HomeMy Public PortalAboutPKT-CC-2020-12-16DECEMBER 16, 2020
SPECIAL CITY COUNCIL MEETING 12:00 P.M.
Consistent with provisions of the Utah Open and Public Meetings Act, Utah Code
Ann. § 54 -2 -207(4), the Moab City Council Chair has issued written determinations
supporting the decision to convene electronic meetings of the Council without a
physical anchor location. Due to the health and safety risks related to the ongoing
COVID -19 pandemic and considering public health orders limiting in -person
gatherings, the Moab City Council will continue to hold meetings by electronic
means. The public is invited and encouraged to view and participate in the
Council ’s electronic meetings by viewing the City ’s YouTube
channel: https://www.youtube.com/MoabCityGovernment
Special City Council Meeting -12:00 PM
ag -cc -2020 -12 -16 special meeting signed.pdf
Confirmation of Mayoral Appointment of John Knight to the
Moab City Planning Commission with a term ending December
31, 2024
agenda summary sheet -confirmation of appointment of john knight
to city planning commission.pdf
john knight letter of interest.pdf
Confirmation of Mayoral Reappointment of Marianne Becnel to
the Moab City Planning Commission with a term ending
December 31, 2024
agenda summary sheet - re -appointment of marianne becnel to city
planning commission.pdf
Confirmation of Mayoral Reappointment of Becky Wells to the
Moab City Planning Commission with a term ending December
31, 2024
agenda summary sheet - re -appointment of becky wells to city
planning commission.pdf
Confirmation of Removing Brian Ballard from the Moab City
Planning Commission
bb agenda summary sheet.pdf
Confirmation of Mayoral Reappointment of Jessica O'Leary to
the Moab City Planning Commission for a fill -in term ending
December 31, 2021
agenda summary sheet - re -appointment of jessica oleary to city
planning commission.pdf
Confirmation of Mayoral Reappointment of Chace Gholson to
the Moab Mosquito Abatement District Board for a term ending
December 31, 2024
agenda summary sheet -re -appointment of chace gholson to
mosquito abatement.pdf
Water Resources Discussion
water resources status worksession agenda summary.pdf
reviewofkolmhsaforcouncil.pdf
Moving to a water -restricted future -Councilmember Duncan
councilpresentationfuturewaterreve.9dec2020.pdf
Adjournment
Special Accommodations:
In compliance with the Americans with Disabilities Act, individuals needing special
accommodations during this meeting should notify the Recorder ’s Office at 217 East Center
Street, Moab, Utah 84532; or phone (435) 259 -5121 at least three (3) working days prior to
the meeting.
Check our website for updates at: www.moabcity.org
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DECEMBER 16, 2020SPECIAL CITY COUNCIL MEETING 12:00 P.M.Consistent with provisions of the Utah Open and Public Meetings Act, Utah Code Ann. § 54 -2 -207(4), the Moab City Council Chair has issued written determinations supporting the decision to convene electronic meetings of the Council without a physical anchor location. Due to the health and safety risks related to the ongoing COVID -19 pandemic and considering public health orders limiting in -person gatherings, the Moab City Council will continue to hold meetings by electronic means. The public is invited and encouraged to view and participate in the Council ’s electronic meetings by viewing the City ’s YouTube channel: https://www.youtube.com/MoabCityGovernmentSpecial City Council Meeting -12:00 PMag-cc -2020 -12 -16 special meeting signed.pdfConfirmation of Mayoral Appointment of John Knight to the Moab City Planning Commission with a term ending December 31, 2024 agenda summary sheet -confirmation of appointment of john knight to city planning commission.pdfjohn knight letter of interest.pdfConfirmation of Mayoral Reappointment of Marianne Becnel to the Moab City Planning Commission with a term ending December 31, 2024agenda summary sheet - re -appointment of marianne becnel to city planning commission.pdfConfirmation of Mayoral Reappointment of Becky Wells to the Moab City Planning Commission with a term ending December 31, 2024
agenda summary sheet - re -appointment of becky wells to city
planning commission.pdf
Confirmation of Removing Brian Ballard from the Moab City
Planning Commission
bb agenda summary sheet.pdf
Confirmation of Mayoral Reappointment of Jessica O'Leary to
the Moab City Planning Commission for a fill -in term ending
December 31, 2021
agenda summary sheet - re -appointment of jessica oleary to city
planning commission.pdf
Confirmation of Mayoral Reappointment of Chace Gholson to
the Moab Mosquito Abatement District Board for a term ending
December 31, 2024
agenda summary sheet -re -appointment of chace gholson to
mosquito abatement.pdf
Water Resources Discussion
water resources status worksession agenda summary.pdf
reviewofkolmhsaforcouncil.pdf
Moving to a water -restricted future -Councilmember Duncan
councilpresentationfuturewaterreve.9dec2020.pdf
Adjournment
Special Accommodations:
In compliance with the Americans with Disabilities Act, individuals needing special
accommodations during this meeting should notify the Recorder ’s Office at 217 East Center
Street, Moab, Utah 84532; or phone (435) 259 -5121 at least three (3) working days prior to
the meeting.
