water resource assessment of the silver city area, arizona

David Jordan, PEINTERA, Inc.

June 17, 2009

Water Resource Assessment of the Silver City Area, Arizona Water Settlements Act Planning Process

Interstate Stream Commission and Southwest New Mexico Stakeholders Group

Project Scope

• Compile Existing Data • Review and Evaluate Existing Data• Silver City Area – analyze

groundwater availability and develop conceptual model

• Identify data gaps

Main Question

• What is the general groundwater availability in the Mimbres Basin (and Gila-San Francisco Basin) and will it support (at least) Silver City?

Water Supply in Mimbres Basin with Emphasis on Silver City Area

• Water budget/water balance• Water use types (municipal, mining,

agriculture)• Silver City water supply source

– Aquifers – Well Fields

• Silver City growth and demand scenarios

Conceptual Water BalanceWater In:• Recharge from rainfall• Inter-basin inflow• Stream loss

Mimbres Basin

Water Out:• Pumping• Stream gain• Springs• Evaporation (playas)• Inter-basin outflow• Plant transpiration

Water in storage

Data Sources• Adelamar Alcantara, 2008. A Report on Historical and Future Population Dynamics in

New Mexico Water Planning Regions. Bureau of Business and Economic Research, University of New Mexico.

• Balleau Groundwater Inc., 2006. Supplement on Water Use and Wellfield Service –Town of Silver City Water Plan

• Daniel B. Stephens and Associates, Inc., 2005. Southwest New Mexico Regional Water Plan

• Hanson, R.T., McLean, J.S., Miller, R.S., 1994. Hydrogeologic Framework and Preliminary Simulation of Ground-Water Flow in the Mimbres Basin, Southwestern New Mexico, U.S. Geological Survey Water Resources Investigations Report 94-4011.

• John Shomaker and Associates, Inc., 2006. Mimbres Basin Ground-Water-Flow Model in Support of Chino Mines Company Supplemental Discharge Permit for Closure, DP-1340, Condition 86.

• Johnson, M.S., Logan, L.M., and D.H. Rappuhn, 2002. Analysis of Effects of Ground-Water Development to Meet Projected Demands in Regional Planning District 4 Southwest New Mexico. NM OSE Hydrology Report 02-04.

Regional Project Location Map

• Mining/Recreational in north (Silver City, Tyrone, Santa Rita)

• Agriculture/Farming/Ranching in south (Deming, Lordsburg, Columbus)

• Gila River is located west of Silver City, west of the Continental Divide, and not in the Mimbres Basin (In Gila-San Francisco Basin)

Existing Groundwater Models

• Silver City Area - Johnson, 2000 (extended by Balleau, 2006)

• Mimbres Basin - Hanson et al., 1994• Mimbres Basin - Shomaker, 2000

Area Geologic Structure and Faults

Shomaker, 2006

Shomaker, 2006

Basin-Fill Thickness

Silver City Water Supply

• Gila alluvial aquifer – basin (“bolson”)-fill aquifer

• Silver City water supply from wells: Franks wellfield, Woodward wellfield, Gabby Hays and Anderson wells

• Franks wellfield is in the Gila-San Francisco Basin

Hydrogeologic Site Conceptual Model

Water In:• Recharge from rainfall – mountain-front recharge• Inter-basin inflow• Stream loss – arroyos after rainfallWater Out:• Pumping• Stream gain• Springs• Evaporation (playas)• Inter-basin outflow• Plant transpiration

Hydrogeologic Site

Conceptual Model

Water Usage – Mimbres BasinHanson, 1994

• Agriculture – primary usage in the basin

• Mining – second-highest usage• Municipal- smallest usage

0

20,000

40,000

60,000

80,000

100,000

120,000

Municipal & Domestic Wells

Mining Irrigation Other

Tota

l Wat

er U

se (A

cre-

Feet

per

Yea

r)

Use Category

Estimated Water Use in the Mimbres Basin in 1975

Hanson, 1994

DBSA, 2005

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000



Tota

l Wat

er U

se (A

cre-

feet

/ Y

ear)

Use Category


0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000



Wat

er U

se (A

cre-

feet

/ Ye

ar)

Use Category

Estimated Water Use in Grant and Luna Counties in 2005

DBSA, 2005

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

Grant County Luna County Total

Acre

s Irr

igat

edMimbres Basin Irrigated Acreage in 2005

Alcantara, BBER, 2008

Water Use Categories for Water Year 2000

Commercial0%

Domestic1% Industrial

0%

Irrigated Agriculture

95%

Livestock0%

Mining0%

Power0%

Public Water Supply

4%

Reservoir Evaporation

0%

Total WithdrawalLuna County119,995 AFY

Commercial0%


0%


52%

Livestock1%

Mining38%

Power1%

Public Water Supply

7%


0%

Total WithdrawalGrant County

57,319 AFYDBSA, 2005

Bayard Casas Adobes

Hurley (Phelps Dodge)

