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Total Maximum Daily Loads (TMDLs)Development and Implementation

Hua Zhang

Tetra Tech, Inc.

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Total Maximum Daily Loads (TMDLs) The

Pollutant Diet

y TMDL is a pollution budget the amount ofpollutants that can be put into a stream before water

quality standards are violatedy TMDL development is required by the Clean Water

Act for all impaired streams. Many TMDLs are resultsof environmental lawsuits.

y TMDL = 7WLA + 7 LA + MOSy WLA = wasteload allocations (point source)

y LA = load allocations (nonpoint source)

y MOS = margin of safety

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Continuous Efforts of TMDL Development and

ImplementationInform

InterestedParties

Identify WaterQuality

Endpoints

Water QualityMonitoring

Evaluate StreamCondition

ImpairedStream List(303d list)

Pollutant SourceTracking

Source andWater QualityData Analysis

ModelDevelopment

and Calibration

Scenario

Analysis

Stakeholder

Negotiation

SourceAllocation and

Reduction

Report

Development

PublicComments

Response andRevision

Federal Approval TMDLImplementation

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Water Quality Standards A Moving Target

Water quality standards

DO, pH, temperature, nutrients, sediments, pathogen, metals, pesticides, emergingpollutants,

Evaluation, revision and EPA approval

Numerical criteria Specifics: maximum, average, chronic, acute, total, dissolved, ..

Biological Criteria

Use of ecological index (e.g., benthic community assessment)

Stressor identification

Reference waterDescriptive criteria

fishable and swimmable

no significant adverse impact to aquatic ecosystems

Change of Designated Use

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Development of TDS/Conductivity

Endpoint A Case Study

Biologicalimpairment

caused by ionic

stress

TMDLrequired

Mountaintopremoval andvalley fill

Marcellus shalenatural gas

drilling

Protests andthreaten of

lawsuits fromenvironmental

activists

Fishkillaccidence

EPA ScienceAdvisory Boardrecommendedconductivity

level

Potentialconflictions

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Stream Assessment An Evolving Processy Spatial coverage and assessment unit

y Sampling frequency and duration

yHydrological, chemical, and biological parameters

y Stressor identification for biologically impaired streams

y Preliminary pollutant source identification

y 303d List: the list of impaired waters all states to submit

for EPA approval every two yearsy New listing and delisting of impaired streams in 303d list

New listing TMDL under development TMDL developed Meet criteria, Delisting

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Pollutant Source Tracking Capture the

Watershed Dynamics

National Polluant Discharge Elimination System (NPDES) Permits

Industrial : Facilities, Construction, Power Plants, Mining, Landfill

Urban : CSOs, SSO, MS4, POTWs, WWTPs

Agricultural : CAFOs

Non-Point Sources

Residential : Stormwater, Unsewered households

Agricultural : Crops, Pastures

Pre-Law Mining Instream : Bank erosion, Polluted sediments

Natural Background

Weather

Topography

Hydrology and hydraulics

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Data Processing Flexible Systems

Permits Land Uses

Streamchannel Climate Data

TopographyManagement

PracticesMonitoring

data

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Water Quality Modeling Customize for

Application

Raw Data

InterfaceGIS

Database

Output

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Watershed Modeling RelateWater Quality to

Pollutant Sources Formatted databasePreprocessing

SubwatershedsWatershed delineation

Processing unitLanduse manipulation

Coupled modulesModel selection

Model configurationSensitivity analysis

Optimized hydrology parametersHydrology calibration

Chemical and biological parametersWater quality calibration

Baseline pollutant loadBaseline simulation

Load reduction limitsScenario assessment

TMDLs, WLAs, LAsSource allocation

Final documentsPost processing

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Margin of Safety (MOS) Reduce Uncertainty

Uncertainties in the data used for TMDL development

Variability of natural water quality contributions Reliability of the models used for estimating load capacity

MOS should account for

Implicit: TMDL development based on conservative assumptions

Explicit: Allocate a fraction of the TMDL as MOS

Current approach

Uncertainty and error propagation analysis of the water quality models

Rarely used because of the technical difficulties

Scientific approach

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Source Allocation Balance between

Environment and Economyy Baseline and allocated loading

capacity

y Reserve load for future economy

growthy Prioritize various pollutant sources

through stakeholder negotiation

y Consider the political and legalrestrictions

y Evaluate the cost-effectiveness ofallocation scenarios

y Search for the practically achievablescenario of attaining water qualitycriteria

EconomyDevelopment

EnvironmentProtection

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TMDL Allocation

Yes

No

No

No

Yes

No

Meet pH &

dissolved Al WQ

endpoint?