Check our website for updates at: www.moabcity.org
1.Documents:2.Documents:3.Documents:4.Documents:
5.
Documents:
6.
Documents:
7.
Documents:
8.
Documents:
9.
Documents:
10.
In compliance with the Americans with Disabilities Act, individuals needing special accommodations during this meeting should
notify the Recorder’s Office at 217 East Center Street, Moab, Utah 84532; or phone (435) 259-5121 at least three (3) working days
prior to the meeting.
217 East Center Street
Moab, Utah 84532-2534
Main Number (435) 259-5121
Fax Number (435) 259-4135
Emily S. Niehaus
Tawny Knuteson-Boyd
Rani Derasary
Mike Duncan
Karen Guzman-
Newton
Kalen Jones
Mayor:
Council:
Memorandum
To: Councilmembers and Media
From: Mayor Emily S. Niehaus
Date: 12/15/2020
Re: Special City Council Meeting
The City of Moab will hold a Special Moab City Council Meeting on Wednesday,
December 16, 2020 at 12:00 p.m. The purpose of this meeting will be:
1. Confirmation of Mayoral Appointment of John Knight to the Moab City Planning
Commission with a term ending December 31, 2024
2. Confirmation of Mayoral Reappointment of Marianne Becnel to the Moab City
Planning Commission with a term ending December 31, 2024
3. Confirmation of Mayoral Reappointment of Becky Wells to the Moab City Planning
Commission with a term ending December 31, 2024
4. Confirmation of Removing Brian Ballard from the Moab City Planning Commission
5. Confirmation of Mayoral Reappointment of Jessica O’Leary to the Moab City
Planning Commission for a fill-in term ending December 31, 2021
6. Confirmation of Mayoral Reappointment of Chace Gholson to the Moab Mosquito
Abatement District Board for a term ending December 31, 2024
7. Water Resources Discussion
8. Moving to a water-restricted future – Councilmember Duncan
Mayor Emily S. Niehaus
Consistent with provisions of the Utah Open and Public Meetings Act, Utah Code Ann. § 54-2-207(4),
the Moab City Council Chair has issued written determinations supporting the decision to convene
electronic meetings of the Council without a physical anchor location. Due to the health and safety
risks related to the ongoing COVID-19 pandemic and considering public health orders limiting in-
person gatherings, Moab City Council will continue to hold meetings by electronic means. The public is
invited and encouraged to view the Council’s electronic meetings by viewing the City’s YouTube
channel: https://www.youtube.com/MoabCityGovernment
DocuSign Envelope ID: 5DEE1D77-7642-4272-AB6D-1A90289ECCA1
Moab City Council Agenda Item Meeting Date: December 16, 2020
Title: Confirmation of Mayoral Appointment to the City Planning Commission
Staff Presenter: n/a
Attachment(s): - Letter of intent
Recommended Motion: I move to confirm the mayoral appointment of John Knight to the City Planning Commission with a term ending December 31, 2024.
Background/Summary: Per Title 2 of the Moab City Code, the Mayor appoints, and the Council confirms the members of the City’s Planning Commission.
Begin forwarded message:
From: John Knight
Subject: CV
Date: December 4, 2020 at 10:49:47 AM MST
To: Emily Niehaus <emily@moabcity.org>
Good morning Emily -
As you are aware, I am excited about the prospect of being on the planning commission for the city. My background
in real estate development, and experience working with rural communities all over the world developing
infrastructure projects, provides a unique perspective to share with the commission.
I look forward to working with you, and members of our community, in making Moab a better place to live and visit.
Attached is my CV for reference.
All the best,
John Knight
Moab City Council Agenda Item Meeting Date: December 16, 2020
Title: Confirmation of Mayoral Re-Appointment to the City Planning Commission
Staff Presenter: n/a
Attachment(s): - Letter of intent
Recommended Motion: I move to confirm the mayoral re-appointment of Marianne Becnel to the City Planning and Zoning Commission. Her term will expire December 31, 2024.
