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1
Introduction
T
he Chesapeake Bay is North America’s largest and most biologically
diverse estuary, home to thousands of species of plants and animals
(CBP, 2000) as well as an important commercial and recreational
resource. The Chesapeake Bay serves as a key economic driver in the mid-
Atlantic region, and the Chesapeake Bay Foundation (2010) valued its
worth at over one trillion dollars to the watershed’s economy. The Bay’s
ecosystem has been affected by human influences since early settlements,
but these influences became known and more pronounced during the 20th
century. Today, almost 17 million people live within the Bay’s 64,000
square mile (166,000 square kilometer) watershed in six states—Delaware,
Maryland, New York, Pennsylvania, Virginia, and West Virginia—as well
as the District of Columbia (Figure 1-1; CBP, 2010a). Excess amounts
of nitrogen, phosphorus, and sediment from human activities and land
development, including agriculture, urban and suburban runoff, wastewa-
ter discharge, and air pollution, are sent to the Bay (CBP, 2010a). These
pollutants and other chemical and physical alterations have disrupted the
ecosystem, causing degraded habitats and harmful algal blooms that impact
the survival of fish, shellfish, and other aquatic life.
The Chesapeake Bay was among the first of the major U.S. estuaries
where concerted efforts were made to understand the causes and conse-
quences of changing ecosystem conditions. During the mid-1970s, a young
U.S. Environmental Protection Agency (EPA) led the first comprehensive
and detailed attempt to understand the Bay’s condition and what would be
necessary to restore it to its former condition. That 7-year research effort
culminated in the report, Chesapeake Bay: A Framework for Action (EPA,
13
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14 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY
FIGURE 1-1 Chesapeake Bay Watershed.
SOURCE: CBP (2008). Available at http://www.chesapeakebay.net/maps.
aspx?menuitem=16825. Figure 1-1 AND S-1.eps
bitmap
1983a,b), which described the condition of the Bay’s ecosystem, its change
over time, and scientific evaluations of the Bay’s functions in relation to its
condition. The report established a framework for action to address some
of the Bay’s most significant problems. Expert panels assembled by the EPA
recommended immediate attention to the cultural eutrophication caused
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15
INTRODUCTION
by nutrient enrichment, which had caused a long-term decline in the Bay’s
health (EPA, 1983a,b).
In 1983, the Chesapeake Bay Program (CBP) was established, based on
a cooperative partnership among the EPA, the state of Maryland, the com-
monwealths of Pennsylvania and Virginia, and the District of Columbia,
to address the extent, complexity, and sources of pollutants entering the
Bay (EPA, 1983a). By 2002, the states of Delaware, New York, and West
Virginia committed to the CBP’s water quality goals by signing a Memo-
randum of Understanding (CBP, 2002).
A key component of the restoration program focuses on improving the
water quality in the Bay and its tidal tributaries. Water quality is evalu-
ated according to three parameters that are linked to one or more of the
Bay’s habitats and faunal communities: dissolved oxygen, water clarity,
and chlorophyll a. Criteria for these three water quality parameters serve
as the basis for the current goals, spurring efforts to reduce nutrient and
sediment loads. Excess nitrogen and phosphorus loads fuel the growth of
algal blooms, which increase chlorophyll concentrations, reduce clarity,
and contribute to hypoxia (or low dissolved oxygen levels). Hypoxia, in
turn, impacts water quality and habitat, especially underwater grasses and
associated aquatic life (reviewed in NRC, 2000). In addition to these direct
responses to nutrient enrichment, indirect responses and nonlinear feed-
back mechanisms, such as increased turbidity associated with the decline
of filter-feeding bivalves and underwater grasses, may play an important
role in the Bay’s degradation (Kemp et al., 2005). Other stressors such as
chemical contaminants from air pollution, climate change, habitat destruc-
tion, and over-harvesting of fish and shellfish also stress the Bay and its
living resources at great environmental, economic, and social costs to the
populations that rely on a healthy ecosystem (CBP, 2010a).
In this introductory chapter, the sources and impacts of nitrogen, phos-
phorus, and sediment pollution in the Bay watershed are reviewed. A brief
history of the CBP’s efforts is presented to provide context for the major
current initiatives, including the total maximum daily load (TMDL) and
the two-year milestone strategy. Finally, the committee’s task and approach
are discussed.
NITROGEN, PHOSPHORUS, AND SEDIMENT
IN THE CHESAPEAKE BAY WATERSHED
Since colonization by Europeans almost 400 years ago, the Chesa-
peake Bay and its watershed have undergone significant human-induced
changes, such as deforestation and urban development. The watershed is
still dominated by wooded and open space (69 percent of the watershed),
but agricultural and developed land uses (22 and 7 percent, respectively) are
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16 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY
significant and increasing (EPA, 2010a). Sedimentation from agricultural
expansion and land-use conversions, runoff of fertilizers and animal wastes,
and atmospheric deposition of nitrogen from fossil fuel combustion and
agriculture have contributed to observed changes to the Bay (Brush, 2009;
Cooper and Brush, 1991). By the mid-1980s, the Bay was receiving 7 times
more nitrogen and 16 times more phosphorus than when English colonists
arrived (Boynton et al., 1995).
