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Jean M. BahrUniversity of Wisconsin -

Madison

Natural tracers as tools to address management issues related to

groundwater – surface water interactionsTwo water management issues

related to sustainability

• Siting of new high capacity wells –potential impacts of groundwater use on surface water resources

• Aquifer storage recovery to facilitate surface water use for municipal supplies – potential impacts of surface water on groundwater quality

I. Regulating high capacity wells(>100,000 gpd)

• WI regulations from the 1940s designed to avoid “interference” impacts on public supply wells

• No consideration for potential impacts on streams, springs or wetlands

Waterkeepers of Wisconsin (WOW) opposes any taking of spring water or any other ground water reserves that feed Wisconsin headwaters, lakes, rivers and streams.

• Permit can be denied on basis of significant impacts on high flow springs (>1 cubic foot per second)

• Requires knowledge of contributing aquifers and of hydraulic connections between pumped aquifers and springs

• Two examples: Madison area springs, Mukwonago River watershed

2003 Wisconsin Act 310

Gov Signs Ground Water Protection BillThe Capital Times, Friday, April 23, 2004

Gov. Jim Doyle signed legislation Thursday that would give the Department of Natural Resources the authority to deny high-capacity wells, with the intention of protecting ground water.

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Major Springs Near Madison WI

Culver springs (Token Creek)

Nine Springs

Frederick springs (Pheasant Branch)

Impacts of groundwater development

Pumping centers in Dane County

(Circles proportional to pumping)

Drawdown in the deepSandstone Aquifer

(Contours in feet)

Three possible sources for spring flow

Deep Bedrock

Glacial Deposits Upper Bedrock

Gaging of streams

and springs

relativelyundisturbed

wetlands

Testing conceptual models of spring flowSampling of wells and springs

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Major ions and tritium-helium dating(Swanson et al. 2001, Chemical Geology)

Lower Bedrock

UpperBedrock

Glacial Deposits

Inferred Aquifer Source

> 40 yrs10-15 yrs3 – 9 yrs3H/He age

Lower conductivity

Elevated and stable Na

Variable alkalinity

Low ClElevated and stable Cl

Low but variable Na

Low NO3Elevated and stable NO3

Variable NO3 and Cl

Major ions

IIIII (springs)

IGroup

Testing of bedrock wells revealed high K zones in the Tunnel City Group

spring boils

Groundwater model with high K layerGood match to water levels, spring flow and

groundwater age estimates

Implications for siting of deep wells

• Limited localized effects of municipal pumping

• Critical to maintain recharge in nearby areas

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Mukwonago River Watershed, southeastern WI

• Rapid suburban expansion near Milwaukee• Lake water cannot be transferred across subcontinental divide• Deep wells produce water with high concentrations of radium• Many new wells proposed in glacial deposits

Proposed high capacity well in glacial aquifer

Bedrock topography reveals buried valley

Bluff Rd. spring

Springs, wetlands and and lakes concentrated along the flanks of the Troy Valley

Evidence suggesting preferential flow(H. Gittings, MS 2005)

Spring

1 2 3 4 5Distance from headwaters (miles)

0

1

2

3

4

Stre

am d

isch

arge

(cfs

)

Spring

Abrupt increase in baseflow near edge of buried valley

Sr isotopes to identify aquifers

0 4 8 12 161/Sr

0.708

0.709

0.71

0.711

0.712

87S

r/86S

rsprings

Ordovician

Cambrian+Ordovician

Silurian +Ordovician

Sand andgravel

Shallow wells

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Simple mixing models with bedrock

0 4 8 12 161/Sr

0.708

0.709

0.71

0.711

0.71287

Sr/86

SrMixing with water from fast flow zones

0 4 8 12 161/Sr

0.708

0.709

0.71

0.711

0.712

87S

r/86S

r

Conclusions and implications

• 15% - 75% of stream baseflow comes from bedrock aquifers and remainder is discharge from the sand and gravel aquifer

• New high capacity wells in sand and gravel have potential to decrease baseflow but effects may be partially buffered by discharge from bedrock aquifers

ASRWater

ASRWater

SurficialAquifer

ConfiningUnit

ASR Storage

Zone

LowerConfining Unit

Storage Recovery

II. Aquifer Storage Recovery

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East of the subcontinental divide in Milwaukee area to• limit continued expansion of cone of depression• meet increasing demands • avoid treatment for radium

Lake water replacing groundwater for public supply

Consultant prediction of flow patterns at Oak Creek ASR

First ASR proposal in WI by Oak Creek

Treatment plant for lake water near limit to meet peak summer demand

Existing wells no longer used for production because of high radium proposed for conversion to ASR wells

Pilot cycle testing approved by WI DNR

Mixing of ambient and injected water inferred from conductivity record

(Data from CH2MHill)

4/19/01 5/29/01 7/8/01 8/17/01 9/26/01

200

400

600

800

Con

duct

ivity

Observation Well W01ASR Well

Injection Storage Recovery

Calcium and sulfate parallel conductivity

4/19/01 5/29/01 7/8/01 8/17/01 9/26/01400

500

600

700

800

Con

duct

ivity

40

60

80

100

Cal

cium

(mg/

L)

4/19/01 5/29/01 7/8/01 8/17/01 9/26/01400

500

600

700

800

Con

duct

ivity

80

120

160

Sul

fate

(mg/

L)

7

Drinking water standard = 50 ug/L

Quantification of mixing required to interpret manganese mobilization

Volume Recovered (million gal.)50

Man

gane

se (u

g/L)

Mixing effects also required to assess fate of disinfection products

groundwater standard 6 ug/L

Chl

orof

orm

(ug/

L)

Volume Recovered (million gal.) 50

30

Green Bay WI also proposed ASR to store treated Lake Michigan Water

Arsenic mobilization by introduction of oxygen

Green Bay Well 10

medium

shallow

deep

3 monitoringintervals

Borehole flowmeter logging by WGNHS to identify possible preferential flow zones

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0

50

100

150

200

250

300

0 4 8 12 16 20 24

Weeks of Storage

Ars

enic

(ug/

L)Deep MediumShallow

Arsenic concentrations during storage phase of Green Bay pilot test

Rapid increase in Tunnel CityDelayed increase in Elk Mound

0

50

100

150

200

250

300

0 50 100 150 200 250 300

Percent Recovery

Ars

enic

(ug/

L)

ASR WellMediumShallowDeep

Arsenic concentrations during recovery phase of Green pilot test

Highest concentrationsin ASR well

Scientific studies, data, and tools needed to evaluate sustainability

• Regional hydrostratigraphy

• Regional scale flow models

Dane County Model

• Collection of site specific data

Flow and water level measurements

Drilling, monitoring well installation and testing

Chemical and isotopic analyses

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• Local scale modeling to test conceptual models and predict impacts

Simulated water levels near Green Bay with ASR system

Capture zone of proposed well near springs