the year.

2. Additional research should be conducted to better understand use of the Dolores River by
Colorado squawfish. This should include additional sampling during spring runoff and during a
high flow year.

3. Monitoring should be continued in the Dolores River to assess biological recovery associated with
ongoing changes in the system. These changes include the continued clean up of the Uravan mill
site, Reclamation's desalinization project in Paradox Valley, and potential changes in the
operation of McPhee Dam.

4. An efficiency evaluation of Reclamation's Dolores River project should be conducted. Since
much of the water withdrawn for the Dolores Project is used to irrigate agricultural land in the
San Juan River Basin, return flows associated with overwatering and other inefficient water use
practices provide no benefit to aquatic resources in the Dolores River drainage. The cost of
inefficient irrigation practices is high for the Dolores River ecosystem and should be evaluated

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