# Presentation: 675995

## Model Support for Developing and Implementing a Nitrogen TMDL for Long Island Sound 

- Mark A. Tedesco
- EPA LIS Office

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## Long Island Sound Study

- National Estuary Program
- CWA 320
- CWA 119
- Sponsored by EPA, NYSDEC, CTDEP
- Begin in 1986

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## The Watershed

**16,000 sq. mile watershed**
**1,300 sq. mile water surface**
**two connections to the ocean**
**East River in the west**
**The Race in the east**
**8 Million People**

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**Notes:**
From colonial times until fairly recently, many uses of Long Island Sound and the surrounding watershed were made without considering the environmental impact on this great body of water. In the last 25 years, since the passage of the Clean Water Act, investments in water pollution control programs have led to measurable improvements in water quality, in spite of ever-increasing numbers of people and activities on the Sound and within its watershed. Obvious sources of pollution are now regulated and controlled through permit programs, tidal wetlands are protected, and major efforts to build and improve sewage treatment plants and control industrial discharges have helped to restore degraded waters.

## Hypoxia Affects Large Areas of LIS

**Hypoxia Affects Large Areas of LIS**

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## Reoccurs Each Summer

**Reoccurs Each Summer**

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## Identify “Water Quality Limited” Waters
Specify Allowable Pollutant Loading
Point Sources
Nonpoint Sources
Margin of Safety
Public Participation

- Specify Allowable Pollutant Loading
- Point Sources
- Nonpoint Sources
- Margin of Safety
- Public Participation

**TMDL Requirements**

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## How it Started

- 1986: LIS TAC recommends modeling approach to support hypoxia management
- Report of the LIS Modeling Workshop, 27-28 January 1986, MRSC Ref. 86-6, Working Paper 26
- 1987: Preliminary modeling and data collection
- 1988-89: Intensive data collection, model development for 3-d model (LIS 3.0)
- Independent Model Evaluation Group (MEG) established for review

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## Sources of Total Nitrogen Delivered

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**Notes:**
Two points should be made:

      1.  The pre-Colonial load probably is an overestimate

      2.  This graphic does NOT reflect the attenuation in LIS, so it over emphasizes the importance of New York City loads

## 108 STP Discharges

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## Key Issues

- Attainment of water quality standards
- Technical basis for DO standard
- High cost burden for POTW upgrades
- Perceived equity between point and nonpoint sources
- NYC vs. CT River
- Uncertainty in managing out-of-basin loads

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## LIS Eutrophication Model (LIS 3.0)

**EUTROPHICATION MODEL (HydroQual, Inc.)**
- Inputs: Pollutant loads
- Outputs: Water quality as function of time and space

**HYDRODYNAMIC MODEL (NOAA/NOS)**
- Inputs: Winds, tides, solar radiation, freshwater flows, boundary S&T
- Outputs: Circulation, volumes, density stratification

**SEDIMENT SUBMODEL (HydroQual, Inc.)**
- Inputs: Deposition of particulate organic matter
- Outputs: Fluxes of sediment oxygen demand and nutrient

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## Management Framework

- Proceed in phases
- Identify conditions that will minimize adverse impacts
- Make cost-effective progress from in-basin sources
- Equitably allocate reductions
- Incorporate in TMDL
- Consider out-of-basin sources and actions
- Atmospheric deposition
- import for outside states

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## Proceed in Phases

- Phase I: nitrogen freeze at 1990 levels (1990)
- Phase II: low-cost nitrogen reduction (1994)
- Phase III: Reduction  targets to achieve water quality objectives

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## DO Benchmarks for Hypoxia Management

- Surface waters
- > 5.0 mg/l (one-day average)
- Bottom waters
- _fully protective:_
- > 5.0 mg/l (one-day average)
- _protective for most species:_
-  > 3.5 mg/l (one-day average)
-  2.0 mg/l minimum

