United States Department of the Interior
OFFICE OF THE SECRETARY
Washington, DC 20240
Operating Guidelines
Colorado River Guidelines for Coordinated Operations of Lake Powell
and Lake Mead
Operating Years 2027 and 2028
August 2026
Recommending Official:
David M. Palumbo
Deputy Commissioner, Operations, Bureau of Reclamation
Date
Approved:
DougBurgum
Secretary of the In
Operating Guidelines – Colorado River Guidelines for 1
Coordinated Operations of Lake Powell and Lake Mead
Operating Years 2027 and 2028
August 2026
Operating Guidelines
Colorado River Guidelines for Coordinated Operations
of Lake Powell and Lake Mead
Operating Years 2027 and 2028
1. Purpose
The Colorado River Guidelines for Coordinated Operations of Lake Powell and Lake Mead
Operating Years 2027 and 2028 (2027–2028 Operating Guidelines) establish operating criteria
applicable to Operating Years 2027 and 2028 (the “Effective Period”). These 2027–2028 Operating
Guidelines are a final agency action issued pursuant to the Record of Decision adopted by the
Secretary of the Interior (Secretary) for the Decision Framework for Colorado River Guidelines:
Coordinated Operations of Lake Powell and Lake Mead (2027–2036) (ROD).
The 2027–2028 Operating Guidelines are for Operating Years 2027 and 2028 only and are not
intended to represent a long-term operational strategy. The Department is establishing these
guidelines at a time of historic low storage conditions in Lake Powell and Lake Mead and with
significant hydrologic risk facing the system should low runoff conditions continue. It is against this
backdrop of hydrologic risk and lack of long-term consensus that Reclamation has prepared these
2027-2028 Operating Guidelines. These 2027–2028 Operating Guidelines and are not and shall not
be construed to create a precedent for future operations as described in Section 10.11 of the ROD.
These 2027–2028 Operating Guidelines contemplate actions that rely upon necessary implementing
and parallel agreements as described in Section 5.9. Where necessary parties do not reach consensus
on proposed operational measures or agreements, the Secretary will proceed consistent with
applicable Federal law, the 2006 Consolidated Decree of the U.S. Supreme Court in Arizona v.
California (Consolidated Decree), the Law of the River, and all other governing statutes, regulations,
and contractual obligations necessary to fulfill the Secretary’s statutory responsibilities, protect
Federal interests, and ensure continued system operations. The absence of such agreements shall not
impair, delay, or otherwise limit the Secretary’s authority to implement operations in 2027 and 2028.
The Department of the Interior (Department) intends to implement the Criteria for Coordinated
Long-Range Operation of Colorado River Reservoirs Pursuant to the Colorado River Basin Project
Act of September 30, 1968 (Long-Range Operating Criteria or LROC) through these 2027–2028
Operating Guidelines and implemented through the Annual Operating Plan for Colorado River
Reservoirs (AOP). These 2027–2028 Operating Guidelines also provide for temporary operational
actions that are not otherwise provided for under the LROC when necessary to protect critical
Federal infrastructure during extraordinary circumstances, consistent with applicable Federal law.
2 Operating Guidelines – Colorado River Guidelines for
Coordinated Operations of Lake Powell and Lake Mead
Operating Years 2027 and 2028
August 2026
2. Process to Develop Guidelines
These 2027–2028 Operating Guidelines were developed pursuant to the ROD and incorporate
operational elements based on input provided by the Basin States, Basin Tribes, and other interested
parties.
Further, these 2027–2028 Operating Guidelines were developed and reflect ongoing discussions
regarding consensus arrangements by the Basin States for 2027 and 2028 which would be supported
by implementing and parallel agreements that will facilitate water management tools such as: Lower
Basin shortage sharing, forbearance, conservation efforts, releases of additional water from the
Colorado River Storage Project (CRSP) Upper Initial Units – specific reservoirs above Lake Powell
pursuant to Section 602 of the Colorado River Basin Project Act – to increase the elevation at Lake
Powell to protect critical Federal infrastructure.
