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

portion of rights transferred from one type of use to another, such as from irrigation to
municipal use. Therefore, there are generally three sources of reusable water.

August 22, 1995

From a legal perspective, the broad category of water reuse can similarly be
broken down into three areas: I) reuse - the subsequent use of imported water for the
same purpose as original use; 2) successive use - the subsequent use by water imported
for a different purpose; and 3) right of disposition - the right to sell, lease, exchange or
otherwise dispose of imported water. For purposes of this report, the term reuse and
reusable effluent will refer, in general, to all three concepts.

Impact on Other Appropriators

Since the right to most imported water is 100% consumptive, appropriators on a
stream have no vested right to the continuance of importation of foreign water which
another has brought to watershed, absent other decrees or agreements. (City & County of
Denver v. Fulton Irrigating Ditch Co., 179 Colo. 47, 506 P.2d 144 (1972). Although
other appropriators often benefit from unused return flows from imported water, they do
not have the right to its continued existence.

Identity of Water Used for Substitution

One common use of reusable effluent is substitution, which includes exchange
and augmentation. Under Colorado water law, water acquired under an exchange or
augmentation plan assumes the identity of the water used for exchange or substitution
supply. Therefore, if reusable effluent is used to provide water to downstream users,
allowing a diversion upstream which meets the no harm rule, the water diverted upstream
would be considered reusable.

Decrees and Agreements Affecting Water Reuse in the Denver Metro Area

There are several decrees and agreements that affect water reuse in the Denver
metropolitan area. Summaries of these documents are included in the Memorandum of
Key Agreements and Decrees. The most noteworthy ones are listed below:

The Blue River Decrees: These decrees impose a limit on Denver Water,
requiring that, within legal and economic limitations, Blue River water be reused and that
its use be for municipal purposes only.

The 1940 Agreement: Under the 1940 Agreement, Denver Water agreed to
relinquish its use of effluent from decreed water rights from Colorado River sources with
appropriation dates preceding May I, 1940, unless those water rights were acquired by
Denver Water subsequent to May I, 1940. This agreement was made in lieu of making
evaporative releases from certain streambed reservoirs in the South Platte River Basin.
Subsequent court decisions have held that Denver Water must abide by the terms of the
1940 Agreement until it is terminated by mutual agreement of Denver Water and the
Consolidated Ditches of Water District No.2 or if the State Engineer requires Denver

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