9388

• UCREFRP Catalog Number: 9388
• Author: Maddux, H. R., W. R. Noonan and L. A. Fitzpatrick.
• Title: Overview of the Proposed Critical Habitat Designation for the Four Colorado River Endangered Fishes.
• USFW Year: 1993.
• USFW - Doc Type: Salt Lake City.
• Copyright Material: NO

1. Current depletions without any actions taken on behalf of the
endangered fishes (the dotted line in row 1 of the figure);

2. Current depletions but with actions taken on behalf of the endangered
fishes (the dashed line in row 1 of the figure);

3. Future depletions to be allowed without considerations of the
requirements of the endangered fishes (dotted line in row 2 of the
figure);

4. Future depletions taking into account the requirements of the
endangered fishes (dashed line in row 2 of the figure).

The solid lines represent Service identified flow levels believed necessary for recovery of the
endangered fishes after being modified to be compatible with outputs of the Colorado River
System Simulation model. A critical element of the economic analysis involved determining
the economic impacts in the study region due to changes in the river flows as required for
recovery of the endangered fishes. This involved assessing the impacts of revised operating
plans of the dam system on recreation, hydroelectric generation, agriculture, municipal, and
industrial water uses.

Hvdroelectric Impacts

Hydroelectric modeling required a cooperative effort among the Service, the Bureau of
Reclamation, the Western Area Power Authority (Western), and Stone and Webster
Consultants, Inc. Utilizing the hydrographs and taking into consideration the alternative
depletion frameworks, the Bureau of Reclamation modeled the potential effects of flow
requirements for the endangered fishes on monthly hydroelectric generating capacity in the
Upper Basin. Western the used the 4ata generated by the models to estimate the changes in
the amount of marketable power, Finally, Stone and Webster Consultants, Inc. input the data
into a model framework that yields the net effects of the change in the power system.

Recreation Impacts

A recreation survey was developed that also relied upon the hydrographs. Outdoor planners
in the seven States and a variety of Federal agencies were asked to assess the impacts of
potentially modified operating plans on recreational activities. Three versions of the survey
were generated to meet the needs of different recreation units along the rivers. These were:
(a) units outside critical habitat areas but impacted by flow changes; (b) units including
critical habitat areas that may be impacted by flow changes; and, (c) units including critical
habitat areas that may not be impacted by flow changes.

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