3. Effective Period
These 2027–2028 Operating Guidelines shall become effective upon (1) execution by the Secretary
and (2) execution of the necessary implementing and parallel agreements, as described in Section
5.9. Absent such implementing and parallel agreements in (2), the Secretary will proceed as
described in Sections 5.2, 5.3, and 5.4, consistent with applicable Federal law, the Consolidated
Decree, the Law of the River, and all other governing statutes, regulations, and contractual
obligations necessary to fulfill the Secretary’s statutory responsibilities, protect Federal interests, and
ensure continued system operations. Once effective, these 2027–2028 Operating Guidelines shall
govern the operation of Lake Powell and Lake Mead for the 2027 and 2028 Operating Years, unless
modified or superseded by subsequent action of the Secretary pursuant to the provisions herein.
Further, these 2027–2028 Operating Guidelines could be superseded during the Effective Period if
consensus operating guidelines, including among the Basin States and the Secretary, are reached.
4. Definitions
Definitions are included in the ROD and are incorporated by reference into these 2027–2028
Operating Guidelines. Additional definitions specific to these 2027–2028 Operating Guidelines are
below.
1. “2027–2028 Operating Guidelines” shall mean the Colorado River Guidelines for
Coordinated Operations of Lake Powell and Lake Mead for Operating Years 2027 and 2028.
2. “Exhibit Run” shall refer to modeling performed in addition to the official modeling runs,
which are used for official operational determinations. Exhibit Runs reflect unofficial dam
operations or sensitivity analysis based on hypothetical conditions or dam operations.
3. “Lower Colorado Regional Director” shall mean the Regional Director of the Lower
Colorado River Basin Region of the Bureau of Reclamation (Reclamation).
4. “Most Probable” shall mean a modeling projection provided by Reclamation in the monthly
24-Month Study, which simulates conditions using a median (50th percentile exceedance)
inflow scenario.
Operating Guidelines – Colorado River Guidelines for 3
Coordinated Operations of Lake Powell and Lake Mead
Operating Years 2027 and 2028
August 2026
5. Guidelines for the Coordinated Operation of Lake Powell and
Lake Mead for Operating Years 2027–2028
For Operating Years 2027 and 2028, the Secretary shall coordinate the operations of Lake Powell
and Lake Mead according to the strategy set forth in this Section 5.
The Secretary will base annual determinations regarding the operations on these 2027–2028
Operating Guidelines unless extraordinary circumstances exist as described in Section 5.1.D. The
Secretary retains full legal authority to ensure ongoing operations of Colorado River facilities,
including operational actions taken to address extraordinary circumstances in order to ensure
protection of critical Federal infrastructure and continuous operational reliability of such facilities.
The Department is establishing these 2027–2028 Operating Guidelines at a time of historic low
storage conditions in Lake Powell and Lake Mead, with combined storage at an all-time low, and
with significant hydrologic risk facing the system should low runoff conditions continue. The
Department recognizes the continued importance of Lake Powell operations that achieve the
objective stated in Article II of the LROC: “the objective shall be to maintain a minimum release of
water from Lake Powell of 8.23 maf for that year.” However, the Department also recognizes that
achievement of this objective may not be possible under the hydrologic and operational conditions
that exist at the time of adoption of these 2027–2028 Operating Guidelines, including low reservoir
elevations, declining river flows, and the need to protect operational reliability. The coordinated
operations described in these 2027–2028 Operating Guidelines are intended to account for these
considerations and are intended to minimize adverse operational effects in the Upper and Lower
Basins while preserving the Secretary’s ability to respond to changing hydrologic conditions.
