DRAFT Chesapeake Bay TMDL

4

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## SECTION 4. SOURCES OF NUTRIENTS AND

SEDIMENT TO THE CHES APEAKE BAY

Nitrogen, phosphorus

, and sediment l oads originate from many sources in the Bay watershed

. Point sources of nutrient and sediment include m unicipal w astewater f acilities , i ndustrial

d ischarge facilities, CSOs, SSOs, NPDES permitted s tormwater (M S4 s and c onstruction and industrial sites), and CAFOs. Nonpoint sources include agricultural lands (AFOs, cropland, hay land, and pasture), a tmospheric deposition, forest lands, on

- site treatment systems, nonregulated stormwater runoff, streambanks and tidal shorelines, tidal resuspension, the ocean, wildlife, and natural background. Unless otherwise specified, the loading estimates presented i n this section are based on results of the Phase 5.3 Chesapeake Bay Watershed Model (Bay watershed model). For a description of the Bay watershed model, see Section 5. Estimates of existing loading conditions are based on the 2009 scenario run through the Bay watershed model.



### 4.1 Jurisdiction Loading Contributions

Analysis of 2009 monitoring data and modeling results shows that Pennsylvania provided the estimated largest proportion of nitrogen loads delivered to the Bay (44 percent), followed by Virginia (2 7 percent), Maryland (20 percent), New York (4 percent), Delaware (2 percent) and West Virginia (2 percent), and the District of Columbia (1 percent ) ( Figure 4

- 1 ). Del ivered loads are the amount of a pollutant delivered to the tidal waters of the Chesapeake Bay or its tributaries from an upstream point

. Delivered loads differ from edge

- of

- stream loads from in

- stream processes in free

- flowing rivers that remove nutrients from the system

.

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4

- 1

. Modeled estimated t otal nitrogen loads delivered to the Chesapeake Bay by jurisdiction in 2009

.DRAFT Chesapeake Bay TMDL

4

- 2 September 24 , 2010

The model estimated phosphorous loads delivered to the Bay were dominated by Virginia (43 percent), followed by Pennsylvania (24 percent), Maryland (20 percent), New York (5 percent), West Virginia (5 percent), Delaware (2 percent), and the District of Col umbia (1 percent) ( Figure

4

- 2 ).

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4

- 2 . Model esti mated total phosphorus loads delivered to the Chesapeake Bay by jurisdiction in 2009.DRAFT Chesapeake Bay TMDL

4

- 3 September 24 , 2010

Similar to the phosphorus loads, 2009 model estimated sediment loads delivered to the Bay are dominated by Virginia (41 percent), followed by Pennsylvania (32 percent), M aryland (17 percent), West Virginia (5 percent), New York (4 percent), Delaware (1 percent), and the District of Columbia (<1 percent) ( Figure 4

- 3 ).

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4

- 3 . Model estimated total sediment loads delivered to the Chesapeake Bay by jurisdiction in 2009.



### 4.2 Major River Basin Contributions

The major river basins ’ model

- estimated contributions to total nitrogen loads delivered to the Bay in 2009 are illustrated in Figure 4

- 4

. The Susquehanna River basin, draining parts of New York, Pennsylvania, and Maryland, is estimated to be responsible for almost half of the nitrogen loads delivered to the Bay (4 6 percent ). T he next major contributor, at 2 2 percent , is the Potomac River basin, draining the entire District of Columbia and parts of Maryland, Pennsylvania, Virginia, and West Virginia. At 12 percent and 8 percent , respectively, are the James River basin (entirely within Virginia) and the Eastern Shore basin (draining parts of Delaware, Maryland, and Virginia), while the Western Shore basin (draining parts of Maryland) is estimated to be responsible for 6 percent of the nitrogen loading to the Bay. Smaller portions, 3 percent , 3

percent , and 1 percent are contributed by the Rappahannock (Virginia), the York (Virginia) and the Patuxent (Maryland) river basins, respectively ( Figure 4

- 4 )

. Tota l Sediment

DC, <1% DE, 1%

PA, 32% VA, 40% NY, 4%

MD, 17% WV, 5%DRAFT Chesapeake Bay TMDL

4

- 4 September 24 , 2010

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4

- 4 . Model estimated total n itrogen loads delivered to the Chesapeake Bay by major tributary in 2009.

The major river basins ’ model estimated contributions to total phosphorus loads to the Bay in

2009 are illustrated in Figure 4

- 5

. Three river basins

— the Potomac (27 percent), the Susquehanna (2 6 percent ), and the James (2 0 percent )

— are estimated to account for about three

quarters of the total phosphorus loading to the Bay. The Eastern Shore contributes 10 percent

, while the balance is provided by the Rappahannock ( 7 percent ), the Western Sho re ( 5 percent )

, the York (4 percent ), and the Patuxent (2 percent ) river basins ( Figure 4

- 5 ).

The major river basins’ model estimated contributions to total sediment loads to the Bay in 2009

are illustrated in Figure 4

- 6 . The Susquehanna (33 percent) and Potomac (32 percent) river

basins are estimated to contribute the majority of the total sediment loads delivered to the Chesapeake Bay, followed by the James (16 percent) and the Rappahannock (9 percent) river basins. The Eastern Shore (4 percent), Western Shore (3 percent), York (2 percent) and Patuxent (1 percent) river basins each contribute relatively small total sediment loads ( Figure 4

- 6 ).DRAFT Chesapeake Bay TMDL

4

- 5 September 24 , 2010

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4

- 5 . Model estimated t otal phosphorus loads delivered to the Chesape ake Bay by major tributary in

2009.

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4

- 6 . Model estimated t otal sediment loads delivered to the Chesapeake Bay by major tributary in 2009

.DRAFT Chesapeake Bay TMDL

4

- 6 September 24 , 2010



### 4.3 Pollutant Source Sector Contributions

Table 4

- 1 and Table 4

- 2 provide m odel estimates of major pollutant sources of nitrogen and phosphorus, respectively, delivered to the Bay by jurisdiction and by major pollution source

sector. Nontidal deposition refers to atmospheric deposition direct to nontidal surface waters (e.g., str eams, rivers). Table 4

- 3 provides estimates of major sediment sources by jurisdiction and by major pollutant source sector and represents the portion of sediment that is from land

- based sources. Stream erosion is also a significant source of watershed sediment delivered to the Bay. Currently, sufficient data do not exist to accurately quantify the portion of the total sediment lo ad specifically from stream erosion.

Table 4

- 1 . Percentage of total nitrogen from each major pollutant source sector by jurisdiction

Jurisdiction Agriculture Forest Stormwater

runoff Point

source Septic Nontidal

deposition

Delaware 3% 1% 1% 0% 2% 1%

District of
Columbia 0% 0% 1% 5% 0% 0%

Maryland 16% 14% 28% 27% 36% 27%

New York 4% 7% 3% 3% 5% 5% Pennsylvania 55% 46% 33% 25% 30% 42% Virginia 20% 27% 33% 39% 24% 25% West Virginia 3% 4% 2% 1% 2% 1%

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Table 4

- 2 . Percentage of total phosphorus from each major pollutant source sector by jurisdiction

Jurisdiction Agriculture Forest Stormwater

runo ff Point

source Septic Nontidal

deposition

Delaware 4% 1% 1% 0% 0% 0%

District of
Columbia 0% 0% 1% 2% 0% 0%

Maryland 19% 14% 28% 21% 0% 27%

New York 5% 7% 3% 5% 0% 5% Pennsylvania 24% 25% 16% 28% 0% 27% Virginia 42% 45% 50% 42% 0% 38%

West Virginia 6% 7% 2% 3% 0% 2%

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario Note: The amount of phosphorus contributed from nontidal deposition is considered to be insignificant.DRAFT Chesapeake Bay TMDL

4

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Table 4

- 3

. Percentage of sediment from each source sector by jurisdiction

Jurisdiction Agriculture Forest Stormwater

runoff Point

source Septic Nontidal

deposition

Delaware 1% 0% 1% 0%

-- -- District of
Columbia 0% 0% 1% 27%

-- -- Maryland 15% 13% 32% 11%

-- -- New York 3% 8% 4% 3%

-- -- Pennsylvania 35% 34% 21% 23%

-- -- Virginia 41% 40% 39% 35%

-- -- West Virginia 5% 5% 3% 1%

-- -- Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

The following sections provide additional details regarding the major pollutant source sectors, including descriptions of the extent/magnitude of the pollutant source, geographic distribution, and long

- term trends relevant to the source sector. The signifi cance of the source sector in terms of loading to the Bay relative to other sources is also discussed.



### 4.4 Regulated Point Sources

Point sources are defined as any ― discernable, confined, and discrete conveyance, including

... any pipe, ditch, channel, tunne l, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation , landfill leachate collection system, or vessel or other floating craft

, from which pollutants are or may be discharged ‖ (CWA section 502(14), 40 CFR 122.2). That definition does not include agricultural stormwater discharges or return flows from irrigated agriculture, which are exempt from the definition of point source under the CWA. The NPDES program, under CWA s ections 318, 402, and 405, requires permits for the discharge of pollutants from point sources.

Two issues that directly affect modeling of the regulated point sources in the Bay watershed are the size of facility flows and permitted discharge limits. For purpose s of the Chesapeake Bay TMDL analysis and modeling, regulated point sources in the Chesapeake Bay watershed have been evaluated under the following categories:

Municipal wastewater facilities

Industrial wastewater facilities

CSOs

NPDES permitted stormwater (MS4s, industrial

, and construction)

NPDES permitted C AFOs

The remainder of this section outlines the distinctions between significant and nonsignificant municipal and industrial wastewater discharge facilities in the Bay watershed, explains how the

facil ities were addressed in modeling, discusses the effect of the basinwide nutrient permitting approach on point source modeling for the TMDL, and provides a summary of model

- estimated loads associated with each of the regulated point source categories of nut rients and sediment toDRAFT Chesapeake Bay TMDL

4

- 8 September 24 , 2010

the Bay. Appendix Q includes an inventory of the regulated point sources accounted for in the Bay TMDL

.



### 4.4.1 Significant and Nonsignificant Municipal and Industrial Facilities

Municipal and industrial wastewater discharge facilities are categorized as significant or nonsignificant primarily on the basis of permitted or existing flow characteristics and comparable loads in the case of industrial discharge facilities. The Bay jurisdictions define significant

facilities as outlined in Table 4

- 4

.

Table 4

- 4

. Jurisdiction

- specific definitions of significant municipal and industrial wastewater discharge fac ilities

Jurisdiction Municipal wastewater facilities (million gallons per day) Industrial wastewater facilities (estimated loads, pounds per year)

Delaware Design flow ≥ 0.4

≥ 3,800 total phosphorus or ≥ 27,000 total nitrogen District of Columbia Blue Plains WWTP

Maryland Design flow ≥ 0.5

New York Design flow ≥ 0.4

Pennsylvania Existing flow ≥ 0.4

Virginia Design flow ≥ 0.5 a

Design flow ≥ 0.1 b

New facilities ≥ 0.04 c

West Virginia Design flow ≥ 0.4

Source: USEPA 2010b

a. Above the fall line/tidal line.
b. Below the fall line/tidal line. c. Also includes expansion of flows ≥ 0.04 mgd.

