WSP00652

• File Number: 8449.850
• Description: Metro Water Supply Investigation - MWSI
• State: CO
• Basin: South Platte
• Date: 8/1/1995
• Author: Hydrosphere, HRS
• Title: Phase II Interruoptible Supply Summary Report - Draft
• Water Supply Pro - Doc Type: Publication

MWSI Project
Phase II Effluent Management Summary Report - DRAFT

August 22, 1995

KEY FACTORS AFFECTING EFFLUENT MANAGEMENT

Effluent management plans must be formulated with consideration of certain
legal, operational, environmental, and public policy issues. Laws and legal precedents
generally limit the sources of water available for reuse to waters imported to the South
Platte Basin, nontributary groundwater and certain waters obtained under changed
irrigation rights. Key operational considerations include the concurrent timing of the
availability of reusable effluent with exchange potential and/or sufficient reuse demands
and any related storage needs. Environmental considerations include potential impacts of
substitutions to South Platte River instream flows through the metro area, water quality
issues, and endangered species issues. These factors are discussed below.

Legal Aspects of Waler Reusability

Definition of Reusable Water

The doctrine of prior appropriation includes the general premise that foreign water
which becomes available in a stream as a result of human efforts can be used without
restriction by the party responsible for its being there. This foreign or imported water is
not subject to appropriation until that party abandons it (Getchcs, 1984). Foreign waters
imported to a new place may be used, recaptured, reused, and sold by the importer.
According to the Colorado Revised Statutes (CRS) under the Appropriation and Use of
Water (Article 82):

37-82-106. Righi to reuse of imported water --- (1) Whenever an appropriator
has lawfully introducedforeign water into a stream system from im unconnecled stream
system, such appropriator may make a succession of uses of such water by exchange or
otherwise 10 the extent that its volume can be distinguished from the volume of the
streams into which it is introduced. Nothing in this section shall be construed to impair
or diminish any waler right which has become vested.

(2) To the extent that there exists a right to make a succession of uses o/foreign,
nontributary, or other developed water, such righl is personal to the developer or his
successor, lessees, contractees, or assigns. Such water. when released from the dominion
of the user, becomes a part of Ihe natural surface stream where released. subject to water
rights of the developer or his successors or assigns, with respect to such foreign,
nontributary. or developed water, nor shall dominion over such water be lost to the
owner or user thereof by reason of use of a natural water course in the process of
carrying such water 10 the place of its use or successive use.

Reusable imported water generally includes water obtained from I) transbasin
diversions and 2) pumping from non-tributary groundwater aquifers. In addition to the
sources mentioned above, another source of reusable water is the consumptive use

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