Appendix F – South Metro
Water Supply Authority
Concept for Discussion
South Platte Basin Implementation Plan
South Platte Basin Roundtable/Metro Basin
Roundtable
April 17, 2015

 APPENDIX F – SMWSA CONCEPT FOR DISCUSSION

Below is a collaborative conjunctive use multi-purpose project concept based on a potential Flaming
Gorge Pipeline project and conjunctive use with the Denver Basin Aquifer System. This is an example
that provides something for others to react to, and should be evaluated and built upon through the
Basin Roundtables and planning process. Although this "straw-man" is conceptualized around a
Flaming Gorge Pipeline project, many of the concepts could extend to other new water supply
projects. Section 1 describes the concept and Section 2 provides additional summary information on
the Denver Basin Aquifer and the opportunity to use it as a drought reserve.

Section 1: Conjunctive Use Multi-Purpose Project Concept
This description outlines potential elements of a conjunctive use multi-purpose new
supply project.1 This conceptual "straw-man" project is prepared to test and
demonstrate the ability of a project to meet stakeholders' concerns including
environmental, recreational, and water users concerns. It could be centered around a
number of potential projects such as the Green Mountain/Blue River Pumpback, Yampa
Pumpback, Blue Mesa Pumpback, or Flaming Gorge Pipeline with conjunctive use of the
Denver Basin Aquifer and interruptible supply agreements in the South Platte Basin.
This description is intended to focus discussions related to new supply development and
provide a framework for analysis and feedback. It is anticipated that the substance of a
specific concept will change and additional details will be developed over time. This
description can help inform recent IBCC and roundtable discussions and ultimately be
included as part of a roundtable-to-roundtable engagement within Section 4.8 Interbasin
Projects and Methods of the South Platte and Metro's Basin Implementation Plan (BIP).
As a starting point, the following elements of a multi-purpose project are described:
Project Description
o Water Source
o Risk Management and Variability
o Headwater Enhancement
Overall Benefits of the Project
Challenges/Issues/Costs of the Project
Potential Area of Origin Compensation
Statewide Policy Objectives
Financing and Governance

1

Several sources were used to compile this memo including: Prior “Basin of Origin” bills (between 1988 and 2000 the
Colorado General Assembly looked at 16 out of basin transfer proposals of which some were
compensation/mitigation approaches, some focused on additional requirements before diversion, and two required
voter authorization); Reports from the Colorado Water Resources Research Institute on area-of-origin
compensation; The South Metro Water Supply Study (February, 2004); SWSI Phase II Section 5 (Addressing the
Water Supply Gap); Discussions between the Yampa/White Roundtable and South Platte Roundtable on the
proposed Yampa Pumpback Project; SWSI 2010 and the December 15, 2010 IBCC Report; and Basin Roundtable
Project Exploration Committee (a.k.a Flaming Gorge Task Force) Phase 1 Report.

 These elements are outlined in general terms below. Additional details such as yield
(average, firm, and dry), water rights, infrastructure, cost estimates, mitigation, funding,
etc. will need to be further developed with additional stakeholder input. In addition, a
section at the end further describes the Denver Basin Aquifers as an opportunity for a
risk and drought reserve. Including the Denver Basin aquifers as an asset to provide
supplies when no project yield is available can be an important element in risk
management of Colorado’s Compact Entitlement.
The specific elements of projects, mutual commitments, and milestones of progress
would be the subject of an exploratory investigation and ultimately negotiation among
multiple parties. It is anticipated that should a package of projects emerge as feasible
and desirable, commitments would be made in tandem. As potential end users made
certain commitments, potential opposers would also make commitments helping to
ensure that a new west slope supply project will, in fact, be a fundamental part of "filling
the gap" package. This approach needs to provide confidence that Colorado River water
supply development will be available for the east slope, thereby providing an alternative
to agricultural to urban water transfers.
Elements of a Conjunctive Use Multi-Purpose Project
Project Description:
For discussion purposes, this concept is centered around the Flaming Gorge Pipeline
Project. It has been initially screened through a sub-committee, and also been
investigated by a variety of agencies over several decades. Much information is already
available, reducing the need to gather new data. A group has also begun to coordinate
with the US Bureau of Reclamation to review hydrologic analyses and model projections
of potential yields and operations. This Conjunctive Use Flaming Gorge Pipeline MultiPurpose Project contains several major components. The components include:
1. Flaming Gorge Pipeline: The source of water for the project would be a contract
with the Bureau of Reclamation (BOR) for an annual average yield from Flaming
Gorge Reservoir of 150,000 + acre feet. The water would be diverted from the
Green River through a pumpstation at Flaming Gorge Reservoir. A 400-mile 7-8
foot diameter pipeline would convey this water to the Front Range. The most
likely pipeline route would travel along Interstate 80 through Wyoming to
Laramie, and then south along the Colorado Front-Range. The pipeline would
convey supplies to municipalities in Wyoming and on the Colorado Front-Range
in the South Platte and Arkansas Basin.
The overall capacity of the pipeline should include consideration of several
opportunities beyond that required to convey 150,000 acre feet for several
reasons:
a) Cost/benefit review of moving additional water under certain hydrologic
conditions;
b) Potential as a water management tool, capable of bringing water to the
Front Range as an alternative diversion method to depletion in the

