7320

• UCREFRP Catalog Number: 7320
• Author: U.S. Fish and Wildlife Service.
• Title: HYDROSS Background at the Fish and Wildlife Service ‎(FWS)‎.
• USFW Year: n.d.
• Copyright Material: NO

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HYDROSS Background at The Fish and Wildlife Service (FWS)
Given the complexity of the Colorado River Basin, The FWS Division of Water
Resources needed a computer model was selected to keep track of the flows.
The initial thought was to develop a daily flow model. However, the lack of
daily flow data for a sufficient period of time, and the large number of days
that would be necessary to model a climatically representative period of time,
forced the decision to a monthly time-step accounting model.
The reac es conce are included in a Bureau of Reclamation model, Colorado
River Simulation System (CR The Service first explored the possibility of
using the CRSS model for 'ha6i~at analysis. ThP nairur-a_1 flnw tabase
developed for CRSS is good, although the documentation is almost non-existent.
l R ama ion is wor ing o c ose t at documen a ion gap. There is one major
_ flaw in CRSS that affects its usefulness in evaluating the impact of water
F°~,~. ~ projects on fishery habitat. CRSS does not include water right priority in
'i distributing flows among water users. Water is distributed from top to bottom
P~~Ss ~ along the stream. In order to more closely approximate the actual diversions
(where downstream users may have rights senior to upstream users), CRSS has
changed the location of some diversions in the model relative to their
physical location. While this may not affect the purposes for which CRSS was
developed (river operation and salinity studies), it does affect the flows in
the habitat areas of concern.
The Fish and Wildlife Service decided to use another model developed by the
Missouri Basin Office of the Bureau of Reclamation in Billings, Montana. This
model is the Hydrologic River Operation Stuff System (HYDROSS~, a mon ly
accounting mod ~ oes include wa er rip t priorities This summary
documents the adaptation of the HYDROSS model to the Colorado River Basin.
The natural flow database from CRSS was used as a starting point for the
HYDRI3SS natural flow data ase. o remain consistent with_the Bureau of
Re ama ion reservoir operating plans, reservoir operations_were taken from
CRSS.
1. Network description
Introduction
The boundaries of the CRSS model were determined in the early
1970's, when the model was developed with the objective of tracing
water quality and quantity from the upper reaches of the Colorado
River to Mexico. In the Upper Colorado River Basin (UCRB), CRSS
starts accounting for water and salt at Glenwood S~ ngs on tie
Colorado, Fontenelle on the reen, and Taylor Park Reservoir on the
Gunnison River. Lesser tributaries such as the Yampa__L
0 ores, and Duchesne are mo eled near their conf ce with the
0 ora o Rivers. Within t is framework, CRSS has a
imi a er o no a points at which to opera a iversions and
extract flow check information.