Jurisdictions also may identify specific facilities as significant in their WIPs ( USEPA 2009 c ). Facilities not meeting the above criteria, a nd not otherwise identified in the jurisdictions’ WIPs, are considered nonsignificant facilities. Table 4

- 5 provides a jurisdictional breakdown of municipal and indust rial discharging facilities in the Chesapeake Bay watershed.

Table 4

- 5

. Significant and nonsignificant municipal and industrial wastewater discharging facilities by jurisdiction

Jurisdiction Significant facility

Total Nonsignificant facility

Total Municipal Industrial Municipal Industrial

DC 1 0 1 0 3 3

DE 3 1 4 1 1 15

MD 76 10 86 165 556 721

NY 26 2 28 17 40 5 7

PA 18 7 30 21 7 1,240 388 1,628

VA 101 24 125 1,23 9 339 1,578

WV 10 12 22 132 102 234

Total 404 79 483 2,79 4 1,4 29 4,236

Source: Facilities identified in the Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Note: There are multiple facilities sharing one NPDES permit in W est V irginia

.DRAFT Chesapeake Bay TMDL

4

- 9 September 24 , 2010

For the TMDL, facilities were represented using various flow and discharge concentrations depending on their status as significant or nonsignificant. Significant facilities received individual WLAs; nonsignificant facilities were generally given aggregate WLAs by Bay segment watershed ( USEPA 2009 c )



### 4.4.2 Basinwide NPDES Permitting Approach

In 2004 EPA and the Bay watershed jurisdictions agreed to take a consistent approach to permitting the 483 significant municipal and industrial wastewater discharging facilities contributing nutrients to the Ches apeake Bay watershed (USEPA 2004 d ). As part of that approach and on the basis of the jurisdictions’ revised Chesapeake Bay WQS, permits are to be reissued with nutrient limits that are sufficient to achieve Bay WQS and that are consistent with the jurisdic tions’ tributary strategies. The basinwide permitting approach also contains additional specific provisions for permitting of nutrients in the Bay watershed , including the following :

Annual load limits

—

Unless such expressions would be impracticable, EPA’s regulations require NPDES permits for non

- publicly owned treatment works to express effluent limits as maximum daily and average monthly limits [40 CFR 122.45(d)(1)] and require NPDES permits for POTWs to express effluent limits as average weekly and avera ge monthly limits [40 CFR 122.45(d)(2)]. In the case of the Chesapeake Bay permitting for nutrients, EPA has determined that because of the long hydraulic durations in the Bay, and the fact that the control of annual loading levels of nutrients from wastew ater treatment plants is much more relevant and appropriate in terms of the effect of nutrients on Bay water quality criteria than daily maximums or weekly or monthly averages, expression of nutrient effluent limits in short periods is impracticable and th at, therefore, such effluent limits may be expressed as an annual load (USEPA 2004c).

Compliance Schedules

— Compliance schedules that are consistent with jurisdiction tributary strategies may be incorporated into permits, where such compliance schedules are needed, appropriate, and allowable under jurisdiction WQS and federal NPDES requirements (USEPA 2004d).

Watershed permits/trading

— Watershed permits, which may accommodate nutrient trading, may be used if such an approach would ensure protection of applica ble jurisdiction WQS and would be consistent with existing EPA policy regarding trading (USEPA 2004d).

In 2005 the seven Bay jurisdictions began implementing the new permitting approach . As of June 2010, the permits for the significant nutrient sources hav e been issued with nutrient limits consistent with the Tributary Strategy allocations (described above at Section 1.2.1) (some of which may include compliance schedules) to 63 percent of the significant wastewater treatment facilities (305 out of the total 483), accounting for 74 percent of the total design flow, 76 percent of the total nitrogen loads and 91 percent of the total phosphorus loads from significant facilities ( Table 4

- 6 ). By the end of 2011, all 483 significant wastewater treatment facilities in the Bay watershed are expected to have annual nutrient load limits in place in their permits (some of which may ha ve compliance schedules as well).DRAFT Chesapeake Bay TMDL

4

- 10 September 24 , 2010

Table 4

- 6

. Nutrient permit tracking summary under the Basinwide NPDES Wastewater Permitting Approach, through June 2010

Jurisdiction Significant

facilities Permits

drafted Permits

issued Design flow

of facilities permits

issued Percent of design

flow for permits issued/sig

facilities

DC 1 1 1 152.5 100%

DE 4 4 4 3.3 100%

MD 85 72 51 357.7 42%

NY 28 1 1 20.0 22%

PA 213 141 103 434.1 67%

VA 124 124 124 1,253.5 100%

WV 28 21 21 38.5 81%

Total 483 364 305 2,259.7 74%

Source: USEPA Region 3, Region 2

Note: Some industrial design flows are not available or not comparable and not listed in the database . Some permits may contain compliance schedules.



### 4.4.3 Data Sources

Information used to characterize loading from regulated point sources in the watershed was

obtained from various sources as described below.

Municipal and Industrial Wastewater Facility Data
Data related to municipal and industrial facilities are in the Phase 5 Chesapeake Bay Watershed

Model Point Source D atabase maintained by the CBP and include inform ation for the 483 significant industrial, municipal, and federal facilities discharging directly to the surface waters

in the watershed

. The wastewater data used to calibrate the Phase 5.3 watershed model cover the 1984 to 2005 time frame and are updated annually as data become available. Data are largely supplied by the seven watershed juri sdictions but are also obtained from NPDES permit databases, including EPA’s Permit Compliance System (PCS) and jurisdiction discharge monitoring reports. For each facility outfall, the database includes monthly flow and monthly average concentrations for total nitrogen, ammonia, nitrate and nitrite, total organic nitrogen, total phosphorus, orthophosphate, total organic phosphorus, total suspended solids, biological oxygen demand, and DO.

Because the Bay jurisdictions are required to submit monthly concent ration and flow data to EPA for only significant dischargers, the Phase 5 Chesapeake Bay watershed model point source database does not include comprehensive information useful for characterizing the nonsignificant facilities (especially nonsignificant ind ustrials) for the Bay TMDL. For nonsignificant municipal facilities, all Bay jurisdictions conducted a one

- time data collection in 2008 for the nutrient discharge data for nonsignificant municipal facilities, and estimates are based on any available

data s ources and default values recommended in Chesapeake Bay Watershed Model Application and Calculation of Nutrient and Sediment Loadings

– Appendix F: Phase IV Chesapeake Bay

Watershed Model Point Source Load (CBP 1998). EPA supplemented this information by

q uerying the Integrated Compliance Information System database (ICIS) for jurisdictions that have migrated to ICIS as of 2009 ( District of Columbia, Maryland, Pennsylvania, and New

York )

, querying the PCS database for jurisdictions that have not yet migrate d to ICIS (Delaware

, Virginia and West Virginia), and obtain ing Maryland and Virginia facility information directlyDRAFT Chesapeake Bay TMDL

4

- 11 September 24 , 2010

from Maryland Department of the Environment (MDE) and Virginia Department of Environmental Quality (VADEQ), respectively.

Discharge monitori ng report (DMR) data from the population of industrial facilities were used to derive loadings where available . The majority of nonsignificant industrial facilities do not have DMR data for nutrients. However, the default values from typical pollutant conc entrations ( Tetra

Tech 1999 ) were used to estimate the loads where DMR data are not available. For more information regarding the data used to represent municipal and industrial facilities and how they were incorporated into modeling for the Bay TMDL , see Section 7 of the Phase 5 Chesapeake Bay watershed mod el d ocumentation at http://www.chesapeakebay.net/model_phase5.aspx?menuitem=26169

.
Power Plant and Other Industrial Facility Da ta

N utrient loads resulting from the use of flue gas desulfurization units, effluent from coal ash ponds and biocide applications at high

- flow facilities were estimated from available databases. Industrial facilities such as power plants, petroleum refiner ies, and steel mills were the focus of

th at evaluation

. Data sets queried include EPA’s PCS and ICIS permit systems, 316(b) cooling water intake structure regulation data, U.S. Department of Energy’s Energy Information Administration data, and EPA’s eGrid database

.
Thirty

- two power plants were identified as being in the Chesapeake Bay watershed

. Eight of

th o se facilities use cooling towers as part of their cooling system . Of those facilities , 18 use coal as a fuel source; 7 use a flue gas desulfurization

, and 13 use ash ponds. Eighty

- nine other industrial sites were identified in the watershed and represent a variety of industrial activities.

Cooling tower loads were estimated for eight facilities. The PCS and ICIS databases were queried for blowdown flows , and cooling tower chemical vendors were consulted to estimate water quality conditions in the towers. Facility use rates were then obtained from EPA’s eGrid database to characterize utilization routines and variability in blowdown events. F lue gas

desulf urization and ash pond loads were estimated using data obtained from the PCS and ICIS

databases

.

Combined Sewer Outfall Data
EPA relied on various sources of information to characterize the prevalence of CSOs in the Bay watershed and to quantify their load s for the Bay TMDL. In the Bay watershed are 64 CSO communities. For the full list of CSO communities, see Section 4.5.3. Overflow volume and pollutant loading from CSO communities are heavily dependent on the service area or catchment

area of the combined system. Service area data obtained from the communities were used to calculate the loading from each community during high

- flow events. Precipitation data observations were also obtained from weather monitoring stations proximate to each community

to deri ve runoff volumes. Overflows and associated pollutant loads from CSO communities were then developed using various sources of water quality data including monitoring data and

literature values.

For four of the largest CSO communities in the watershed

— Alexa ndria, Virginia; Lynchburg, Virginia; Richmond, Virginia; and the District of Columbia

— EPA relied heavily on readily available and relatively detailed Long

- Term Control Plans (LTCPs) to characterize overflows. In addition, EPA ran simulations of existing s ewer models for those communities to supportDRAFT Chesapeake Bay TMDL

4

- 12 September 24 , 2010

developing overflow and water quality estimates. EPA used the District of Columbia’s combined sewer system (CSS) model to develop loading estimates for the CSOs. For the Alexandria, Richmond, and Lynchburg CSSs, various versions of EPA’s Storm Water Management Model (SWMM) model were used to estimate overflows. CSO d ischarge monitoring data were

available for the Alexandria and Richmond CSSs, but no samples were available from Lynchburg because the LTCP calls for complete separation of this system (i.e., separation of the storm sewers from sanitary sewers).

Information related to loading from the other 60 CSO communities in the watershed includes spatial data collected as a result of a direct survey of the communi ties to support the TMDL, limited water quality and overflow data from some of the CSO communities in the watershed, and representative water quality concentrations available in the literature. For further information regarding the data used to estimated C SO loads, see Section 7 of the Phase 5 Chesapeake Bay

watershed model documentation at http://www.chesapeakebay.net/model_phase5.aspx?menuitem=26169

.
To avoid the difficulty of mea suring L TC P implementation progress with weather

- dominated CSO loading estimates, EPA used the 10

- year average CSO loads for 1991

– 2000

, which

correlates with the hydrologic period selected for the TMDL (see Section 6.1.1). The loads from

this 10

- year perio d were used to assess CSO progress and WLAs

. Any CSO implementation progress will be input as a reduction factor to represent a reduction achieved from the baseline

. Thus, any reduction will be from management actions only and not from climate variation

. The CSS land use will be changed to urban area for stormwater simulation in the model if there is CSS separation in the implementation plan.

