RGDSS_Task6-9_HistoricMonthlyModel_InstreamFlowFiles

• Title: RGDSS Task 6-9 - Develop Phase IA Historic Monthly Model - Prepare Instream Flow Files
• Description: Memo documenting development of Phase 1a instream flow files.
• Decision Support - Doc Type: Task Memorandum
• Date: 9/10/1999
• DSS Category: Surface Water
• DSS: Rio Grande
• Basin: Rio Grande
• Contract/PO #: C153863
• Grant Type: Non-Reimbursable
• Bill Number: HB98-1189, SB99-173
• Prepared By: Leonard Rice Engineering

RGDSS Memorandum
Final
TO: Ray Bennett
FROM: Ed Armbruster, Hydrosphere
SUBJECT: RGDSS Surface Water, Task 6.9 -Prepare Instream Flow Files
DATE: September 10, 1999
CC: Randy Seaholm
Introduction
This memorandum represents delivery associated with Task 6.9, Prepare Instream Flow Files /
Memoranda. The objective ofthis task is as follows:
Develop and operate a command file for the DMI watright that generates the instream
flow station, instream flow right, and instream flow annual demand files for the Rio
Grande model.
Instream Flow Rights in the San Luis Valley
The CWCB is the owner of 212 instream flow water rights in Colorado's Water Division 3.
Many of these rights are located on small tributaries and headwater streams, although there are
several rights located on larger rivers such as the Rio Grande and the Conejos. The amounts of
these rights often vary by season to reflect the natural hydrologic regime of the rivers and
streams. In addition to the instream flow rights owned by CWCB, two instream filings by
Federal interests (one on Medano Creek and one on Sand Creek) and one instream flow
associated with development of Platoro Reservoir were identified for inclusion in the model.
Additional information concerning instream flow rights in Division 3 may be found in a
memorandum documenting an interview with the CWCB.
Modeled Instream Flow Rights
A total of 30 instream flow rights are represented in the Rio Grande Surface Water Model (Table
1). The instream rights that are represented are those located on mainstem rivers or tributaries
that are explicitly represented in the model. Some instream flow rights are not represented
because the tributaries on which they are located are not explicitly represented in the model.
These minor tributaries are not being represented, because they do not contain any other key
water resource structures (diversion ditches, reservoirs, etc.). A discussion of key basin structures
can be found in a memorandum documenting Task 6.2 of the surface water model development
rp ocess.
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