5.1 Operation of Lake Powell for Operating Years 2027–2028
These operations are designed to protect a minimum Lake Powell elevation of 3,500 feet by initially
seeking to maintain a minimum elevation of 3,510 feet. This provides an operational buffer and
provides additional flexibility in recognition of the operational risks associated with sustained
operations below elevation 3,490 feet, at which releases from Glen Canyon Dam can only pass
through the river outlet works. As described in Section 3.1 of the ROD, there are infrastructure
concerns associated with the uncertainty of extended operations through the river outlet works as
the sole means of sustained water releases from Glen Canyon Dam that could compromise the
reliability and operational flexibility of Glen Canyon Dam and affect the ability to meet critical
downstream water supply needs. There are additional impacts to hydropower associated with
operating below 3,490 feet, as this is the minimum power pool.
These operations involve various consultations and coordination with the Basin States, Basin Tribes
and other affected parties. These consultations are described in Section 5.7.B.
The Most Probable August 24-Month Study projections of the October 1 Lake Powell elevation, for
the following Water Year, shall be used to determine the applicable operational range for the
coordinated operation of Lake Powell and Lake Mead as described below.
Releases from Lake Powell for coordinated operations will be consistent with the provisions of the
2016 Glen Canyon Dam Long-Term Experimental and Management Plan Environmental Impact
Statement and Record of Decision and the 2024 Glen Canyon Dam Long-Term Experimental and
Management Plan Supplemental Environmental Impact Statement and Record of Decision.
4 Operating Guidelines – Colorado River Guidelines for
Coordinated Operations of Lake Powell and Lake Mead
Operating Years 2027 and 2028
August 2026
As described below, determinations in Operating Years 2027 and 2028 throughout this section will
be based on the current month’s Most Probable 24-Month Study projections of Lake Powell
elevations. In each range, the Lake Powell Water Year release could be reduced to a minimum of 6.0
million acre-feet (maf) if necessary to maintain elevation 3,510 feet. Releases may be further reduced
as described in Section 5.1.D, should Lake Powell be projected to reach elevations below 3,500 feet.
Any such adjustments shall not require re-initiation of the AOP consultation process. Sections
5.1.A – 5.1.D describe the months and criteria for determining such adjustments.
A. Upper Elevation Range
1. In Water Years when the projected October 1 Lake Powell elevation is at or above 3,565
feet, the initial Water Year release will be determined by performing an incremental
modeling approach using Exhibit Runs. Reclamation shall first evaluate a Water Year release
of 8.23 maf and, if necessary, successively evaluate releases of 8.0 maf and 7.5 maf. The
initial Water Year release shall be the first release evaluated that is projected to maintain a
minimum Lake Powell elevation of 3,510 feet throughout the Water Year.
2. Beginning in October, and continuing each month through April, if the projected Lake
Powell elevation is less than 3,510 feet, adjust Lake Powell releases downward as needed to
no less than 6.0 maf, such that when combined with additional releases from the CRSP
Upper Initial Units, a minimum of 3,510 feet is maintained through March of the following
Water Year.
3. Should Lake Powell be projected to reach elevations below 3,500 feet, Reclamation shall
consider and consult as described in Section 5.1.D on additional actions that may be
necessary.
4. Beginning in October, and continuing each month through April, if the projected Lake
Powell elevation at the end of the Water Year is greater than 3,565 feet, adjust releases
upward, such that half the difference in volume from the projected September 30 Lake
Powell storage at elevation 3,565 feet is added to the release.
B. Mid-Elevation Range
1. In Water Years when the projected October 1 Lake Powell elevation is below 3,565 feet and
at or above 3,540 feet, the initial Water Year release will be determined by performing an
incremental modeling approach using Exhibit Runs. Reclamation shall first evaluate a Water
Year release of 8.0 maf and, if necessary, shall successively evaluate releases of 7.5 maf and
7.0 maf. The initial Water Year release shall be the first release evaluated that is projected to
maintain a minimum Lake Powell elevation of 3,510 feet throughout the Water Year.
2. Beginning in October, and continuing each month through April, if the projected Lake
Powell elevation is less than 3,510 feet, adjust releases downward as needed to no less than
6.0 maf, such that when combined with additional releases from the CRSP Upper Initial
Units, a minimum of 3,510 feet is maintained through March of the following Water Year.