Permitted Stormwater Facility and MS4 Data
Data used to characterize loads from regulated stormwater activities and to represent these sources in the model are available from the jurisdictions’ NPDES programs and from EPA Region 3’s NPDES permitting, the permitting authority in the District of Columbia and for

federal facilities in Delaware.

Details related to how load s for MS4s and NPDES

- permitted construction and industrial stormwater activities were derived for the Bay TMDL are in Section 7 of the Phase 5 Chesapeake Bay Watershed Model Documentation at http://www.chesapeakebay.net/model_phase5.aspx?menuitem=26169

.
Permitted Concentrated Animal Feeding Operations Data
In the Chesapeake Bay watershed

, EPA and the Bay jurisdictions have estimated the number of state or federal permitted CAFOs ( se e Section 4.5.6 ) . Two sources of information used to generate these CAFO estimate are the state data submitted to EPA for the Senate Environment and Public Works Committee Hearing on the Chesapeake Bay on April 20, 2009, and EPA Office of Wastewater Manage ment’s latest quarterly national update. As the jurisdictions finalize

the ir Phase I WIPs in November 2010, the estimates will be updated to reflect a greater level of specificity according to how jurisdictions reflect WLAs for livestock and poultry operat ions

.



### 4.5 Regulated Point Source Load Summaries

This section presents load estimates for each major point source sector.DRAFT Chesapeake Bay TMDL

4

- 13 September 24 , 2010



### 4.5.1 Municipal Wastewater Discharging Facilities

A municipal wastewater facility is defined as a facility discharging treated wastewater from municipal or quasi

- municipal sewer systems. EPA identified 3,206 NPDES permitted facilities as discharging municipal wastewater into the Chesapeake Bay watershed. Table 4

- 7 provides a summary of municipal wastewater facilities by jurisdiction; a complete list is available in Appendix Q

.

Table 4

- 7 . Municipal wastewater facilities by jurisdiction

Jurisdiction Significant Nonsignificant

DC 1 0

DE 3 1

MD 76 164

NY 26 17

PA 182 1,246

VA 101 1,248

WV 10 134

Total 399 2,810

Source: EPA Region 3

Note: Blue Plains wastewater treatment plant serves DC and portions of Maryland and Virginia but is counted once in this table as a DC plant.

Table 4

- 8 and Table 4

- 9 summarize modeled 2009 municipal wastewater loading estimates by jurisdiction and major river basin, respectively, for total nitrogen and phosphorus loads delivered to the Chesapeake Bay. Modeled sediment loads for th o se facilities are not presented because wastewater discharg ing facilities represent a d e minim i s source of sediment (i.e. less than 0.5 percent of the 2009 total sediment load). In 2009 municipal wastewater treatment facilities

contributed an estimated 17 percent of the total nitrogen and 16 percent of the total phosphorus loads delivered to Chesapeake Bay.

Table 4

- 8 . Model estimated 2009 municipal wastewater loads by jurisdiction delivered to Chesapeake Bay

Jurisdiction Flow

(mgd) Total nitrogen delivered

(lb/yr) Total phosphorus delivered (lb/yr)

DC 140 2,387,918 20,456

DE 2 42,529 4,984

MD 563 11,928,717 568,905

NY 62 1,360,684 159,096

PA 335 9,391,741 740,397

VA 585 16,926,806 1,047,998

WV 13 188,137 62,674

Total 1,698 42,226,535 2,604,509

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 ScenarioDRAFT Chesapeake Bay TMDL

4

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Table 4

- 9

. Model estimated 2009 municipal wastewater loads by major river ba sin delivered to Chesapeake Bay

Basin Flow (mgd) Total nitrogen delivered (lbs/yr) Total phosphorus delivered (lbs/yr) Susquehanna River 383 10,556,831 835,426
MD Eastern Shore 25 696,872 70,540

MD Western Shore 254 7,279,406 331,362

Patuxent River 58 640,507 61,948

Potomac River 635 9,475,644 412,464 Rappahannock River 23 376,453 46,463

York River 20 691,550 45,012

James River 299 12,494,335 798,615
VA Eastern Shore < 1 14,937 2,679

Total 1,698 42,226,535 2,604,509

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4

- 7 and Figure 4

- 8 illustrate the prevalence and locations of significan t and nonsignificant municipal was tewater discharge facilities, respectively, across the watershed.

Appendix Q provides facility

- specific information including NPDES ID, location, and more for all wastewater dischargers accounted for in the Bay TMDL.

For more information regarding the data used to represent municipal wastewater discharge

facilities and how they were incorporated into modeling for the TMDL, see Section 7 of the

Phase 5 Chesapeake Bay watershed model documentation at http://www.chesapeakebay.net/model_phase5.aspx?menuitem=26169DRAFT Chesapeake Bay TMDL

4

- 15 September 24 , 2010

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4

- 7 . Significant wastewater treatment facilities in the Chesapeake Bay watershed.DRAFT Chesapeake Bay TMDL

4

- 16 September 24 , 2010

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4

- 8 . Nons ignificant municipal wastewater treatment facilities in the Chesapeake Bay watershed.DRAFT Chesapeake Bay TMDL

4

- 17 September 24 , 2010



### 4.5.2 Industrial Discharge Facilities

Industrial discharge facilities are facilities discharging process water, cooling water

, and other

contaminated waters from industrial or commercial sources . EPA identified 1,534 NPDES permitted facilities discharging industrial waste waters in the Chesapeake Bay watershed ( Table

4

- 10

, Appendix Q ), with 75 significant facilities ( Figure 4

- 9 ) and 1,459 nonsignificant facilities ( Figure 4

- 10 ). In 2009 industrial wastewater discharging facilities contributed an estimated 7.3

m illion pounds of the total nitrogen and 1.27 million pounds of the total phosphorus loads delivered to Chesapeake Bay ( Table 4

- 11 and Table 4

- 12 ) an estimated 3 percent and 8 percent

, respectively, of all nitrogen and phosphorus loads delivered to the Chesapeake Bay.

Table 4

- 10

. Industrial wastewater facilities

Jurisdiction Significant Nonsignificant

DC 0 6

DE 1 1

MD 9 566

NY 2 40

PA 30 394

VA 24 338

WV 9 101

Total 75 1,446

Source: USEPA Region 3, Region 2

Table 4

- 11

. 2009 Load estimates of industrial facility discharges

Jurisdiction Flow

(mgd) Total nitrogen delivered

(lbs/yr) Total phosphorus delivered (lbs/yr)

DC 13 183,490 20,433

DE < 1 95,438 71

MD 48 1,989,243 267,093

NY 7 126,897 19,971

PA 179 2,010,639 260,140

VA 160 2,883,828 649,266

WV 14 55,213 53,592

Total 422 7,344,748 1,270,566

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Error! Not a valid bookmark self

- reference.

, Table 4

- 13 and Table 4

- 14 summarize modeled wastewater nutrient loading estimates using 2009 loading conditions. Modeled sediment loads

for th o se facilities are not presented because wastewater discharges do not represent a significant

source of sediment (i.e. less than 0.5 percent of the 2009 total sediment load).DRAFT Chesapeake Bay TMDL

4

- 18 September 24 , 2010

Table 4

- 12

. 2009 Flow, total nitrogen, and total phosphorus load estimates of industrial wastewater facility discharges by major river basin

Basin Flow (mgd) Total nitrogen delivered (lbs/yr) Total phosphorus delivered (lbs/yr) Susqueha nna River 184 2,171,197 281,922
MD Eastern Shore 5 302,210 45,626

MD Western Shore 21 1,369,383 105,100

Patuxent River 3 50,615 38,689

Potomac River 71 779,885 420,997 Rappahannock River 5 78,006 36,039

York River 81 478,892 81,675

James River 51 1,979,297 259,331
VA Eastern Shore 1 135,211 1,160

Total 422 7,344,697 1,270,539

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 ScenarioDRAFT Chesapeake Bay TMDL

4

- 19 September 24 , 2010

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4

- 9

. Significant industrial wastewater discharge facilities in the Chesapeake Bay watershed.DRAFT Chesapeake Bay TMDL

4

- 20 September 24 , 2010

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario.

Figure 4

- 10

. Nonsignificant industrial wastewater discharge facilities in the Chesapeake Bay watershed.DRAFT Chesapeake Bay TMDL

4

- 21 September 24 , 2010



### 4.5.3 Combined Sewer Overflows

CSSs are sewers that are designed to collect rainwater runoff, domestic sewage, and industrial wastewater in the same pipe. Normally, the systems transport wastewater to a treatment plant, where it is treated and discharged to surface waters. However, during heavy rainfall or snowmelt, flow volumes in a CSS can exceed the capacity of the sewer system or treatment plant. To avoid

situatio ns where excess flows overwhelm the sewer network or the treatment capacity of the treatment system, CSSs are designed to overflow during times of high volume, discharging untreated excess wastewater directly to nearby streams, rivers, or other waterbodies

.
Such overflows, called combined sewer overflows (CSOs), contain stormwater and untreated human and industrial waste, toxic materials, and debris. There are 64 CSO communities in the Chesapeake Bay watershed ( Table 4

- 13 and Figure 4

- 11 ).

Table 4

- 13 . Combined sewer system communities in the B ay watershed

Jurisdiction River basin NPDES ID Facility name

DC Potomac DC0021199 Washington, District of Columbia

DE Eastern Shore DE0020265 Seaford Waste Treatment Plant

MD Eastern Shore MD0020249 Federalsburg WWTP

MD Eastern Shore MD0021571 City of Salisbury WWTP

MD Potomac MD0021598 C umberland WWTP

MD Patapsco MD0021601 P atapsco WWTP

MD Eastern Shore MD0021636 C ambridge WWTP

MD Eastern Shore MD0022764 Snow Hill W & S Dept.

MD Potomac MD0067384 W esternport CSO

MD Potomac MD0067407 A llegany County CSO

MD Potomac MD0067423 F rostburg CSO

MD Potomac MD0067547 L avale Sanitary Commission CSO

NY Susquehanna NY0023981 J ohnson C ity (V) O verflows

NY Susquehanna NY0024406 B inghamton (C) CSO

NY Susquehanna NY0035742 C hemung Co Elmira SD STP

PA Susquehanna PA0020940 T unkhannock Boro Mun. Auth.

PA Susquehanna PA0021237 N ewport Boro STP

PA Susquehanna PA0021539 W illiamsburg Municipal Auth.

