Bay TMDL 101Gary Shenk

CBPO

2017 01 06

1

New Targets are Nothing ‘New’

Year Model Phase Goal

• 1987 0 40% reduction

• 1992 2 40% of controllable loads

• 1997 4.1 Confirm 1992 loads

• 2003 4.3 Reallocation

• 2010 5.3.0 TMDL

• 2011 5.3.2 Phase 2 WIP targets

• 2017 6.0 Phase 3 WIP targets

2

TMDL Timeline

• 1999 – Lawsuit by American Canoe Association and American Littoral Society

• 2010 – TMDL put in place, Phase I WIPs completed

• 2011 – 2 updates to Watershed Model, Phase II WIPs completed

• 2017 MidPoint Assessment• 60% of the management practices implemented

• Improved models

• Mid-Course Correction?

• 2025 TMDL Goal Date• 100% of the management practices implemented

3

Chesapeake Bay TMDL

Necessitated by failure to meet water quality standards

4

Decision Support System

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10

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50

60

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80

90

100

0 10 20 30 40 50 60 70 80 90 100

Percent of Space

Perc

ent

of T

ime

CFD Curve

Area of Criteria

Exceedence

Area of Allowable

Criteria

Exceedence

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

Percent of Space

Perc

ent

of T

ime

CFD Curve

Area of Criteria

Exceedence

Area of Allowable

Criteria

Exceedence

Data

Watershed Model

Bay Model

CriteriaAssessmentProcedures

Effects

Allocations

AirshedModel

Land UseChange Model

5

6

Chesapeake Bay Partnership Models

7

Chesapeake Bay Partnership Models

Bay Dissolved Oxygen Criteria

Minimum Amount of Oxygen (mg/L) Needed to Survive by Species

Migratory Fish Spawning & Nursery Areas

Hard Clams: 5

Striped Bass: 5-6

Worms: 1

Shallow and Open Water Areas

Deep Water

Deep Channel

6

5

3

2

1

4

0

Crabs: 3

Spot: 2

White Perch: 5

American Shad: 5

Yellow Perch: 5

Alewife: 3.6

Bay Anchovy: 3

8

Rockfish, BluefishMenhaden Habitat

Shad, Herring, Perch and Rockfish Spawning Habitat

Local “Zoning” for Bay and Tidal River Fish, Crab and Grasses Habitats

Bay GrassesHabitat

Oyster, Crab, Croaker and SpotHabitat

Summertime Crab Food Habitat

Redefined ‘swimmable/fishable’ in terms the public could relate to9

Rockfish, BluefishMenhaden Habitat

Local “Zoning” for Bay and Tidal River Fish, Crab and Grasses Habitats

Oyster, Crab, Croaker and SpotHabitat

Summertime Crab Food Habitat

Redefined ‘swimmable/fishable’ in terms the public could relate to

1 mg/l Oxygen

3 mg/l Oxygen

5 mg/l Oxygen

10

An Assessment of Dissolved Oxygen Criteria

Spatial Extent of Low Oxygen =>

Tem

po

ral E

xten

t o

f Lo

w O

xyge

n =

>

11

An Assessment of Dissolved Oxygen Criteria

Spatial Extent of Low Oxygen =>

Tem

po

ral E

xten

t o

f Lo

w O

xyge

n =

>

12

Curve representative of an acceptable level of Oxygen

Test curve for a particular deep water segment

An Assessment of Dissolved Oxygen Criteria

Spatial Extent of Low Oxygen =>

Tem

po

ral E

xten

t o

f Lo

w O

xyge

n =

>

13

Red area = unallowable exceedance

‘Stoplight’ Table

Deep Water Attainment

Cbseg Base Draft Allocation E3

CB3MH 2.5% 0.1% 0.0%

CB4MH 23.3% 3.8% 1.5%

CB5MH 5.3% 0.0% 0.0%

CB6PH 0.6% 0.0% 0.0%

CB7PH 0.4% 0.0% 0.0%

CHSMH 5.5% 0.0% 0.0%

EASMH 3.3% 0.0% 0.0%

Calculated January 200914

Critical Period 1993-1995

• Stoplight tables are calculated over a 3-year period

• Regulations require that ‘critical conditions’ be determined where variable environmental factors make attainment more difficult

• Often interpreted as a ‘once in 10 years’ event

• 1993–1995 selected for stream flows with a 10-year return. • 1996-1998 was more extreme

• Choice of the critical period affects the overall effort required to meet the TMDL

15

Hydrologic Averaging Period 1991-2000

• Loads from the watershed model are based on the weather during the hydrologic averaging period

• Wetter periods would show more load from nonpoint source

• Dryer periods would show more load from point source

• Any 10-year period is representative, 1991-2000 chosen as • slightly more representative

• Includes the critical period

• Choice of hydrologic averaging period affects point/nonpoint balance.

