WSP12650

• File Number: 8221.109
• Description: Colorado River Basin Projects - Long Hollow
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 5/25/2004
• Author: Colorado-La Plata WCD
• Title: Proposed Long Hollow Reservoir Project - PowerPoint Presentation - 05-25-04
• Water Supply Pro - Doc Type: Report/Study

001533

COLORADO WATER RESOURCES &
POWER DEVELOPMENT AUTHORITY

Logan Tower Bldg. - Suite 620, 1580 Logan Street, Denver, Colorado 80203-1942
303/830-1550 . Fax [phone] . [e-mail]

Memorandum

May 25, 2004

TO:

Mark Langford
Randy Seaholm
Mike Serlet
David Robbins

RECEIVED
MAY 26 2004

Oclorado Water Conservation Board

FROM:

Daniel L. Law, Executive Director

RE:

PowerPoint Presentation on Long Hollow Reservoir

Enclosed is the subject presentation prepared by Eric Bikis of Wright Water Engineers. I have forwarded copies of
this presentation to my Board of Directors. Once I receive the Phase I Study on Long Hollow Reservoir, I will
forward that as well.

Summary of the important facts in this presentation:

1. Drainage area of the La Plata River in Colorado is 331 square miles.
2. The Hesperus Gauge has 86 years of records with an average flow of31,888 ac-ft. The minimum
flow was 6,230 ac-ft and the maximum flow was 65,547 ac-ft.
3. The La Plata River is governed by the La Plata River Compact of 1922 with the following
components:
A) Each state has umestricted use of water within its boundaries between December 151 and
February 15th ("non-compact period") or when Stateline Gauge flow is 100 cfs or more; and
B) If Stateline Gauge is less than 100 cfs between February 15th and December 151 ("compact
period") then Colorado shall deliver Y2 mean flow at the Hesperus Gauge to the State line
Gauge the following day.
4. The Long Hollow Reservoir has two principal purposes:
A) Help Colorado meet the La Plata River Compact
B) To provide irrigators in Colorado and New Mexico with a more dependable and plentiful
irrigation water supply.
5. There are 31 river miles between the Hesperus Gauge and the state line.
6. Long Hollow Reservoir has a drainage area of 43 square miles and a maximum storage capacity of
5,432 ac-ft. A pool of 300 ac-ft. was dedicated for use in New Mexico to help meet the compact
requirements when the La Plata River is operated under "split river conditions."
7. A 14-year study period was used to simulate the river flows and water supplies.
8. Long Hollow had an average fill of3,540 ac-ft. It filled in 4 years out of 14 and was emptied in
10 years out of 14.
9. The upstream senior ditches were allowed an incremental average annual diversion of2,731 ac-ft.
The ditches and land owners benefiting from the incremental diversions were not mentioned. The
average annual return flow from this incremental diversion was estimated at 1,292 ac-ft.
10. Total irrigated acreage is 20,400.
11. Compact delivery requirements are met 12 years out of 14.

Enclosure

)