This section briefly describes the specific sources of nitrogen, phospho-
rus, and sediments to the Bay and its watershed. These sources are internal
(e.g., biological processes in soils, sediments, and the water column) and
external (e.g., commodity imports, atmospheric deposition). On the whole
for the Bay and its watershed, anthropogenic sources of both phosphorus
and nitrogen are several-fold larger than natural sources (Boynton et al.,
1995; reviewed in Rabalais et al., 2009).
Annual loads of nutrients and sediment vary widely with climatic
conditions, with wet years leading to much higher loads (see Figure 1-2).
Because this variability can create challenges for calculating source contri-
butions, the pollutant source data presented in this section are largely based
on model output. The data were produced by the CBP Phase 4.3 Watershed
Model or the CBP Airshed Model (Box 1-1) and were presented in the Bay
Barometer (CBP, 2010a). Recent watershed model updates provided new
estimates, but the committee was unable to disassociate Phase 5.3 Water-
shed Model source load data to account for the specific contributions of
atmospheric sources.1 The Phase 4.3 Watershed Model data presented in
this section represent loading averages based on simulations over 14 years
of hydrologic record using land use, best management practices (BMPs),
and point-source controls reflecting 2007 conditions.
Nitrogen
Imported fertilizer and commodities (e.g., grain), primarily from other
regions in the United States, and atmospheric deposition are important
external sources of nitrogen to the Bay watershed. Atmospheric deposition
of oxidized reactive nitrogen (NOy; the sum of nitric oxide [NO] and nitro-
gen dioxide [NO2] [collectively termed NOx] + all other oxidized nitrogen
1 In many CBP reports, atmospheric deposition is frequently lumped into the source sector
on which the nitrogen is deposited (i.e., nitrogen deposition on forested lands is considered
a forest source). Thus, atmospheric deposition is reported as a much smaller fraction than
the plots included in this chapter (e.g., Figure 1-3), which consider the original sources of the
nutrients. Plots showing the actual sources were not available from the CBP Watershed Model
Phase 5.3; therefore, these source data reflect model output from the earlier model, Phase 4.3.
Comparison data to the latest model version are provided in subsequent footnotes.
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17
INTRODUCTION
Figure 1-2.eps
FIGURE 1-2 Nitrogen and phosphorus loading (millions of pounds) delivered to
bitmap
the Chesapeake Bay and total river flow (billions of gallons), 1990-2009. These
loading estimates are based on direct measurements (i.e., monitoring in tributary
rivers and point source discharges) supplemented by model estimates for ungaged
portions of the watershed. The red lines indicate the 10-year average load targets
for nitrogen and phosphorus (175 million pounds and 12.8 million pounds, respec-
tively) established in EPA (2003).
SOURCE: CBP (2010a).
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18 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY
BOX 1-1
Chesapeake Bay Models
The CBP relies upon models to forecast the effects of changing
nitrogen, phosphorus, and sediment management in the Chesapeake
Bay. The models also form the basis of the current total maximum daily
load (TMDL) allocations. The models are of two types: (1) models that
simulate the physical, chemical, and biological processes in the airshed
(Chesapeake Bay Airshed Model), watershed (Chesapeake Bay Water-
shed Model), and estuary (Chesapeake Bay Water Quality and Sediment
Transport Model [or Bay Model]) and (2) models that convert land-use
practices and implementation of best management practices (BMPs)
into predictions of nutrient and sediment loads under average hydrologic
conditions (the Land Use Change Model and Scenario Builder).
The Bay Airshed Model combines a wet deposition regression model
with a continental-scale air quality model called the Community Multi-
scale Air Quality (CMAQ) Model. The Airshed Model provides the quan-
tity of nutrients deposited via rainfall and dry deposition to the watershed
and the Bay’s surface.
The Watershed Model is based on the Hydrologic Simulation Program-
Fortran (HSPF) model. It receives the atmospheric and other nutrient in-
puts and stimulates the quantity of nutrients and sediment discharged to
the tributaries and main stem Bay. It is a lumped-parameter model, which
means that it is not able to represent spatial locations of specific land use
categories in each of the many small watersheds in the overall Chesa-
peake Bay basin. Further, HSPF does not mathematically characterize
the time dependency (lag) of the farm plot scale response to agricultural
BMPs, nor does it consider lag times introduced by groundwater flow. In
other words, an assumption in the HSPF model is that nutrient reduc-
tions due to BMP implementation are instantaneous load reductions as
a simple fraction of the pre-BMP load.
