'' '"u','
Chesapeake Bay Watershed Model
Application & Calculation of Nutrient
& Sediment Loadings
Appendix H:
Tracking Best Management
Practice Nutrient Reductions
in the Chesapeake Bay
Program
Prepared by the
Modeling Subcomittee
of the
Chesapeake Bay Program
EPA 903-R-98-009
CBP/TRS 201/98
August 1998
EPA Report Collection
Regional Center for Environmental Information
U.S. EPA Region III
Philadelphia, PA 19103
Chesapeake Bay Program
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-------
CHESAPEAKE BAY WATERSHED MODEL
APPLICATION AND CALCULATION OF
NUTRIENT AND SEDIMENT LOADINGS
Appendix H: Tracking Best Management
Practice Nutrient Reductions in the
Chesapeake Bay Program
A Report of the
Chesapeake Bay Program
Modeling Subcommittee
Annapolis, MD
al Ccnu-rtfH f iuirniinicnl.il Inlormnrion
I STP \Rcpon III
165(1 Atdi s. Aueust 1998
Philadelphia. PA 19103 ^VUgUSL 1 770
Chesapeake Bay Program
PA 19103
Printed by the U.S. Environmental Protection Agency for the Chesapeake Bay Program
-------
Principal Authors
Michael W. Palace
Chesapeake Research Consortium
Chesapeake Bay Program Office
Annapolis, MD
James E. Hannawald
United States Department of Agriculture
Natural Resources Conservation Service
Chesapeake Bay Program Office
Annapolis, MD
Lewis C. Linker
United States Environmental Protection Agency
Chesapeake Bay Program Office
Annapolis, MD
Gary W. Shenk
United States Environmental Protection Agency
Chesapeake Bay Program Office
Annapolis, MD
Jennifer M. Storrick
Chesapeake Research Consortium
Chesapeake Bay Program Office
Annapolis, MD
Michael L. Clipper
Chesapeake Research Consortium
Chesapeake Bay Program Office
Annapolis, MD
-------
Tributary Strategy Workgroup
Tom Simpson
Chairman
MD Department of Agriculture
Chesapeake Bay Agricultural Programs
Annapolis, MD
Mark Bennett
VA Dept. of Conservation &
Recreation
Division of Soil and Water Conservation
Richmond, VA
Don Fiesta
PA Dept. of Environmental Protection
Bureau of Water Quality Protection
Harrisburg, PA
Jim Hannawald
US Dept. of Agriculture
Natural Resource Conservation Service
Chesapeake Bay Program Office
Annapolis, MD
Wayne Jenkins
MD Dept. of the Environment
Chesapeake Bay Watershed Management
Administration
Baltimore, MD
Tim Karikari
DC Dept. of Health
Washington, DC
Russ Mader Jr.
US Dept. of Agriculture
Natural Resource Conservation Service
Chesapeake Bay Program Office
Annapolis, MD
Mary Searing
MD Department of Natural Resources
Watershed Management and Analysis
Division
Annapolis, MD
Mohsin Siddique
DC Dept. of Health
Washington, DC
Helen Stewart
MD Dept. of Natural Resources
Watershed Management and Analysis
Division
Annapolis, MD
Tom Tapley, Chair, Pt. Source Workgroup
MD Dept. of the Environment
Technical and Regulatory Services Administration
Baltimore, MD
Allison Wiedeman
US Environmental Protection Agency
Chesapeake Bay Program Office
Annapolis, MD
Kenn Pattison
PA Dept. of Environmental Protection
Bureau of Water Quality Protection
Harrisburg, PA
-------
Modeling Subcommittee Members
James R. Collier
Chairman
Water Resources Management Division
Washington, DC
Dr. Joseph Bachman
US Geological Survey
Towson, MD
Mark Bennett
Department of Soil and Water Conservation
Richmond, VA
Dr. Peter Bergstrom
Chesapeake Bay Field Office
US Fish & Wildlife Service
Annapolis, MD
Dr. Arthur Butt
Chesapeake Bay Office
VA Department of Environmental Quality
Richmond, VA
Brian Hazelwood
Metropolitan Washington Council of
Governments
Washington, DC
Dr. Albert Y. Kuo
VA Institute of Marine Science
Gloucester Point, VA
Lewis C. Linker
Coordinator
US EPA Chesapeake Bay Program Office
Annapolis, MD
Dr. Robert Magnien
MD Department of Natural Resources
Assessment Administration
Annapolis, MD
Dr. Ross Mandel
Interstate Commission on the Potomac
River Basin
Rockville, MD
Dr. Bruce Parker
National Oceanic and Atmospheric
Administration/NOS/OES33
Coastal & Estuarine Oceanography
Silver Spring, MD
Kenn Pattison
PA Dept. of Environmental Protection
Bureau of Water Quality Protection
Harrisburg, PA
Ron Santos
US Army Corps of Engineers
Baltimore, MD
Dr. Tom Stockton
MD Dept. of Environmental Resources
Watershed Modeling & Analysis
Annapolis, MD
Paul Wella
USDA Natural Resources Conservation Service
East Regional Office
Beltsville, MD
Dr. Alan Lumb
Hydrologic Analysis Support Section
USGS National Center
Reston, VA
in
-------
Acknowledgments
The writers would like to acknowledge the contribution of the Nutrient Subcommittee's
Tributary Strategy Workgroup for their guidance in the development and review of this
document. This document, and other Chesapeake Bay Program modeling documents, can be
found on the Modeling Subcommittee web page:
http://www.chesapeakebay.net/bayprogram/committ/mdsc/model.htm
IV
-------
Appendix Summary
Appendix H documents the work of the Chesapeake Bay Program Nutrient Subcommittee and
the Tributary Strategy Workgroup. The Tributary Strategy Workgroup is made up of
Chesapeake Bay Program scientists, engineers, and managers who work closely with the
Chesapeake Bay Watershed Model in estimating the progress toward Chesapeake Bay nutrient
reduction goals. Appendix H provides a summary of the methodologies used in tracking nutrient
reduction goals with the Phase IV Watershed Model and outlines the data management
procedures used for BMP tracking within each state. Information on nutrient application rates,
land use conversions, and the application of land use-based BMP efficiency rates within the
Phase IV Watershed Model is presented.