Background/Summary: Per Title 2 of the Moab City Code, the Mayor appoints, and the Council confirms the members of the City’s Planning Commission.
Moab City Council Agenda Item Meeting Date: December 16, 2020
Title: Confirmation of Mayoral Re-Appointment to the City Planning Commission
Staff Presenter: n/a
Attachment(s): n/a
Recommended Motion: I move to confirm the mayoral re-appointment of Becky Wells to the City Planning Commission. Her term will expire December 31, 2024.
Background/Summary: Per Title 2 of the Moab City Code, the Mayor appoints, and the Council confirms the members of the City’s Planning Commission.
1
Moab City Council Agenda Item
Meeting Date: December 16, 2020
Title: An agenda item removing Brian Ballard from the Moab City Planning Commission.
Presenter: Mayor Niehaus
Attachment(s):
Suggested Motion: "I move to remove Brian Ballard from the Moab City Planning
Commission as required by the Moab City Code §2.52.030”
Background/Summary:
Moab City Code §2.52.030 outlines the Moab City Planning Commission. This section states
that the term of office of each member of the Planning Commission shall be for three years.
Planning Commission members must attend a minimum of seventy-five percent of all Planning
Commission meetings held during the course of a calendar year in order to remain a member of
the Planning Commission. This ongoing determination of attendance shall be conducted by
planning department staff and forwarded to the chairperson of the Planning Commission, the
City Manager and Mayor and City Council. Vacancies and/or removals occurring otherwise than
through the expiration of terms shall be filled by appointment by the Mayor with the consent of
City Council. Members may be removed, with or without cause, by a majority vote of City
Council.
Moab City Council Agenda Item Meeting Date: December 16, 2020
Title: Confirmation of Mayoral Re-Appointment to the City Planning Commission
Staff Presenter: n/a
Attachment(s): n/a
Recommended Motion: I move to confirm the mayoral re-appointment of Jessica O’Leary to the City Planning Commission for a fill-in term ending December 31, 2021. She will replace the appointment formerly held by Brian Ballard.
Background/Summary: Per Title 2 of the Moab City Code, the Mayor appoints, and the Council confirms the members of the City’s Planning Commission.
Moab City Council Agenda Item Meeting Date: December 8, 2020
Title: Confirmation of Mayoral Re-Appointment to the Moab Mosquito Abatement District Board
Staff Presenter: Levi Jones, Public Works Director
Attachment(s): - N/A
Recommended Motion: I move to confirm the mayoral re-appointment of Chace Gholson to the Moab Mosquito Abatement District Board. His term will end on December 31, 2024.
Background/Summary: Mosquito District Board appointments are governed by Utah Code sections 17A-1-302, 17A-1-303, and 17A-2-906. The Mayor appoints and the Council confirms the appointments to the Moab Mosquito Abatement District Board.
Moab City Council Agenda Item Meeting Date: December 16, 2020
Title: Water Resources Discussion Worksession
Disposition: Discussion Only
Staff Presenter: Chuck Williams, City Engineer
Attachment(s): - Attachment 1: Water Resources Status presentation
Recommended Motion: None.
Background/Summary: As the City grows the need for continued management of our water resources becomes even more important. Add in the deleterious effects of climate change and the state of our aging infrastructure and the need is intensified even more. Determining water availability and comparing against current and future water needs/use is part of the management that the City and other agencies do. Recent and ongoing studies by the City, State and Federal governments have brought new information to the water resources understanding in the Moab-Spanish Valley. Much of the information is available at the following links: Kolm Phases 1 through 4: https://moabcity.org/DocumentCenter/View/2817 https://moabcity.org/DocumentCenter/View/2815 https://moabcity.org/DocumentCenter/View/2962 https://moabcity.org/DocumentCenter/View/2832 USGS: https://pubs.er.usgs.gov/publication/sir20195062 UDWR presentation: https://www.waterrights.utah.gov/meetinfo/2020/m20201104/20201104_slides.pdf The purpose of this worksession is to inform Council of some of the recent studies, upcoming system investments, and to discuss possible new water conservation practices and policies.