The Bay Model combines a three-dimensional curvilinear hydrody-
namic model (CH3D) with an eutrophication model (CE-QUAL-ICM) and
computes the concentrations of nutrients and suspended sediment that
result from the Watershed Model inputs, the quantity of phytoplankton
that grow and decay, and the resulting water clarity and dissolved oxygen
(DO) concentrations. In addition, the quantities of submerged aquatic
vegetation (SAV) and water column (zooplankton) and benthic (deposit
and filter feeding) organisms are also computed as well as specific
simulations of oyster and menhaden populations. Modeled estimates of
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19
INTRODUCTION
DO, chlorophyll, and light attenuation are used to determine if Bay water
quality standards for DO, chlorophyll a, and water clarity have been vio-
lated. The models of the watershed and estuary have been continuously
developed and refined over a 25-year period (Table 1-1) (Linker et al.,
2000, 2002, 2008).
The Land Use Change Model and Scenario Builder are used to
construct input scenarios for the Watershed Model to analyze current
loads and forecast future loads under various land-use conditions. The
Land Use Change Model provides annual time series of land use in the
watershed and forecasts the land-use changes expected through 2030.
Scenario Builder converts the numerous BMPs, which have various pol-
lution reduction efficiencies depending on type and location in the water-
shed, to a common currency of nitrogen and phosphorus load that will be
generated by a given land use and estimates the area of soil available
to be eroded. Loads are input to the Watershed Model to generate mod-
eled estimates of loads delivered to the Bay (EPA, 2010a). The linkages
between these models are illustrated in Figure 1-3.
FIGURE 1-3 Key models used in the1-3.eps
Figure Chesapeake Bay Program.
bitmap
SOURCE: EPA (2010a).
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20
TABLE 1-1 Historical Development of the Watershed and Bay Models
Watershed Model Bay Model Notable Period of Management
Model Revisions Characteristics Characteristics Advances Simulation Decisions Supported
Phase 1 (1985) Based on HSPF. Steady state First coupling 4-month General goal of 40%
Contained 5 land of watershed, summer of controllable loads
uses, 64 segments hydrodynamic, simulation (CBP, 1987)
and water quality only of 3 years
models (1965, 1984,
and 1985)
Phase 2 (1992) Expanded Dynamic 4,000 First integrated 4 continuous Nutrient load
agriculture grid cell model sediment flux years (1984- reductions to
simulation detail model; first 1987), hourly achieve CBP (1987)
inclusion of time step goals
atmospheric
deposition.
Phase 4.3 (2003) 9 land uses, Dynamic 13,000 Integrated 14 continuous Expanded nutrient
94 watershed grid cell model simulation of years (1985- allocations
segments land and soil 1994), hourly
contaminant time step
runoff processes;
SAV, benthic
deposit, and filter
feeders models
Phase 5.3 (2010) 25 land uses Dynamic 57,000 Enhanced 21 continuous TMDL
(time variable), grid cell model segmentation, years
899 watershed land uses, and (1985-2005)
segments mechanistic detail
SOURCE: EPA (2010b); L. Linker, EPA, personal communication, 2011.
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21
INTRODUCTION
BOX 1-2
Forms of Atmospheric Nitrogen
Total oxidized reactive nitrogen, NOy
NOy = NO + NO2 + NO3 + HNO3 + N2O5 + HONO
+ organic nitrates + particulate nitrates
Nitrogen oxides, NOx
NOx = NO + NO2
Reduced inorganic nitrogen, NHx
NHx = NH3 + NH4
Unreactive nitrogen: N2
compounds except N2O) primarily results from combustion sources (see
Box 1-2).
Atmospheric deposition of reduced inorganic nitrogen (NHx; ammo-
nia [NH3] + aerosol ammonium [NH4]; Box 1-2) primarily results from
agricultural sources, such as manure. Sources internal to the watershed are
primarily natural biological nitrogen fixation (e.g., soils) and cultivation-
induced nitrogen fixation (e.g., soybeans).2 For the Bay itself, the primary
internal source is biological nitrogen fixation. Nitrogen that originates from
sources internal and external to the watershed is delivered to the Bay waters
by atmospheric deposition, direct discharges from wastewater treatment
plants and stormwater systems, and groundwater and riverine inputs.
Once introduced into the watershed, the fate of nitrogen is dependent
upon its source. A large fraction of the nitrogen from municipal and indus-
trial wastewater point sources and urban runoff, which can be categorized
either as a nonpoint source or regulated point source,3 is rapidly trans-
2 Nitrogen fixation is a natural process by which unreactive nitrogen (N2) in the atmosphere
is converted to biologically available ammonia by enzymatic reduction.