PA Susquehanna PA0021571 M arysville Borough WWTP

PA Susquehanna PA0021687 W ellsboro WWTP

PA Susquehanna PA0021814 M ansfield Boro WWTP

PA Susquehanna PA0022209 B edford WWTP

PA Susquehanna PA0023248 B erwick Area Joint Sewer Auth. WWTP

PA Susquehanna PA0023558 A shland WWTP

PA Susquehanna PA0023736 T ri

- Boro Municipal Authority WWTP

PA Susquehanna PA0024341 C anton Boro Auth. WWTP

PA Susquehanna PA0024406 M ount Carmel WWTF

PA Susquehanna PA0026107 W yoming Valley Sanitary Authority WWTP

PA Susquehanna PA0026191 H untingdon Borough WWTF

PA Susquehanna PA0026310 C learfield Mun. Auth. WWTP

PA Susquehanna PA0026361 L ower Lackawanna Valley San. Auth. WWTP

PA Susquehanna PA0026492 S cranton Sewer Authority WWTP

PA Susquehanna PA0026557 S unbury City Mun. Auth. WWTP

PA Susquehanna PA0026743 L ancaster City WWTP

PA Susquehanna PA0026921 G reater Hazelton Joint Sewer Authority WWTP

PA Susquehanna PA0027014 A ltoona City Auth.

- Easterly WWTPDRAFT Chesapeake Bay TMDL

4

- 22 September 24 , 2010

Jurisdiction River basin NPDES ID Facility name

PA Susquehanna PA0027022 A ltoona City Auth.

- Westerly WWTF

PA Susquehanna PA0027049 W illiamsport Sanitary Authority

– West Plant

PA Susquehanna PA0027057 W illiamsport Sanitary Authority

– Central Plant

PA Susquehanna PA0027065 LRBSA

- A rchbald WWTP

PA Susquehanna PA0027081 LRBSA

- C linton WWTP

PA Susquehanna PA0027090 LRBSA

- T hroop WWTP

PA Susquehanna PA0027197 H arrisburg Advanced WWTF

PA Susquehanna PA0027324 S hamokin Coal Twp Joint Sewer Auth.

PA Susquehanna PA0028631 M id

- C ameron Authority

PA Susquehanna PA0028673 G allitzin Borough Sew and Disp. Auth.

PA Susquehanna PA0036820 G aleton Borough Authority WWTP

PA Susquehanna PA0037711 E verett Area WWTP

PA Susquehanna PA0038920 B urnham Borough Authority WWTP

PA Susquehanna PA0043273 H ollidaysburg STP

PA Susquehanna PA0046159 Houtzdale Boro Municipal Sewer Authority

PA Susquehanna PA0070041 M ahanoy City Sewer Auth. WTP

PA Susquehanna PA0070386 S henandoah Mun. Sewer Auth. WWTP

PA Susquehanna PAG062202 L ackawanna River Basin Sewer Auth.

PA Susquehanna PAG063501 Steelton Boro Authority

VA James VA 0063177 Richmond

VA James VA0024970 Lynchburg

VA James VA0025542 Covington Sewage Treatment Plant

VA Potomac VA0087068 Alexandria

WV Potomac WV0020150 C ity of M oorefield

WV Potomac WV0021792 C ity of P etersburg

WV Potomac WV0023167 C ity of M artinsburg

WV Potomac WV0024392 C ity of K eyser
WV Potomac WV0105279 C ity of P iedmontDRAFT Chesapeake Bay TMDL

4

- 23 September 24 , 2010

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4

- 11 . CSO communities in the Chesapeake Bay watershed.DRAFT Chesapeake Bay TMDL

4

- 24 September 24 , 2010

CSOs are considered point sources and are assigned WLAs in this TMDL. EPA’s CSO Control Policy is the national framework for implementing controls on CSOs through the NPDES permitting program

. The p olicy resulted from negotiations among municipal organizations, environmental groups, and s tate agencies. It provides guidance to municipa lities and s tate and

f ederal permitting authorities on how to meet the CWA’ s pollution control goals as flexibly and

cost

- effectively as possible. The CSO p olicy was published in the Federal Register (FR) ( 59 FR

18688

, April 19, 1994 ). CSO communities are required to develop LTCPs, detailing steps necessary to achieve full compliance with the CWA.



### 4.5.4 Sanitary Sewer Overflows

Properly designed, operated, and maintained sanitary sewer systems are meant to collect and transport all the sewage that flows int o them to a POTW. Sanitary s ewer o verflows (SSOs) are illegal discharges of raw sewage from municipal sanitary sewer systems. Frequent SSOs are indicative of problems with a community’s collection system and can be due to multiple factors:

Infiltration and inflow contributes to SSOs when rainfall or snowmelt infiltrates through the ground into leaky sanitary sewers or when excess water flows in through roof drains connected to sewers, broken pipes, or badly connected sewer service lines. Poor service

connec tions between sewer lines and building service lines can contribute as much as 60 percent of SSOs in some areas.

Undersized systems contribute to SSOs when sewers and pumps are too small to carry sewage from newly developed subdivisions or commercial areas

. Pipe failures contribute to SSOs as a result of blocked, broken, or cracked pipes; tree roots growing into the sewer; sections of pipe settling or shifting so that pipe joints no longer match; and sediment and other material building up causing pipes to break or collapse.

Equipment failures contribute to SSOs because of pump failures or power failures.

SSOs represent a source of nutrients to the Chesapeake Bay; however, information available to

characterize their contribution to the overall nutrient loads delivered to the Bay is limited largely because of their illegality and infrequency. Although the Phase 5.3 Chesapeake Bay watershed model does not specifically account for SSOs, the nutrient load contributions from SSOs are part of the background conditi ons incorporated into the Phase 5.3 watershed model and, therefore, such loads are accounted for in the data used for calibration of the Bay watershed model. Because SSOs are illegal, however, the Chesapeake Bay TMDL assumes full removal of SSOs

and makes no allocation to them.



### 4.5.5 NPDES Permitted Stormwater

Urban and suburban stormwater discharges contain nutrients and sediment from sources such as pet wastes, lawn fertilizers, construction activity, impervious surfaces, and air contaminants. The

in

- stre am bank and bed scouring caused by increased volumes and durations of stormwater discharges contribute additional sediment and nutrient loads to the Bay and its tributaries. These nutrients and sediment affect local water quality, habitats, and the Bay dow nstream and represent a significant proportion of nutrient and sediment loads to Bay. The CBP estimates that in 2009 stormwater from urban and suburban development contributed to 16 percent of the sediment loadings, 15 percent of the phosphorus loadings, a nd 8 percent of the nitrogen loadings to the Bay ( P hase 5.3 Chesapeake Bay Watershed Model 2009 Scenario )

.DRAFT Chesapeake Bay TMDL

4

- 25 September 24 , 2010

Under the federal stormwater regulatory program, three broad categories of stormwater discharges are regulated (see 40 CFR 122.26, CFR 122.30

- 37) :

St ormwater discharges from medium and large MS4s and small MS4s in Census Bureau

defined urbanized areas

Stormwater discharges associated with construction activity 1 acre and larger

Stormwater discharges associated with specified categories of industrial ac tivity

In addition, EPA established a process for designating and requiring NPDES permit coverage for additional stormwater discharges, implementing section 402(p)(2)(E) and (6). This ―residual designation authority‖ (RDA) is in 40 CFR 122.26(a)(9)(i)(C) and (D).

EPA’s intent in creating the MS4 Stormwater Program was to regulate stormwater discharges by requiring the municipalities to develop management programs to control stormwater discharging via the MS4, i.e., stormwater collected by the MS4 from thro ughout its service area.

CWA section 402(p) establishes the framework for EPA to address stormwater discharges. In Phase I, EPA established NPDES permit requirements for stormwater discharges associated with

11 categories of industrial activity, one of whi ch is construction activity disturbing 5 acres or greater, including sites smaller than 5 acres if they are associated with a common plan of development or sale that is at least 5 acres in size

Discharges from MS4s serving populations of 100,000 or more

In Phase II, EPA established permit requirements for stormwater discharges from :
Construction activity disturbing 1 to 5 acres, including sites smaller than 1 acre if they are associated with a common plan of development or sale that is at least 1 acre in si ze
Small MS4s serving populations of fewer than 100,000 in urbanized areas

With respect to Phase II MS4s, EPA considers stormwater discharges from within the geographic boundary of the urbanized area (and designated areas) served by small MS4s to be regula ted (64 FR 68722, 68751

- 52 and 68804, Appendix 2, December 8, 1999 ). The reason for regulating small MS4s in urbanized areas was based on the correlation between the degree of development/ urbanization and adverse water quality impacts from stormwater disc harged from such areas.

EPA can and has designated additional stormwater discharges, such as those from impervious surfaces above a certain size threshold, using its residual designation authority under 40 CFR 122.26(a)(9)(i)(C) and (D). At the discretion of the NPDES permitting authority, s tormwater dischargers that require NPDES permits can either obtain individual permits or, with the exception of medium and large MS4s, obtain coverage under general permits (see 40 CFR 122.28).

Figure 4

- 12 shows the locations of Phase I and II MS4s in the Bay watershed.DRAFT Chesapeake Bay TMDL

4

- 26 September 24 , 2010

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4

- 12 . Phase I and II MS4s in the Chesapeake Bay watershed.DRAFT Chesapeake Bay TMDL

4

- 27 September 24 , 2010

Unless stormwater discharges are identified in EPA’s Phase I or Phase II regulations or are designated pursuant to either CWA section 402(p)(6) RDA, the discharges are no t regulated under CWA section 402. As explained in EPA guidance, ―stormwater discharges that are regulated under Phase I or Phase II of the NPDES stormwater program are point sources that must be included in the WLA portion of a TMDL‖ (USEPA 2002)

. Appendi x Q provides a n inventory of the stormwater permits subject to this Bay TMDL.

It is estimated that existing NPDES MS4 areas contributed approximately 7 ,027,362 lbs total nitrogen, 900,868 lbs total phosphorus, and 287,295 tons of sediment annually in 2009. That compares to the total load delivered annually to the Bay of 251,040,081 lbs total nitrogen

, 16,619,332 lbs total phosphorus and 4,000,118 tons sediment by all sources (Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario).

T he contribution from ind ustrial stormwater discharges subject to NPDES has been estimated on the basis of data submitted by jurisdictions in their Phase I WIPs, including the number of industrial stormwater permits per county and the number of urban acres regulated b y industrial stormwater permits. For the Bay TMDL, the permitted industrial stormwater load is subtracted from the MS4 load when applicable. Table 4

- 14 provides an accounting of t he current individual and general stormwater NPDES permits issued within the Chesapeake Bay watershed.

Table 4

- 14 . NPDES stormwater permittees by jurisdiction and in the Chesapeake Bay watershed,

summer 2009

Jurisdiction NPDES Stormwater permit type

MS4

Phase I MS4

Phase II Industrial Construction Total %
Permittees in the Bay

DC Baywide 1 0 60 212 273 1.6 %

District wide 1 0 60 212 273

DE Baywide 1 0 48 NA 49 0. 3 %

Statewide 14 3 337 1,375 1,729

MD Baywide 11 82 1,578 8,300 9,971 57.6 %

Statewide 11 82 1,578 8,332 10,003

NY Baywide 0 34 122 470 626 3.6 %

Statewide 1 502 1,393 7,251 9,147

PA Baywide 0 206 1,238 906 2,350 13.6 %

Statewide 2 727 2,494 2,399 5,622

VA Baywide 11 75 975 2,252 3,313 19.2 %

Statewide 11 90 1,432 2,851 4,384

WV Baywide 0 3 113 651 767 4.4 %

Statewide 0 45 933 2,488 3,466

Total Bay 23 400 4,086 12,791 17,300 100 %

States 40 1,449 8,227 24,908 34,624

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario Note: Numbers of permittees are not static, and especially for categories like construction are fluctuating regularly. * Not including DelawareDRAFT Chesapeake Bay TMDL

4

- 28 September 24 , 2010



### 4.5.6 Concentrated Animal Feeding Operations

The NPDES program regulates the discharge of pollutants from point sources to waters of the United States. CAFOs are point sources, as defined by CWA s ection 502(14). To be considered a CAFO, a facility must first be defined as an AFO.