BRIEF REVIEW OF THE KOLM HYDROLOGIC ASSESSMENT
City of Moab Water Conservation and Drought Management Advisory Board
For the last several years the Moab Water Conservation and Drought Management Advisory Board has
been, along with many in the community, looking to understand the water available in Moab. As you
are probably aware, the aquifers in Spanish Valley are complex, and also are intersected by several
administrative boundaries. To this end, the USGS produced Evaluation of Groundwater Resources in
the Spanish Valley Watershed, Grand and San Juan Counties, Utah Scientific Investigations Report
2019-5062. To supplement this report, the City hired Ken Kolm, a professional hydrologist, to assess the
hydrogeology of the aquifer and more specifically our overall water availability in his report Hydrologic
and Hydrogeologic Assessment of the Surface Water and Groundwater Resources Affecting the Moab City
Springs and Wells, Moab, Utah, Phases 1 2 3 and 4, produced between 2018 and 2020.
The Water Advisory Board has spent a good deal of time reviewing Ken’s work. In the four report phases
Ken presents the complexity of the ground water and surface water systems that supply Moab and
Spanish Valley. The Drinking Water Protection Zones presented in Phase 3 are useful and ample. The
Groundwater Monitoring Plan presented in Phase 4 is a good starting point for developing a
comprehensive, collaborative monitoring plan.
Kolm’s analysis, his conceptual model, of our complex water situation has shed useful light on our water
supply. However, if the conceptual model is inaccurate, the water budget determined from it is also
inaccurate. There are elements that are significantly uncertain, i.e. that may be in error.
These include:
• Recent geochemical analyses, useful to establish sources and destinations of groundwater, are
not used to substantiate the conceptual model. Those results do not support Kolm’s model for
the Mill Creek system.
• The science of estimating water consumption of phreatophytes (plants) has a wide range of
estimated values. Further, the presence of Russian olive and tamarisk means the current density
and extent of phreatophytes in the riparian area is arguably higher and broader than it would be
if native plants were the primary components of the system.
• Groundwater inputs to and outputs from the model are subject to considerable uncertainty.
• Infiltration into the ground of precipitation in the high La Sal Mountains is not integrated into the
model.
• Surface water balance is not integrated into the model.
The Kolm reports are best viewed in conjunction with the other reports, including the Gardner Report,
Rethinking a Groundwater Flow System Using a Multiple-Tracer Geochemical Approach: a Case Study in Moab-
Spanish Valley, Utah. While not an official USGS publication, it is a peer reviewed article in the Journal of
Hydrology and in our opinion provides a better estimate of safe yield for our aquifer. The Water
Advisory Board recommends that the City carefully consider the uncertainty of any numerical results
from the Kolm reports prior to considering changes in policy or practices based upon those results.
In conclusion, until the Utah Division of Water Rights establishes a legal value for safe yield and earnest
discussions with the City begin for a groundwater management plan that will limit withdrawals, the City
might best protect its interest by asserting its intention to use its senior water rights according to the
City’s 40 year plan by encouraging and participating in a groundwater monitoring plan that will
accurately determine aquifer(s) status and protect the interest of its residents and consider
implementing policies for a water restricted future.
Respectfully Submitted by the Moab Water Conservation and Drought Management Advisory Board
after discussion at their December 16th meeting.
BRIEF REVIEW OF THE KOLM HYDROLOGIC ASSESSMENT
City of Moab Water Conservation and Drought Management Advisory Board
Moving to a water-restricted future
Now would be a good time
Mike Duncan
Moab City Council, mduncan@moabcity.org, 720.281.2430 cell
12/9/2020, Rev E
Have you noticed?
2-3% growth compounds over the years
Well and spring levels are declining
Periodic little snow in the mountains
Periodic summer drought
El Niño / La Niña precipitation cycles
Climate Change –getting hotter
WIIIIRT IS AN ACRE-FOOT?
1 fact
1 Acre-foot (AF) =
325,851 gallons
One acre-foot of water
covers approximately
1 acre of land
1 foot deep
300 feet
Ken's Lake_ when full,
holds approximately
3,000 acre-feet
1 acre -Toot vok amv =-
325.851 gallons of water
Spanish Valley Watershed, the USGS Study Area
Moab Irrigation Co.
diversions
The Glen Canyon Group and Valley Fill Aquifers
Well levels are a portent of what’s likely to come:
Dry in 1970’s, wet in ‘80s, slowly declining since
" T h e C i t y p r e s e n t l y a s s u m e s i t c a n s e r v e w a t e r t o n e w
r e s i d e n t i a l a n d c o m m e r c i a l d e v e l o p m e n t s
" W i l l s e r v e c o m m i t m e n t s a r e n e i t h e r e x p l i c i t l y s t a t e d
n o r c o n s i d e r e d b y P l a n n i n g .