3 The Clean Water Act (CWA) defines a point source of water pollution as “any discernible,
confined and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel,
conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation,
or vessel or other floating craft, from which pollutants are or may be discharged.” Federal
regulations require that all point sources meet discharge limitations provided for in National
Pollutant Discharge Elimination System (NPDES) permits. More recently, stormwater runoff
in urban areas meeting certain population density criteria or land use conditions has been
defined as a regulated point source requiring an NPDES permit. Some urban and agricultural
sources that are categorized as point sources under the CWA may be indistinguishable from
unregulated nonpoint sources, both in terms of character and the management practices that
may be effective in their control. The only difference is often size and whether a NPDES
permit has been issued. To avoid confusion in this report, especially for readers who may
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22 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY
ported to the Bay. Of the nitrogen introduced into agricultural systems,
most is used in the system and then lost to the atmosphere, discharged
into an aquatic system, or stored in the soil. Less than 50 percent is actu-
ally incorporated into feed or food (Smil, 1999; Cassman et al., 2002). If
nitrogen infiltrates into groundwater (e.g., from a septic system leach field
or agricultural fertilizers), then it potentially could be stored for significant
lengths of time (i.e., years to decades) before it is discharged to surface
waters (Phillips and Lindsey, 2003; Lindsay et al., 2003; see Box 1-3).
Reactive nitrogen is lost from the watershed system by denitrification
within the watershed and its waters and by export. Denitrification converts
nitrate primarily to nitrogen gas (N2), with smaller amounts of N2O and
NO produced. N2 formation represents a conversion of reactive nitrogen
to an unreactive nitrogen form and thus removes the nitrogen from interac-
tion with the earth systems’ processes for millions of years. N2O and NO
formation, however, represent the conversion of one type of reactive nitro-
gen to other types of reactive nitrogen, each with their own environmental
impacts. The amount of NO formed by denitrification is small compared
to the NO formed from fossil fuel combustion within the watershed. In
contrast, denitrification forms the primary source of N2O, a potent green-
house gas, within the Bay and its watershed (Galloway et al., 2004, 2008).
Overall, how much denitrification occurs in the Bay watershed remains the
largest uncertainty of the nitrogen cycle.
Nitrogen is exported out of the watershed through three pathways:
(1) atmospheric advection of the nitrogen emitted to the watershed’s atmo-
sphere, (2) hydrologic transport of nitrogen to the coastal ocean in the
waters leaving the Bay, and (3) shipment from the watershed of nitrogen-
containing commodities that are produced in the Bay (e.g., shellfish, fish)
or its watershed (e.g., food, feed).
Estimates of Nitrogen Source Loads to the Bay
Approximately 400 million pounds (181 million kg) of nitrogen com-
pounds emitted to the atmosphere are deposited on the Bay’s watershed
each year, with approximately 68 percent coming from NOy and 32 per-
cent from NHx (R. Dennis, EPA, personal communication, 2011). Sources
of atmospheric nitrogen are described in Box 1-4. Most of the deposited
nitrogen is retained by forests or other vegetation and in other biological
not be as familiar with federal regulatory programs, the terms “point” and “nonpoint” will
be appropriately qualified as to origin, i.e., “municipal” and/or “industrial” point sources,”
“urban” and/or “agricultural” point or nonpoint sources. In many cases, it is expeditious to
aggregate urban and agricultural point sources and nonpoint sources, in which case the terms
“urban runoff” and “agricultural runoff” are used to incorporate the two but do not include
discharges from municipal or industrial wastewater treatment facilities.
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23
INTRODUCTION
processes before it reaches the Bay. Of all the atmospheric nitrogen that is
deposited on the watershed annually, the Watershed Model estimates that
approximately 75 million pounds (34 million kg) actually reach the Bay’s
tidal waters, largely washed off impervious surfaces. Another 19 million
pounds (8.6 million kg) are deposited directly on the Bay’s tidal waters,
for a total of approximately 94 million pounds (43 million kg) or 33 per-
cent of the total nitrogen load to the Bay (CBP, 2010a; Figure 1-4). Of the
nitrogen that enters the watershed, that which is not quickly discharged
to the Bay or denitrified to N2 is stored in the watershed in groundwater
and can potentially be released to the Bay in the future (also called legacy
nitrogen; see Box 1-3).
FIGURE 1-4 Sources of nitrogen to Chesapeake Bay.
NOTES: Based on model simulations using the Watershed Model Phase 4.3 and
the Airshed Model, considering land use and pollution control measures in place
as of 2007. The data reflects the average output when simulated over 14 years of
hydrologic record and does not include loads from the ocean or tidal shoreline
erosion. Atmospheric deposition loads are categorized by the source of the atmo-
spheric nitrogen, except for the deposition directly to tidal waters, which includes all
sources. For example, agricultural atmospheric deposition includes the atmospheric
deposition that emanates from agricultural lands. Wastewater loads are based on
measured discharges.
SOURCE: CBP (2010a).