3. Should Lake Powell be projected to reach elevations below 3,500 feet, Reclamation shall
consider and consult as described in Section 5.1.D on additional actions that may be
necessary.
4. Beginning in October, and continuing each month through April, if the projected Lake
Powell elevation at the end of the Water Year is greater than 3,565 feet, adjust the Lake
Powell releases upward, such that half the difference in volume from the projected
Operating Guidelines – Colorado River Guidelines for 5
Coordinated Operations of Lake Powell and Lake Mead
Operating Years 2027 and 2028
August 2026
September 30 Lake Powell storage at elevation 3,565 is added to the release, up to 8.23 maf
or greater.
C. Low Elevation Infrastructure Protection Range
1. In Water Years when the projected October 1 Lake Powell elevation is below 3,540 feet, the
initial Water Year release will be determined by performing a modeling approach using an
Exhibit Run. Reclamation shall first assume a release of 7.0 maf. If Lake Powell is projected
to remain above 3,510 feet during the Water Year, begin the year with an initial release of 7.0
maf if conditions allow and while preserving the flexibility to make reductions under Section
5.1.C.1.a and proceed as follows:
a. Beginning in October, and continuing each month through April, if the projected
Lake Powell elevation is less than 3,510 feet, adjust Lake Powell releases downward
as needed to no less than 6.0 maf, such that when combined with additional releases
from the CRSP Upper Initial Units, a minimum of 3,510 feet is maintained through
March of the following Water Year.
b. Beginning in October, and continuing each month through April, if the projected
Lake Powell elevation at the end of the Water Year is greater than 3,565 feet, adjust
releases upward, such that half the difference in volume from the projected
September 30 Lake Powell storage at elevation 3,565 feet is added to the release.
2. If the Exhibit Run of the August 24-Month Study assuming a release of 7.0 maf (from
Section 5.1.C.1) results in Lake Powell elevation projected to decline below 3,510 feet at any
time during the Water Year, defer the determination of the Water Year release until April
and proceed as follows in Table 1 below.
Table 1
Low Elevation Infrastructure Protection Range Determination Table
Steps Reclamation will Follow to Determine Water Year Release in the Low Elevation
Infrastructure Protection Range for 2027–2028 Operating Guidelines
(when Lake Powell elevation is less than 3,510 feet in the August 24-Month Study Exhibit Run)
Aug State that the expected Water Year release will be between 6.0 and 7.0 maf
Determine monthly release pattern October-April that results in maintaining a minimum target
elevation of 3,510 feet in March of the following year
- Perform at least 2 “official” August 24-Month Studies
o Runs assume a Water Year release of 6.0 maf and 7.0 maf
o All runs include the same release pattern Oct-Apr that maintains a minimum
target elevation of 3,510 feet in March of the following year
Sept-
Dec
Perform the same 2 “official” 24-Month Studies each month as described above (may include
adjustments to the October-April monthly release pattern if needed to maintain a target of 3,510
feet)
Jan-
Mar
Continue potential adjustment of Lake Powell monthly releases per above but begin including
assumptions regarding use of the CRSP Upper Initial Units for May of the current year through
April of the following year, into the 6.0 maf run only, as appropriate
6 Operating Guidelines – Colorado River Guidelines for
Coordinated Operations of Lake Powell and Lake Mead
Operating Years 2027 and 2028
August 2026
Steps Reclamation will Follow to Determine Water Year Release in the Low Elevation
Infrastructure Protection Range for 2027–2028 Operating Guidelines
(when Lake Powell elevation is less than 3,510 feet in the August 24-Month Study Exhibit Run)
Apr Determine Water Year release according to the following steps:
1. Evaluate the projected Lake Powell elevation in March of the following year assuming a
7.0 maf release. For the purpose of Water Year 2027 and 2028 only, this will be
considered as the baseline for determining whether releases should be less than 7.0 maf,
and additional releases from CRSP Upper Initial Units should be considered.