" T h i s m a y b e b e c a u s e t h e c i t y h a s a m p l e p a p e r w a t e r
r i g h t s f o r g r o w t h .
" T h i s m u s t c h a n g e & .
Y e a r s o f d r o u g h t a n d f a m i n e c o m e a n d
y e a r s o f f l o o d a n d f a m i n e c o m e , a n d t h e
c l i m a t e i s n o t c h a n g e d w i t h d a n c e ,
l i b a t i o n o r p r a y e r .
J o h n W e s l e y P o w e l l
The end game for this discussion:
Suggested city policy changes for calendar year 2021:
•Begin “metering” new requests for residential or commercial water
•Requests are in units of Equivalent Residential Connections
•One ERC is one typical residential housing unit
•400 gal/day = 0.45 acre-feet/year
•Participate in upcoming Groundwater Management Plan process
•These policy changes need not and should not wait for the GWMP
process to complete.
•GWMP completion is likely a few years away.
•New development continues apace.
•Wise water policy means not making commitments we can’t fulfill.
•The city can adopt any water policy we wish as long as we don’t
violate state law.
The end game for this discussion, continued…
What do we mean by “metering” ? To be debated. Some ideas:
•Explicitly accepting or denying requests for new water in Planning apps.
•Keeping better records of such requests
•Establishing an annual new ERC quota
•Establishing a maximum ERC limit for any single application
•Offering ERC “bonuses” for conservation or secondary water use
•Metering rules amended periodically as required
•Applicants who contribute their own existing GCGA withdrawals not
subject.
•Applicants who contribute their own non-GCGA water not subject.
The basic Water Budget issue:
•We’re talking “culinary” (drinking) water here, not irrigation
•We’re talking ground, not surface, water, i.e. aquifers
•Water rights are not the issue
•Aquifer capacity is the issue
First, how much water each year are we currently using?
•Well known numbers
•Moab City –2300 acre-feet
•Grand County –1100 acre-feet
•San Juan County Spanish Valley SSD –500 acre-feet
Then, how much water do we have to use? Read on…
•Poorly estimated numbers, often apples and oranges confusion
•USGS study 2018-19
•Ken Kolm (city sponsored consultant) 2018-19 study/reports
•USGS/Journal of Hydrology 2019 study
In more detail, how much water each year are we currently using?
History of the city’s water supply:
•Since 1890, Skakel Springs (near Moab Springs Ranch, N of town)
•In 1950’s, purchase of George White (the GW of Red Cliffs fame)
ranch (now the Golf Course area)
•Culinary water reported to DWR of 2159 acre-feet in 2019:
•Four springs, presently in use
•Two wells, #6 and #10, presently in use
•Well #7 used for golf course irrigation; culinary quality water
•2009-2012 average of 120 acre-feet/yr reported to DWR
•City’s springs and wells totaled 2279 acre-feet/yr in 2019
Grand County wells also tap GCGA:
•In GCGA rather than Valley Fill Aquifer since good quality
•George White #4 and #5
•Chapman
•Spanish Valley
•Withdrawals reported to DWR in 2019 were 1039 acre-feet
" A p p r o v e d , t e s t e d f o r 5 0 0 a c r e - f e e t
" I n s e r v i c e s o o n t o s e r v e S I T L A
S o u t h M o a b d e v e l o p m e n t
" A p o t e n t i a l l y l a r g e ( 1 5 K p e o p l e )
c o m m u n i t y
" J u n i o r w a t e r r i g h t s f r o m 2 0 1 1
" C o n d i t i o n a l a p p r o v a l f o r a n o t h e r
4 5 0 0 a c r e - f e e t
" D i v e r s i o n f r o m 2 0 + G C G A
w e l l s d e s i r e d b y D i s t r i c t
" C o l o R i v e r w i t h d r a w a l ( u p K a n e
C r k ) i s a b a c k u p
S a n J u a n C o u n t y S V S S D W e l l # 1 a l s o t a p s G C G A
" W h a t i s o u r p r e s e n t G C G A w i t h d r a w a l ?