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48 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY
400
350 NTWDep
Total Nitrogen (M lbs/year)
Forest
Septic
300 Point Source
Urban runoff
Agriculture
250
200
150
100
50
0
1985 2009 Trib. Strategy TMDL E3
30
NTWDep
Forest
Total Phosphorus (M lbs/year)
25
Septic
Point Source
Urban runoff
20 Agriculture
15
10
5
0
1985 2009 Trib. Strategy TMDL E3
12000
NTWDep
Forest
10000
Total Sediment (M lbs/year)
Septic
Point Source
Urban runoff
8000 Agriculture
6000
4000
2000
0
1985 2009 Trib. Strategy TMDL E3
Figure 1-13.eps
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49
INTRODUCTION
RECENT INITIATIVES (2008-2010)
Recognition that the CBP would again fail to meet its goals set in the
2000 Agreement (CBP, 2000), combined with a highly critical review by the
Government Accountability Office (GAO, 2005), led to a renewed focus
on accountability and tracking of progress in the restoration process. In its
2005 report, GAO stated:
The Bay Program does not have a comprehensive, coordinated implemen-
tation strategy to better enable it to achieve the goals outlined in Chesa-
peake 2000. Although the program has adopted ten key commitments to
focus partners’ efforts and developed plans to achieve them, some of these
plans are inconsistent with each other or are perceived as unachievable by
program partners.
In addition, the GAO questioned the effectiveness and credibility of
the CBP’s annual progress reports, which had not clearly distinguished
monitoring results from model projections. To address these concerns, the
CBP developed the Chesapeake Action Plan (CAP), which was intended to
enhance coordination and engagement among CBP partners, increase the
CBP’s transparency, and heighten the CBP’s accountability (CBP, 2008).
The Obama administration injected new energy into Bay restoration
efforts. On May 12, 2009, President Obama released an executive order
directing the federal government to lead restoration efforts and the EPA
FIGURE 1-13 Average annual (a) total nitrogen loading, (b) total phosphorus load-
ing, and (c) total sediment loading (in million lbs/yr) delivered to Chesapeake Bay
as estimated in five scenarios of the Phase 5.3 Watershed Model (see Table 1-1).
SOURCE: S. Ravi, CBPO, personal communication, 2011.
NOTES: The scenarios are modeled using the same hydrologic conditions (1985-
2005) and changing land use, point source, and BMP conditions. The scenarios
include 1985 baseline conditions, 2009 progress, the tributary strategy (TS) goals
based on the cap loads set in 2003, total maximum daily load (TMDL), and maxi-
mum feasible reduction (E3) scenarios. The E3 scenario is a “what if” scenario of
watershed conditions with theoretical maximum levels of managed controls on load
sources (“everything, by everyone, everywhere”), with no cost and few physical
limitations to implementing BMPs for point and nonpoint sources. Source sec-
tors include agriculture, urban runoff, point sources (including wastewater), septic
systems, forested lands, and non-tidal waters atmospheric deposition (NTW Dep).
Note that in these bar graphs, atmospheric deposition is considered separately
only when it falls directly on non-tidal waters; otherwise, the source is attributed
to the land-use type on which the deposition falls. The data are also provided in
Appendix A.
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50 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY
to coordinate efforts with several federal agencies, in collaboration with
state governments, to reduce pollutants flowing into the Bay (Executive
Order 13508). In response, by November 2009, federal CBP partners had
completed reports that outlined a new state and federal accountability
framework and actions to reduce pollution and improve compliance (DOD,
2009; DOI, 2009; DOI and DOC, 2009a,b,c; EPA, 2009; USDA, 2009).
Chesapeake Bay Total Maximum Daily Load (TMDL)
A TMDL, or total maximum daily load, is defined as the maximum
allowable load of a pollutant that a water body can receive while still meet-
ing its water quality standard. Under President Obama’s executive order,
the EPA Administrator was charged with developing a management plan
to address the negative consequences of nutrient and sediment loading into
the Chesapeake Bay. Under the lead of EPA Region III, a multistate TMDL
analysis was conducted. The Bay jurisdictions produced watershed imple-
mentation plans (WIPs) in support of the TMDL. The EPA established the
final TMDL in December 2010.
The EPA established the Chesapeake Bay TMDL in response to a
number of existing authorities, including the CWA, several judicial consent
decrees, a settlement agreement resolving litigation brought by the Chesa-
peake Bay Foundation, the 2000 Agreement, and Executive Order 13508.
The TMDL’s executive summary identifies the effort as “…a ‘pollution
diet’ that will compel sweeping actions to restore the Chesapeake Bay and
its vast network of streams, creeks and rivers” (EPA, 2010a). Further, the
TMDL addresses three pollutants—nitrogen, phosphorus, and sediment—
related to dissolved oxygen and water clarity standards necessary to restore
the Bay ecosystem. The TMDL articulates the following expectation: “The
TMDL is designed to ensure that all pollution control measures to fully
restore the Bay and its tidal rivers are in place by 2025, with 60 percent of
the actions completed by 2017” (EPA, 2010a).
