9570

• UCREFRP Catalog Number: 9570
• Author: U.S. Department of the Interior.
• Title: Preliminary Analysis
• USFW Year: 2000.
• USFW - Doc Type: Wayne N. Aspinall Unit Operations and the Federal Water Right Claim, Black Canyon of the Gunnison National Park.
• Copyright Material: NO

At the present time, Reclamation is also working with the Fish and Wildlife Service and the
Upper Colorado River Endangered Fish Recovery Program to develop Aspinall Unit operations
to assist in the recovery of downstream endangered fishes. Preliminary endangered fish flow
recommendations call for spring peak flows, summer base flows, and minimum flows for fish
passage in the lower 3 miles of the Gunnison River. Reclamation will complete consultation
under the Endangered Species Act in determining operations for fish recovery while meeting
Aspinall Unit purposes. An Environmental Impact Statement is planned to be completed prior to
reservoir operation changes.
Hydrology Modeling
RiverWare Model
RiverWare is a software modeling tool. developed by CADSWES (University of Colorado) for
the Bureau of Reclamation and the Tennessee Valley Authority for operation and planning
studies of river basins and river systems. A daily planning model of the Gunnison River was
developed using RiverWare modeling software. The model includes the Gunnison River Basin
from the inflows to Blue Mesa Reservoir down to just upstream of the Colorado River
confluence. The modeling period runs from January 1975 through July 1998. A description of
the model is included in Attachment C.
National Park Service Input
The NPS has provided Reclamation with hydrograph criteria to define the minimum annual
hydrograph for any year. The minimum annual hydrograph consists of a spring peak with
appropriate ramping, an 85-day inundation period including the peak, and a base flow of 300 cfs
for the rest of the year. The suggested peaks for the modeled period range from 1,400 cfs in an
extremely dry year such as 1977 to 13,755 cfs in a very wet year such as 1984. The peaks can
occur in May or June. Table B-1 in Attachment B includes the NPS suggested peaks for the
years 1975 through 1998.
Model Runs and Results
Seven (A-G) operation runs were modeled for this analysis, including a baseline, three May peak
plans, and three June peak plans. The model reflects a cooperative type of operation in which
Reclamation operates the Aspinall Unit to meet NPS desired flows subject to certain limitations.
The legal availability of water and water rights are not included in the model. Reclamation
modeled a combination of natural flows and storage releases to attempt to meet the NPS desired
flows.
Run Description
3