Quantitative approaches to understanding groundwater and surface water availability in the Twin Cities Metropolitan area:

Metro Model 3 and WEAP

Evan Christianson (Barr Engineering) and Ailsa McCulloch (Stantec Consulting)

Overview

• Introduction– Groundwater – surface water review– Minnesota’s water context (availability, water

law, tools)– Quantitative modeling as a decision support tool

• Case study 1: Metro Model 3 (Twin Cities)• Case study 2: WEAP Water Allocation Model (CA)• Applicability to Minnesota

Overview

• Introduction– Groundwater – surface water review– Minnesota’s water context (availability, water

law, tools)– Quantitative modeling as a decision support tool

•••

Groundwater and Surface Water Interaction

Discharge lake/wetlandGraining Stream

Flow-through lake/wetland

Recharge lake/wetlandLosing Stream

Disconnected withshallow water table

Disconnected withdeep water table

Groundwater “Capture”

Capture = increased recharge and/or decrease in groundwater discharge

Time scale depends on characteristics of aquifer and distance of well from water body

(Days to Decades to Centuries)

GroundwaterVolume 52, Issue S1, pages 100-111, 28 MAY 2014 DOI: 10.1111/gwat.12204http://onlinelibrary.wiley.com/doi/10.1111/gwat.12204/full#gwat12204-fig-0001

Metro-Wide Thought Experiment

Go from no-pumping to current conditionsHow long for changes in baseflow to equilibrate?

Current Pumping

Time to obtain equilibrium,

steady-state condition

No Pumping

Perc

ent R

educ

tion

in T

otal

R

egio

nal B

asef

low

Years

Drawdown in Jordan Aquifer Near Pumping Well

Rapid response in source aquifer near pumping wellLess than 2 days to get over 90% steady-state drawdown

Steady-State Equilibrium

Drawdown at Water Table Near Pumping Well

Slow Response at Water Table

Steady-State Equilibrium

84% of steady-state drawdownafter 10 years

Potential Vulnerability of Surface-Water Features to Groundwater Pumping

The picture can't be displayed.

Available data indicate likely not vulnerable to pumpingAvailable data indicates potentially vulnerable to pumpingPotentially vulnerable with wide littoral zone

Barr Engineering for Metropolitan Council, 2011

Overview

• Introduction– Groundwater – surface water review– Minnesota’s water context (availability, water

law, tools)– Quantitative modeling as a decision support tool

•••

Minnesota Groundwater Recharge

Smith and Westenbroek, 2015

Minnesota Groundwater Recharge

1

2

3

4

5

0

Avg. Infiltration(in/month)

Barr Engineering for Metropolitan Council, 2014

Introduction:

Water Rights Overview

The Hydrologic Significance of the 100th Meridian

Introduction:

Water Rights Overview

The Hydrologic Significance of the 100th Meridian

Sanford and Selnick, 2013. JAWRA Vol 49, No. 1

Introduction:

Water Rights Overview

…and the Implication for water rights in the U.S.

Minnesota Water Priority Classes

• Minnesota has a riparian water law system. • Lakes, streams, and groundwater = “Waters of the

State” • New permit applicants have same priority as existing

permit holders, assuming water is for the same purpose

• If a conflict exists, water users have the opportunity to develop a plan for proportionate distribution of limited water available among all users in the same priority class.

Minnesota Water Use Priority Classes1.) Municipal water supply and power production with contingency plan2.) < 10,000 gallons per day3.) Agriculture irrigation and agriculture processing4.) Power production in excess of contingency plan5.) Other > 10,000 gal/day6.) nonessential uses

Groundwater Appropriations and Relationship to Surface Waters

Groundwater appropriations that will have potential impacts negative impacts to surface waters are subject to applicable provisions in section 103G.285

What is a negative impact?

MN Section 103G.287

Subd 1 - DNR Commissioner may waive a requirementSubd 2 - Limited consumptive use during periods of low flow

Subd 3 - Protective elevations on surface waters (>500 acres)Aquatic VegetationExisting UseTotal volume and slope of littoral zone

Subd 4 – Support of property owners (< 500 acres)Subd 5 - Extra restrictions on trout streamsSubd 6 - Contingency Planning

Impact to Surface Water Thresholds

Report to the Minnesota State Legislature: Definitions and Thresholds for Negative Impacts to Surface Waters, January 2016

Streams • Diversion limit of no more than 10% of the August median base flow

Lakes• with constant stream outflow = apply stream threshold• without constant stream outflow = protection elevation• Goal is to maintain characteristic hydrology, ecology, and riparian uses of

the lake most of the time

Wetlands• Currently proposing establishing target hydrographs for various wetland

types• Currently very limited wetland-related hydrologic data

Effect on Permitting Process

1.) Establish negative impact thresholds for surface water

bodies

2.) Establish sustainable diversion limits that will maintain

protected flows and protection elevations for those water bodies

3.) Conduct groundwater modeling to determine the effects of

groundwater withdrawals on the surface water bodies

4.) Assess to what degree individual groundwater withdrawals

may need to be adjusted.

