PUB00108

• Year: 1986
• Title: St. Vrain Basin Reconnaissance Study
• CWCB Section: Administration
• Author: Colorado Water Resources and Power Development Authority
• Description: Extensive study for future study and development toward meeting the water-related needs of residents with the St. Vrain Basin
• Publications - Doc Type: Brochure

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EXECUTIVE SUMMARY

A. Introduction

The St. Vrain Basin Reconnaissance Study was authorized by the
Co lorado Water Resources & Power Deve lopment Author i ty (CWRPDA) in February
1983. This Study is the first comprehensive basin-wide study undertaken since
the State Legislature created the CWRPDA in 1981. The initial objectives of
the Study were: (1) to identify the needs of the St. Vrain Basin for future
water resources development, and (2) to identify and evaluate, at a reconnais-
sance level of detai I, the means avai lable to meet those needs through the
development of new water suppl ies and through the improved regulation and dis-
tribution of already developed waters, including imported waters.

The Study Area, which includes about 480 square mi les, was estab-
I ished as the St. Vrain Basin exclusive of the Boulder Creek Watershed area
and with minor adjustments reflecting present water service areas. It is
located in the Front Range region of Colorado, approximately 30 to SO mi les
north and northwest of Denver in Boulder, Weld and Larimer counties. The 1980
population of the Study Area, which includes the cities of Longmont and Lyons,
is estimated to be 63,000. Under a medium-growth scenario, population is pro-
jected to increase nearly three-fold to 172,000 by year 2020. The principal
cities are Longmont and Lyons. Adjacent areas lying to the north and south of
the St. Vrain Basin, together with the Study Area, were designated as a Siting
Area, in which potential water development projects to serve the Study Area
could be sited. The Siting Area includes the Little Thompson River Basin and
Carter Lake to the north, and the Boulder Creek Basin to the south. Water
needs outside of the Study Area were not to be considered.

Step 1 of the Study, completed in August 1984, resulted in identi-
fication of water-related needs and physical, social, and economic character-
istics of the Basin. Revised objectives for Step 2, begun in October 1984,
were adopted, which are "To formulate and evaluate alternative water manage-
ment plans which meet present and future demands for agricultural, municipal,
and industrial water supplies in the St. Vrain Basin with consideration for
other uses of the Basin's water and associated land resources." Non-structural
measures were to be considered equally with structural measures, with consid-
erable emphasis given to evaluation of potential social and envi ronmental
effects of alternative plans. The thi rd and final step of the Study as
originally planned, Reconnaissance-Level Evaluation of Candidate Alternatives,
was deleted when the Step 2 scope was redefined and expanded.

A Management Committee, consisting of representatives of the North-
ern Colorado Water Conservancy District, the Colorado Water Conservation
Board, and the CWRPDA, guided the Study. The Study was performed by an asso-
ciation of R. W. Beck and Associates and Dames & Moore, assisted by Leonard
Rice Consulting Water Engineers, and W. B. Lord and Associates.