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## Unit Response Matrix

- LIS 3.0 run to calculate DO response from different Management Zones
- What-if scenarios
- Cost curves
- Estimated  incremental nitrogen reductions and costs from different levels of management
- Calculated incremental DO improvement from actions taken in different areas
- Plot incremental nitrogen reductions and incremental DO improvement versus incremental cost

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## Nitrogen Management Zones

**NY - CT Domain**

**Nitrogen Management Zones**

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## Variable N Control Costs

**Variable N Control Costs**

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## Efficient Use of Capital Possible

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## LIS 3.0 Nitrogen Loading Scenarios

- Base Case
- Phase 2 Reductions
- Cost-Sensitive Reductions
- Limit of Technology
- DO Targets (Protective of Species)
- Pastoral

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## Characterize Ecological Effects of Scenarios

- Describe biological impacts in 0.5 mg/l intervals from 0-5 mg/l dissolved oxygen
- For each model scenario, assess duration of time and areal extent of exposure
- Develop indices to estimate relative, biological  impact for different model scenarios
- survival impairment-area-days (SAD)
- biomass impairment-area-days (BAD)

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## Response to Low DO 

- Percent Impairment  at 0.5 mg/l DO Intervals

- - CTDEP Long Island Sound Finfish Survey
- - EPA Marine WQ Criteria for DO (Say Mud Crab)

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## Conclusions From Cost Curve and Model Analysis

- Approximately 80% of the benefit (DO improvement) can be obtained for 25% of cost
- Achievable reductions can greatly reduce the time and area affected by hypoxia
- 75% reduction in area
- 85% reduction in duration
- Greatly reduce biological effects
- effects on fish abundance: 95-100%
- effects on larval mortality: 65-84%

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## Challenges to Traditional TMDL and Allocation Process

- Use of cost-effectiveness
- Phasing
- Cost estimates vary
- Incentive for dischargers to inflate
- Impact on resources debated
- Lack of incentives to do more, sooner

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## Use Flexibility and Market Forces to Achieve Efficient Allocations

- Identify optimal reduction levels relative to cost
- Cost-effective level of reduction at publicly owned treatments works
- Aggressive nonpoint source pollution control program
- Allocate equal reductions to each management zone and discharger
- Allow flexibility in how to achieve reductions within a zone and among facilities considering relative impacts (equivalency factors)
- bubble permit (NY)
- general permit (CT) and credit trading

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## Nitrogen Reduction Goals Have Been Established

- Nitrogen reduction targets established in 1998
- A Total Maximum Daily Load Analysis to Achieve Water Quality Standards for Dissolved Oxygen in Long Island Sound (2001)
- 58.5 percent reduction to anthropogenic sources in the Connecticut and New York portions of the basin
- Establishes WLAs and LAs
- Establishes "equivalency factors" for relative effect on DO
- additional reductions from out-of-basin sources (MA, VT, NH) and atmospheric deposition
- identifies alternatives, i.e. aeration

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## Schedule for Achieving Reduction Targets

- Achieve targets in 15 years
- 40% in five years
- 75% in ten years
- Reevaluate every five years
- assess system response
- revise DO standards
- establish out-of-basin nitrogen allocations
- identifies alternatives, i.e. aeration, if needed

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## 50 %

- A 58.5% Reduction from primary anthropogenic sources in CT and NY
- 10% reduction from urban and agricultural runoff (LA)
- Balance (65%) from point sources (WLA)

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**Notes:**
I’ve often found that the 58.5%, 10% NPS for urban and Agricultural lands ONLY, and the 64% for CT point sources vs. 58.5% for NYC point sources, confuses everyone.  What it boils down to, with all sources considered, is a 50% reduction in nitrogen  loading from baseline.  People can understand that it’s a BIG change and that point source reductions are emphasized.