-------
List of Phase IV Watershed Model Reference Appendices
Appendix A Phase IV Chesapeake Bay Watershed Model Hydrology Calibration Results
Appendix B Phase IV Chesapeake Bay Watershed Model Water Quality Calibration
Appendix C Phase IV Chesapeake Bay Watershed Model Nonpoint Source Simulation
Appendix D Phase IV Chesapeake Bay Watershed Model Precipitation and Meteorological
Data Development and Atmospheric Nutrient Deposition
Appendix E Phase IV Chesapeake Bay Watershed Land Use & Model Linkages to the Airshed
& Estuarine Models
Appendix F Phase IV Chesapeake Bay Watershed Model Point Source Loads
Appendix G Observed Water Quality Data Used for Calibration, A Simulation of Regression
Loads, and a Confirmation Scenario of the Phase IV Chesapeake Bay Watershed
Model
Appendix H Tracking Best Management Practice Nutrient Reductions in the Chesapeake Bay
Program
Appendix I Model Operations Manual
VI
-------
Table of Contents
Principal Authors i
Tributary Strategy Workgroup Members ii
Modeling Subcommittee Members Hi
Acknowledgments : iv
Appendix Summary v
List of Phase IV Watershed Model Reference Appendices v/
Table of Contents vii
List of Figures ix
List of Tables jc
Acronym Index xii
H.I BMP Data Management 1
H. 1.1 Federal Cost-Share Programs 6
H.I.2 State Programs 9
H. 1.3 Land Use Conversions 20
H, 2 Implementation of Nutrient Management BMP Application Rates and BMP
Nutrient Reduction Efficiency Rates 25
H.2.1 BMPs Involving Land Use Conversion 25
H.2.1.1 Conservation Reserve Program 26
H.2.1.2 Forest Conservation 26
H.2.1.3 Tree Planting .- 26
H.2.1.4 Conservation Tillage 27
H.2.1.5 Forest and Grass Buffers 28
H.2.2 BMPs Involving Nutrient Reduction Efficiencies 30
H.2.2.1 Urban BMPs 33
H.2.2.1.1 Erosion and Sediment Controls 33
H.2.2.1.2 Stormwater Management Systems 34
H.2.2.1.3 Onsite Wastewater Management Systems 35
H.2.2.1.4 Onsite Wastewater Management System Loading 36
H.2.2.1.5 Urban Nutrient Management 43
H.2.2.2 Agriculture/Silviculture BMPs 46
H.2.2.2.1 Cropland Nutrient Management..,. 46
H.2.2.2.2 Soil Conservation and Water Quality Plan 46
H.2.2.2.3 Animal Waste Management Systems 48
H.2.2.2 A Manure Applications to Pastureland 63
H.2.2.2.5 Runoff Control for Animal Confinement Areas 70
H.2.2.2.6 Grazing Land Rotation 70
vii
-------
H.2.2.2.7 Stream Protection (with and without fencing) 70
H.2.2.2.8 Forestry BMPs 71
H.2.2.2.9 Forest and Grass Buffers 72
H.2.2.2.10 Cover Crops 72
H.2.2.3 BMPs Affecting Direct Loads to Tidal Bay Waters 72
H.2.2.3.1 Marine Sewage Disposal Facilities 73 ,
H.2.2.3.2 Shoreline Protection 73
H.2.2.3.3 Combined Sewer Overflows 73
H.3 Summary of Watershed Model Operations 74
H.3.1 Scenario Characteristic Modification 75
H.3.2 Initial Model Run for the Edge of Stream Loads 75
H.3.3 Adjustment of Bed Concentration 75
H.3.4 Second Model Run 75
H.3.5 Delivery Factors 75
H.3.6 Final Model Run 75
Reference 77
Vlll
-------
List of Figures
Figure
Page
H.I.I Watershed Model Scenario Operations 2
H.I.2 Major Basins in the Chesapeake Bay Watershed 3
H. 1.3 Conservation Tillage vs Conventional Tillage for the Chesapeake
Bay Watershed 23
H. 1.4 Conservation Tillage vs Conventional Tillage for the United States 24
H.2.1 Determining Fertilizer Nutrient Application Rates for Pervious Urban Areas ... 44
H.2.2 Fertilizer Application to the Phase IV Watershed Model for Pervious
Urban Land 45
H.2.3 Cropland Mass Balance Used to Calculate the Amount of Nutrients
Needed Under Nutrient Management Conditions 47
H.2.4 Calculating Manure Acres and their Incorporation into the Phase IV
Watershed Model 49
H.2.5 Manure Mass Balance for each Phase IV Watershed Model Segment 50
H.2.6 Total Animal Units by County 53
H.2.7 Method Used to Estimate Nitrogen Applied to Pasture 64
H.2.8 Comparison of Modeled and Observed Manure Application Rates of
TN and TP to Conventional Tillage 67
H.2.9 Comparison of Modeled and Observed Manure Application Rates of
TN and TP to Conservation Tillage 68
H.2.10 Comparison of Modeled and Observed Manure Application Rates of
TN and TP to Hayland 69
IX
-------
List of Tables
Table Page
H. 1.1 Chesapeake Bay Watershed Model (WSM) BMP Identities
with Associated Land Use Code 4
H. 1.2 Correlation of Tributary Strategy BMPs with Phase IV Watershed
Model BMPs 5
H. 1.3 Federal Conservation Reporting and Evaluation System (CRES)
Practice Identities and Corresponding Phase IV Watershed Model BMP
Identities (used from 1985 to 1992) 6
H. 1.4 Federal Conservation Reporting and Evaluation System (CRES)
Practice Identities and Corresponding Phase IV Watershed Model BMP
Identities (used from 1993 to Present) 7
H. 1.5 An Example of Percentages of Selected Counties within each
Corresponding Chesapeake Bay Phase IV Watershed Model Segment 8
H. 1.6 Pennsylvania Cost-Share BMP Identities and Corresponding
Chesapeake Bay Phase IV Watershed Model BMP Identities