 APPENDIX F – SMWSA CONCEPT FOR DISCUSSION

headwaters of the Colorado River. That might position the project as a
riparian restoration project as well as a new supply project, and;
c) In a fashion similar to the transaction between the Southern Nevada
Water Authority and the Arizona Water Banking Authority2, Colorado
could perhaps develop underground storage of other Upper Basin state’s
compact entitlement as a component of risk management and oversize
the conveyance system for that type of possibility.
2. Risk Management and Project Variability Strategies: In 2010, the IBCC
agreed that the development of new water supplies from the Colorado River
"should be accompanied by a risk management program that ... is integrated with
'triggers' and utilizes other dry cycle sources to fill the gaps when the new supply
water is unavailable." Because populations and economies would be dependent
upon this new water supply from Flaming Gorge, mechanisms would need to be
in place to deal with periodic supply shortages. The IBCC recommended a twopronged approach: 1) "to put in place an 'early warning' system that shuts down,
curtails, or offsets [the new supply project] in advance of a Compact curtailment.
The early warning system would be based on hydrologic triggers;" and 2) "the
water supply triggers would be coupled with an emergency water bank or other
operational scenario that would meet the critical needs of all of Colorado's post1922 users if a curtailment cannot be avoided."
a) Triggers and Dry-Period Sources
i. Triggers: Hydrologic triggers could include Lake Powell levels, overall
storage in the CRSP system, the 10-year rolling average of upper basin
deliveries, or some combination. The IBCC notes, "additional work is
needed to define which triggers would be used ... and how they would
work."
ii. Sources to meet shortages: Regardless of the triggers, the end users of
the project would need supplies that can be used conjunctively with the
Flaming Gorge supplies. This is not a new concept for many front-range
utilities. For example, the South Metro region recently secured a
permanent, but variable, renewable water supply through the WISE
Project. In years when no delivery occurs, they will continue to rely on
Denver Basin well pumping. Similar strategies could be used to deal with
the variability of a Flaming Gorge project and associated triggers.
1) Denver Basin Aquifer Conjunctive Use and ASR: Diversion of
water from Flaming Gorge could be tied to levels in Lake Powell or
other triggers to avoid compact curtailment. This strategy involves
diverting a larger amount of water in wet years for front range
groundwater users to store water in Denver Basin aquifers through an
ASR (aquifer storage and recovery) program to assure sustained
productivity. In dry periods when supplies are not available from