AFOs are agricultura l operations where animals are kept and raised in confined situations. AFOs generally congregate animals, feed, manure, dead animals, and production operations on a small land area. Feed is brought to the animals rather than the animals grazing or otherwis e seeking feed in pastures. Such operations are defined as AFOs if animals are confined for 45 or more days per year in facilities where vegetation and other growth are not present during the normal growing season [ 40 CFR 122.42(b)(1) ]

.
AFOs that meet the regulatory definition of a CAFO or that are designated as a CAFO are regulated under the NPDES permitting program and are required to seek NPDES permit coverage if they discharge or propose to discharge. The NPDES regulations define AFOs as CAFOs based pri marily on the number of animals confined ( Table 4

- 15 ) (for example, a large dairy CAFO confines 700 or more dairy cattle) [ 40 CFR 122.23(b)(2), (4), and (6) ] . AFOs that are not defined as a CAFO may be designated as a CAFO if they meet certain conditions [ 40

CFR 122.23(c) ]

.

Table 4

- 15 . Federal numeric thresholds for small, medium

, and large CAFOs

Animal sector Size thresholds (number of animals) Large CAFOs Medium CAFOs Small CAFOs Cattle or cow/calf pairs 1,000 or more 300

– 999 less than 300 Mature dairy cattle 700 or more 200

– 699 less than 200

Veal calves 1,000 or more 300

– 999 less than 300 Swine (weighing over 55 pounds) 2,500 or more 750

– 2,499 less than 750 Swine (weighing less than 55 pounds) 10,000 or more 3,000

– 9,999 less than 3,000

Horses 500 or more 150

– 499 less than 150 Sheep or lambs 10,000 or more 3,000

– 9,999 less than 3,000 Turkeys 55,000 or more 16,500

– 54,999 less than 16,500 Laying hens or broilers (liquid manure handling systems) 30,000 or more 9,000

– 29,999 less than 9,000

Chickens other than laying hens (other than a liquid manure handling systems) 125,000 or more 37,500

– 124,999 less than 37,500

Laying hens (other than a liquid manure handling systems) 82,000 or more 25,000

– 81,999 less than 25,000

Ducks (other than a liquid manure handling systems) 30,000 or more 10,000

– 29,999 less than 10,000

Ducks (liquid manure handling systems) 5,000 or m ore 1,500

– 4,999 less than 1,500

Source: 40 CFR 122.23(b)

Under federal regulations, NPDES permits for CAFOs require CAFOs to implement the terms of

a site

- specific nutrient management plan (NMP) that includes a number of critical minimum

elements [ 40 CFR 122.42(e)(1) ]. These requirements limit nutrient loads from the production area as well as from the land application area, where manure

, litter and process wastewater must be applied in accordance with site specific practices to ensure that nutrients in t he manure will be

u s ed appropriately. NPDES permits for all CAFOs must include technology

- based effluent limits

in accordance with 40 CFR 122.44. Permitted Large CAFOs that land

- apply manure, litter orDRAFT Chesapeake Bay TMDL

4

- 29 September 24 , 2010

process wastewater must comply with technology

- based e ffluent limitations for land application per the effluent limitations guidelines (ELG) at 40 CFR 412 (C) and (D) . Unpermitted Large CAFOs may not have any discharges except for agricultural stormwater discharges from the land application area.

Agricultural stormwater discharges are the precipitation

- related discharges from CAFO land application areas where the CAFO land applies in accordance with nutrient management practices ―that ensure appropriate agricultural utilization of the nutrients in the manure, litter or process wastewater‖ applied to the land

— i.e., for permitted CAFOs, the terms of an NMP concerning land application [ 40 CFR 122.23(e)(1) ]. State technical standards are used in calculating the technology

- based effluent limits in NPDES permits of Large CAFOs

. Requirements for land application areas at small and medium CAFOs are based on the best professional judgment of the permit writer, and may also incorporate state technical standards. The agricultural stormwater exemption does not apply to a CAFO’s production area. As a nonpoint source, an a gricultural stormwater discharge is not subject to NPDES permitting requirements or water quality

- based effluent limitations (WQBELS)

.

Any permit issued to a CAFO of any size must include a requ irement to implement a n NMP that contains, at a minimum, BMP s that meet the requirements specified in 40 CFR 122.42(e)(1)

. These include

1. Ensuring adequate storage of manure, liter, and process wastewater, including procedures to ensure proper operation and maintenance of the storage facility.

2. M anag ing mortalities to ensure that they are not disposed of in a liquid manure, stormwater, or process wastewater storage or treatment system that is not specifically designed to treat

animal mortalities.

3. Ensur ing tha t clean water is diverted, as appropriate, from the production area.

4. Prevent ing direct contact of confined animals with waters of the United States.

5. Ensur ing that chemicals and other contaminants handled on

- site are not disposed of in any manure, litter, p rocess wastewater, or stormwater storage or treatment system unless specifically designed to rate such chemicals and other contaminants.

6. Identify ing appropriate site specific conservation practices to control runoff of pollutants to

waters of the United St ates.

7. Identify ing protocols for appropriate testing of manure, litter, process wastewater, and soil.

8. Establish ing protocols to land apply manure, litter, or process wastewater in accordance with

site

- specific nutrient management practices that ensure appropriate agricultural utilization of the nutrients in the manure, litter or process wastewater.

9. Identif ying specifi c records that will be maintained to document the implementation and management of the minimum elements described above

.

In the Chesapeake Bay watershed

, EPA and the jurisdictions have estimated the number of state or federal permitted CAFOs ( Table 4

- 16 ). As the jurisdictions finalize the ir Phase I WIPs in November 2010, the estimates will be updated to reflect a greater level of specificity according

to how the jurisdictions reflect WLAs fo r livestock and poultry operations

.DRAFT Chesapeake Bay TMDL

4

- 30 September 24 , 2010

Table 4

- 16

. Estimated number of state or federal permitted CAFOs

Jurisdiction # State or f ederal p ermitted CAFOs

Delaware a 122

Maryland a 426

New York 90 Pennsylvania 325 Virginia 30 West Virginia 30
Sources: State data submitted to EPA for the Senate Environment and Public Works Committee Hearing on the Chesapeake Bay on April 20, 2009 and EPA Office of Wastewater Management ’ s latest NPDES CAFO Rule Implementation Sta tus quarterly national CAFO number update

. http://www.epa.gov/npdes/pubs/tracksum1Q10.pdf

. a. The numbers of CAFOs in Maryland and Delaware with permits are estimated based on the number of Notic es of Intent (NOIs) received as a result of the EPA February 2009 permit application deadline. T hese NOIs are being reviewed for permit requirement completeness

.



### 4.6 Nonpoint Sources

The term nonpoint source mean s any source of water pollution that does not meet the legal

definition of point source (see Section 4.5). Nonpoint source pollution generally results from land runoff, precipitation, atmospheric deposition, drainage, seepage or hydrologic modification.

For purposes of the Chesapeake Bay TMDL analysis and modeling, nonpoint sources in the Chesapeake Bay watershed have been evaluated under the following categories:

Agriculture (manure, biosolids, chemical fertilizer)

Atmospheric deposition

Forest lands

On

- sit e wastewater treatment systems (OSWTSs)

Nonregulated stormwater runoff

Oceanic inputs

Streambank and tidal shoreline erosion

Tidal resuspension

Wildlife

Appendix Q provides an inventory of nonpoint sources represented in the Bay Watershed Model by various geographic scales (county, land

- river segment, and such)



### 4.6.1 Data Sources

Information used to characterize loading from nonpoint sources in the Bay watershed was

obtained from various sources.

Agriculture

Data sources used to estimate nutrients and sedim ent from agriculture

- related sources include information related to livestock production and manure generation, crop production and nutrient management, fertilizer use and application, and implementation of BMPs. EPA relied on the many sources of informati on to characterize loads related to agriculture that are summarized in

Section 2 of the Scenario Builder documentation Estimates of County

- Level Nitrogen and Phosphorus Data for Use in Modeling Pollutant Reduction, September 2010 (USEPA 2010 d )

.DRAFT Chesapeake Bay TMDL

4

- 31 September 24 , 2010

Examples of data sources are the U.S. Department of Agriculture (USDA) agricultural census; USDA, state, and university nutrient management standards and handbooks; peer

- reviewed journal articles; agricultural conservation data from state agricultural and environment al agencies; county agencies, and nongovernmental organizations; and extensive input from members of the Chesapeake Bay Program’s Agricultural Nutrient and Sediment Reduction Workgroup.

Atmospheric Deposition
Atmospheric deposition monitoring in the Chesap eake watershed is through National Atmospheric Deposition Program (NADP) and AirMon stations throughout the watershed. Measured deposition at these discrete stations is used to extrapolate to all the land and waters of the Chesapeake watershed through a wet deposition regression model developed by Grimm and Lynch (2000, 2005; 2007; Lynch and Grimm 2003). Dry deposition data are estimated through the Community Multiscale Air Quality Model (CMAQ) (Dennis et al. 2007; Hameedi et al. 2007) (for more details, see Section 5.4).

Other Nonpoint Sources
For the Bay TMDL, Scenario Builder was used to provide the land use

- based scenario inputs to the Phase 5.3 Chesapeake Bay Watershed Model including forest lands, OSWTSs , nonregulated

stormwater runoff, oceanic inputs, streambank and tidal shoreline erosion, tidal resuspension, and wildlife (Section 5). Scenario Builder provides nutrient loads to the land and the area of soil available to be eroded. Loads are input to the Bay Watershed Model to ge nerate modeled estimates of loads delivered to the Bay. Additional information related to Scenario Builder and its application in Bay TMDL development ( USEPA 2010 d ) is at http://www.ch esapeakebay.net/modeling.aspx?menuitem=19303

.



### 4.7 Nonpoint Source Load Summaries

4.7.1 Agricultur

e
Agricultural lands account for 22 percent of the watershed, making agriculture one of the largest land uses in the area, second only to forests (58 percent). The Bay watershed has more than 87,000 farm operations and 6.5 million acres of cropland.

Farms in the Chesapeake Bay watershed produce more than 50 named commodities. The area’s primary crops are pasture, hay, corn, wheat, soybeans, vegetables, and fruit s. The eastern part of the region is home to a rapidly expanding nursery and greenhouse industry.