(Practices tracked from 1985 to 1996) 9
H.I.7 Maryland Cost-Share BMP Identities and Corresponding
Chesapeake Bay Phase IV Watershed Model BMP Identities
(Practices tracked from 1985 to 1996) 10
H.I.8 Virginia Cost-Share BMP Identities and Corresponding
Chesapeake Bay Phase IV Watershed Model BMP Identities
(Practices tracked from 1985 to 1996) 11
H. 1.9 Example of Maryland BMP Data Format for the Phase IV Watershed
1996 Progress Scenario 12
H.I .10 List of Maryland BMPs and Data Sources 14
H.I.I 1 Example of Pennsylvania BMP Data Format 16
H.I.12 Example of Virginia BMP Data Format 18
-------
Table Page
H.I.13 Example of District of Columbia's BMP Data 19
H.I.14 BMPs Resulting in a Land Use Conversion 21
H.2.1 Maryland's Nutrient Reduction Efficiencies for Forest or
Grass Buffers 29
H.2.2 Chesapeake Bay Watershed Model BMP Matrix with Associated
Nutrient Reduction Efficiencies 30
H.2.4 Population Estimates & Projections for Chesapeake Bay Program
Model Segments 37
H.2.5 Septic Loading Projections for the Chesapeake Bay Program
Model Segments 40
H.2.6 Distribution of Total Nitrogen from Manure for each Phase IV
Watershed Model (WSM) Segment in the Manure Mass Balance
Calculation for the Phase IV Watershed Model 52
H.2.7 Estimated Quantities of Voided Manure from Livestock and
Poultry (Normalized to 1,000 pounds of animal body weight) 52
H.2.8 Manure in All Confined Areas 55
H.2.9 Manure in Areas Susceptible to Run-off (BMPs possible) 57
H.2.10 Manure in Areas Always Susceptible to Run-off 59
H.2.11 Manure in Areas Never Susceptible to Run-off 61
H.2.12 Breakdown of TN Manure Applications per 2 Days 65
H.2.13 Breakdown of TN Manure Applications per Year 66
XI
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Acronym Index
Acronym
AU
AWMSL
AWMSP
BF
BG
BMP
CBP
CBPLU
CC
CIMS
CUES
CRP
CSO
CT
CTIC
ESC
ESWM
FC
FCA
FHP
FSA
CIS
HSPF
MSDF
NCRI
NMPI
NRCS
OSWMS
RC
RHEL
SC
SCWQP
SCWQPI
SD
SP
SPWF
SPWO
SWCD
SWM
SWMC
SWMR
TN
TPLANT
TP
TSWG
UNM
USDA
USEPA
WDM
WSM
Term
Animal Unit
Animal Waste Management System (livestock)
Animal Waste Management System (poultry)
Buffer Forested
Buffer Grassed (on agricultural land)
Best Management Practice
Chesapeake Bay Program
Chesapeake Bay Program Land Use
Cover Crop
Chesapeake Information Management System
Federal Conservation Reporting and Evaluation System
Conservation Reserve Program
Combined Sewer Overflow
Conservation Tillage
Conservation Technology Information Center
Erosion and Sediment Control
Enhanced Stormwater Management
Forest Conservation
Forest Conservation Act (Maryland)
Forest Harvesting Practice
Farm Services Agency
Geographic Information System
Hydrologic Simulation Program FORTRAN
Marine Sewage Disposal Facility
National Center for Resource Information
Nutrient Management Plan Implementation
National Resources Conservation Service
On-site Wastewater Management System
Runoff Control
Retirement of Highly Erodible Land
Septic Connection
Soil Conservation and Water Quality Plan
Soil Conservation and Water Quality Plan Implementation
Septic Denitrification
Septic Pumping
Stream Protection With Fencing
Stream Protection Without Fencing
Soil & Water Conservation District
Stormwater Management
Stormwater Management Conversion
Stormwater Management Retrofit
Total Nitrogen
Tree Planting
Total Phosphorous
Tributary Strategy Workgroup
Urban Nutrient Management
United States Department of Agriculture
United States Environmental Protection Agency
Watershed Data Management
Watershed Model
Xll
-------
Section H.I BMP Data Management
Nutrient reduction tracking involves: 1) accurate annual land use data, 2) annual Best
Management Practice (BMP) installation or implementation data, and 3) using the land use and
BMP data to simulate the effect of implemented BMPs. Annual land use and BMP data are used
as input for the Phase IV Watershed Model scenarios of past, present, or projected BMP
implementation conditions to calculate nutrient loads and sediment delivered to the Bay. The
land use and BMP databases are necessarily large and complex due to the 64,000 square miles of
land area within the Bay watershed and the wide range of BMPs applied to reduce nutrient and
sediment loads. Figure H. 1.1 is a schematic representation of that process. The watershed
includes parts of Delaware, New York, West Virginia, Pennsylvania, Maryland, Virginia, and all
of the District of Columbia (Figure H.I.2).
Since 1984, the four signatory Bay Agreement jurisdictions (Maryland, Pennsylvania, Virginia,
and the District of Columbia) have expanded existing nonpoint source (nps) pollution control
programs and started new programs. Cost share programs, a major component of nps control
programs provide financial assistance to landowners for BMP implementation. The BMP cost
share implementation data set is used as a major source of BMP tracking data within the Phase
IV Watershed Model and throughout the Bay watershed.