2

http://www.snwa.com/ws/future_banking_arizona.html

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 Flaming Gorge, municipalities with access to the Denver Basin Aquifer
would meet their water needs from local groundwater supplies.
Through ASR and changing the use of the Denver Basin Aquifer from
a base supply to a drought supply, the aquifers can be managed to
assure long-term reliability. Additional information on this concept is
included in the section below "Denver Basin Aquifers - Our Best
Opportunity for a Risk and Drought Reserve."
2) East Slope Temporary Ag. Transfers: Interruptible supply
agreements with east slope agricultural water rights could also provide
a back up water supply during dry-cycles. An alternative agricultural
transfer project could build on the FLEX Market concept and include
the temporary transfer of agricultural water rights similar to substitute
water supply plans (CRS 37-92-308) and interruptible supply contracts
(CRS 37-92-309). It could also include supporting the development of
additional storage and infrastructure in the Arkansas and South Platte
river basins to facilitate the temporary transfer of agricultural water
rights to Front Range municipalities.
b) Emergency West Slope Water Bank for pre-1922 Water Rights: The
triggers and dry-sources above would be coupled with an emergency west
slope water bank to help ensure the critical needs of all of Colorado's post1922 users would be met if a curtailment cannot be avoided. As described
by the IBCC, "this water bank would utilize the consumptive uses of
Colorado’s pre-1922 water rights on a willing buyer/lessee–willing
seller/lessor basis. The bank could be combined with or include the use of
the capacity of existing reservoirs such as Blue Mesa. The concept of such a
bank is the effort of a current study by West Slope and Front Range water
users."
3. Headwater Enhancements: This multi-purpose project could include nonconsumptive environmental and recreational benefits to the headwaters of the
Colorado River system. This could involve exchanges with current transbasin
diverters for additional flows in Colorado headwaters and could utilize specifics
from the Grand County Streamflow Management Plan and the Colorado
Roundtable's Nonconsumptive Needs Assessment. This concept would need to
be explored with current transbasin diverters.
Potential Area of Origin Compensation
Through the IBCC and Basin Roundtable process, west slope representatives have said
that they would need several commitments before being supportive of this type of multipurpose project. These included:
Continued viability of the west slope’s regional economy
Certainty – ensure an increment of water is available for development in each
west slope basin
Front-Range commitment to conservation and reuse
Environmental mitigation and enhancement

 APPENDIX F – SMWSA CONCEPT FOR DISCUSSION

These elements could be met through a combination of water related benefits for the
west slope sub-basins and/or socio-economic compensation.
Water related benefits for west slope sub-basins
Even though the diversion may not occur directly in each basin, different elements could
be included to distribute statewide benefits, ensure continued viability of the west slope’s
economy, and provide certainty.
Yampa/White
o Infrastructure for irrigation of additional acres in Moffat County (20,00030,000 acres of land could be irrigated)
o Water for future municipal development particularly in Steamboat and
Craig. Upper basin interests have previously secured 60,000 a.f.
subordinations to protect future uses and they have indicated they would
want a similar subordination or component of the project.
Colorado
o Exchanges with current transbasin diverters for additional flows in
Colorado headwaters (Grand County Streamflow Management Plan;
Blue River Flow enhancement)
o Maintain Dillon Reservoir Levels
o Wolcott Reservoir for future west slope water demands and additional
yield to the Grand Valley
Gunnison
o Agricultural firming projects in the upper basin (Tomichi Creek, etc.) to
help with current agricultural shortages
o Water quality improvements in the Uncompahgre River and Lower
Gunnison (selenium)
Southwest
o Financial assistance and support developing their identified projects and
processes
Socio-Economic Compensation (Development Fund)
Generally, the most useful form of compensation would be unrestricted monetary
compensation to be used by the west slope to compensate unprotected parties and for
whatever other purposes its citizenry prefers. Rather than committing to specific
projects, a development fund could be established. The money from this fund would be
available to provide assistance for future water needs (see above) or other economic
development on the west slope.
The fund could be financed in a number of ways as further described below. These
financing mechanisms could also be accompanied by a charge placed on users of the
multi-purpose project water (perhaps indexed to the current price of water in the South
Platte Basin). The fund could be held by the state (CWCB) or potentially by west slope