Animal operations account for more than 60 percent of the region’s annual farm product sales. In the watershed, the six major types of animal operations are d airy cows, beef cattle, pigs, egg production, broilers, and turkeys. The three major animal production regions in the watershed, according to livestock concentration, are the lower Susquehanna River in Pennsylvania, the Shenandoah Valley in Virginia and We st Virginia, and the Delmarva Peninsula in Delaware, Maryland, and Virginia. The Delmarva Peninsula is considered to be one of the country’s top poultry producing regions and, according to the 2002 Census, 3 Bay counties are among the top 20 poultry produc ing counties in the nation (for either poultry/eggs, broilers, or layers): Sussex County, Delaware; Lancaster County, Pennsylvania; and Wicomico County, Maryland. In addition, at least one Bay county is among the top 20 counties for production of the follo wingDRAFT Chesapeake Bay TMDL

4

- 32 September 24 , 2010

farm commodities: turkeys; cattle and calves; milk and other cow dairy products; hogs and pigs; horses and ponies; corn for silage; snap beans; apples; short rotation woody crops; and nursery, greenhouse, floriculture, and sod.

Agriculture is the larg est single source of nitrogen, phosphorus, and sediment loading to the Bay through applying fertilizers, tilling croplands, and applying animal manure. Agricultural activities are responsible for approximately 44 percent of nitrogen and phosphorus loads

de livered to the Bay and about 65 percent of sediment loads delivered to the Bay (CBP Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario). Figure 4

- 13 compares modeled loads from agricultural lands for 1985 and 2009.

Source: Phase 5.3 Chesapeake Bay Watershed Model 1985 and 2009 Scenarios

Figure 4

- 13 . 1985 and 2009 modeled total nitrogen, phosphorus, and sediments loads from agricultural lands across the Chesapeake Bay watershed. 0 20,000,000 40,000,000 60,000,000 80,000,000 100,000,000 120,000,000 140,000,000 160,000,000 180,000,000

TN (lbs/yr) TP (lbs/yr)



### Agricultural Loads (Nutrients)

1985

2009

0 500,000 1,000,000 1,500,000 2,000,000 2,500,000 3,000,000 3,500,000 4,000,000

TSS (tons/yr)



### Agricultural Loads (Sediment)

1985

2009DRAFT Chesapeake Bay TMDL

4

- 33 September 24 , 2010 Manure

Animal populations vary across the Bay watershed by animal type and management. Pastures

exist in the wate rshed for dairy and beef heifers, goats, hogs, and in some places even chickens and turkeys. Animal feed BMPs are recognized by the Chesapeake Bay watershed model , and managing manure from production areas can include a suite of BMPs for storage and handli ng. Land application of manure is an important nutrient recycling process in agriculture. Because manure is so extensively used as a resource of nutrients, it is considered as important as inorganic fertilizer as a source of nonpoint source pollution. Figure 4

- 14 and Figure 4

- 15 provide historical population data of poultry and non

- poultry animals in the watershed, respectively.

Source: 2007 Agriculture Census

Figure 4

- 14 . 2007 Chesapeake Bay w atershed poultry populations by jurisdiction

.DRAFT Chesapeake Bay TMDL

4

- 34 September 24 , 2010

Source: 2007 Agriculture Census

Figure 4

- 15 . 2007 Chesapeake Bay w atershed livestock populations by jurisdiction

. Annual manure production is calculated as a daily excreted amount per animal equivalent unit ( 1

animal equivalent unit equals 1

, 000 lbs live animal weight )

. Animal units are estimated for

counties on the basis of USDA Ag ricultural Census data. The total amount of manure produced is then distributed among the applicable land uses, which include pasture, AFO, and other row crop land uses. Th e percentage of time animals spend in pasture (based on state recommendations) is used to estimate the percentage of total manure produced that is produced on pasture lands. For example, 50 percent pasture time equates to 50 percent of the total manure

pro duction occurring on pasture lands. Manure produced that is associated with time spent confined is considered to be generated on AFO acres. A fraction of that amount, (15

– 21 percent depending on animal type) is assumed to remain on the AFO acres (i.e., not captured by storage and handling activities), while the rest is redistributed by land application to pasture and row crop lands. The model simulates AFO acres similarly to urban impervious areas.

Biosolids

Applying biosolids, the nutrient

- rich organic mat erials resulting from treat ing sewage sludge , as fertilizer to croplands represents another significant source of nutrients to the Bay. Biosolids typically contain plant nutrients ( nitrogen, phosphorus, and potassium )

, although the amount of

nutrients avai lable from biosolids are normally lower than the amounts from most commercial

fertilizers ( Huddleston and Ronayne 1990; USEPA 1976, 1978) . Nitrogen and phosphorus are the most prevalent nutrients found in sewage sludge.DRAFT Chesapeake Bay TMDL

4

- 35 September 24 , 2010

Regulations governing use, disposal and application of sewage sludge are in EPA’s Sewage Sludge Use or Disposal Regulation (Part 503), which provides a framework for permitting sewage sludge use or disposal. No jurisdictions in EPA Region 3 have applied for program

authorization of the feder al Part 503. Although all Bay jurisdictions have their own sewage sludge programs in place, only Virginia routinely submits to EPA information regarding land application of biosolids. As a result, information available to characterize biosolids as a source and to represent it in the model is limited.

For model characterization, jurisdiction

- specific data on biosolids application were used. Land uses receiving biosolids include crops and pasture/hay, with different monthly proportions based on seasonal growi ng patterns. Modeled application rates are the same as manure because biosolids are applied to land in the same fashion as manure.

For additional information related to representation of biosolids in the Phase 5.3 Chesapeake Bay Watershed Model, see Sectio n 7 of the Scenario Builder Documentation at http://www.chesapeakebay.net/model_phase5.aspx?menuitem=26169

Chemical Fertilizer

Chemical fertilizer application practices across the watershed can be estimated through

commercial sales information. Fertilizer sales data are prepared by the Association of American

Plant Food Control Officials on the basis of fertilizer consumption information submitted by

state fertilizer control offices . The consumption data include total fertilizer sales or shipments for

farm and non

- farm use. Liming materials, peat, potting soils, soil amendments, soil additives,

and soil conditioners are excluded

. Materials used for the manufacture or blending of repo rted fertilizer grades or for use in other fertilizers are excluded to avoid duplicate repo rting. A review of commercial fertilizer sales records (from 1982 to 2007) showed that in all states

, the sales are increasing

. The increase can be attributed to both increasing yields and increasing application. Removing the yield increases resulted in persistent increasing trends in nutrient application (except in Maryland where the trend is flat)

.

Model estimates of commercial f ertilizer loads have been derived by back

- calculating load from agricultural lands and determining the proportion of nutrient species applied from commercial

fert ilizer , manure
, and atmospheric deposition.

As phosphorus

- based nutrient management plans increase, the reliance on nitrogen fertilizer is expected to increase because less manure will be legally permitted to be applied to agricultural lands. Therefore chemical fertilizers are and will remain a significant potential source of

nutrients to the B ay.



### 4.7.2 Atmospheric D eposition

Air sources contribute about one

- third of the total nitrogen loads delivered to the Chesapeake Bay by depositing directly onto the tidal surface waters of Chesapeake Bay and onto the surrounding Bay watershed

. Direct deposi tion to the Bay ’s tidal surface waters is estimated to be

6 to 8 percent of the total (air and non

- air) nitrogen load delivered to the Bay. The nitrogen deposited onto the Bay’s watershed and subsequently transported to the Bay is estimated to

account for 25 to 28 percent of the total nitrogen loadings delivered to the Bay.DRAFT Chesapeake Bay TMDL

4

- 36 September 24 , 2010

Atmospheric loads of nitrogen are from chemical species of oxidized nitrogen, also called NOx, and from reduced forms of nitrogen deposition, also called ammonia (NH 4 + ). Oxidized forms o f nitrogen deposition originate from conditions of high heat and pressure and are formed from inert diatomic atmospheric nitrogen (N 2 ). The principle sources of NOx are industrial

- sized boilers such as electric power plants and the internal combustion engi nes in cars, trucks, locomotives, airplanes, and the like.

Reduced nitrogen, or a mmonia

, is responsible for approximately one

- third of the total nitrogen atmospheric emissions that eventually end up as loads to the Bay. Ammonia sources are predominately ag ricultural, and ammonia is released into the air by volatilization of ammonia

from manures and emissions from ammonia based fertilizers. Minor sources include mobile

sources, slip ammonia released as a by

- product of emission controls on NOx at power plants, and industrial processes

.
Two types of atmospheric deposition

— wet and dry

— are input to the Bay Watershed and Bay Water Quality Models daily. Wet deposition occurs during precipi tation events and contributes to only nitrogen loads during days of rain or snow. Dry deposition occurs continuously and is input at a constant rate daily in Bay Watershed and Bay Water Quality Models.

Because the Bay Watershed and Bay Water Quality Models are mass balance models, all sources of nutrient inputs to the tidal Bay must be accounted for. Given atmospheric deposition of phosphorus and organic forms of nutrients are minor inputs, the Bay Watershed and Bay Water Quality Model s account for estimated loads of phosphorus and organic nutrients to open surface

waters only, on the assumption that all phosphorus and organic nutrients are derived from aeolian processes, which result in no net change in organic nitrogen on terrestrial surfaces but result in a net gain when deposited directly on water surfaces.

Organic nitrogen is simulated only as wet deposition as dissolved organic nitrogen because the magnitude of dry deposition of organic nitrogen is not well characterized in the lit erature.

T herefore

, the limited dry deposition of organic nitrogen simulated by the Bay Airshed Model is lumped into the oxidized nitrogen atmospheric dry deposition.

Chesapeake Bay A irshed
The Bay's NOx airshed

— the area where emission sources that contrib ute the most airborne nitrates to the Bay originate

— is about 570,000 square miles, or seven times the size of the Bay’s

watershed ( Figure 4

- 16 ). Close to 50 percent o f the nitrate deposition to the Bay is from air emission sources in Bay watershed jurisdictions. Another 25 percent of the atmospheric deposition load to the Chesapeake watershed is from the remaining area in the airshed. The remaining 25 percent of deposi tion is from the area outside the Bay airshed. The ammonia airshed is similar to the NOx airshed, but slightly smaller.DRAFT Chesapeake Bay TMDL

4

- 37 September 24 , 2010

Source: Dr. Robin Dennis, EPA/ORD/NERL/AMAD/AEIB

Figure 4

- 16

. Principle a rea of NO X e missions (outlined in blue) t hat c ontribute n itrogen d eposition to the

Chesapeake Bay and its w atershed (solid blue fill) (the Bay airshed).

Atmospheric deposition emissions sources and trends
Between 1985 and 2005, the simulation period of the Phase 5 Wat ershed Model, atmospheric deposition loads of nitrate (NOx) in the Chesapeake watershed have decreased by about 30 percent ( Figure 4

- 17 ). C onsiderable variability exis ts across the watershed, however, with the greatest reductions occurring in the northern and western portions (Grimm and Lynch 2000; 2005; Lynch and Grimm 2003). In Figure 4

- 17, the average annual concentration over a 1984 to 2005 period is used as an adjustment to smooth out the high

- and low

- rainfall years

, which bring different amounts of deposition load to the watershed due primarily to the volume of precipitation

. Much of the reduction has been from point source air emission reductions, particularly from electric generating units (EGUs). Reductions from mobile sources are another large contributor to the downward trend.DRAFT Chesapeake Bay TMDL

4

- 38 September 24 , 2010

Source: Phas e 5.3 Chesapeake Bay Watershed Model.

