Atmospheric Deposition and the Role of the Chesapeake Bay Program

1. Atmospheric Deposition and the Role of the Chesapeake Bay Program Jeffrey S. Sweeney University of Maryland Chesapeake Bay Program Office jsweeney@chesapeakebay.net 410-267-9844 Nutrient Subcommittee Meeting MD NRCS Office December 13, 2006

2. Nitrogen Loads Delivered to the Chesapeake Bay By Jurisdiction Point source loads reflect measured discharges while nonpoint source loads are based on an average-hydrology year From 2004: All jurisdictions decrease 337.5 277.7 275.1 270.2 266.3 183.1

3. Nitrogen Loads Delivered to the Chesapeake Bay By SourcePoint source loads reflect measured discharges while nonpoint source loads are based on an average-hydrology year From 2004: Point source = -3.3 million lbs. Agriculture = -0.9 million lbs. Slight increase from all other sources except non-tidal water deposition 337.5 277.7 275.1 270.2 266.3 183.1

4. 2005 Annual Model Assessment Continuing Issues • Atmospheric Deposition • All jurisdictions credited with lower atmospheric deposition of nitrogen as assessed through trends in monitoring data used in calibration of the Phase 5 Watershed Model. • Benefits of NOx SIP Call and other air programs. • Nutrient Subcommittee Discussion • How should deposition component be accounted for and reported?

5. Environmental Indicators:Reducing Pollution Answer two questions: • How is the Bay/Watershed doing? • What’s being done and are we on track in our efforts to restore the Bay? Provide accountability • Connecting efforts with results Provide guidance for future efforts • Intended audience is “interested public” and environmental managers

6. Historic and Projected Atmospheric Deposition to the Chesapeake Bay Watershed Monitored Modeled CAIR+CAMR+BART • Models-3/Community Multi-scale Air Quality (CMAQ) Modeling System) • Provides estimates of N deposition resulting from changes in precursor emissions from utility, mobile, and industrial sources due to management actions or growth. • Adjusts deposition determined by wet-fall concentration model and precipitation volumes • Predicts the influence of source loads from one region on deposition in other regions. • Provides estimates of wet:dry for NO3- and NH4-. NADP/NTN + Atmospheric Integrated Research Monitoring Network (AirMoN)

7. Atmospheric Deposition and the Response in LoadsHow do emission controls impact deposition to the watershed and loads to the Chesapeake Bay? Goal is nitrogen load reduction from all air programs from 1996 = 15 million lbs. NOx SIP call, etc. = 7 million lb. reduction Other air programs, i.e., CAIR = 8 million lbs.

8. Reducing Pollution Environmental Indicator:Air Pollution Modeled Projection Controlling Nitrogen Goal is nitrogen load reduction from all air programs from 1996 = 15 million lbs. Projected reduction primarily from NOx SIP Call = 7 million lbs. Projected reduction from other air programs, i.e., CAIR = 8 million lbs. Percent of Goal Achieved Monitored/ Modeled Monitored/ Modeled Interpolation Interpolation Accounting Begins

9. Reducing Pollution Environmental Indicator:Air Pollution Controlling Nitrogen Percent of Goal Achieved 5% of Goal Achieved Accounting Begins

10. Reducing Pollution Environmental Indicators:Air Pollution, Agriculture, Urban/Suburban Lands Air Nitrogen Pollution 5% of Goal Percent of Goal Achieved Agriculture Nitrogen Pollution 44% of Goal Urban/Suburban Lands Nitrogen Pollution -88% of Goal

11. Reducing Pollution Environmental Indicators:Current (2004) Restoration Efforts How important is urban versus agriculture versus wastewater versus air? Individual Sources Nitrogen All Sources Nitrogen

12. Reducing Pollution Environmental Indicators:Air Pollution, Agriculture, Urban/Suburban Lands Air Nitrogen Pollution For reporting purposes, it’s necessary to account for the air piece, but how? Percent of Goal Achieved Agriculture Nitrogen Pollution Should 2005 include impact of reduced deposition? Urban/Suburban Lands Nitrogen Pollution Should 2005 include impact of reduced deposition?