As a result of the Chesapeake Bay Program 1992 Baywide Nutrient Reduction Strategy, the
Chesapeake Reevaluation Executive Council Directive 93-1 established target load reductions
for each of the ten major Chesapeake Bay Tributaries depicted in Figure H.I.2. The Directive
commits each signatory jurisdiction to establish a strategy for achieving the required nutrient
reductions within each tributary by the year 2000. Directive 93-1 has two implications: (1)
achieving the established nutrient loading cap requires accounting for all nutrient reductions
throughout the entire watershed, and (2) locations of BMP installations are needed at a sub-basin
level to determine current nutrient reduction delivered to the Chesapeake Bay as estimated by the
Phase IV Watershed Model.
The tracking process begins with data sets from each of the signatory state jurisdictions (Figure
H.I.I, Boxes A, B, and C). In the non-signatory jurisdictions of Delaware, New York, and West
Virginia, the USDA Farm Service Agency's (FSA) Federal Conservation Reporting and
Evaluation System (CRES) data are used to track practices. CRES data are also used to
supplement the signatory state's cost-share BMP data (i.e. BMPs implemented on private
property with state or federal financial assistance). Data from the Conservation Technology
Information Center (CTIC) are used to track conservation tillage.
The management, documentation, and reporting of BMP installation tracking data are the
responsibility of the individual signatory jurisdictions. Each jurisdiction tracks BMP
installations through cost share as well as non cost-share programs. This means that BMP
installation progress reported from a signatory jurisdiction may include non-cost shared BMPs
that may or may not have been installed with Soil Conservation District technical assistance.
The signatory jurisdictions have agreed to use a common set of BMPs and efficiencies developed
by the Tributary Strategy Workgroup as the basis for evaluating Tributary Strategy progress.
Non-signatory jurisdictions use only federal CRES data in tracking BMP implementation
progress.
-------
Box A
(Sect. H.1.1)
Federal cost
share data
Figure H.1.1 Watershed Model Scenario Operations
BoxB
(Sect. H.1.2)
State BMP data
BoxC
State BMP data
sets
BoxD
(Sect. H.1.3) .
Land use data set
development
BoxE
(Sect. H.2.1-.11)
Compiled landuse
BMPs by
Watershed Model
Segment
BoxF
Modify scenario
land uses with
land use BMPs
BoxG
(Sect. H.2.2)
Apply BMP efficiency
rates and nutrient
application rates
BoxH
Modify Model Mass
Links to reflect BMP
efficiencies, special
actions for
fertilizer/manure
changes, external
sources for point source
and atmospheric
deposition changes
Box I
Run Watershed
Model to get
preliminary
edge-of-stream
loads
BoxJ
Post process
Watershed Model
data in order to obtain
edge-of-stream loads
BoxK
Use ratio of edge-of-
stream loads for
Watershed Model
scenario and
calibration runs to set
sediment nutrient
release rates
BoxL
Run Watershed Model
sediment nutrient release
rates
BoxM
Develop scenario
specific transport
factors
i
BoxN
Post process
Watershed Model
nutrient management
to allocate ail nutrient
and sediment loads
BoxO
Quantify BMPs not
simulated by the
Watershed Model but
used to track nutrient
reduction progress
including marine
pumpouts, shoreline
protection, or combined
sewer overflows
BoxP
Post Watershed
Model scenario
documentation and
results on web site
-------
Major Basins of the Chesapeake Bay Watershed
LOCATION MAP
OF THE
Chesapeake Bay Watershed
NY, PA, MD, D C , DE.
WVANDVA
Susquehanna River Basin
Potomac River Basin
Western Shore Maryland
Patuxent River Basin
Western Shore Virginia
Rappahannock River Basin
York River Basin
Eastern Shore Maryland
Eastern Shore Virginia
[ James River Basin
Figure H.I.2 Major Basins in the
Chesapeake Bay Watershed
KJH Map Dale Jjnuaiy 1998
Source: U.S. E.P.A. Chesapeake Bay Program
-------
Table H.I.I lists the Chesapeake Bay Program Watershed Model BMPs in conjunction with tb
applicable land use. The land use code is an accounting code which represents the land use
simulated by the Phase IV Watershed Model (WSM).
Table H.1.1 BMP Identities With Associated Land Use Code
WSM
BMP 1
BMP 2
BMP 3
BMP 4
BMPS
BMP 6
BMP?
BMPS
BMP 9
BMP 10
BMP 11
BMP 12
BMP 13
BMP 14
BMP 15
BMP 16
BMP 17
BMP 18
BMP 19
BMP20
Unit
acres
acres
acres
acres
acres
acres
acres
acres
acres
acres
acres
acres
systems
systems
systems
acres
acres
acres
acres
acres
Land Use Applied To
all cropland
pasture
conventional/conservation
tilled cropland
manure
forest
manure
pasture
all cropland (NM)
pasture
forest
urban (pervious/impervious)
urban (pervious/impervious)
urban (pervious only)
urban (pervious only)
urban (pervious only)
urban (pervious only)
all cropland
all cropland
pasture
conventional tilled cropland
Land Use Code
60
40
23
70
10
70
40
60
40
10
50
50
50
50
50
50
60
60
40
20
A listing of all the various BMP types and categories used in the tributary strategies has been
developed by the Chesapeake Bay Program Nutrient Subcommittee's Tributary Strategy
Workgroup. Table H.I.2 shows how these field BMPs relate to Chesapeake Bay Watershed
Model BMPs.