Figure 4

- 17 Trend of estimated average nitrate and ammonia deposition concentrations in the Phase 5 Model
domain from 1984 to 2005

. .

Table 4

- 17 shows the estimated portion of de posited NOx loads on the Chesapeake watershed from four sectors including EGUs, mobile sources, industry, and all other sources. From 1990 to 2020 considerable reductions have been made in the power sector. In addition, both on road and

off

- road mobile sou rces have ongoing fleet turnover and replacement, which is putting cleaner spark and diesel engines in service, and that is expected to continue beyond 2030. Table 4

- 17 shows that in 1990, EGUs are the dominant source of NOx; in 2020, mobile sources will be the

dominant sources of NOx with EGUs the least contributor of NOx. However Figure 4

- 17 shows that all sources will be decreasing their NOx emissions, and the total deposition load in 2020 will

be less than 1990.

Average ammonia loads over the Phase 5 domain have followed the tr end in overall manure loads in the watershed and have remained steady over the 1985 to 2000 simulation period ( Figure 4

- 17 ). A mmon ia deposition is very site

- specific and strongly influenced by local

emissions . Local and regional trends in manure, such as the rise of poultry animal units in the Eastern Shore and Shenandoah and dairy’s diminishment in the northern portions of the watershed in the late 1980s, affect regio nal ammonia deposition in the Chesapeake watershed.

Table 4

- 17

. Estimated portion of deposited NOx loads on the Chesapeake watershed from four

source sectors

— EGUs, mobile sources, industry, and all other sourc es in 1990 and 2020

Source s ector 1990 2020 Power plants (EGUs) 40% 17% Mobile sources (on

- road) 30% 32% Industry 8% 20% Other (off

- road

- construction; residential, commercial) 21% 31%

Source: Dr. Robin Dennis, EPA/ORD/NERL/AMAD/AEIBDRAFT Chesapeake Bay TMDL

4

- 39 September 24 , 2010



### 4.7.3 Forest Lands

Forested areas represent a significant portion of the Chesapeake Bay watershed ( see Figure 2

- 3 ), as approximately 70 percent of the watershed is composed of forested and open wooded areas. This land use contributes the lowest loading rate per acre of all the land uses, however. Compared with other major pollutant source sectors in 2009, forest lands contributed an estimated 20 percent ( 49 million pounds per year) of total nitrogen, 15 percent ( 2

. 4 million pounds per year) of total phosphorus, and 18 percen t ( 730 ,000 tons per year ) of sediment of the total delivered loads to the Bay from the watershed (Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario).

Forest land differs from most land uses in that a significant portion of the loads that come off the land do not originate in the forests. Most of the forest loads come from atmospheric deposition of nitrogen (Campbell 1982; Langland et al. 1995; STAC 1997; Ritter et al. 1984; Stevenson et al. 1987; Nixon 1997; Castro et al. 1997; Goodale et al. 2002; Pan et al. 2005; Aber et al. 1989; 2003; Stoddard 1994). Sediment and phosphorus loads originate from poorly managed forest harvesting with unprotected stream crossings and unhealthy forest biota (Riekerk et al. 1988; Clark et al. 2000).

The Phase 5.3 Chesape ake Bay Watershed M odel differentiates between harvested and un

harvested forest land s as distinct land uses

. Un

- harvested forest land s contributed 1.63 lbs of nitrogen , 0.08 lb of phosphorus , and 0.02 ton of sediment per acre, which is the lowest loading rate of any land use

. In contrast, harvested forest contributes 10.30 lbs of nitrogen , 0.47 lb of phosphorus , and 0.19 ton of sediment per acre. The loads from harvested forest can be greatly reduced by using forest h arvesting BMP s

. The loads are estimated through model calibration

, which estimates loading rate per area on the basis of monitoring stations in forested areas.

For additional information related to the representation of forest lands, see the Phase 5.3

Ches apeake Bay watershed model documentation at http://www.chesapeakebay.net/model_phase5.aspx?menuitem=26169

.



### 4.7.4 On

- site Wastewater Treatment S ystems

OSWTSs, commonly referred to a s septic systems, have the potential to deliver nutrients to surface waters because of system failure and malfunction. Septic systems treat human waste using a collection system that discharges liquid waste into the soil through a series of distribution

li nes that compose the drain field. In properly functioning (normal) systems, phosphates are adsorbed and retained by the soil as the effluent percolates through the soil to the shallow, saturated zone. Therefore, functioning systems do not contribute nutrie nt loads to surface waters. A septic system failure occurs when there is a discharge of waste to the soil surface where it is available for washoff. As a result, failing septic systems can contribute high nutrient loads to

surface waters. Short

- circuited s ystems (those close to streams) and direct discharges also contribute significant nutrient loads.

OSWTSs represented an estimated 6 percent of the total nitrogen load from the Chesapeake watershed in 2009 (Phase 5.3 Chesapeake Bay Watershed Model 2009 Scen ario). Information on the watershed loads from OSWTSs is generally sparse. Detailed descriptions of data procedures, source information, and assumptions used in estimating these loads are in Palace et al. (1998).DRAFT Chesapeake Bay TMDL

4

- 40 September 24 , 2010

For the Chesapeake Bay watershed model, th e number of OSWTS s in each modeling segment was estimated by calculating the number of households outside areas currently served by public

sewer

. One septic system was assumed to exist for each household

. Digital maps of 2009 sewer service areas were provi ded by 257 of the 403 major wastewater treatment plants in the watershed contacted during a 2009 survey sponsored by EPA

. Digital data were also provided by the Maryland Department of Planning for all of Maryland, Fairfax County, and the Washington

Council of Governments

. In 2008 the CBP O ffice contacted some local jurisdictions and

collected sewer service area data for all three Delaware c ounties, Albemarle, Arlington, Henrico, Loudoun, and Rockingham c ounties in Virginia and for James City, Newport News C ity, Virginia Beach

, and Richmond in Virginia. Data were also collected for Perry, Dauphin, Lancaster, Lycoming, and Cumberland c ounties in Pennsylvania, and for Broome County in

New York

. For those major wastewater treatment plants that did not provide da ta and were not included in data supplied by county or state agencies, the extent of their sewer service area was

estimated on the basis of population density

.

The CBP O ffice simulated the extent of existing sewer service areas using a thresholded and log

transformed raster data set of year 2000 population density

. A population density raster was created using a dasymetric mapping technique with 2000 Census Block Group data an d a secondary road density raster map (Claggett and Bisland 2004)

. A logarithmic transformation was used to normalize the population density data in the surface raster

. The standard deviations in the data range were examined to find the optimal threshold f or representing sewer service areas in Maryland because statewide maps of existing sewer service areas were provided by the Maryland Department of Planning

. A threshold of 1.5 standard deviations from the mean (>

– 0.4177) was chosen and used to reclassify the surface raster into a binary grid

. A low pass filter (ignoring no data) was then used to smooth the data and the output was converted from a floating point to an integer grid

. The resulting integer grid was used to represent potential sewer service

are as for wastewater treatment plants that did not submit digital data

. Households in the Bay watershed were mapped using a similar dasymetric mapping technique and 2000 Census

household data

. The resulting raster data set of households was overlaid on the se wer service area map to estimate the number of households outside sewer service areas

. The data were scaled from the year 2000 to the year 2009 using published annual county

- level population estimates adjusted for changes in average household size

. In addi tion, the data were scaled back through time using county

- level population estimates and spatially distributed raster data sets representing 1990 and 2000 Census Block Group data on the total number of households.

Using th at methodology, the number of OSW TS s is estimated nitrate loads discharged to the

river are simulated . Phosphorus loads are assumed to be entirely attenuated by the OSWTSs. Standard engineering assumptions of per capita nitrogen waste and standard attenuation of nitrogen in the septic sys tems are applied. Overall, the assumption of a load of 4.0 kg/person

year is used at the edge of the OSWTS field, all in the form of nitrate.

Using an average water flow of 75 gallons/person

- day for a septic tank (Salvato 1982), a mean value of 3,940 grams /person

- year for groundwater septic flow, 4,240 grams/person

- year for surface flow of septic effluent, and typical surface/subsurface splits as reported by Maizel et al. (1995), a total nitrogen concentration of about 39 mg/L at the edge of the septic fiel d was calculated. This concentration compares favorably with Salvato (1982) who calculated OSWTS total nitrogen concentrations of 36 mg/L. It is assumed that attenuation of the nitrate loadsDRAFT Chesapeake Bay TMDL

4

- 41 September 24 , 2010

between the septic system field and the edge

- of

- river nitrate loa ds represented in the Phase 5 Model is due to (1) attenuation in anaerobic saturated soils with sufficient organic carbon (Robertson et al. 1991; Robertson and Cherry 1992), (2) attenuation by plant uptake (Brown and Thomas 1978), or (3) attenuation in low

- order streams before the simulated river reach. Overall, the total attenuation is assumed to be 60 percent (Palace et al. 1998).

Additional information related to how the number of OSWTSs is estimated and how they are represented in the model is available in the Phase 5.3 watershed model documentation at http://www.chesapeakebay.net/model_phase5.aspx?menuitem=26169



### 4.7.5 Nonregulated Stormwater Runoff

The sources of nutrient s and s ediment from nonregulated stormwater are generally the same as those from regulated stormwater

. Sou r ces include residential and commercial application of fertilizer, land disturbance and poorly vegetated surfaces, atmospheric deposition of nutrients,

pet w astes, developed properties, and a variety of other pollutants. Together with regulated stormwater, the nutrients and sediment impact local water quality and habitats and represent a significant proportion of nutrient and sediment loads to the Bay. The CBP estimates that, in 2009, urban and suburban development and runoff contributed to 16 percent of the sediment loadings, 15 percent of the phosphorus loadings, and 8 percent of the nitrogen loadings to the Bay ( P hase 5.3 Chesapeake Bay Watershed Model 2009 Scenario )

.
The regulated sources of stormwater are discussed in the point sources section above (4.5.5). For the purposes of the TMDL, urban and suburban runoff occurring outside the NPDES regulatory purview is considered nonpoint source loading and is a c omponent of the LA. However, note that CWA section 402(p) provides the authority to regulate many of these discharges. If any of the discharges are designated for regulation, they would then be considered part of the WLA. Some jurisdictions may have state stormwater regulatory programs and, therefore, could have little to no nonregulated stormwater sources.

For additional details related t o how the loads were estimated in the Phase 5.3 Chesapeake Bay Watershed Model, see Section 7 in the Watershed Model Doc umentation at http://www.chesapeakebay.net/model_phase5.aspx?menuitem=26169

.