If the March projected elevation is > 3,510 feet,
o Set the Water Year release to 7.0 maf
o No releases from the CRSP Upper Initial Units will be made for infrastructure
protection purposes
2. If the March projected elevation is 2.0 maf; or
b. if any Basin State believes there is inequity between the volume available for
release from the CRSP Upper Initial Units and the Lake Powell release reductions,
it may request consultation; or
c. if a Lake Powell release of 2.0 maf; or
if any Basin State believes there is inequity between the volume available for release from
the CRSP Upper Initial Units and the Lake Powell release reductions, it may request
consultation; or
if a Lake Powell release of < 6.0 maf is required to protect 3,500 feet in March of the
following year; or
if the Lake Powell elevation at the end of the water year is projected to be greater than
3,565 feet; or
5. The Secretary shall consult with the Basin States if Lake Powell is projected to reach an
elevation of above 3,665 feet during Water Years 2027 or 2028, to determine to what extent
releases above 8.23 maf, including the potential for releases consistent with Section 602(a)
storage requirement contained in the Colorado River Basin Project Act.
6. The Secretary shall consult with the Lower Division States in the event of any of the
following conditions:
Should the Most Probable projection of any 24-Month Study show Lake Mead falling
below 1,010 feet at any time in the subsequent 12-month period, the Secretary shall
with the Basin States and Basin Tribes, and other affected parties as appropriate, to
consider potential actions throughout the Basin to respond to and address
hydrologic and operational conditions.
Should the Most Probable forecast indicate a likelihood of achieving Lake Mead
elevation 1,125 feet or above during 2027 or 2028, the Secretary will consult with the
Lower Division States regarding the potential to increase apportionments.
7. Reclamation will coordinate and consult throughout the 2027–2028 Operating Guidelines
with Basin Tribes and Mexico pursuant to the circumstances detailed in this section.
C. Accounting
For Operating Years 2027–2028, Reclamation will continue to account for and verify Lower
Division States water use, including reductions and ICS activity through the Lower Colorado River
Water Accounting and Water Use Report.
D. Operations During the Effective Period
For Operating Years 2027–2028, the Secretary will base annual determinations regarding the
operations of Lake Powell and Lake Mead on these 2027–2028 Operating Guidelines unless further
extraordinary circumstances arise. As identified in Section 10.7 of the ROD, such circumstances
could include operations that are prudent or necessary for safety of dams, public health and safety,
other emergency situations, or other unanticipated or unforeseen activities arising from actual
operating experience.
Operating Guidelines – Colorado River Guidelines for 15
Coordinated Operations of Lake Powell and Lake Mead
Operating Years 2027 and 2028
August 2026
Beginning no later than October 1, 2027, the Secretary shall initiate the process to determine the
next set of guidelines as described in Section 10.5 of the ROD. The Secretary shall consult with the
Basin States and Basin Tribes, and other affected parties as appropriate, during this process.
5.8 Authority and Operations for Operating Years 2027–2028
The provisions of Section 10.11 of the ROD apply to these 2027–2028 Operating Guidelines.
5.9 Implementing and Parallel Agreements
These 2027–2028 Operating Guidelines contemplate actions that rely upon necessary implementing
and parallel agreements as referenced herein. Agreements are anticipated to be executed within a
sufficient timeframe to support implementation of 2027 and 2028 operations, including agreements
to which the United States is a party or an approver, and non-federal agreements. Namely, the
Secretary acknowledges that portions of Sections 5.3 and 5.4, as described, will be implemented
only when a Lower Basin implementing agreement takes effect as well as the drought operations at
the CRSP Upper Initial Units pursuant to the process outlined in an agreement concerning drought
operations at these facilities and as referenced in Section 5.2. The absence of such agreements shall
not impair, delay, or otherwise limit the Secretary’s authority to act and any Basin State or Basin
Tribe or Contractor shall retain any rights as set forth in Section 10.11 of the ROD.
16 Operating Guidelines – Colorado River Guidelines for
Coordinated Operations of Lake Powell and Lake Mead
Operating Years 2027 and 2028
August 2026
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