13. The Impacts of Emission Controls on Chesapeake Bay Watershed Deposition and Loads DISCUSSION • How do emission controls impact deposition to the watershed and loads to the Chesapeake Bay? • 7 million lb. load reduction goal is built into jurisdictional Tributary Strategies. • Comparison is made between baseline and 1990 Clean Air Act projected benefits – as assessed during the time of allocating the nutrient cap loads. • Primarily Tier II tail pipe standards on light duty vehicles. • Utility emissions with Title IV (Acid Rain Program) fully implemented. • 20-state NOx SIP call reductions at 0.15 lbs/MMbtu during the May to September ozone season only. • 8 million lb. load reduction goal is EPA’s commitment beyond what’s built into jurisdictional Tributary Strategies. • Comparison is made between 1990 Clean Air Act projected benefits and projection from CAIR + CAMR + BART.

14. The Impacts of Emission Controls on Chesapeake Bay Watershed Deposition and Loads DISCUSSION • How do emission controls impact deposition to the watershed and loads to the Chesapeake Bay? • The benefits in load reductions to the Chesapeake Bay – from reductions in emissions and deposition – are dependent on the land cover the air flux falls on. • For most Bay Program air impact assessments, this land condition is held constant so only changes in loads to the Bay due to changes in deposition are quantified. • Scenarios are run with the same watershed conditions for landuses, manure and chemical fertilizer applications, nonpoint source BMPs, point sources, septic, etc. • The baseline watershed condition is a scenario where each jurisdictional portion of the major tributaries hits their cap load allocations for nutrients and sediment exactly. • The baseline landuse is not the strategies’ condition exactly. • Strategies were developed at different times over several years. • It is not prudent to do the entire suite of air impact scenarios every time a jurisdictional plan is finalized or revised. • There would be confusion among stakeholders and decision-makers working with air programs if the deposition-to-load cause-and-effect relationship changed constantly because of landuse changes.

15. The Impacts of Emission Controls on Chesapeake Bay Watershed Deposition and Loads DISCUSSION • How do emission controls impact deposition to the watershed and loads to the Chesapeake Bay? • The benefits in load reductions to the Chesapeake Bay – from reductions in emissions and deposition – are dependent on the land cover the air flux falls on. • Forests, on average, retain more than 85% of the nitrogen deposited on them from the air. • “If all of the 5.5 million acres of the forest that both maximizes water quality but is vulnerable to development is lost, an additional 29 million lbs. of nitrogen annually will reach the Bay.” (Forest Sector Issue Paper, Expansion and Retention of Forested Area, Chesapeake Bay Program Implementation Committee, 10/19/06) • Impervious surfaces don’t retain nutrients but channel the load directly to adjacent land or water.

16. Inputs of Nitrogen to the Watershed and Loads Delivered to the Chesapeake Bay • Nitrogen Attenuation •  Uptake by vegetation • Soil storage • Denitrification 28% of nitrogen load from atmospheric deposition  Rooted in relative proportion of inputs  Does not include deposition to tidal water

17. Sources of Nitrogen Loads to the Chesapeake BayHow much of the nitrogen load delivered to the Chesapeake Bay is from atmospheric sources? Sources by Watershed Model Major “Landuse” Category Sources with the Break-out for Atmospheric Deposition • Based on year 2004 estimates from the Chesapeake Bay Program Phase 4.3 Watershed Model. • Sources of nitrogen loads in the break-out chart are rooted in the relative inputs of natural and anthropogenic sources. • Contributions exclude atmospheric deposition directly to tidal waters of the Chesapeake Bay. • Point source loads reflect measured discharges while nonpoint source loads are based on an average-hydrology year.

18. Reducing Pollution Environmental Indicators:Air Pollution, Agriculture, Urban/Suburban Lands Air Nitrogen Pollution For reporting purposes, it’s necessary to account for the air piece, but how? Percent of Goal Achieved Agriculture Nitrogen Pollution Should 2005 include impact of reduced deposition? Urban/Suburban Lands Nitrogen Pollution Should 2005 include impact of reduced deposition?

