PUB00102

• Year: 1998
• Title: Denver Basin and South Platte River Basin Technical Study
• CWCB Section: Water Conservation & Drought Planning
• Author: Simpson/Lile
• Description: Results of study to investigate Denver Basin groundwater management and South Platte River Basin issues
• Publications - Doc Type: Brochure

I
I,
I
I
I
I
I
I
I
I
I
I
I
I
I,
I
I
,
I

rights 5) Non-tributary groundwater and 6) New South Platte water development.
These six sources each have positive and negative impacts on environmental,
political, social, and economic issues depending on one's perspective. No
alternative entirely benefits all interests. However, the range of water supply
options available to the South Platte basin and Denver Metro area provide some
flexibility and possible opportunities for cooperative approaches and balancing of
impacts.

A computer-based interactive tool was developed as part of the SB74 study to
illustrate the interrelationships between population, water demands, water supply
options and resulting effects on surface water and groundwater resources within
the South Platte basin of Colorado. The illustrative tool presents the concept of net
impacts to the South Platte Basin resulting from a range of surface and groundwater
use and management activities. The tool allows the user to select a future water
supply scenario based on population growth and water supply options for each of
three regions within the South Platte basin. Relevant information on population,
existing water supplies and future water supply plans is provided in the input
page along with several example future scenarios.

The initial area of public water policy is based on the current and near term water
resource development in the South Platte River Basin and Denver Basin aquifers.
Legislative decisions regarding changing existing statutes that deal with Denver
Basin aquifers and impacts on senior surface water rights do not appear to be
necessary at this time. Prior to making decisions regarding the long-term impacts
on existing water rights resulting from Denver Basin Aquifer use, it is
recommended that additional studies be conducted to integrate the surface water
and Denver Basin ground water models, obtain additional ground water use
(pumping) data in the basins, refine the aquifer properties used in the models and
further examine South Platte River water use and potential water right injury. The
long range plans for both the Colorado Water Conservation Board and State
Engineer propose extending the decision support system that was developed for
the Colorado River basin (CRDSS) into the South Platte River basin. The
development of a decision support system would complement and build on the
results of studies proposed by the peer reviewers.

A second area of public water policy is consideration of the additional runoff in
streams resulting from impervious surfaces created by population growth. The
entire Front Range from Pueblo to Ft. Collins is growing in population. The
increased runoff to certain streams may offset the depletions to these streams
from pumping of Denver Basin aquifers. Some metropolitan water providers that
use the Denver Basin aquifers believe that this additional runoff should be
carefully considered as a potential offset to the depletion from groundwater use.
This concept would be consistent with viewing the South Platte River flow as a
whole, considering all of the increases and decreases resulting from population
growth and the resulting net stream flow condition. The proposed offset discussed
above is currently inconsistent with Colorado water law. The owners of senior

- 3-