The TMDL stipulates Bay watershed load limits of 185.9 million
pounds (85.3 million kg) of nitrogen, 12.5 million pounds (5.67 million
kg) of phosphorus, and 6.45 billion pounds (2.93 billion kg) of sediment
per year based on average hydrologic conditions during the 1985-2005
period. These loads represent a 24 percent reduction in nitrogen and phos-
phorus and a 20 percent reduction in sediment from the model-simulated
loads based on 2009 land use conditions (EPA, 2010a). These loads are
allocated among the seven Bay jurisdictions. The overall TMDL nutrient
and sediment reduction goals reflect relatively small modifications to the
cap load goals set in 2003 (EPA, 2003). The TMDL supports the CBP’s goal
of removing the Bay from the EPA’s list of impaired waters.
The Bay TMDL covers a larger area than any other U.S. TMDL.
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51
INTRODUCTION
Although EPA lists over 4,700 nutrient TMDLs nationwide that have been
established since October 1995, relatively few address estuaries.9 However,
the Chesapeake Bay TMDL is within the range of reductions (by percent-
age) for several other estuaries, including the nutrient TMDL for New York
and Connecticut’s Long Island Sound (58.5 percent reduction in nitrogen
discharges from the adjusted 1990 baseline load; NYS DEC and CT DEP,
2000), the Caloosahatchee Estuary in Florida (23 percent reduction in total
nitrogen loading; Bailey et al., 2009) and Newport Bay in California (50
percent reduction from current nutrient and sediment loadings; EPA, 2002).
Watershed implementation plans (WIPs), developed by the seven Bay
jurisdictions, define how and when they will meet their nitrogen, phospho-
rus, and sediment load allocations. The EPA will evaluate WIP implemen-
tation and the Bay jurisdictions’ progress toward meeting their two-year
milestones (described in the next section). If implementation progress is
insufficient, the EPA can take appropriate “backstop measures” to ensure
compliance with the TMDL. Backstop measures can include targeted
enforcement actions on regulated sources, expansion of requirements to
obtain discharge permits for currently unregulated sources, or additional
reductions from federally permitted sources of pollution (e.g., wastewater
treatment plants, large animal operations, municipal stormwater systems)
(EPA, 2010a).
The Bay jurisdictions will submit draft Phase II WIPs that provide
local area nutrient allocations on a smaller scale by December 2011. Phase
II WIPs are expected to include roles for local governments and munici-
palities, especially for managing nutrient loading from urban and suburban
areas (EPA, 2010a).
Two-Year Milestones
To accelerate progress and increase accountability in the Bay restora-
tion, the CBP introduced a two-year milestone strategy for nutrient load
reductions in May 2009. In the past, Bay recovery goals involved decadal
increments and did not identify specific strategies for achieving the neces-
sary pollution reductions. The prior decadal goals were characterized as
“ladder[s] without rungs” (CBP, 2009b). In addition, elected officials were
not held accountable for attaining the goals because the timeframes for
achieving them often extended beyond their terms of office. As a result,
progress was sluggish, and major goals were not met (CBP, 2009b). The
two-year milestone program introduced a revised strategy aimed at reduc-
ing overall pollution in the Bay by focusing on short-term, incremental
implementation goals. The CBP envisioned that through a series of two-
9 See http://www.epa.gov/waters/ir/index.html.
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52 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY
year milestone periods with routine assessments of the pace of progress, by
2025 the Bay jurisdictions could implement all of the nutrient and sediment
control practices needed for a restored Bay, although actual Bay water qual-
ity response and recovery likely will lag behind the 2025 implementation
target.
The two-year milestone strategy required each Bay jurisdiction to com-
mit to an initial suite of actions in the first milestone period to be completed
by December 31, 2011. The jurisdictions identified specific actions, includ-
ing application of land-based BMPs and wastewater treatment facility
upgrades, anticipated to keep them on track to meet the long-term imple-
mentation goals by 2025. Each Bay jurisdiction also identified contingency
actions that could be taken if some of the primary nutrient reduction
practices could not be implemented in this timeframe. The CBP aims ulti-
mately to reduce nitrogen and phosphorus loading in the watershed by 15.8
million pounds (7.2 million kg) and 1.1 million pounds (500 thousand kg),
respectively, by actions completed during the first milestone (CBP, 2009b).
If all proposed actions are implemented, the first milestone actions are
anticipated to ultimately provide about 21 percent of the nitrogen load
reduction and 22 percent of the phosphorus load reduction needed to meet
the Tributary Strategy cap loads (Table 1-5). See Box 1-5 for a Bay-wide
summary of the first milestone actions. Reductions for nitrogen and phos-
phorus in the first milestone period are shown by sector in Figure 1-14.
No sediment milestone was set for the first milestone period (2009-
2011) because of uncertainties in the overall sediment target at the time,
although sediment milestones are expected to be added for the next two-
year milestone (2012-2013). Many of the two-year milestone measures to
control nutrient loading, however, will also significantly reduce sediment
loading.
The Bay jurisdictions are currently developing strategies for the sec-
ond milestone period. Through tracking and accounting mechanisms (see
Chapter 2), the CBP will assess each Bay jurisdiction’s implementation
progress toward the two-year milestones. Given lags between land-based
BMP implementation and nutrient and sediment reduction in the Bay (see
Box 1-3), the CBP primarily assesses progress toward the two-year mile-
stone goals by tracking implementation of practices rather than monitoring
nutrient loads in streams.