-------
Table H.1.2 Correlation of Tributary Strategy BMPs with Phase IV Watershed Model BMPs
Category
Tributary Strategy BMPs
WSM BMPs
Land Use Conversions
Urban
Erosion and Sediment Control
Storm Water Management
Agriculture
Septic Systems
Nutrient Management
Forest
Soil Conservation WQ Plan
Animal Waste
Barnyard Runoff Control
Grazing Land Protection
Streambank Protection
Forest Harvesting
Nutrient Management Plans
Riparian Buffers
Cover Crop
Tributary Model BMPs
Marine Pumpouts
Shoreline Protection
Combined Sewer Overflows
retirement of highly erodible land *
Conservation Reserve Program (CRP) *
forest conservation *
forest/grass buffers *
tree planting *
conventional tillage to conservation tillage *
erosion and sediment control BMP 11
extended detention (dry) BMP 12
pond-wetland system (series) BMP12
stormwater well and (one step) BMP12
retention ponds (wet) BMP 12
SWM conversions (dry->retention) BMP12
sand filters BMP 12
septic pumping BMP 13
septic connections BMP15
septic denitrification BMP14
nutrient management (residential) BMP 16
forest BMP 10
cropland (conventional & conservation tillage) BMP 1
hayland BMP 1
pasture BMP 2
animal waste management systems (dairy/beefswine) BMP 4
animal waste management systems (poultry) BMP 4
supplemental (added to existing waste management system) BMP20
full system (total barnyard control) BMP 4
grazing land protection (rotational grazing) BMP 9
stream protection with fencing BMP 7
stream protection without fencing BMP 19
stream restoration (non-tidal) BMP 7
forest harvesting practices BMP 5
nutrient management plans BMP 8
forested BMP 18
grassed BMP 17
cover crops (cereal grain) BMP 3
marine pumpouts (installation) **
structural shore erosion control **
nonstructural shore erosion control **
treatment **
conversion of combined sewer overflow to sewer **
* Note 1: Land use conversions are directly simulated as a land use change and are not reduction efficiencies, therefore they are no assigned a
Phase IV Watershed Model BMP number.
** Note 2: Simulated as a load reduction by the Phase IV Watershed Model or the Chesapeake Bay Water Quality Model.
-------
Section H.1.1 Federal Cost-Share Programs
Box A.
Federal cost
share data
The USDA Farm Services Agency's Conservation Reporting and Evaluation System (CRES)
tracks conservation practices implemented through the USDA federal cost-share program. This
data set documents sediment and erosion control practices installed, and acres treated annually
throughout the United States. A data subset may then be created which includes practices
installed and acres treated for the counties within the Bay watershed. Each practice is
cumulative from 1985 to the year of the Phase IV Watershed Model scenario with the exclusion
of practices which regularly change on an annual basis, i.e. cover crop practices, which are not
cumulative. The smallest unit of geographic reference for these BMP installations is by county.
Tables H.I.3 and H.I.4 list the Conservation Reporting and Evaluation System BMP identities
and corresponding Chesapeake Bay Program BMP identities used from 1985 to 1992, and from
1993 to the present, respectively.
Table H.1.3 Conservation Reporting and Evaluation System (CRES) Practice Identities and
Corresponding Watershed Model BMP Identities (used from 1985 to 1992)
CRES Practices Tracked 1985-1992
contour farming
Stripcropping, contour or field
terrace system
diversion system
waterway system
sediment retention/erosion or water control structure
field windbreak
windbreak restoration
grass filter strip
water impoundment reservoirs
grazing land protection system
stream protection system
stream bank stabilization
fertilizer management
cropland protection cover
tree planting
forest tree stand improvement
CRES BMP ID
SL13
BMP3, SL3
BMP4, SL4
BMP5, CP6, SL5
BMP?, CP8, WP3
BMP 12, CP7, WP1
CP5
SL7
CP13
WC1
BMP6, SL6
BMP 10, WP2,
SP10
BMP 15
SL8
FP1
FR2
WSM BMP ID
BMP 1
BMP 1
BMP 1
BMP 1
BMP 1
BMP 1
BMP 1
BMP 1
BMP 1
BMP 1
BMP 2
BMP?
BMP?
BMP 8
BMP 3
BMP 5
BMP 5
-------
Table H.1.4 Conservation Reporting and Evaluation System (CRES) Practice Identities and
Corresponding Watershed Model BMP Identities (used from 1993 to present)
CRES Practices Tracked 1993
-------
Delaware is only 33 percent within the Chesapeake watershed and comprises a portion of five
Phase IV Watershed Model segments. This information, obtained by over-laying state, county,
and Phase IV Watershed Model boundary information using GIS is documented in Chesapeake
Bay Watershed Model Application and Calculation of Nutrient and Sediment Loading: Appendix
E, Phase IV Water shed Land Use.
Table H.I.5 An Example of Percentages of Selected Counties Within Each Corresponding
Chesapeake Bay Watershed Model (WSM) Segment. A Complete Account of percentages of
counties within Phase IV Watershed Model segments can be found in Appendix E.
County
Kent
Kent
Kent
Kent
Kent
New Castle
New Castle
New Castle
New Castle
Sussex
Sussex
Sussex
Sussex
District of Columbia
District of Columbia
District of Columbia
District of Columbia
Allegany
Allegany
Allegany
Anne Arundel
Anne Arundel
Anne Arundel
Anne Arundel
Anne Arundel
Anne Arundel
3altimore
Baltimore
Baltimore
Baltimore
Baltimore
Baltimore
Baltimore
Calvert
Calvert
Calvert
State
DE
DE
DE
DE
DE
DE
DE
DE
DE
DE
DE
DE
DE
DC
DC
DC
DC
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
WSM
Segment
380
400
410
770
780
370
380
800
810
410
420
430
780
220
540
890
910
160
170
175
340
490
500
510
870
880
110
450
470
480
490
760
860
500
880
990
Percent of County
In WSM Segment
4.99
3.77
10.64
12.86
1.79
2.65
2.57
2.90
1.50
38.88
0.21
4.50
6.40
5.24
24.63
54.06
16.08
60.67
0.01
39.32
13.68
20.95
15.91
11.19
10.07
28.18
0.01
1.99
61.17
13.31
4.49
8.78
10.25
70.79
28.10
1.12
-------
The federal BMP data (CRES) are also used for tracking BMP implementation in the three non-
signatory states of New York, West Virginia, and Delaware. Linear interpolation between 1991
and 1996 CRES data are used to estimate annual BMP implementation while linear extrapolation
was used to project BMP implementation to the year 2000 for the non-signatory jurisdictions.