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 conservation districts or counties. Expenditures would be made against the fund for
projects proposed by municipalities, conservancy districts, and other public entities on
the west slope. Appropriate expenditures could be solely water related3, or appropriate
expenditures could include other economic development projects.
An alternative, predicated on the pipeline becoming a riparian restoration management
tool, would be application of funds in two ways: First, for compensatory projects in the
Colorado River basin, and; Secondly, to fund the increased cost associated with
alternative diversions of transbasin sources. The first compensation is an early
milestone in the process, bringing environmental benefits to the headwaters on the way
to project permitting. The second form of compensation, where water providers with low
cost, gravity delivery systems accept alternative deliveries, may also be necessary to
have the required support for the project.
The major Front Range water providers have invested enormous capital in transbasin
diversion structures. That investment yields lower cost water supply for their customers.
The offset to the increased cost of alternative delivery might take the form of cash or
delivery of more water than could have been historically diverted. The combination of a
hold harmless economic approach, coupled with compensatory water stored
underground, might be sufficient to garner enthusiastic support for the project.
Financing
In addition to the configuration of the project, the other major outstanding questions
relate to how the project would be financed, managed and implemented. Four models
could be further explored:
1. Federal/State partnership similar to the Central Arizona Project
2. State water project such as the California State Water Project
3. State/Local partnership where the state facilitates the project, but end users
finance and manage it
4. Local/Local partnership similar to WISE and Chatfield as water examples and E470 as a transportation example
5.
Public/Private partnership similar to transportation projects (Hwy 36) 4
Under any funding model it is most appropriate for use rates and tap fees to be the
primary base of funding. This connects the customers with what they are paying for.
However, the conceptual package of projects described above will likely also include
broader public benefits that are more dispersed than those that accrue to the specific
end users of the transmountain diversion project. Therefore broader public funding

3

New storage projects, repair and rehabilitation of existing water storage and delivery facilities, municipal water
systems, improvement of irrigation systems, on-farm improvements resulting in greater efficiency, water based
recreation facilities, securing in-stream flows, and other water-related projects.

4

Western Resource Advocates published a report, “Economic and Financial Impacts of the Proposed Flaming Gorge
Pipeline” by Honey Creek Resources, Inc. September 6, 2011. The report compares public and private finance
approaches. The report does not consider a public-private partnership.

 APPENDIX F – SMWSA CONCEPT FOR DISCUSSION

mechanisms should also be explored. Two funding mechanisms, a "water" mill levy and
a Container Fee, are briefly described as examples of how some of the broader public
components of this multi-purpose concept could be funded. These funding mechanisms
are described in order to demonstrate that broader funding mechanisms could be
available if a package of projects is generally agreed to. SMWSA is not advocating for
nor necessarily supportive of either method; rather, they are described as possibilities in
order to spark further discussion.
Finance - "Water" Mill Levy
A two (2) mill property tax on the nine largest front-range counties will generate about
$107 million/year. (Adams $9m; Arapahoe $15.2m; Boulder $11m; Denver $20.2m;
Douglas $8.6; El Paso $11.6; Jefferson $14.4; Larimer $7.6m; Weld $9m). As a point of
comparison most fire districts collect an 8+ mill. An additional two mills might incentivize
linking land-use planning and water supply planning in the “Big 9.”
One (1) mill, or about $54 million/year could help provide water and economic
development for the west slope. This could be done through a “Development Fund” as
described above or it could be divided between the west slope counties.
The other (1) mill or about $54 million/year could help fund construction and operation
and maintenance of the multi-purpose project, including headwaters exchanges.
As a point of comparison, the 2009 General Fund Revenue for the following counties Gunnison $10.388M; Montrose $10.1M; Logan $4.5M; Garfield $28M; Otero $1M
(estimate) - approximate what this fund could generate.
Finance – The Container Fee Ballot Initiative of 2010
In 2010, two citizens filed a Ballot Initiative seeking a fee on beverage containers sold in
Colorado. Unofficially captioned “Container Fee to Fund Water Preservation and
Protection” by legislative staff for tracking purposes, the initiative was heard by the Ballot
Title Setting Board at its hearing April 21, 2010. The minutes of that hearing document
that the legislative staff determined such a fee would generate approximately $100
Million per year in revenue.
The Title Board’s opinion setting the initiative title for the ballot was appealed to the
Colorado Supreme Court. The basis of the appeal was that by naming the Basin
Roundtables specifically (the funds were to be allocated in part based on roundtable
approval of grants), the initiative was not a single subject. The Supreme Court granted
the appeal. Given the timeline of the Colorado Water Plan, consideration could be given
to a similar ballot initiative in November, 2015. The funds generated could go
immediately to riparian restoration projects with future use for compensatory offsets. In
the long run, the funding stream would support project development, permitting and
eventually debt service.
Overall Benefits of the Project
Front-range municipalities get an increment of high quality reusable water.