### 4.7.6 Oceanic inputs

The Chesapeake Bay is an estuary and, by definition, a mixture of fresh and salt w ater. The relative proportion of ocean water in any region of the Bay can be roughly estimated by its salinity because salt is a perfectly conservative tracer. The salinity of full strength seawater just outside the Chesapeake Bay mouth is about 35 parts p er thousand (ppt)

. At mid

- Bay around the where Potomac River enters the mainstem Bay, the salinity drops to about 15 ppt, or a mixture of about half seawater and at the Bay Bridge between Annapolis and Kent Island, Maryland, salinity drops to about 6 ppt or 20 percent seawater . While nutrient and sediment concentrations are relatively low in ocean water, the large volume of seawater entering the Bay brings considerable nutrient and sediment loads to the Bay.

Ocean input loads of nutrients and sediment to the Chesapeake Bay are determined by calibration to the three Bay water quality monitoring stations at the mouth of the Chesapeake Bay by using the CH3D Hydrodynamic Model, which has a model grid and domain that extends about 10 km beyond the mouth of the Bay. Ocean boundary con centrations are set monthly in the WQSTM toDRAFT Chesapeake Bay TMDL

4

- 42 September 24 , 2010

best represent the nutrient and total suspended solids concentrations of the monitoring stations at the Chesapeake Bay month on an incoming tide.

A previous study of ocean boundary loads found that when accounting for all input loads to the Chesapeake Bay, including atmospheric deposition to tidal waters and ocean inputs, the ocean inputs were significant and accounted for about one

- third of the total nitrogen and about half the total phosphorus loads to the Bay (Thomann et al. 1994). Ocean sediment inputs are predominantly sand and have little influence on light attenuation beyond the Bay mouth and lower mainstem Bay.

Several nutrient budgets of the ocean waters off the Chesapeake, also called the Middle Atlantic Bight, have been made (Fennel et al. 2006; Howarth et al. 1995; Howarth 1998). Howarth (1998) estimates that for the northeast coast of the United States, which includes the discharge of all watersheds from Maine to Virginia draining to the Atlant ic, the watershed inputs of nitrogen to coastal waters are 0.27 teragram (10 12 grams) from rivers and estuaries. Estimated inputs from direct atmospheric deposition to coastal waters are 0.21 teragram, and inputs from deep ocean upwelling are 1.54 teragram s for a total input to the coastal ocean of 2.02 teragrams.

The direct a tmospheric deposition loads are roughly equivalent to the waters hed loads in the

northeast United States. The estimated distribution of 2001 atmospheric deposition loads to

North Ameri ca and adjacent coastal ocean is shown in Figure 4

- 18

. Using the CMAQ Model estimates of atmospheric deposition loads to the coastal ocean under different air scenario s provides a means of adjusting the ocean boundary loads to changes in atmospheric deposition. Appendix M describes how the ocean boundary loads were adjusted to reflect projected changes in nitrogen atmospheric deposition to the coastal ocean and, therefo re, coastal ocean nitrogen loads delivered to Chesapeake Bay.DRAFT Chesapeake Bay TMDL

4

- 43 September 24 , 2010

Source: Dr. Robin Dennis, EPA/ORD/NERL/AMAD/AEIB

Figure 4

- 18 . Estimated 2001 annual total deposition of nitrogen (kg

- N/ha) to North America and adjacent

coastal ocean.



### 4.7.7 Streambank and T idal S horeline Ero s ion

Steambank erosion
Streambank erosion is erosion from the reworking of streams and rivers, either as flow rates change as in the case of increased imperviousness in a watershed (Center for Watershed Protection 2003), because of long

- term changes in the landscape ( Walter and Merritts 2008 ; Trimble 1999), or as a natural process of river channel dynamics ( Leopold et al. 1995).

In the Chesapeake Bay watershed, the relative amounts of stream ba nk erosion and erosion from the land is difficult to quantify (Gellis et al. 2009) because the water quality monitoring stations measure the total suspended sediment in the free

- flowing rivers, which is composed of sediment from both sources. The Bay Water shed Model has estimates of land erosion derived from

RUSLE estimates made in the National Resource Inventory ( http://www.nrcs.usda.gov/technical/NRI/ ), which could be used to quantify that source of

se diment relative to the scour and erosion simulated in the rivers, but both sources of information are thought to be too crude to estimate the splits in erosion loads on a segment basis. On a

watershed

- wide basis, the estimate is for about 70 percent of the sediment delivered to the Bay from erosion from land and 30 percent from bank erosion. This is consistent with other estimates from research and field studies that find a wide variance of the portions of delivered erosion from

land surfaces and bank erosi on but could be generalized to about one

- third of the erosion as coming from bank erosion ( Figure 4

- 19 ).DRAFT Chesapeake Bay TMDL

4

- 44 September 24 , 2010

Source: Gellis et al. 2009

Figure 4

- 19 . Relative estimates of sources of erosion from land sources (crop, forest, or construction) or bank sources banks and ditch beds).

Because sediment monitoring stations in the watershed collect all the sediment loads passing the station, including both land erosion and from bank erosion sources, the stream bank load is accounted for, ultimately, both in the Chesapeake Bay watershed monitoring network and in the Bay Watershed Model, at least as part of the total combination of sedi ment from land and riverine sources. In the same way, streambank loads are also accounted for in tracking sediment load reductions from stream restoration actions and through reductions of sediment and nutrients tracked in the jurisdictions’ WIPs.

Tidal sh oreline erosion
Tidal shoreline erosion is a combination of the erosion of fastland (or shoreline) and nearshore

erosion. Figure 4

- 20 illustrates the tidal shoreline e rosion process. Fastland and nearshore is subtidal and usually unseen. Subtidal erosion can be accelerated when shoreline protection

activities such as stone r evetment are used. That practice typically cuts off fastland erosion, but

the reflected wave ener gy continues subtidal erosion until the wave energy no longer scours the bottom to the depth of a meter or more.

Estimates of shoreline erosion were provided for the WQSTM. Estimates of the shore recession rate, the elevation of the fastland, and the subti dal erosion rate were used to develop these

shoreline erosion estimates. Figure 4

- 21 demonstrates considerable variation in the sediment load delivered by sediment erosion from segment to segment.DRAFT Chesapeake Bay TMDL

4

- 45 September 24 , 2010

Source: CBP Sediment Workgroup

Figure 4

- 20

. Sources of total suspended solids in the Chesape ake including the two components of shoreline erosions, fastland and nearshore erosion.

Source: Water Quality and Sediment Transport Model.

Figure 4

- 21 . Estimated tidal sediment inputs for 1990 from the Chesapeake Bay watershed and from shore erosion. Shoreline sediment inputs (here labeled bank load) are estimated to be about equal to watershed inputs (here labeled as nonpoint source).



### 4.7.8 Tidal R esuspension

The bottom of the Chesapeake Bay is covered by sediment that has been either carried into the estuary by rivers draining the Bay’s extensive watershed; eroded from the Bay’s lengthy shoreline; transported up

- estuary from the Atlantic Ocean, through the mouth of the Bay; introduced from the atmospher e; or generated by primary productivity ( Langland and CroninDRAFT Chesapeake Bay TMDL

4

- 46 September 24 , 2010

2003). Tidal resuspension is generated by episodic wave or current energy that scours the bottom sediment and resuspends the surficial sediment layers.

In the Bay WQSTM, a wave resuspension model simulates these episodic events. In some regions of the Bay, resuspended sediment can be one of the most detrimental sediment loads to SAV restoration as shown in results of sediment scoping scenarios run on the WQSTM ( Table

4

- 18 ). The WQSTM was run to compare the base scenario of the 2010 Tributary Strategy against model scenarios that individually eliminated watershed loads of total suspended sediments (TSS), fall l ine loads of TSS, shore erosion loads, sediment resuspension loads, and ocean

sediment loads. These model scenarios were run to determine which sediment source was the more important source of sediment. In most of the mainstem Bay, sediment resuspension lo ads were relatively more detrimental to SAV growth than were other sediment sources.

Table 4

- 18 . Chesapeake Bay WQSTM simulated SAV acres under a range of sediment scoping scenarios compared with the 2010 Trib utary Strategy scenario

CBSEG SAV

acre No

watershed

loads %
increase

over base SAV

acre No fall

line

loads%
increase

over base SAV

acre No

shore
erosion

loads%
increase

over base SAV

acre No

resus
pension

loads%
increase

over base SAV

acres No ocean

sed loads

%
increase

over base

CB1TF 11,253 23% 11,001 20% 9,751 6% 10,344 13% 9,173 0%
CB2OH 212 63% 192 47% 177 36% 269 107% 138 6%

CB3MH 609 44% 539 28% 478 13% 704 67% 450 7%

CB4MH 1,150 30% 1,039 18% 1,096 24% 1,671 89% 980 11%
CB5MH 9,432 9% 9,086 5% 10,341 20% 14,055 63% 9,177 6%

CB6PH 825 21% 695 2% 701 3% 980 44% 728 7%
CB7PH 14,236 4% 13,798 1% 13,959 2% 14,582 7% 14,162 4%

CB8PH 6 25% 5 17% 5 5% 6 29% 5 18%
a. The percentages are the percentage increase in simulated SAV acres over the 2010 Tributary Strategy scenario
SAV acres.



### 4.7.9 Wildlife

Wildlife sources are rarely, if ever, considered in nutrient TMDLs because wildlife cycle only nutrients that already exist in the system. To the extent that wildlife increases the availability of

nutri ents for runoff, wildlife nutrient loads are inherently represented in land use sources. As a specific example, the loads from the wooded land incorporate nutrient loads that are cycled through wildlife. The overall loads from the watershed and each land u se type are calibrated to observed data and literature load estimates, which also include loads cycled through wildlife. As a result, no explicit allocation to wildlife is necessary or appropriate in the Bay TMDL.



### 4.7.10 Natural B ackground

The Bay Airshed model, Watershed model, and WQSTM all include the loads from natural background conditions because all the Bay models are mass balance models and are calibrated to observed conditions. For example, the atmospheric deposition loads are monitored principally at the NADP sites. The deposition measured at those sites includes NOx from natural sources, which includes lightning, forest fires, and b acterial processes such as nitrification

, which oxidizes ammonia (NH 3 ) to NO 2 or NO 3 . Those sources compose about 1 percent of the NOx deposition in the Chesapeake region (USEPA 2010 i ). Natural background sources of ammonia are easily volatilized from land and water surfaces and are generated from the decayDRAFT Chesapeake Bay TMDL

4

- 47 September 24 , 2010

(ammoniafication) of natural so urces of organic nitrogen. Those are likewise a relatively small portion, relative to anthropogenic sources, of the atmospheric loads estimated by the NADP sites.

Natural loads of nutrients and sediment from forested land are also part of the monitored lo ad at

the free

- flowing stream, river and river input monitoring stations located throughout the Chesapeake Bay watershed. Because the loads are part of the total loads to which the Bay Program mass balance models are calibrated, the natural nutrient and se diment loads in the system, while small, are fully accounted for in the Bay TMDL assessment.

The natural background loads can best be estimated by simulating the all forest scenario, which includes no point source, manure, or fertilizer loads. Atmospheric deposition loads in that scenario are set at estimated pristine levels. The scenario yields delivered nutrient and sediment loads that are more than an order of magnitude less that current conditions (see Appendix K ).