North Hurley

MDWCASanta Clara

Silver City

SystemDeming Columb

us

Well Production 336.4 26.8 184.2 26.9 228.9 2,820 4,075 208.5

0

500

1000

1500

2000

2500

3000

3500

4000

4500Am

ount

(Acr

e-fe

et/Y

ear)

2002 Well Production for Public Water Systems in the Mimbres Basin

DBSA, 2005

7%

75%

18%

Source of Water Used in the Mimbres Basin in 1975

Surface Water

Groundwater

Combined Surface Water and Groundwater

Hanson, 1994

0

20,000

40,000

60,000

80,000

100,000

120,000

Irrigation Minerals Municipal & Domestic Wells

Other Total

Wat

er U

se (A

cre-

feet

/ Ye

ar)


Surface Water Groundwater Combined Surface Water and GroundwaterHanson, 1994

Mimbres Basin Water Budget

• Hanson (1994)• Southwest Regional Water Plan (DBSA,

2005)• Shomaker (2006)

Inflow (AFY) Outflow (AFY) DifferenceShomaker 108,572 108,584 -12Hanson 90,691 90,742 -51DBSA 91,190 124,945 -33,755

-60,000

-40,000

-20,000

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000W

ater

(Acr

e-Fe

et /

Year

)Mimbres Basin Water Budget

DBSA, 2005; Hanson, 1994 & Shomaker, 2006

Water BudgetsHanson DBSA Shomaker

Inflows Recharge Recharge Recharge

Gain from rivers and streams Gain from rivers and streams Gain from rivers and streams

Infiltration from springs

Underflow from Mangas Trench Storage (sub-flow into the basin)

Return flow from municipalities

Return flow from mining

Return flowm from irrigation

Outflows Evapotranspiration Evapotranspiration Evapotranspiration

Loss to rivers, streams, springs Loss to rivers, streams, springs Loss to rivers, streams, springs

Underflow out of basin Drains

Flow across Mexico-US border Storage (sub-flow out of the basin)

Consumptive Use Municipal Wells Wells

CommercialDomesticIrrigationIndustrialLivestockMiningPower

DBSA, 2005; Hanson, 1994 & Shomaker, 2006

Water Budget Uncertainties• Recharge in the Mimbres Basin

– Mostly in the upper portion (in Grant County)• Average 2.8% of the precipitation results in recharge (DBSA, 7-

13)

• Discharge to Mexico?– Not included in SWRP

• Hawley et al. noted a reversal of groundwater flow at the border, indicating flow is entering the basin rather then exiting at the border (DBSA, 7-14)

• Difference between Inflows and Outflows– Overestimation of evapotranspiration– Underestimation of recharge in Luna County

-60,000

-40,000

-20,000

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

Inflow Outflow Difference

Tota

l Bas

in F

low

(ac-

ft/yr

)Water Budgets for the Gila, San Francisco, and

Mimbres Basins

Gila Basin

San Francisco Basin

Mimbres

DBSA, 2005

Silver City Groundwater Resources

• Town Permitted Water Use: 4,566 AF/Y

• Silver City growth curves from Balleau and Southwest Regional Plan

• Uncertainty in growth estimates results in different water demand vs. supply outcomes

Demand - Growth Rates• Balleau, 2006• High estimate: 2.9%/year• Low estimate: 1.2%/year

0

500

1000

1500

2000

2500

3000

3500

4000

2010 2020 2030 2040

With

draw

als

(ac-

ft/yr

)

Estimated Future Silver City Withdrawals

Low Growth

High Growth

• DBSA, 2005• High estimate: 1.2%/year• Low estimate: 0.6%/year

DBSA, 2005

0

2000

4000

6000

8000

10000

12000

2000 2010 2020 2030 2040 2050 2060

Amou

nt (A

cre-

Feet

per

Yea

r)

Year

Projected Silver City Water Demand Based on Water Connections (Balleau, 2006)

2.9 % Growth Rate

1.2% Growth Rate

2004 Silver City Population = 9,911Average water use = 2,842.4 AFY

Permitted Use =4,566.64 AFY

Permitted UseExceeded in 2021


Balleau, 2006

0

2000

4000

6000

8000

10000

12000

2000 2020 2040 2060 2080 2100 2120 2140

Amou

nt (A

cre-

Feet

per

Yea

r)

Year

Projected Silver City Water Demand Based on Population (DBSA, 2005)