16

TMDL Allocation Calculation

17

•Areas that contribute the most to the problem must do the most to resolve the problem.

•All tracked and reported reductions in nutrient loads are credited toward achieving final assigned loads.

•Allocated N and P loads must result in attainment of water quality standards

Guidelines for Allocations

18

•Areas that contribute the most to the problem must do the most to resolve the problem.

•All tracked and reported reductions in nutrient loads are credited toward achieving final assigned loads.

•Allocated N and P loads must result in attainment of water quality standards

Guidelines for Allocations

19

0

5

10

15

20

25

30

35

40

45

1985 Base 2009 Target Tributary Loading Loading Loading E3 All

Scenario Calibration Scenario Load A Strategy Scenario Scenario Scenario Scenario Forest

342TN 309TN 248TN 200TN 191TN 190TN 179TN 170TN 141TN 58TN

24.1TP 19.5TP 16.6TP 15.0TP 14.4TP 12.7TP 12.0TP 11.3TP 8.5TP 4.4TP

Nu

mb

er

of

Seg

men

ts in

DO

Vio

lati

on

Open Water Violations

Deep Water Violations

Deep Channel Violations

Dissolved Oxygen Criteria Attainment

Basin-wide load is190 N and 12.7 P (MPY)

20

•Areas that contribute the most to the problem must do the most to resolve the problem.

•All tracked and reported reductions in nutrient loads are credited toward achieving final assigned loads.

•Allocated N and P loads must result in attainment of water quality standards

Guidelines for Allocations

21

Determining Who Contributes the MostKey factors:

Distance from Tidal water • Riverine transport

Position along mainstem bay• Estuarine circulation

Existence of riverine estuary

Riverine delivery:Pound delivered per pound produced

Estuarine deliveryOxygen reduced per pound delivered

Overall EffectivenessOxygen reduced per pound produced

22

23

Relative Effect of a Pound of Pollution on Bay Water Quality

24

Relative effectiveness (Riverine * Estuarine Delivery)

0

1

2

3

4

5

6

7

8

UpE

S, M

DU

pES,

DE

Mid

ES, M

DSu

sq, M

DLo

wES

, MD

Wsh

, MD

UpE

S, P

ALo

wES

, DE

Susq

, PA

PxtB

, MD

EshV

A, V

APo

tB, D

CM

idES

, DE

PotA

, DC

PotB

, MD

PotB

, VA

Susq

, NY

Rap

B, V

APo

tA, M

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kB, V

APo

tA, V

AW

sh, P

APo

tA, W

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tA, P

APx

tA, M

DJm

sB, V

AR

apA

, VA

YrkA

, VA

JmsA

, VA

JmsA

, WV

Major River Basin by Jurisdiction Relative Impact on Bay Water Quality

•Areas that contribute the most to the problem must do the most to resolve the problem.

•All tracked and reported reductions in nutrient loads are credited toward achieving final assigned loads.

•Allocated N and P loads must result in attainment of water quality standards

Guidelines for Allocations

25

Accounting for Previous Reductions

•An allocation method that requires all states to make a similar effort from here on out would disadvantage states that have already done more.

•Require a percentage of the way between:• No Action: no BMPs, low level of WWTP• Everyone, Everything, Everywhere (E3)

26

27

TN, p5.3, goal=190, WWTP = 4.5-8 mg/l, other: max=min+20%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 1 2 3 4 5 6 7 8 9 10

Relative Effectiveness

Pe

rce

nt

red

uc

tio

n f

rom

20

10

no

BM

Ps

to

E3

All Other

WWTP

4.5 mg/l

8 mg/l

20 percent slope

Allocation Method Agreed to by Majority of Principals’ Staff

Committee Members

Wastewater Loads

All other sources

TP, p5.3, goal=12.67 WWTP = .22 - .54 mg/l, other: max=min+20%,

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 1 2 3 4 5 6 7 8 9 10

Relative Effectiveness

Pe

rce

nt

red

uc

tio

n f

rom

20

10

no

BM

Ps

to

E3

All Other

WWTP

1. Plot effectiveness vs percent effort2. Use 2010 as the base year3. Set upper half of WWTP line at 3 mg/l equivalent; intercept at 8 mg/l4. Most effective basin is 20 percentage points higher than least effective

28

29

5. Add special cases

30

State/basin allocations (N/P (MPY))

Changing No Action and E3 Year - Theoretical

31

Allocation = 140Both basins are the same percent of the difference between NA and E3

