modeling fecal bacteria fate and transport to address pathogen impairments in the united states...

Modeling Fecal Modeling Fecal Bacteria Fate and Bacteria Fate and

Transport to Address Transport to Address Pathogen Pathogen

Impairments in the Impairments in the United StatesUnited States

Brian BenhamExtension Specialist and Associate Professor,

and Director, Center for Watershed StudiesBiological Systems Engineering

Virginia Tech

Center for Watershed StudiesCenter for Watershed Studies


Objectives Background

What is watershed management? What is a TMDL?

Review the VA TMDL process with generalizations

Impairment Designation TMDL Development Implementation

Discuss fecal indicator bacteria modeling for TMDL development in the U.S.

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What is Watershed Management? Watershed management recognizes that the water quality

of our streams, lakes, and estuaries results from… human activities watershed characteristics in upstream areas

The goal of watershed management is… an environmentally and economically healthy watershed that

benefits all stakeholders

Each watershed management plan includes… unique goals site-specific management strategies to achieve those goals


Watershed Management: Historical Perspective

Nineteenth an early to mid-twentieth Century Goal was to enhance value of water bodies for residential,

agricultural, industrial, navigational, recreational, and power generating uses, and to reduce flooding

1970’s Increasing national concern with water quality.

Clean Water Act (CWA) passed in 1972 – restore chemical, physical, and biological integrity of nation’s waters.

Focus on point sources, wastewater treatment

Major improvements in water quality

1980’s to today Broader concern with ecosystem management and restoration.

Nonpoint source pollution control. Ambient water quality.

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What is a TMDL? A Total Maximum Daily Load (TMDL) quantifies the

amount of a particular pollutant a waterbody can receive and still meet water quality standards (pollutant budget).

TMDL = WLA + LA + MOSWhere: WLA = waste load allocation (point sources)

LA = load allocation (nonpoint sources)MOS = Margin of safety

3-phase process Impairment Designation TMDL Development Implementation

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6

Conceptual TMDL

Time

Con

cent

ratio

n, C

(m

g/L)

Water Quality

Standard

Existing Condition

TMDL Scenario

Con

cent

ratio

n6


TMDL ProcessWater quality standards met

Clean

Implementation Planning

How many and what type of ‘fixes’ are needed?

Implementation

Monitoring

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Study

Watershed study to determine needed pollutant reduction

TMDL Development

Water quality standards not met

Impairment Designation


Adaptive management


Why is a bacterial impairment Bad? Fecal indicator bacteria (FIB) are fecal

coliforms originating from the feces of humans or animals

Presence of FIB indicate that other disease causing organisms may be present

Human Health Concern Chance of gastrointestinal illness or

infection during primary contact (e.g., water in mouth, nose, eyes, open wounds)

14% of 76,000 currently listed impairments are bacterial impairments (USEPA, 2009)

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Clean



Implementation

Monitoring

9

Study


TMDL Development




Adaptive management


TMDL Development Phase

1. Determine existing and potential future pollutant loads in the watershed watershed characterization and pollutant source

characterization (model inputs)

2. Link loads to waterbody water quality pollutant fate and transport modeling existing and future conditions

3. Define the pollutant load reductions required to achieve applicable water quality criteria allocation analysis: use model(s) to allocation pollutant loads

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Link pollutant sources to water quality with aid of models

Watershed model Watershed characterization Source characterization Climate variability Fate and transport Allocation analysis

Stream Network

=X

Models are used to predict how watersheds

respond, and to evaluate pollutant reduction options

Land use andManagement

Source: EPA 841-B-05-005


FIB modeling Computer-based water

quality simulation models used extensively to develop pathogen TMDLs

Models have the capability to estimate watershed-scale FIB loads over range of flow conditions and can evaluate effectiveness of proposed control measures (BMPs)

HSPF – Hydrological Simulation Program-FORTRAN SWAT – Soil Water Assessment Tool

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~~

ModelWatershed


HSPF – Hydrological Simulation Program-FORTRAN

Supported by USEPA and Aqua-Terra consultants Watershed scale, process oriented, lumped parameter,

continuous simulation Spatial variability represented in limited way by dividing

watershed into subwatersheds and various land uses Land surface FIB loads determined externally and input as

monthly varying loads Loads directly deposited into waterbody (e.g., sewage

treatment, livestock, wildlife, etc) input as time series Groundwater and interflow are input as monthly varying

loads

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Production and Distribution of Bacteria

Livestock

Humans and Pets

Wildlife

Crop land

Pasture

In-streamResidential

Forest

Die off

Watershed and Source Characterization


Bacteria Source Load Calculator (BSLC)

Excel/Visual Basic program designed to facilitate watershed and bacteria source characterization data entry and analysis for HSPF

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BSLC: a tool for bacteria source characterization for watershed management. Applied Eng. Agric. 21(5): 879-889.