" C i t y i n 2 0 1 9 , 2 2 7 9 a c r e - f e e t
" G r a n d C o u n t y i n 2 0 1 9 , 1 0 3 9 a c r e - f e e t
" S J S V S S D p l a n n e d f r o m o n e a p p r o v e d w e l l 5 0 0 a c r e - f e e t
" T o t a l G C G A e x i s t i n g w i t h d r a w a l s = 3 8 1 8 a c r e - f e e t
" G r o w i n g w i t h n e w d e v e l o p m e n t s i n p i p e l i n e
" V a r i e s f r o m y e a r t o y e a r s i n c e c u l i n a r y w a t e r u s e d f o r i r r i g a t i o n
" D o e s n o t c o u n t L o w e r S V S p r i n g s o r P r i v a t e W e l l s
" A g r e e s w e l l w i t h G a r d n e r / U S G S v a l u e o f 3 6 0 0 a c r e - f e e t
Now, in more detail, how much water do we have to use?
How is it estimated? Three techniques:
•By modeling groundwater recharge by precipitation (snow/rain)
•Difficult to do accurately
•By observing discharge in surface (streams, springs) and ground
waters
•Better accuracy estimates
•Then assume that recharge equals discharge;
•An assumption not easily verifiable
•By some combination of the above two
•Three contemporary studies,two by USGS (or related authors), one
by a consultant (Ken Kolm) hired by city
What did the USGS 2018-19 study say?
•Recharge method: 10 –30K acre-feet/yr
•Discharge method: 13-15K acre-feet/yr
•Largest discharge is Mill Creek (base flow) surface water
•Both methods subject to variable climate data
•These count groundwater in the whole watershed (upper, east
side of La Sals; and lower, the valley floor), both:
•Good (culinary) water, from GCGA aquifer
•Poorer (salty, irrigation) water, from Valley Fill aquifer
What useful things came out of Kolm’s 2018-19 Phase 1-4 study?
•Phase 1 laid the ground work for the remaining reports
•Phase 3 proposed expanded Source Protection Zones for the city’s
springs
•Phase 4 proposed an expanded monitoring plan for the area’s ground
water table, useful as part of upcoming Groundwater Management
Plan sponsored by DWR
•Phases 2 and 4 presented water budgets for the GCGA and Valley fill
aquifers respectively
What did the Kolm Phase 2 Water Budget study say?
•18K acre-feet/yr passing through “Water Budget Area”
•Currently depleting (mining) the GCGA
•Difficult to make policy decisions on the basis of this study alone
•WBA chosen to represent GCGA flow
•WBA chosen to have mostly “no flow” boundaries
•Surface and ground water flows in to and out of WBA at a few
points
The Water Budget
Area for Phase 2,
the GCGA
" A u t h o r a d m i t s c o n s i d e r a b l e u n c e r t a i n t y , r e l u c t a n c e t o m a k e
c o n c l u s i o n s , m o r e s t u d y r e q u i r e d
" G r o u n d w a t e r i n / o u t e s t i m a t e s s u b j e c t t o c o n s i d e r a b l e
u n c e r t a i n t y
" V e g e t a t i o n l o s s e s s u b j e c t t o c o n s i d e r a b l e u n c e r t a i n t y
" G e o c h e m i c a l t r a c e r s n o t i n t e g r a t e d i n t o m o d e l
" I n f i l t r a t i o n i n h i g h L a S a l s n o t i n t e g r a t e d i n t o m o d e l
" S u r f a c e w a t e r b a l a n c e n o t i n t e g r a t e d i n t o m o d e l
What does the USGS/JofH article say?
•3400 acre-feet/yr recharge of “deep” GCGA
•This is the part of the aquifer from which city wells draw
•Uncertainty? –could be from1500 to 5300 acre-feet
•Nominal case –we’re at Safe Yield limit now
•Best case –we have 50% to grow on
So, do we have culinary water to grow on for some time?
Not really. Less than you think. There’s a new hooker, which is:
•The city’s (and county’s) existing culinary water rights and
withdrawals are to the “Glen Canyon Group” aquifer.
•The latest USGS/Journal of Hydrology study says the GCGA is
already being withdrawn at its long term recharge rate, what
the state defines as “Safe Yield.”
•Utah Division of Water Rights is the authority who determines
the legal Safe Yield value.
•That value has not yet been determined, a subject of the
Groundwater Management Plan process.
•When established, it implies no new (net) withdrawals from the
GCGA aquifer, regardless of paper water rights
•This is a finding that precipitates a paradigm shift for local
governments, who must plan far into the future
What exactly does the state say about “Safe Yield” ?
•“Safe Yield” -the amount of groundwater that can be
withdrawn from a groundwater basin over a period of time
without exceeding the long-term recharge of the basin or
unreasonably affecting the basin’s physical and chemical
integrity
•Utah Code 73-5-15 4(a)(i) :“…the withdrawal of water from
a groundwater basin shall be limited to the basin’s safe
yield.”