2010 2010

Changing No Action and E3 Year - Theoretical

32

Allocation = 140Both basins are the same percent of the difference between NA and E3

2010 2010 2012 2012

Changing No Action and E3 Year - Theoretical

33

Allocation = 140Both basins are the same percent of the difference between NA and E3

2010 2010 2012 2012 2017 2017

TN Allocation Percent of Base Year 2010

0%

20%

40%

60%

80%

100%

120%

PA MD VA NY WV DE DC

Pe

rcen

t o

f a

llo

ca

tio

n u

sin

g 2

01

0

BY 2010

BY 2002

BY 1985

34

2009 WQGIT presentationTN Allocation Relative to using 2010 for No Action and E3

35

Allocation Percent of Base Year 2010 TP

0%

20%

40%

60%

80%

100%

120%

140%

PA MD VA NY WV DE DC

Pe

rcen

t o

f a

llo

ca

tio

n u

sin

g 2

01

0

BY 2010

BY 2002

BY 1985

TP Allocation Relative to using 2010 for No Action and E3

36

State/basin allocations (N/P (MPY))

Phase I WIPs developed to meet these numbers

Scenario Year for WIP Development

• Once load targets are established jurisdictions develop WIPs to meet those loads in the watershed model.

• To generate the loads, the partnership must choose a scenario year to estimate the available land for BMP implementation, the human and animal populations, agricultural systems, etc.

• Choosing a current year answers the question: “What BMPs are needed to meet the goals given the current state of the watershed”.• Future growth might be handled through offsets

• Choosing a future year answers the question: “What BMPs are needed to meet the goals given the projected state of the watershed”.• Future growth might already be included

• 2010 was chosen for Phase I and Phase II WIPs

37

Phase II WIPs - 2011

• 2010 TMDL based on Phase 5.3 watershed model

• Partnership requested changes to Phase 5.3 during 2010• Land use

• Nutrient Management

• Phase I WIPs (plus small adjustments to meet WQS) were run on the Phase 5.3.2 watershed model to generate planning targets• Consistent with the 2010 TMDL

• Numbers were different but represented the same level of effort

• Phase II WIPs were developed to meet the planning targets.

38

150

175

200

225

250

275

2009 2011 2013 2015 2017 2019 2021 2023 2025

De

liv

ere

d N

Lo

ad

s (

mil

lb

s/y

r)

Assumes Constant Reduction Over Time

Interim Target: 60% by

2017

Two-Year Milestones and 2017

39

Planning Target

StartingPoint

Phase III WIPs and Planning Targets

40

Target Method

Changes

• New Watershed Model Loads• Higher coastal plain loads

• Change in seasonality

• New Estuarine Model• Biogeochemical changes

• Wetland and shoreline

• Climate Change

41

Changes

• New Watershed Model• Change in delivery factors

• New Estuarine Model• Biogeochemical changes

42

Changes

• New Watershed Model• Definition of E3

• Effectiveness of BMPs

• Loading rate of land uses

43

Default Target Method

• Plot effectiveness vs percent effort

• Use 2010 as the base year

• Set upper half of WWTP line at 3 mg/l equivalent; intercept at 8 mg/l

• Most effective basin is 20 percentage points higher than least effective for ‘all other’ line

• Special cases

• Hydro Period

• Critical Period

• Conowingo

• Climate Change

44

Special Request Topics

• How are we doing relative to the WWTP hockey stick?

• Why does historical data matter?

• What about monitoring trends?

45

46

Draft values – for WQGIT discussion purposes

Differences reflect jurisdictional choices on the source of reductions

47

Draft values – for WQGIT discussion purposes

Differences reflect jurisdictional choices on the source of reductions

Historical Data Matters

48

Critical Period 1993-1995

One way to understand the TMDL question:How much more do we need to implement in addition to what was already on the ground in the early 1990s to meet water quality standards

Historical Cleanup

• A lack of historical data during the calibration period (1985-2013) will result in a calibrated Phase 6 Model which does not accurately account for the effect of changes in implementation.

• However, states will have the opportunity to update their Phase 6 historical record each year as part of reporting progress to NEIEN.

• Accurate revisions to historical data will be beneficial in assessing progress during each progress year and milestone period.

49

Monitoring Trends

• As currently formulated, monitoring trends are not part of the formula for calculating planning targets.

• Monitoring concentrations and estimated loads are used in the calibration of the models.

• Monitoring generates new knowledge about the watershed which is incorporated into decision tools.• Conowingo

• Phosphorus

• Other Explaining Trends work

• Monitoring can be used to inform jurisdictional choices. For example: • Move implementation to areas where loads are climbing

• Move implementation to areas with shorter lag times

50

Role of Monitoring

51From Scott Phillips, USGS