19. The Impacts of Emission Controls on Chesapeake Bay Watershed Deposition and Loads DISCUSSION • Is it necessary to isolate the air piece from agriculture and urban/suburban land and, if so, how? • Keep the air component as part of agricultural and urban/suburban lands? • CAA reductions were built in during the development of Tributary Strategies. • Typically report loads by model landuses – rather than as the more-fundamental manure, chemical fertilizers, and atmospheric deposition. • Model is calibrated by model landuse “source”, not the more-fundamental sources. • “Lands” are managed by states and localities while air emissions are typically, but not entirely, regulated at the federal level (CAA, CAIR, etc.). • Emission controls from as distant as Texas, Canada, and the Bahamas can impact the Bay watershed’s deposition. • But an indicator specifically for air is necessary.

20. The Impacts of Emission Controls on Chesapeake Bay Watershed Deposition and Loads DISCUSSION • Is it necessary to isolate the air piece from agriculture and urban/suburban land and, if so, how? • Up until this point, the agriculture and developed sectors are not moving closer to their goals much because of reductions in atmospheric deposition since deposition is largely unchanged. • Regulated reductions mostly from the EGUs have been offset by increases in emissions from the mobile sector (primarily) and increases in ammonia emissions from the agricultural sector (secondarily). • As net reductions in deposition increase through CAIR, as projected, need to determine how to best account for this in reporting.

21. The Impacts of Emission Controls on Chesapeake Bay Watershed Deposition and Loads DISCUSSION • Is it necessary to isolate the air piece from agriculture and urban/suburban land and, if so, how? • Completely isolate the air component from agriculture and developed lands? • Issue, in itself, is complicated and goes far beyond a new need to look at Tributary Strategies in a different manner with the air component separated.

22. The Impacts of Emission Controls on Chesapeake Bay Watershed Deposition and Loads DISCUSSION • Is it necessary to isolate the air piece from agriculture and urban/suburban land and, if so, how? • Completely isolate the air component from agriculture and developed lands? • Some jurisdiction’s interest in getting “credit” for state emission controls that go beyond, for example, ozone-season NOx SIP or Tier II tail pipe standards. • Reductions in deposition are determined through monitoring program information coming from sites throughout and just beyond the watershed. • The root cause and location of the emission controls that yield deposition reductions to the watershed are difficult to ascertain accurately. • How do you “credit” emission controls in one watershed state that also benefit other states’ deposition? • Who gets “credit” for emission controls outside the Bay watershed boundary that yield deposition reductions to the watershed? • Bay Program partners have been considering – and working at answering – these questions for a few years through the development of more-local tools relating emissions, deposition, and loads.

23. Peer-Review • Meeting of regional air experts will be convened in early January to discuss air issues: • Robin Dennis, NOAA/EPA • John Sherwell, MD DNR • Mark Garrison, Environmental Resources Management • Jeff Stehr, UMD • Dan Salkovitz, VA DEQ • Mike Kiss, VA DEQ • Kenn Pattison, PA DEP (invited) • Jeff Grimm, Penn State (invited) • etc. • Need direction from NSC and TSWG now on how to determine air environmental indicator for 2006 Chesapeake Bay Restoration Assessment.

24. Reducing Pollution Environmental Indicators:Air Pollution, Agriculture, Urban/Suburban Lands Air Nitrogen Pollution For reporting purposes, it’s necessary to account for the air piece, but how? Percent of Goal Achieved Agriculture Nitrogen Pollution Should 2005 include impact of reduced deposition? Urban/Suburban Lands Nitrogen Pollution Should 2005 include impact of reduced deposition?

25. Peer-Review and the Nutrient Subcommittee’s Role with Air at the Chesapeake Bay Program DISCUSSION • Need for a Peer-Review Process • Is it the NSC’s job to put a peer-review process in place? • How do we establish a peer-review process? • Who could serve as peer-reviewers? • STAC? • Air experts from jurisdictions? • What role, if any, should the NSC have in addressing air issues? • What are NSC recommendations concerning air?