PUB00053

• Year: 1999
• Title: Metropolitian Water Supply Investigation Final Report
• Author: Hydrosphere Resource Consultants
• Description: Metropolitian Water Supply Investigation Final Report
• Publications - Doc Type: Water Resource Studies

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Metropolitan Water Supply Investigation

MWSI Results

Metro Denver area providers will continue to look to the South Platte River basin for a
major portion of the future water supplies. Based on an inventory of water supply plans,
approximately 45% of the metro Denver area's future water supplies will be obtained
from South Platte Basin water sources. These include additional South Platte Basin
surface water development, conversion of in-basin irrigation rights, Denver Basin
groundwater use and reuse of these sources.

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There are several areas of concern related to additional development of South Platte Basin
water sources. The presence of threatened and endangered species on the Platte River in
Nebraska continues to be a major area of concern. Colorado has entered into a
Cooperative Agreement with the u.S. Department ofInterior and the States of Nebraska
and Wyoming to implement recovery efforts for these species and their associated
habitats. Under this Cooperative Agreement, Colorado is developing a plan to mitigate
the impacts of new water-related activities in Colorado on the species and their habitats
through the use ofreregulation storage at the Tamarack Project, located along the South
Platte River near Julesburg.

Large scale conversion of irrigation rights, particularly from agricultural lands located far
from urban areas, have raised concerns about impacts to agricultural economies and local
government tax bases. The majority of irrigated agriculture in the basin is located within
the boundaries of the Northern Colorado Water Conservancy District. As discussed
above, Northern has adopted policies to discourage the transfer of native base supplies
outside of this region.

Increased reliance on Denver Basin groundwater as a principal supply by some water
providers in Douglas and Arapahoe Counties has raised concerns about the long-term
sustainability and economic viability of this groundwater resource. While the amount of
groundwater in storage in these aquifers is vast, natural recharge of these aquifers is
believed to be very limited. As future groundwater pumping increases, aquifer levels are
expected to decline. There is a concern that this may lead to higher pumping costs, the
eventual need for additional wells and reduced supplies, Groundwater-dependent
providers have recognized this problem and are actively working to increase the
renewable portion of their water supplies.

Water quality in the South Platte and its tributaries has been significantly affected by
agricultural and municipal water use and land use, Development of additional South
Platte Basin water supplies will put further stresses on water quality in the basin.

Upstream of the metro Denver area, the South Platte River is a major aquatic habitat and
recreational amenity. Construction of water supply reservoirs has inundated several
reaches of river and created significant flatwater recreational opportunities. The
operation of water supply systems has substantially altered the character and flow regime
of much of the remaining free-flowing portions of the river. There is a significant
concern among recreational users, natural resource management agencies and
environmental interests that further development and future operations of water supply
systems do not unreasonably impair existing aquatic environmental and recreational
values. This issue is being addressed in the U.S. Forest Service's Wild and Scenic Rivers
Program Eligibility Study for the South Platte River above Denver.

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Prepared fOT the Colorado Water Conservation Board, Colorado Department of Natural Resources by
Hydrosphere Resource Consultants. 1002 Walnut Street. Suite 200. Boulder. CO 80302