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 New water supply development minimizes loss of irrigate acres in South Platte
and Arkansas Basins. Transfers of east slope agricultural would no longer be the
dominant strategy for meeting front-range water needs. East slope agriculture
could participate in the project and receive additional yields (either directly or
through “second use” of fully consumable return flows).
Acceptable water quality that does not require advanced water treatment and
may be used to blend with lower quality South Platte supplies.
Allows development of new water supplies and utilization of Colorado’s compact
entitlements while protecting recreation, environmental flows, and future
economic development on the west slope.
Depending upon the location of the diversion it could diversify the state’s M&I
water supplies. The CRWAS indicates that climate change impacts are less
severe in northern basins such as the Green River. Adding a more northerly
water supply, and a basin other than the Colorado mainstem, would diversify the
state’s M&I water supply and could mitigate potential risks from climate change.
Challenge/Issues/Costs of the Project
Potential endangered fish and depletion issues downstream of the diversion
would need to be analyzed.
May require enlargement or construction of additional storage in the South Platte
or Arkansas basins. This storage could be surface water storage or underground
storage.
Additional cost analysis of the various component of the package of projects will
be needed. This will include, but not be limited to, the cost of equipping existing
wells for ASR, implementing a regional ASR program, and comparing the costs
of ASR with above ground storage.
Complexities of water right administration in the event of a compact call.
Although the Colorado Compact recognizes the right of one state to move water
through another state, there will likely be a need for an agreement with Wyoming,
perhaps Utah and perhaps between all four Upper Basin States.
Statewide Policy Objectives
Safe reliable drinking water supply for all Colorado citizens
Conservation – the project can include elements to require or encourage different
conservation measures
Reuse – the project can be configured for maximum utilization of fully
consumable water either through M&I reuse or “second use” by east slope
agriculture
Maximum utilization of the state’s Colorado River Compact entitlements
Environmental and recreational preservation and enhancements

 APPENDIX F – SMWSA CONCEPT FOR DISCUSSION

Section 2: Denver Basin Aquifers - Our best opportunity for a
risk and drought reserve
Existing Groundwater Conditions
Denver Basin Aquifers (Laramie-Fox-Hills, Arapahoe, Denver, and Dawson) comprise a
huge groundwater storage reserve immediately beneath much of the central Front
Range. The aquifers extend from roughly Greeley on the north to Colorado Springs on
the south, the Foothills on the west, and the eastern boundaries of Adams, Arapahoe
and Douglas counties on the east, comprising around 6700 square miles. The combined
aquifers hold over 450 million acre-feet of water, and over 250 million of that may be
economically pumped. Wells have been drilled and can produce up to as much as 1000
gallons per minute (gpm).
Historically, the South Metro area has relied almost exclusively on this non-tributary,
nonrenewable groundwater supply. Estimates are that approximately 38MAF of
recoverable water exists under the South Metro area. However, recent work reinforces
previous observation regarding steady rates of aquifer declines. The 2013 Douglas
County Rural Water Supply System Feasibility Study included a comparison of USGS
groundwater modeling, measurements in active wells, and CDWR investigation of
Denver Basin aquifer levels. The USGS modeling predicts a -1 to -5 feet per year
average annual groundwater level decline and the CDWR investigation predicts a -5 to 13 feet per year decline. South Metro water providers continue to experience declines in
aquifer levels and the cascading reduction in well yields.
Given the historic, current, and predicted declines in aquifer levels, the volume of Denver
Basin Aquifer production will have a future economic limit which is likely to fall short of
urban demands. Numerous studies between 2004 and 2013 all suggest that costs
associated with continued reliance on non-tributary, nonrenewable groundwater are
expected to be comparable or higher than costs for developing a regional renewable
water supply system, thereby providing appropriate incentive to import renewable
supplies that can be used conjunctively with the Denver Basin Aquifer.
Future Scenarios for Denver Basin Aquifer Groundwater Use
There are two likely scenarios for South Metro entities involving future use of Denver
Basin groundwater: the first scenario is the status quo use of non-renewable
groundwater supplies at increasing cost due to declining well production capacities. For
the reasons discussed above, this scenario is generally unacceptable as it is an
expensive and non-sustainable model.
A second – preferable - scenario is a large-scale conjunctive use plan involving
development of renewable supplies and implementation of a robust wet-year aquifer
recharge program in which reliance on Denver Basin Aquifer groundwater is primarily as
a drought supply. While efforts to increase renewable supplies are currently underway,
formalization of a significant conjunctive use plan involving a new transbasin diversion is
urgently needed.