## TMDL Trading Ratios

- Adjustments in WLA allowed consistent with TMDL exchange ratios
- Watershed attenuation factors
- Delivery to LIS

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## Implementation: NY Bubble Permits

- Nitrogen "bubble" by management zone
- aggregate, annual limit for point sources within a zone
- individual, annual limit based on facility's share of aggregate, annual load
- Monitoring and reporting requirements
- Compliance for 12-month rolling average
- Final WLA phased in five-year increments
- Reallocation among zones allowed consist with  TMDL equivalency factors

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## How it Works

- Option of doing more at upper East River STPS and less at lower East River STPs
- 1.9:1.0 trading ratio
- NYCDEP and NYSDEC modified consent order for Newtown Creek STP to eliminate nitrogen control
- Estimated savings of $600 million
- NYCDEP and NYSDEC signed consent order on upper ER nitrogen control to meet TMDL

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## Implementation: CT General Permit and Trading

- Public Act No.01-180 (June 2001)
- framework for Nitrogen Credit Exchange Program and Advisory Board
- authorization for general permit for the discharge of nitrogen
- General Permit (September 2001)
- 79 POTWs get annual mass loading
- phased in annually over 15 years to attain WLA
- contains performance, monitoring, reporting, and trading requirements
- opt-out option

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## How it Works

- State finances upgrades
- Facilities monitor and report on annual discharge
- March 31 audit of calendar year discharge
- Comply by...
- meeting annual mass loading, or
- purchasing credits equal to exceedance
- State acts as banker
- sells credits by July 31
- purchases credits by August 14

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## How it Works

- State sets price of credits and administers and tracks transaction
- Nitrogen Credit Advisory Board proposes value based on statewide cost of nitrogen reduction
- No banking, no credit for grant portion (only loan)
- Nonpoint sources not currently included in trading program, but desired outcome

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## 0.14

**0.14**

** ****0.18**

** ****1.00**

** ****0.32**

** ****0.46**

** ****0.17**

** ****0.19**

** ****0.11**

** ****0.93**

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**Notes:**
These exchange ratios are sound wide.  Most people won’t notice that, but if you want to clarify, Connecticut’s NCE normalizes to zone six, which alters the ratios a little bit.  IF we were to sell excess credits to NYC or other NY counties, these ratios would likely be used.

##  10

** ****10**

** ****100**

** ****50**

** ****40**

- DRAFT

**Notes:**
Here I usually try to make the point about why trading provides an economic incentive for plants with higher exchange ratios to remove extra nitrogen.  Conversely, it’s also the reason why smaller, more distant plants would find it cheaper to buy credits rather than pay of debt for a full upgrade.  At the same time, even those smaller, more distant plants will operate their plants as efficiently as possible to remove nitrogen under their existing capabilities to save money!

## Point Source Nitrogen Reductions

- The 1990 estimates include 98 municipal, 4 state, and 4 industrial discharges = 109
- CTDEP adjusted its data in 2001 to include reports from plants not previously submitted
- and change estimates to actual reported numbers.

**Point Source Nitrogen Reductions**

- DRAFT

**Notes:**
You can use this graph to show progress, or I’ve inserted another graph (next slide) I did for Tom that focuses on CT and provides a better comparison to the prior graph, I think.

##   Maximum Area and Duration of Hypoxia

- CT DEP LIS Water Quality Monitoring Program

- (less than 3.0 mg/l)

- DRAFT

## Meanwhile...

- 1992: NYCDEP initiates Systemwide Modeling
- 1994-95: NYCDEP initiates comprehensive field program to add to 1988-89 data sets
- 1999: Model Evaluation Group approves SWEM for LIS application
- 2001: LISS Management Committee accepts use of SWEM to support hypoxia management program
- NYCDEP provides SWEM for LISS use through HydroQual

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## And Now...

- Systemwide Nutrients Work Group directs SWEM application
- NY/NJ Harbor Estuary Program and LISS
- Charged with providing recommendations on TMDL development and reassessment

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## Work Group Goals

**Work Group Goals**

- By September 2004 prepare assessment:
- Revised DO standards
- Load estimates from atmospheric deposition and upstream sources
- Technology advancements in N control
- Exchange ratios of relative effects

- DRAFT