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Comprehensive Update of the Arkansas Water Plan Groundwater Supply Availability January 2014
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Page 1: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

Comprehensive Update of the Arkansas Water Plan

Groundwater Supply Availability

January 2014

Page 2: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability

Groundwater

AvailabilityGroundwaterAvailability

GroundwaterQuality

Fish and Wildlife Flows

Quality

Surface Water

Page 3: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

What Constrains our Ability to Supply Water?

Available Supply

Water Law/Regulatory

Physical Availability

Infrastructure

Page 4: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

Groundwater Availability

Page 5: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.
Page 6: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.
Page 7: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

Arkansas Groundwater Demand Data Trends

1935 1955 1975 1995 2015 2035 20550

1,0002,0003,0004,0005,0006,0007,0008,0009,000

10,0007,934

8,566

8,9809,055

9,074

Historic Groundwater Use Projected Groundwater Use

Gro

undw

ater

Dem

and

(MG

D)

Updated Demand Data Added from 2010-2050

~ 13% increase

Page 8: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

Comparison of Demand and Achievable Pumping Rate

Page 9: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

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Page 10: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

Groundwater Modeling Scenarios Scenario 1 and 2:

Minimum water elevation equal to the bottom elevation of both unconfined and confined aquifers for wet and dry climate conditions

Scenario 3 and 4: Minimum water elevation equal to half the aquifer thickness in the alluvial aquifer and the top of formation in the confined aquifer for wet and dry climate conditions

Page 11: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.
Page 12: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.
Page 13: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

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Page 14: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

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Page 15: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

Interior Highlands of Northern and Western Arkansas Qualitative Evaluation of Water Supply

Availability

Groundwater use has declined and surface water use has increased dramatically, and the vast majority of the population in northern Arkansas is served by surface water

Various aquifers generally occur in shallow, fractured, well-indurated, structurally modified bedrock

Many formations are capable of supplying volumes sufficient for small community-supply sources of water

Page 16: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

Northern Interior Highlands AquifersSpringfield Plateau Aquifer

Widely used throughout its extent in northwestern ArkansasNumerous domestic and livestock wells, although surface-water

systems have replaced the aquifer as a general source of water supplyOzark Aquifer

Primary use of the Ozark aquifer is for public supply; 76 MGD was withdrawn for public supply in 2010

Irrigation use was about 20 MGD from the Ozark aquifers in 2010; 70% of irrigation occurs in counties in the aquifer’s far eastern extent, where row crops like cotton, rice, and soybeans are commonly grown

Depth to water in most of these wells is approximately 100 ft

Page 17: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

Southern Interior Highlands AquifersArkansas River Valley Alluvial Aquifer

Irrigation pumpage is smallMunicipal supply withdrawals induce recharge from the river

Ouachita Mountains AquiferShould not be considered as a source of supply for municipal growth

and economic development unless the required quantity was smallWestern Interior Plains Confining System

Well yields sufficient only for household, small municipal, and non-irrigation farm use.

Page 18: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

Groundwater Quality

Page 19: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

Groundwater Quality Analyses

Groundwater quality information provided by USGS

Page 20: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

Groundwater Quality MethodologyWater quality data from approximately 8,000 groundwater

sites: 7000 from the ANRC and USGS database1,000 from the ADEQ database

Statistical analyses and spatial distribution maps for chemical constituents associated with 16 aquifer systems in Arkansas.

Major ions (calcium, magnesium, sodium, potassium, chloride, sulfate, and bicarbonate) and selected trace metals (iron, manganese, and arsenic).

Page 21: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

Drinking Water StandardsWater quality of drinking water will be compared to:US EPA drinking water standards (Maximum Contaminant

Levels (MCL))Health advisories Secondary drinking water regulations for cosmetic effects

(such as tooth or skin discoloration) or aesthetic effects (such as taste, odor, or color)

Page 22: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

East Regional Planning AreaMississippi River Valley alluvial aquifer

Water quality generally is goodElevated iron concentrations in most areas prevent use for commercial,

industrial, and municipal without treatmentElevated salinity additionally occurs in different areas of eastern

Arkansas

Cockfield aquifer Principal aquifer in southeast Arkansas In outcrop area, lower pH values and dissolved solids but higher nitrate

and iron concentrationsDowndip higher pH and dissolved solids; lower concentrations of

nitrate and iron

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Page 23: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

East Regional Planning AreaSparta aquifer

Second highest of volume of useGenerally is of very high quality Isolated areas contain slightly elevated chloride concentrations Downdip increases in dissolved solids and decreases in iron and nitrate

Cane River, Carrizo, Wilcox, Nacatoch, Ozan, Tokio, and Trinity aquifersIncreasing salinity at various distances downdip from the outcrop

areas that renders the groundwater unusable for most purposes.

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Page 24: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

North Regional Planning AreaOzark and Springfield Plateau aquifers

Rapid influx of surface-derived contaminants, especially nitrogen, in karst landscape

Nutrients, bacteria, and other surface-derived contaminants associated with agricultural activities pose the greatest threat to groundwater quality

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Page 25: Groundwater Supply Availability January 2014. The Arkansas Water Plan Update Requires Assessment of Current And Future Water Supply Availability Groundwater.

West-central, South-central, and Southwest Regional Planning AreasOuachita aquifer and the Western Interior Plains

Dominant changes in geochemistry were attributed to rock type, residence time along individual flow paths, and resultant rock- water interaction

Elevated iron and manganese concentrations and production of methane

Nutrients, bacteria, and other surface-derived contaminants pose the greatest threat to groundwater quality

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