Along with cost share data from the states, CRES provides supplemental BMP tracking data for
the signatory states (Maryland, Pennsylvania, and Virginia). For 1996 and beyond, CRES data
are not used to augment Maryland BMP tracking data.
Section H.1.2 State Programs (Figure H.1.1, Box B)
Box A
Federal cost
share data
BoxB
State BMP data
The signatory jurisdictions of Pennsylvania, Maryland, and Virginia submit data sets
documenting the installation of BMP cost-shared with Chesapeake Bay Program Implementation
Grants. The data sets are submitted on computer disks in various formats including ASCII,
Lotus 1-2-3, QuatroPro, MS Access, and dBASE DBF. The Chesapeake Bay Program Office
processes these data in order to compile a database containing information on the state, county,
state BMP code, acres treated, and animal waste stored. Tables H. 1.6-8 list the BMPs used in the
Pennsylvania, Maryland, and Virginia cost-share programs, respectively, and their corresponding
Chesapeake Bay Watershed Model BMP identity.
Table H.1.6 Pennsylvania Cost-Share BMP Identities and Corresponding Chesapeake Bay
Watershed Model BMP Identities (Practices tracked from 1985 to 1996)
BMP NAME
stripcropping, contour or field
terrace system
diversion system
waterway system
sediment retention/erosion or water control
grazing land protection system
stream protection system
cropland system (cover crop)
animal waste management
nutrient management
PA BMP ID
^
j
4
5
7
12
6
10
8
2
16
WSM BMP ID
BMP1
BMP1
BMP1
BMP1
BMP 1
BMP 2
BMP 2
BMPS
BMPS
BMP 4
-------
Table H.1.7 Maryland Cost-Share BMP Identities and Corresponding Watershed Model BMP
Identities (Practices tracked from 1985 to 1996)
BMP NAME
contour fanning
stripcropping, contour or field
stripcropping, contour or field
terrace system
diversion system
waterway system
waterway system
contour orchard/fruit area
sediment basin
field border
field windbreak
grass filter strip
spring development
trough or tank
fencing
cover and green manure crop
animal waste control facility
animal waste control facility
animal waste control facility
forest land erosion control system
forest land management
roof runoff management
grade stabilization structure
MD BMP ID
330
585
586
600
362
412
468
331
350
386
392
393
574
614
382
340
313
359
425
408
409
558
410
WSM BMP ID
BMP 1
BMP 1
BMP 1
BMP 1
BMP1
BMP1
BMP 1
BMP 1
B-MP 1
BMP 1
BMP 1
BMP 1
BMP 2
BMP 2
BMP 2
BMP 3
BMP 4
BMP 4
BMP4
BMP 5
BMP 5
BMP 4
BMP 1
10
-------
Table H.1.8 Virginia Cost-Share BMP Identities and Corresponding Watershed Model BMP
Identities (Practices tracked from 1985 to 1996)
BMP NAME
stripcropping, contour or field
buffer stripcropping
terrace system
diversion system
waterway system
sediment retention/erosion or water control
grass filter strip
grass filter strip (restrictive)
water table control structure
grazing land protection system
stream protection system
intensive rotational grazing
protective cover for specialty crops
specialty cover crop for nutrient management
legume cover crop
animal waste control facility
VA BMP ID
SL-3
SL3-B
SL-4
SL-5
WP-3
WP-1
WQ-1
WQ-2
WQ-5
SL-6
WP-2
WQ-3
SL-8
SL-8B
WQ-4
WP-4
WSM BMP ID
BMP 1
BMP1
BMP]
BMP1
BMP 1
BMP]
BMP1
BMP1
BMP!
BMP 2
BMP?
BMP 9
BMP 3
BMP 3
BMP 3
BMP 4
Information from state databases are submitted on a county basis, not by Chesapeake Bay
Watershed Model segment. The same process used with the CRES data to distribute BMP
implementation data to Watershed Model segments is applied to these cost share databases.
Each practice is cumulative from 1985 except for practices which change regularly on an annual
basis such as conservation tillage.
Development of tributary strategies by the signatory jurisdictions brought changes in how BMP
data are submitted to the Chesapeake Bay Program Office. Watershed Model data sets represent
the cumulative implementation of BMPs since 1985, from all sources, including, but not limited
to state cost-share and federal cost-share programs as well as from other programs, such as the
USDA Natural Resources Conservation Service and Conservation Districts programs. These
data are developed by the signatory jurisdictions. Practices tracked for these signatory
jurisdictions correspond to those listed in their tributary strategies. Tables H. 1.9-1.12 are
examples of the data submitted by individual state jurisdictions to the Chesapeake Bay Program
Office. These databases can be accessed on the Chesapeake Bay Program Modeling
Subcommittee Web Page at:
http://www.chesapeakebay.net/bayprogram/committ/mdsc/model.htm.