•Utah Code 73-5-15 4(a)(ii) : “Before limiting withdrawals in a
groundwater basin to safe yield, the state engineer shall:
•determine the groundwater basin’s safe yield; and
•adopt a groundwater management plan for the
groundwater basin
If the GCGA were closed to new withdrawals, what other water
sources could be tapped for culinary city use?
•Nothing is easy. Tapping any other source is fraught with
legal, water right, water quality, cost, infrastructure and
environmental consequences
•The biggest GCGA discharge is Mill Creek, its surface rights
owned by Moab Irrigation Co., a non-profit with senior water
rights
•Could trade agricultural uses for municipal uses
•The only other aquifer is the “Valley Fill Aquifer” with poorer,
but treatable, quality water whose rights are held by other
users.
•Tapping its underflow to the Colorado River could impact
wetlands
•The county owns unused modest rights to the Colorado River.
•Expensive to pump and store
•Could be subject to Colorado River Compact restrictions
More study is needed!
•The city is drilling new well #12 in the golf course area this
coming spring
•An opportunity to cheaply observe aquifer characteristics
and do drawdown tests against other wells in the area
•More monitoring elsewhere in the valley is critical
•City contributions to funding will be necessary
To say it again…
•We have a painful, but manageable paradigm shift in front of us
•Until now, the water’s always been there, essentially free
•No more:
•Water will get more expensive.
•We’ll have to conserve.
•We’ll have to buy, trade, share or bank for new water.
•This may limit new residential and commercial growth.
The remaining slides get into the details,
the weeds of water budget and Safe Yield issues
Policy makers can skip this part if you wish…
What do we mean by “mining” an aquifer?
Recharge R, af/yr;
Also is Safe Yield, say 3000 af/yr
Aquifer area
A acres, say 20K acres
Well withdrawals
W, af/yr
Spring flow s @ height h, af/yr;
s is proportional to height h;
Pre-devel spring flow S
(@ W=0, no well withdrawals)
(@ pre-devel height h = H0)
is just the recharge R;
Thus s = kh, where k = R/H0
Pre-devel height H0,
say 100 ft
height h, ft
Pre-devel water level
Current water level
Change in storage volume is A(dh/dt) af/yr;
Change = (recharge –withdrawals) –spring rate
(yA)(dh/dt) = (R-W) –kh;
Bucket full of alluvial sand;
Specific Yield y = 10-30%;
ie relatively little space for water
Think of an aquifer as a bucket of wet sand
At a recharge of R = 3000 af/yr,
from pre-development state (i.e. full aquifer),
suppose we suddenly begin withdrawing 1000 af/yr
It takes hundreds of years to come to new equilibrium,
because the aquifer volume is much bigger
than the volume withdrawn each year.
Spring flow eventually declines
to 2/3 of pre-devel value,
2000 af/yr
Initial pre-devel spring flow
equal to recharge = 3000 af/yr
Not mining the aquifer since withdrawals < recharge = safe yield
At a recharge of R = 3000 af/yr,
from pre-development state (i.e. full aquifer),
suppose we suddenly begin withdrawing 4000 af/yr
It still takes > hundred years to come to new equilibrium,
because the aquifer volume is still much bigger
than the volume withdrawn each year.
Spring flow eventually
declines to zero
Initial pre-devel spring flow
equal to recharge = 3000 af/yr
Mining the aquifer since withdrawals > recharge = safe yield
What is the title and who authored the latest USGS4 report?
1,2Gardner, Phillip M., 1,2Nelson, N.C., 3Heilweil, 3V.M., Solder, J.E.,
1Kip Solomon, D., Rethinking a groundwater flow system using a
multiple-tracer geochemical approach: a case study in Moab
Spanish Valley, Utah, Journal of Hydrology (2020), doi:
https://doi.org/10.1016/j.jhydrol.2020.125512
1University of Utah Department of Geology and Geophysics, Salt Lake City, UT
2United States Geological Survey, Nevada Water Science Center, Carson City, NV
3United States Geological Survey, Utah Water Science Center, Salt Lake City, UT
•This report is currently published as a “pre-proof” Journal of Hydrology article.
•All authors were authors of the previous 2018-2019 USGS study, Evaluation of
Groundwater Resources in the Spanish Valley Watershed, Grand and San Juan
Counties, Utah
•This report draws heavily on that previous study.
