GMA Modeling and Decision Making_James Beach

1. James Beach, PG
LBG-Guyton Associates
October 27, 2016
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2. Execu&ve Summary
1. What are we deciding?
Ø The Joint planning process
2. How do we decide?
Ø Modeling toolbox
3. Who is the decider?
Ø You and stakeholders
4. What could possibly go wrong?
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3. What are we deciding?
Highest Practicable Level
of Groundwater
Production
Conservation,
Preservation, Protection,
Recharging, and
Prevention of Waste of
Groundwater, and Control
of Subsidence
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The Balancing Act for DFCs

4. CompeDng ObjecDves
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5. DFC Considera&ons
Aquifer Uses or
Conditions
Supply Needs
and Management
Strategies
Hydrological
Conditions
Environmental
Impacts
Subsidence
Impacts
Socioeconomic
Impacts
Private Property
Rights
DFC Feasibility
Other Relevant
Information
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6. Joint Planning
Strategies
MAG
RWPG
TWDB $$$
RWP

7. There is a lot at stake
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8. Desired Future Condi&ons
— allowable water level decline in the future
— volume of groundwater remaining in the future
— minimum spring flow
— water quality goals
— allowable subsidence
— combinaDons or other aquifer-specific goals
— other…….
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9. Modeling
ü Should include mulDple pumping scenarios
ü May need to consider pumping that is higher and lower than
current or historical needs
ü May need to consider pumping that is higher and lower than
SWP needs
ü May need to consider droughts
ü May need to consider other anomalies (demands of a new or
changing industry)
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10. GMA-8 Example
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No pumping
1.9 Dmes current
pumping
0.7 1.0 1.3 1.6

11. Assessing Modeling Results
— Remaining saturated thickness maps/tables
— Percent of Current Water Remaining in Storage
— Percent of Available Drawdown above Top of Aquifer
— Drawdown
— Percent Decline in Water Level
— Impact on ExisDng Public Water Supply Wells
— Regional impact of Local Pumping changes
— Decrease in Springflow (especially in droughts)
— Subsidence
— Many others…
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12. Simula&on Results
Average Drawdown
-200
-100
0
100
200
300
400
500
600
2010 2020 2030 2040 2050 2060 2070
Average Drawdown, Feet
Hensell Aquifer Average Drawdown - Hill County

13. Hosston Aquifer Hensell Aquifer
SimulaDon Results
Percent of 2010 Average Artesian Head Remaining in 2070
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14. Impact of
LOCAL
changes on
the REGION
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Woodbine Fredericksburg
/ Washita
Paluxy Glen
Rose
Hensell Pearsall Hosston
Ellis 1,312 192 280 32 0 4 3,181
Hill 604 262 362 118 231 55 3,368
Johnson 711 916 876 586 449 2 1,460
Somervell 0 20 229 3,343 50 1,356
County Increase in Pumping for Run 7 (acre-feet per year)

15. Public Water Supply Well Impacts – Ellis County

16. Stakeholders
— Consult your a_orney
— You are the “Decider”
— Engage stakeholders early and oben
— Document engagement a_empts
— Document input from stakeholders
— Consult your a_orney
— As appropriate, develop modeling scenarios to address
stakeholder input
— Ask regularly if you have considered the 9 factors as
quanDtaDvely as possible
— Consult your a_orney
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17. If all goes well, this won’t be you
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18. Ongoing Debates about
the Process
— conceptually sound - but difficult to implement
— How to apply regional, long-term DFCs on a local basis today?
— leaves districts vulnerable to peDDons/lawsuits
— is too complex and is prone to favor local uses over “exports”
— doesn’t provide a volume of water that could pracDcably be
produced
— inappropriately “reverse-engineers” groundwater availability
— allows districts to micro-manage local groundwater availability
— allows the districts to inappropriately deny permits
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19. Take Home
— Two 5-year rounds of planning over a 10-year Dme frame indicate that each GMA
focuses on different goals and prioriDes in order to find “the balance”
— In some management areas – nobody is happy – some stakeholders feel there is
too much impact on springs/streams while groundwater developers think the
pumping is too restricDve to support growth
— In agricultural areas, maintaining irrigaDon has been a key objecDve, even if aquifer
storage is depleted over Dme
— In some environmentally sensiDve areas, maintaining springflow is a high priority
— ProtecDng the private landowners access to groundwater for domesDc & livestock
purposes is criDcal almost everywhere.
— In dipping aquifers, finding a balance that protects well owners and streams/
springs in the outcrop while increasing downdip producDon seems to be focus
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James Beach
LBG-Guyton Associates
(512) 327-9640