11
-------
Table H.1.9 Example of Maryland BMP Data Format for the Phase IV Watershed Model 1996
Progress Scenario
WSM
Segment
110
110
110
110
110
110
110
no
110
110
110
110
110
110
110
110
110
110
110
no
110
110
110
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
140
BMP Code
AWMSL
AWMSP
BF
BG
CC
CT
ESC
ESM
FC
FHP
NMPI
RC
RHEL
SC
SCWQP
SD
SMC
SMR
SP
SPWF
SPWOF
TP
UNM
AWMSL
AWMSP
BF
BG
CC
CT
ESC
ESM
FC
FHP
NMPI
RC
RHEL
SC
SCWQP
SD
SMC
SMR
SP
SPWF
PROGRESS
1996
1.20
0.00
0.79
0.98
15.47
1182.36
0.65
1.39
0.00
0.00
674.13
0.17
0.33
0.40
930.47
0.00
0.02
0.01
0.00
0.75
0.69
0.20
0.00
17.22
0.00
15.49
0.00
60.32
7000.33
13.93
27.45
0.56
0.00
6188.91
16.85
3.38
2.09
8738.55
0.00
1.92
3.50
0.00
431.40
UNIT
systems
systems
acres
acres
acres
acres
acres
acres
acres
acres
acres
systems
acres
systems
acres
systems
acres
acres
systems
acres
acres
acres
acres
systems
systems
acres
acres
acres
acres
acres
acres
acres
acres
acres
systems
acres
systems
acres
systems
acres
acres
systems
acres
BMP Description
animal waste management systems livestock
animal waste management systems poultry
buffers forested
buffers grassed (agricultural land)
cover crops
conservation tillage
erosion and sediment control
enhanced stormwater management
forest conservation
forest harvesting practices
nutrient management plan implementation
runoff control
retirement of highly erodible land
septic connections
SCWQP treatment of highly erodible land
septic denitrification
stormwater management conversion
stormwater management retrofits
septic pumping
stream protection with fencing
stream protection without fencing
tree planting
urban nutrient management
animal waste management systems livestock
animal waste management systems poultry
buffers forested
buffers grassed (agricultural land)
cover crops
conservation tillage
erosion and sediment control
enhanced stormwater management
forest conservation
forest harvesting practices
nutrient management plan implementation
runoff control
retirement of highly erodible land
septic connections
SCWQP treatment of highly erodible land
septic denitrification
stormwater management conversion
stormwater management retrofits
septic pumping
stream protection with fencing
12
-------
Maryland submits Chesapeake Bay BMP tracking data in spreadsheet format using Quattro Pro
(Table H.I. 10). Maryland tracks BMP implementation through several different databases,
including the Maryland Agriculture Water Quality cost-share program database, the Maryland
Department of Natural Resources (MD DNR) Forest Service Target and Accomplishment
Reporting System, the Federal Conservation Technology Information Center, the Maryland
Department of Environment (MDE) Water Management Administration (WMA) Notice of Intent
(NOI) database, the MDE Environment Technical And Regulatory Services Administration
(TARSA) Urban BMP database, the MD DNR Forest Service, the Nutrient Management
Program of Maryland Department of Agriculture Office of Resource Conservation, the MDE
Nonpoint Source database, the Soil Conservation Districts reports to the USDA-Natural
Resources Conservation Service (USDA-NRCS) and the Maryland Department of Agriculture
(MDA). Table H.I. 10 lists Maryland's BMPs used within the Phase IV Watershed Model and
the sources of these BMP data. In addition to these databases, the MD DNR Waterway
Resources Division marina database is used to track shoreline erosion BMPs throughout the
state. MD DNR Shore Erosion Control staff developed this database to account for the number
of marine pumpouts installed, and structural and nonstructural shore erosion control installations
throughout Maryland. Additional documentation on the data sources for Maryland's BMPs may
be found in the tributary strategy team's annual reports.
13
-------
Table H.1.10 List of Maryland BMPs and Data Sources
Maryland's
BMP Code
Option
Maryland's Sources of BMP Data
ESC
ESM
SMR
SMC
SP
SD
SC
UNM
SCWQP
AWMSL
AWMSP
RC
RHEL
SPWF
SPWOF
NMPI
BF
BG
FHP
C
TP
T
Erosion and Sediment Control
Enhanced Stormwater
Management
Stormwater Management
Retrofits
Stormwater Management
Conversion
Septic Pumping
Septic Denitrification
Septic Connections
Urban Nutrient Management
SCWQP Implementation
Animal Waste Management
Systems livestock
Animal Waste Management
Systems poultry
Runoff Control
Retirement of Highly Erodible
Land
Stream Protection with
Fencing
Stream Protection without
Fencing
Nutrient Management Plan
Implementation
Cover Crops
Buffers Forested
Buffers Grassed (agricultural
land)
Forest Harvesting Practices
Forest Conservation
Tree Planting
Conservation Tillage
MDE WMA Notice of Intent database
MDE TARSA Urban BMP database
MDE Nonpoint Source database
MDE Nonpoint Source database
Data currently not yet available
MDE Nonpoint Source database
MDE Nonpoint Source database
Data currently not available
Soil Conservation Districts reporting to
USDA, NRCS and MDA
MD Agricultural Water Quality
Cost-share program database
MD Agricultural Water Quality
Cost-share program database
MD Agricultural Water Quality
Cost-share program database
MD Agricultural Water Quality
Cost-share program database
MD Agricultural Water Quality
Cost-share program database
MD Agricultural Water Quality
Cost-share program database
Nutrient Management Program of
MDA Office of Resource Conservation
MD Agricultural Water Quality
Cost-share program database
MD DNR Forest Service Target and
Accomplishment Reporting System
MD Agricultural Water Quality
Cost-share program database
Data currently not available
MD DNR Forest Service
MD DNR Forest Service Target
and Accomplishment Reporting System
Federal Conservation Technology
Information Center
14
-------
Pennsylvania submits Watershed Model BMP tracking data in a Microsoft Excel spreadsheet
format (Table H.I.I 1). For example, Pennsylvania's Watershed Model 1996 Progress Scenario
BMP data were compiled from data received from the USDA Farm Service Agency (FSA), the
USDA-NRCS, the Pennsylvania Game Commission, and the Pennsylvania Department of
Environmental Protection (PADEP) cost-share program. BMP data from these agencies are first
compiled on a county basis. Due to the differences in reporting methods used by the various
agencies, the possibility exists that permanent vegetative cover, strip cropping systems, cropland
protection systems, and conservation tillage practices reported by the federal and state cost-share
programs may be double-counted. To avoid this problem, the acres reported under
Pennsylvania's cost-share program are subtracted from the acreage reported by the federal
programs. The county data were then redistributed among the Phase IV Watershed Model
segments using a method similar to that previously described for the federal cost-share program.