•Four of the five authors are still employed by the USGS.
•4For these reasons, I have called this study a “USGS” report. However, note that it
has been independently published
What does it say that changes the game?
Using a lumped parameter model and 14C groundwater ages, we
estimate recharge to the deeper GCGA (DGCGA) to be 4.2 ±2.3 X
106 m3 /yr [3400 ±1900 acre-feet/yr], which is approximately equal to
the measured discharge from wells and springs [3600 acre-feet/year,
tabulated in the slides preceding this one].
Why do I have more confidence in this report than in others?
Gardner used geochemistry and environmental tracers
(groundwater dating with tritium/helium and industrial gases,
pore-water tritium and chloride measurements from rock cores,
etc.) together with what is now a common Lumped Parameter
Model technique to focus on water budgets and concepts of
physical groundwater flow. This permits better definition of where
groundwater comes from and where it did and didn’t go.
Gardner’s agreement between an independently calculated
recharge and observed discharge gives confidence in the lumped
parameter model.
Where does GCGA water come from
and where does it go?
from high in
the La Salsto the NE side
of the valley
" G a r d n e r t h i n k s t h e K a y e n t a m i d d l e l a y e r o f t h e G C G A
( N a v a j o , K a y e n t a , W i n g a t e ) o f t e n c o n f i n e s w a t e r i n t h e
N a v a j o ( t h e S h a l l o w G C G A ) a n d t h e W i n g a t e ( t h e D e e p
G C G A ) t o t h o s e l a y e r s .
" W e l l s a n d s p r i n g s a r e s o u r c e d i n t h e D G C G A
" M i l l C r e e k i s s o u r c e d i n t h e S G C G A
" I t t a k e s a l o n g t i m e ( 2 7 0 0 y e a r s , o b s e r v e d v i a c a r b o n 1 4
d a t i n g ) t o g e t f r o m t h e m o u n t a i n s t o t h e v a l l e y .
The basic Lumped Parameter Model:
Water moves horizontally at speed X/T m/year;
Recharge rate R = V/T m3/yr = X*Y*Z / T.
X m Y m
Z m
Water enters aquifer
at time zero
Aquifer
Water exits aquifer
at time T years
(Exponential Piston) Lumped Parameter Model
R = L*θ*(1 + Xcon/X) /τ, where
R is the recharge rate in m3/year over the aquifer portion X;
τ is the mean transit time in years;
L is the aquifer thickness in m;
θ is the porosity;
Xcon is the confined portion of the aquifer;
This results in
R = 4.2E6 m3/yr (3400 acre-feet)/yr
which well matches observed discharges
of 3600 acre-feet/yr
L
X
Xcon
Y
Springs discharge,
Wells withdrawals
Snow, rain
infiltration
An estimated recharge rate of 3400 acre-feet/yr.
About what we’re discharging/withdrawing now!
Is it believable?
•Yes, to the extent of its error bounds.
•There are uncertainties in all LPM parameters
•Their net effect, the total uncertainty in recharge rate
R (or Q here) can be calculated assuming all errors
are statistically independent
•This results in a 1-sigma standard deviation (i.e.
uncertainty) σQ of 2.3E6 m3/yr = 1865 acre-
feet/yr.
" T h u s , t h i s S a f e Y i e l d e s t i m a t e i s 1 5 3 5 t o 5 2 6 5 a c r e - f e e t / y e a r
" N o m i n a l c a s e , w e r e a t S a f e Y i e l d n o w , 3 4 0 0 a c r e - f e e t
" B e s t c a s e , w e h a v e ( 5 2 6 5 3 4 0 0 ) / 3 6 0 0 ~ 5 0 % t o g r o w o n .
" M o r e s t u d y i s n e e d e d !
" T h e c i t y i s d r i l l i n g n e w w e l l # 1 2 i n t h e g o l f c o u r s e a r e a t h i s
c o m i n g s p r i n g
" A n o p p o r t u n i t y t o c h e a p l y o b s e r v e a q u i f e r
c h a r a c t e r i s t i c s a n d d o d r a w d o w n t e s t s a g a i n s t o t h e r
w e l l s i n t h e a r e a
" M o r e m o n i t o r i n g e l s e w h e r e i n t h e v a l l e y i s c r i t i c a l
" C i t y c o n t r i b u t i o n s t o f u n d i n g w i l l b e n e c e s s a r y
Thank you for reading!
Questions?
Mike Duncan
Moab City Council
mduncan@moabcity.org
720.281.2430 cell