Yes

Alkalinity addition to neutralize

acidic atmospheric deposition

Reduce total Al concentration of

AMD seeps to 0.75 mg/L

Meet dissolved Al

WQ endpoint

(0.75m /L)?

Yes

No need for TMDL

Final TMDL

No

Reduce total Al load of land based

AML to background

Meet dissolved Al

WQ endpoint

(0.75mg/L)?

Reduce bond forfeiture sites and

technology based mining permits total

Al concentration to 0.75 mg/L

Meet pH &

dissolved Al WQ

endpoint

(0.75mg/L)?

Meet pH &

dissolved Al WQ

endpoint for

trout water

(0.087mg/L)? (if

applicable)

Yes

AMD seep alkalinity

addition to attain pH and

dissolved aluminum

endpoints

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TMDL Allocation

Abandoned Mine

Land37%

BankErosion

14%

BarrenLand2%

BondForfeitur

e Sites1%

Harvested Forest

5%

Oil andGas

0%

OtherNPS29%

Permitted Mines

1%

FutureGrowth

4%

Urban/Res/Road

7%

NPDES0%

Cheat River WatershedBaseline Iron Load

Abandoned Mine

Land

2%

BankErosion

23%

Barren

Land3%

BondForfeiture

Sites1%

HarvestedForest

5%

OilandGas0%

OtherNPS49%

PermittedMines

1%

FutureGrowth

7%

Urban/Re

s/Road9%

NPDES

0%

Cheat River WatershedTMDL Iron Load

0

200

400

600

800

1000

1200

1400

1600

TotalIronLoad

(tons/yr)

Cheat River WatershedTotal Iron Allocation

Baseline

TMDL

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TMDL Implementation

Economy

Available Resources

Cost Effectiveness

Impact on economygrowth

Water quality trading

Politics

Equitable betweeninvolved parties

Public perception

Political boundaries andjudiciary authorities

Inter-agency cooperation

Technologies

Water qualityInformation

Suitable sites

Best ManagementPractices (BMPs)

Monitoring

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TMDL Implementation Two Systems

NPDES Permits : Legal authority

Water Quality based effluent limits

Technology based effluent limits

Stormwater runoff

NPS Program : Volunteer and cooperative efforts

Best management practices (BMPs)

Stream and riparian restoration

Stormwater management (green infrastructure)

Agricultural BMPs

Forest BMPs

Brown fields Technical and financial resources

Available Funding

Water Quality information

Potential implementation sites

Public outreach and education

Stakeholder engagement

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Nonpoint Pollutant Source Reduction

Best Management Practices (BMPs)

Selection Placement

DesignConstruction

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BMP Implementation Cost Effectiveness

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Adaptive Implementation Phased Approach

ImplementationPlan

ImmediateActions

Long-TermActions

Experiments

Monitoring

Water quality

target

Interim target

Avoid Further

Degradation

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Public Participation

PublicOutreach

InformationGathering

VolunteerSource

Tracking

StakeholderNegotiation

TMDLAllocation

CommunityInvolvement

WatershedOrganization

PublicEducation

Fund Raisingand Volunteer

Activities

LandownerCooperation

ImplementBMPs

Monitoringand

Assessment

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AdaptiveW

atershed Management

Public

Raising Awareness and interest

Economy development

Environmental activists

Nature

Climate change

Restoration efforts

Ecosystem response

Policy

New Laws

Regulation changes

Administrative activity

Science

Data availability

Model advancement

Treatment technologies

AdaptiveWatershedManagement

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Email: hua.zhang@tetratech.com