1.2% Growth Rate

0.6% GrowthRate

Permitted Use =4,566.64 AFY

2010 Projected Use (2,610 afy) based on2002 actual use (2,820 afy) and an initial.60% decrease in population served.

DBSA, 2005



Supply and Demand Uncertainty

2010 2020 2030 2040 2050 2060 2070 2080 2090 2100 2110 2120

Balleau

DBSA

Growth Rate (%) Exceedance DateLow High Earliest Latest

Balleau 1.2 2.9 2021 2044

DBSA 0.73 1.2 2057 2118

Exceedance Dates of Silver City’s Permitted Water Use

Balleau, 2006 & DBSA, 2005

0

500

1000

1500

2000

2500

3000

3500

4000

2010 2020 2030 2040

With

draw

als

(ac-

ft/yr

)Estimated Future Silver City Withdrawals

Low GrowthHigh Growth

DBSA, 2005

0200400600800

10001200140016001800

Frank's Wellfield

Woodward Wellfield

Gabby Hayes Well

Anderson Well

Acre

-feet

/ Ye

arSilver City Well System Production 2002

Permitted (AFY)Production 2002

0200400600800

10001200140016001800

Frank's Wellfield

Woodward Wellfield

Gabby Hayes Well

Anderson Well

Acre

-feet

/ Ye

ar

Silver City Well System Production 2003Permitted (AFY)Production 2003

OSE Waters Database

Balleau, 2006

0

50

100

150

200

250

2000 2001 2002

Gal

lons

Per

Cap

ita D

eman

d (g

pcd)

Estimated Per Capita Demand

BayardSilver City

Silver City's water system provides bulk water to Arenas Valley, Pinos Altos, Rosedale, and Tyrone.

DBSA, 2005

Still the Main Question

• What is the general groundwater availability in the Mimbres Basin (and Gila-San Francisco Basin) and will it support (at least) Silver City?

Groundwater in Storage (ac-ft)

San Francisco

Gila

Mimbres - Grant CoMimbres - Luna Co

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

San Francisco Gila Mimbres -Grant Co

Mimbres - Luna CoAm

ount

(Mill

ion

acre

-feet

)Estimated Groundwater in Storage

*DBSA notes: "As they are just an approximation, the values provided in this table should be used only as a general guide in thewater planning process." (5-67)

DBSA, 2005

Water Use Categories for Water Year 2000

Commercial0%


0%


95%

Livestock0%

Mining0%

Power0%

Public Water Supply

4%


0%

Total WithdrawalLuna County119,995 AFY

Commercial0%


0%


52%

Livestock1%

Mining38%

Power1%

Public Water Supply

7%


0%

Total WithdrawalGrant County

57,319 AFYDBSA, 2005

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

Grant County Luna County Total

Acre

s Irr

igat

edMimbres Basin Irrigated Acreage in 2005

Alcantara, BBER, 2008

Hanson, 1994

Silver City

Deming

Columbus

Shomaker, 2006

Basin-Fill Thickness

Shomaker, 2006

The Bottom Line…?

“…Silver City’s existing wells have a total capacityof about 6,319 acre-feet per [This] represent[s]the estimated physical capacities of the wells,unlimited by water rights considerations.Current rights associated with…the well fieldsare less than the wells might be capable ofproducing. Based on a demand estimate of 5,061acre-feet in 2060 (Wilson, 2001; table 3) and anassumed distribution of pumping among thewells, the capacity of these existing wellsexceeds Silver City’s 2060 demand.”

(OSE Hydrology Bureau, 2002, p10)

“In the long term, the Town of Silver citywells can divert a portion of theestimated 15,900 acre feet per year at theexpense of depleting flow that otherwisewould flow into Mangas Spring, the GilaRiver and would discharge to vegetationon the Mimbres River and to playas in theMimbres Basin.”

(Balleau, 2006, p3)

Other Conclusions• Hydrologically, it is likely that that there is

adequate groundwater to supply Silver City (Johnson and Balleau)

• According to Johnson (2002), water is available for irrigators as well

• However there are cost considerations associated with deepening wells and/or new wellfield(s)

• Water comes from storage (the bathtub), springs, or streamflow

Conceptual Water BalanceWater In:• Recharge from rainfall• Inter-basin inflow• Stream loss

Mimbres Basin

Water Out:• Pumping• Stream gain• Springs• Evaporation (playas)• Inter-basin outflow• Plant transpiration

Water in storage

Path Forward

• Refine Supply and Demand Estimates/Assumptions

• Develop better certainty of supply and demand outcomes, based on refined assumptions

• Further evaluate geology and hydrogeology

• Groundwater flow modeling

Thank You

water resource assessment of the silver city area, arizona

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