Integrating Two-Year Milestones, Watershed Implementation
Plans, and the TMDL for Chesapeake Bay
Although the two-year milestones were originally conceived as steps
toward meeting the cap load goals, they are now being used as measures
of incremental progress toward meeting the TMDL WIP goals for 2017
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TABLE 1-5 Estimated Contribution of the First Milestone Toward Reductions to Meet Tributary Strategy Cap Loads
Model-estimated
Average Load based Tributary Strategy 2009-2011 Percentage of Load
on 2008 Progress Cap to Meet Water Reduction Required Estimated Milestone Reduction to meet
Run Quality Standards by 2025 Reduction Tributary Strategy Cap
(million pounds (million pounds (million pounds (million pounds Loads Targeted in First
per year) per year) per year) per year) Milestone
Nitrogen 258.5 183.1 75.4 15.8 21.0
Phosphorus 17.8 12.8 5.0 1.1 22.1
Sediment 9,500 8,293 1,207 NA NA
NOTES: All load estimates, including the Tributary Strategy cap loads, were developed based on Phase 4.3 of the Chesapeake Bay Watershed
Model. The TMDL (EPA, 2010a) was developed using Phase 5.3, and therefore, for consistency, the overarching goals are presented in terms of
the Tributary Strategy goals. The original milestone commitments would need to be simulated using the Phase 5.3 Watershed Model to calculate
the percentage of the TMDL to be accomplished by the first milestone.
SOURCES: CBP (2009b); K. Antos, CBPO, personal communication, 2011.
53
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54 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY
BOX 1-5
Best Management Practices to Be Implemented in
First Milestone Period (2009-2011) across the
Chesapeake Bay Watershed
The following best management practices represent the sum of total
activities to be implemented under the first milestone period in the
Chesapeake Bay watershed.
Agriculture
Nutrient Management 1,082,251 acres
Conservation Tillage 306,991 acres
Cover Crops 652,152 acres/year
Pasture Grazing BMPs 168,800 acres
Streamside Forest Buffers 39,110 acres
Streamside Grass Buffers 14,910 acres
Forest Harvesting Practices 125 acres
Wetland Restoration 3,809 acres
Land Retirement 81,676 acres
Tree Planting 27,965 acres
Carbon Sequestration/Alternative Crops 25,740 acres
Conservation Plans/SCWQP 584,648 acres
Animal Waste Management Systems 1,016 systems
Mortality Composters 22 systems
Water Control Structures 25,000 acres
Horse Pasture Management 300 acres
Non-Urban Stream Restoration 232,088 feet
Poultry Phytase 19,626 fewer pounds P
and 2025. The milestones are intended to improve accountability and
allow for adjustments if needed. These issues are discussed in more detail
in Chapter 3.
A summary of how the two-year milestone strategy is incorporated into
the existing Bay restoration goals and TMDL accountability framework
is depicted in Figure 1-15. In the two-year milestones, Bay jurisdictions
identify practices to be implemented during every 2 year period until 2025.
WIPs present cumulative practice implementation goals for 2017 (Phase 1)
and 2025 (Phase 2).The TMDL defines the total load reductions (nitrogen,
phosphorus, and sediment) necessary to meet water quality criteria. The
ultimate goal is to meet the ecological endpoints associated with a fully
restored Bay (extent of underwater grasses, fisheries abundance, and diver-
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55
INTRODUCTION
Manure Transport 131,503 net tons
Dairy Precision Feeding and/or 291,203 pounds N
Forage Management 51,264 pounds P
Heavy Use Poultry Area Concrete Pads 400 farms
Livestock and Poultry Waste Structures 198 structures
Dairy and Poultry Manure Incorporation Technology 5,000 acres
Wastewater
1,887,350 pounds nitrogen reduced
201,500 pounds phosphorus reduced
Urban/Suburban
Urban Stormwater Management 148,740 acres
Tree Planting 30 acres
Urban Stream Restoration 18,656 feet
Erosion and Sediment Control 62,731 acres
Nutrient Management 133,000 acres
Wetland Restoration 350 acres
Abandoned Mine Reclamation 2,219 acres
Dirt and Gravel Road Erosion 124,913 feet
Septic Improvements 27,125 systems
Air
Heavy Truck Anti-Idling Rule 9.78M hours reduced
NOx Reductions 56,000 tons
Maryland Healthy Air Act 305,882 fewer pounds N/year
SOURCE: CBP (2009b).
sity and other natural resource goals), as defined by the CBP (see Table
1-2). The EPA will review progress toward these two-year milestones, in
the context of the TMDL, and will evaluate whether sufficient actions are
being planned and undertaken to achieve the necessary pollution reductions
(EPA, 2010a).