Effect on Permitting Process

Effect on Permitting Process

Effect on Permitting Process

September 26, 2018

Barr Engineering, 2012

Effect on Permitting Process

Effect on Permitting Process

1

2

3

4

6

5

1. Straight River GMA2. Bonanza Valley GMA3. NE Metro GMA4. Little Rock Creek5. Cold Spring6. Rochester

Introduction:

Background in Modeling

Metro Model 3

• 11- County Metro Area• All major aquifers and aquitards• All high capacity pumping • Soil Water Balance recharge

model• land use, topography, daily

climate, soils, etc..• Calibrated to > 80,000

observations• Hydraulic head, baseflow,

transmissivity, etc.

Metro Model 3Model Row 267

A A’McLeod Co. Scott Co. Dakota Co.Carver Co.

Quaternary Sediments

Jordan Sandstone

St. Lawrence Formation

Tunnel City Group

Wonewoc SandstoneEau Claire Formation

Mt Simon – Hinckley Sandstone

Cretaceous and Paleozoic sandstone and siltstone St. Peter SandstonePrairie du Chien Group

Vertical exaggeration ~ 150x

faul

t

faul

t

faul

t

faul

t

Metro Model 3

Surface Water Boundary Conditions

Negative (purple) indicates flux out of modelPositive (green) indicates flux into model

Cubic Meters Per Day

Metro Pumping Optimization

• Distribute pumping to maximize total groundwater withdrawals while not exceeding pre-determined threshold (sustainability constraints)

Metro Pumping Optimization

Fens – No more than 1 foot of drawdown

Trout Streams – No more than 10% change in flux between surface water and groundwater

Mississippi River – No more than 25% change in flux between surface water and groundwater

All other surface water bodies – No more than 15% change in flux between surface water and groundwater

Metro Pumping Optimization -Constraints

Constraint Type Threshold NumberDrawdown from available head for confined bedrock aquifers above the Mt. Simon-Hinckley 50% 2955

Drawdown in the Mt. Simon-Hinckley aquifer 1 foot 1897Drawdown at Calcareous fens 1 foot 6Change in net baseflow to trout streams -10% 13 reachesChange in net baseflow to other river reaches -15% 67 reachesChange in net baseflow to the Mississippi River -25% 12 reaches

Change in net groundwater flux for high and outstanding biodiversity -15% 108 areas

Change in net groundwater flux to potentially vulnerable lakes with wide littoral zone -10% 68

Change in net groundwater flux for remaining lakes at grouped by Township -15% 103

Change in flow directions at site of groundwater contamination 10 degrees 8Total 5237Direction

Metro Pumping Optimization -Wells

n = 2074

Metro Pumping Optimization -Results

Mill

ion

Gal

lons

per

Day

Time Groundwater/Surface-water understandingDefinition of sustainabilityTechnological advancement

USGS &Met Council

(1973)

Recent

Schoenberg(1990)

Metro Pumping Optimization –Binding Constraints

Tow

nshi

p R

ange

La

kes/

Wet

land

s

Stre

ams

and

Riv

ers

Vuln

erab

le

Basi

ns

Biod

iver

sity

Area

s

Trou

t Stre

ams

Safe

Yie

ld

Hyd

raul

ic H

ead

Fens

Flow

Dire

ctio

n

Mt.

Sim

onH

ydra

ulic

Hea

d

AverageBinding Constraint

Overview

•––

•• Case study 2: WEAP Water Allocation Model (CA)•

Case Study 2: WEAP Water Allocation Model For the CA State Water Resources Control Board

• Development in desert environments• Urban stressors

– 39 million people– Large population centers: SF Bay Area, LA

• Agricultural stressors– 6 million acres irrigated farmland– $46 billion/yr exports

• $2.2 trillion economy• Droughts• Spatial challenges with precipitation• Water rights challenges

The Need for Water Allocation Models

+

Complex, Artificial Water System

Complex, Artificial Water System

• Development in desert environments• Urban stressors

– 39 million people– Large population centers: SF Bay Area, LA

• Agricultural stressors– 6 million acres irrigated farmland– $46 billion/yr exports

• $2.2 trillion economy• Droughts• Spatial challenges with precipitation• Water rights challenges

The Need for Water Allocation Models

+

Complex, Artificial Water System

Complexity of System

Complexity of System

Water Agencies in CA

– Drought– Flood control– State Water Project

• 34 storage facilities• 20 pumping plants• ~700 miles of open

canals/pipelines

– Allocates water rights• Surface Water• Groundwater

– Water quality• Contaminants• Instream Flow Requirements

Water Rights Databases

Mixed Riparian/Prior Appropriation

Riparian

eWRIMS MPARS

The Problem

The Problem

Water Balance:Why it is so important to understand

Supply • Rivers and Streams• Canals• ReservoirsDemand • Urban Demands• Agricultural Demands• Ecological/Instream Flow

RequirementsWater RightsSystem Operations

Overview

•––

••• Applicability to Minnesota

Water Balance:Why it is so Important to understand

Applicability to Minnesota

+

Applicability to Minnesota

Questions?• Evan Christianson:

EChristianson@barr.com

• Ailsa McCulloch: Ailsa.McCulloch@stantec.com