HSPF cont. No specific modules to simulate FIB fate and

transport, but PQUAL is used FIB simulated as free-phase constituent (also

described as planktonic, water-column, “dissolved”) While HSPF can discriminate between free-phase and

particle-associated FIB, data needed to parameterize particle-associated FIB simulation do not exist

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HSPF cont. FIB fate and transport

On the land surface: die-off simulated by limiting “build-up” and specifying amount of runoff needed to “wash-off” accumulated load. Both build-up and wash-off can be land use specific.

In-stream: die-off simulate with 1st order temperature-dependent kinetics, Chick’s Law. Re-growth/re-suspension not simulated.

No distinction made between sources; FIB from all sources subject to same die-off and transport parameters

Representation of BMPs Reduce loads to land surface Performance efficiencies (i.e., average % load reduction factor)

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Pasture

Crops Storage

In-stream

Direct

Deposit

Fate and Transport of Bacteria: Livestock

Die-off

Die-off

Die-off

Source Breakdown19

Center for TMDL and Watershed StudiesCenter for Watershed StudiesCenter for Watershed Studies


SWAT Supported by USDA-ARS Conceptually similar to HSPF Spatial variability represented in limited way by

Hydrologic Response Units (HRU). Combination of soil land use, topography, etc.

Has specific FIB module Allows for variable loading and partitioning to and between the

waterbody, soil, and foliage Allows for variable wash-off and attachment, and for

differential die-off and re-growth in-stream and in the soil

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Consequences of limited confidence in FIB inputs and knowledge about fate and transport mechanisms

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(Novotny and Chesters 1981)


Needed Advancements Additional data to more accurately characterize fate

and transport FIB generation (fecal densities), die-off, attachment, re-

growth, and re-suspension, etc.

Advancements in microbial source tracking (MST) Improvements in technique accuracy More consistency among methods Advances in MST could allow for more effective prioritization

i.e., addressing those impairments that pose most heath-related risk

Better understanding of how models handle extreme events (high and low flows)

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Clean



Implementation

Monitoring

23

Study


TMDL Development




Adaptive management

Identify and prioritize appropriate BMPs

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Pollutants Addressed by the BMP

Best Management Practice (BMP) sediment organic matter nutrients bacteria

detention ponds/basins x x x xDiversions x x x xfield borders x xincreased E & S inspections xinfiltration BMPs x x x xlivestock exclusion BMPs (fencing) x x x xlow impact development x x x xnutrient management x x xpublic education x x x xrestoration of channelized sections xriparian buffer zones x x x xseptic system maintenance/pump-outs x x x

streambank protection and stabilization x x x

street sweeping x xvegetated filter strips x x x x

Establish goals and milestones25


August, 2006Implementation Begins:12.6% Instantaneous Fecal Coliform Viol.

August, 2014

2nd Milestone:10.1% Instantaneous Fecal Coliform Viol.

August, 2019

3rd MilestoneFullImplementation

August 2006

August 2011

August 2014

August 2019

August, 2011

1st Milestone:11.1% Instantaneous Fecal Coliform Viol.

Stage 1 Stage 2 Stage 3

39% Stream Exclusion Fencing 22% Pasture Land Management35% Septic System Repair/Replace



Flyer for pet waste education program – Courtesy Roanoke River Roundtable

Fencing and Riparian Buffer

Photos: Virginia Department of Conservation and Recreation


Adaptive management

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www.epa.gov/nps/watershed_handbook/EPA 841-B-08-002


http://www.epa.gov/owow/tmdl/pathogen_all.pdf EPA 841-R-00-002


Good resource

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www.epa.gov/nps/watershed_handbook/EPA 841-B-08-002

http://www.epa.gov/owow/TMDL/pdf/draft_handbook.pdf


Thank you

감사합니다Brian Benham, [email protected]

modeling fecal bacteria fate and transport to address pathogen impairments in the united states...

Documents

goal of watershed management

watershed management

healthy watershed

study watershed study

ambient water quality

va tmdl process

impairment designation

ecosystem management