STATEMENT OF COMMITTEE TASK AND REPORT OVERVIEW
In 2009, the NRC’s Committee on the Evaluation of Chesapeake Bay
Program Implementation for Nutrient Reduction to Improve Water Qual-
ity was formed to undertake an evaluation of the CBP’s nutrient reduction
program and to respond to the GAO (2005) recommendation for indepen-
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56 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY
FIGURE 1-14 Percentage of nutrient reductions planned in the first milestone period
from agriculture, wastewater, urban/suburban, air, and other sectors.
SOURCE: CBP (2009b).
Figure 1-14.eps
bitmap
Restoration of underwater grasses, fisheries, benthic communities, and
Ecological faunal diversity
Endpoints
Meet Bay water quality criteria for dissolved oxygen, clarity, and
chlorophyll-a concentrations; 60 percent of Bay segments attaining
Water
standards by 2025.
Quality
Criteria
Chesapeake Bay total maximum daily load: Achieve loads of 185.9
Load
million lbs/yr N, 12.5 million lbs/yr P, and 6.45 billion lbs/yr sediment.
Reduction
Goals:
TMDL
Watershed implementation plans: Have in place by 2025 all practices
needed to meet TMDL limits; 60 percent in place by 2017.
Practice
Two-year milestones: At the end of each two-year milestone period,
Implementation
have in place all practices planned for that period.
Goals
Figure 1-15.eps
FIGURE 1-15 Integration of the goals and strategies used in the CBP, including
two-year milestones and the TMDL accountability framework.
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57
INTRODUCTION
dent review to enhance the credibility and objectivity of its reports. This
study was sponsored by the EPA, with additional funding support from the
states of Virginia, Maryland, Pennsylvania, and the District of Columbia.
The committee was specifically tasked to address the following questions,
broken down into two themes:
Evaluation Theme I: Tracking and Accountability
1. Does tracking for implementation of nutrient and sediment point and
nonpoint source pollution (including air) best management practices ap-
pear to be reliable, accurate, and consistent?
2. What tracking and accounting efforts and systems appear to be work-
ing, and not working, within each state (i.e., the six states in the watershed
and DC), including federal program implementation and funding? How
can the system be strategically improved to address the gaps?
3. How do these gaps and inconsistencies appear to impact reported pro-
gram results?
Evaluation Theme II: Milestones
4. Is the two-year milestone strategy, and its level of implementation, likely
to result in achieving the CBP nutrient and sediment reduction goals for
this milestone period?
5. Have each of the states (i.e., the six states in the watershed and DC) and
the federal agencies developed appropriate adaptive management strategies
to ensure that CBP nutrient and sediment reduction goals will be met?
6. What improvements can be made to the development, implementation,
and accounting of the strategies to ensure achieving the goals?
It is important to note, as discussed further in Chapter 2, that the com-
mittee charge (particularly Task 4) focuses on implementation of strategies
during the two-year milestone period, rather than on actual water quality
improvement during this period. Realistically, interannual variability and
delayed responses preclude the determination of conclusive relationships
between action and water quality improvement for such a short increment
of time. Additionally, because there are no milestones for sediment dur-
ing the first reporting period, which the committee was tasked to analyze,
the committee places greater emphasis on issues affecting nutrient loads,
although sediment issues are included throughout and have been more
recently quantified in the 2010 TMDL.
Although most of the tasks are narrowly focused, the committee took
a broad view in its interpretation of Task 6 on what improvements can be
made to the development, implementation, and accounting of the strategies
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58 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY
to ensure achieving the goals. The committee considered “the goals” to
include the long-term nutrient and sediment reduction goals and subsequent
recovery of the Bay ecosystem, not just the first two-year milestone goals.
In addition, the committee considered both practices and policies that could
improve the likelihood of achieving the goals, because the feasibility of
implementing specific practices is often affected by broader policy decisions.
The committee’s conclusions and recommendations are based on a
review of relevant technical literature, briefings, and discussions at its four
meetings and the experience and knowledge of the committee members in
their fields of expertise. Following this brief introduction, the statement of
task is addressed in four subsequent chapters of this report:
• In Chapter 2, the committee assesses the tracking and accounting
for BMPs and infrastructure upgrades for nutrient and sediment control
and identifies key issues facing the Bay jurisdictions and the CBP (Tasks
1, 2, and 3). The committee also identifies ways to improve tracking and
accounting procedures.
• In Chapter 3, the committee evaluates the two-year milestone
strategy and, based on the information presented, discusses the likelihood
of achieving the nutrient reduction goals for the first milestone period
(Task 4).
• In Chapter 4, the committee assesses the CBP’s adaptive manage-
ment approaches (Task 5), and identifies the challenges to and opportunities
for using adaptive management to meet nutrient and sediment reduction
goals.
• In Chapter 5, the committee describes overarching issues affect-
ing achievement of the nutrient reduction goals (Task 6), and discusses
improvements that, if implemented, could enhance the likelihood of achiev-
ing the program goals.