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 Such a conjunctive use plan can operate largely through existing and planned
infrastructure. Water providers in the southern metro region rely on multiple wells for
their water supply, and have constructed infrastructure connecting them with community
water distribution systems. There are around 150 municipal supply wells in Douglas
County alone. Recently, the WISE project included plans to link these service areas over
the majority of the region. This will provide a water link both internally and to sources of
renewable water from outside the region. The opportunity to recharge the Denver Basin
Aquifers and a large-scale conjunctive use project is here.
Current annual well production in the area exceeds 40,000 afy (acre feet per year), which
corresponds to an average rate of 35 mgd. Assuming the majority of wellfields are sized
to meet summer demands and typically triple the average rate, there may be over 100
mgd of peaking capacity available in off-peak periods. With proper equipping and
treatment capacity, a significant volume of renewable water could be supplied to the
Denver Basin in wet periods for use during droughts.
A rough approximation of rates of flow into the aquifers can begin with the assumption
that typical provider demands in the summer are sized for triple that year round rate, or
105 mgd in the aggregate. This leaves an average of up to 70 mgd in off-peak months.
If off-peak demands are met with imported water making wells available for recharge,
this rate could be returned to the aquifers for a total ranging between 25,000 and 45,000
af per year. Specific rates and durations of flows would be examined in detail during the
feasibility review process. Generally, the initial projections affirm the potential viability of
this concept.
The potential of a conjunctive use approach to integrating local non-tributary
groundwater supplies and storage with interruptible surface water supplies from the
South Platte and West Slope drainage basins was outlined in the State of Colorado’s
Metro Water Supply Investigation, Final Report (Colorado Water Conservation Board,
1998). Subsequently, the South Metro Water Supply Study (prepared for the South
Metro Water Supply Study Board in February, 2004) carried the concept further through
a joint effort between the Douglas County Water Resources Authority, Denver Water,
and the Colorado River Conservation District.
Conjunctive Use is characterized as “The coordinated use of surface and groundwater
resources and facilities to produce a larger, more reliable and cost effective combined
water supply that could be generated from either source alone.” (SMWSSB, page 1-12)
Centennial Water and Sanitation District in Douglas County has operated a conjunctive
use plan since the early 1980’s and an aquifer storage and recovery project with Denver
Basin deep wells since 1992. The technology and recharge operation have met no
significant impediments after over 20 years of and over 14,000 acre-feet of treated
potable water back into the aquifers. South Metro WISE participants are currently
evaluating the feasibility of expanding this operation with future WISE deliveries.

 APPENDIX F – SMWSA CONCEPT FOR DISCUSSION

To date, many water suppliers along the Front Range who rely on deep bedrock aquifers
have not been able to capture wet year supplies. With the addition of WISE Project
infrastructure and Parker’s Rueter-Hess Reservoir, the South Metro Area will soon have
necessary infrastructure for a large-scale conjunctive use program. A large-scale
conjunctive use plan could bring renewable surface water into the South Metro Region
by utilizing:
Interruptible raw water deliveries from existing transbasin diversion systems,
Flaming Gorge, or another new transbasin project.
Deliveries only in wet periods of low-risk hydrologic and administrative
conditions.
Distribution to existing deep aquifer wells equipped for recharge.
Dry period use of reliable, drought-proof deep aquifer production to provide water
when surface yields are not available.
No increase of risk to yields controlled by partner entities.
Protecting the integrity of the Colorado River Compact under a working
cooperative operation.
This concept has been investigated and described for over 15 years (if not longer) by key
parties who would potentially be involved and is now worthy of serious consideration by
the IBCC and the CWCB through Colorado's Water Plan. This concept is recommended
for further investigation and a role as a practical and viable means to manage Colorado’s
statewide water resources. It should be vigorously pursued in subsequent stages of the
Colorado Water Plan.

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