Table H.I. 11 displays Pennsylvania's BMP data per Watershed Model segment and land use.
The conservation tillage column values are given in units of acres converted from conventional
tillage to conservation tillage. The nutrient management column values are provided in units of
cropland acres converted to nutrient management practices. These nutrient management
practices include manure storage/handling and fertilizer applications at rates that agree with the
agronomic needs of the land. The farm plan column provides values in acres of cropland under
farm plans and covers a wide range of BMP practices. Farm plan BMP practices can be
generally described as pasture and cropland management practices. The stream bank fencing
column provides acreage values where stream bank fencing is implemented.
15
-------
Table H.I.11 Example of Pennsylvania BMP Data Format
WSM
Segment
10
10
10
10
10
10
10
20
20
20
20
20
20
20
30
30
30
30
30
30
30
Land Use Conservation
Tillage1
conventional tillage 16137.00
conservation tillage
hayland
pasture
animal waste
forest
urban
conventional tillage 4648.00
conservation tillage
hayland
pasture
animal waste
forest
urban
conventional tillage 507 1 4.60
conservation tillage
hayland
pasture
animal waste
forest
urban
Nutrient
Management
(acres)
5077.00
23.00
3549.00
28.00
17376.00
155.00
Farm Plan
(acres)
15129.67
2255.33
2913.00
3653.86
261.14
279.00
40449.20
14568.80
9600.00
Stream Bank
Fencing
(acres)
26.00
20.00
128.00
1 given in units of acres converted from conventional tillage to conservation tillage
16
-------
Virginia submits Chesapeake Bay Watershed Model Progress Scenario BMP tracking data in
comma delimited text file format (Table H.I. 12). Virginia's BMP data are submitted to the
Chesapeake Bay Program Office on a Watershed Model segment basis. Several sources are used
in Virginia to "obtain BMP data but the majority of the data are obtained through the Virginia
Agricultural cost-share program BMP database. This Virginia cost-share program is
administered through local Soil and Water Conservation Districts. As part of the cost-share
program, each Soil and Water Conservation District is required to make quarterly reports of
BMP implementation to the Virginia Department of Conservation and Recreation in a database
format. This database includes the latitude and longitude of each BMP implemented and is
easily translated into Watershed Model segments. The cost-share program database is
supplemented with data from an extensive Virginia farm operator survey of BMP
implementation without state or federal cost-share assistance. Conservation tillage information
is derived from CTIC data. Nutrient management data are provided from a Virginia Department
of Conservation and Recreation database, which includes information on all nutrient
management plans written or approved by state nutrient management specialists. During
Virginia's Tributary Strategy development process, agricultural specialists at the local level
verified all of these data.
Urban BMP implementation data were also collected from participating localities during the
tributary strategy development process. These data include erosion and suspended sediment
control, storm water management retrofits, urban nutrient management, and septic pumping.
Data are typically collected on a county basis and are aggregated to Watershed Model segments
on a proportional basis. Shoreline erosion protection data are taken from a study on highly
erodible shoreline and BMP implementation in the Virginia portion of the Chesapeake Bay. The
source of the forest harvesting data is the Virginia Department of Forestry.
17
-------
Table H.1.12 Example of Virginia BMP Data
BMP Treatment '
conservation tillage
farm plans
nutrient management
highly erodible land retirement
grazing land protection
stream protection
stream fencing
stream protection
cover crops
grass filter strips
woodland buffer filter area
forest harvesting
animal waste control facilities
Doultry waste control facilities
loafing lot management
erosion and sediment control
urban SWM/BMP retrofits
urban nutrient management
septic pumping
shoreline erosion protection
Units Model Model Model Sum of
Segment 170 Segment 200 Segment 220 Potomac Basin
Model Segments
acres
acres
acres
acres
acres
acres
linear feet
linear feet
acres
acres
acres
acres
systems
systems
systems
acres
acres
acres
systems
linear feet
270
1,386
1,322
535
1.200
0
0
0
43
313
4
233
0
2
0
3
0
2
0
0
20.854
69,551
73.469
3.126
16.400
708
9.959
469
5,581
2,981
298
2,215
72
232
5
272
0
161
0
0
23,855
68.497
17,712
2,716
4.242
925
206
0
161
858
97
591
3
1,152
446
1 ,402
489
791
15
0
156,533
392.139
276.471
23,133
36,609
3.298
167.328
14.012
19,643
11.483
900
8.378
212
4,907
1.851
6,199
1.965
16.398
72
9,575
The District of Columbia reports BMP implementation in both a text file and hard copy printout
(Table H.I. 13). Data submitted by the District of Columbia is taken from DC's BMP
implementation programs. Stormwater management implementation databases are ground-
truthed within the District and these databases include information on the type, location, status,
and drainage area of stormwater management facilities. Site inspections are conducted by the
Soil Resources Management Division (Department of Consumer and Regulatory Affairs) to
verify the presence of each BMP, thereby obtaining an accurate accounting of all urban BMPs
implemented within a given year.
18
-------
Table H.1.13 Example of District of Columbia's BMP Data
BMP
dry pond (extended)
dry pond (extended)
dry pond (extended)
wet ponds
infiltration trenches
infiltration trenches
infiltration trenches
infiltration trenches
infiltration trenches
infiltration trenches
infiltration trenches
oil/grit
oil/grit
oil/grit
oil/grit
oil/grit
oil/grit
sand filters
sand filters
sand filters
sand filters
sand filters
sand filters
sand filters
sand filters
underground detention
(i.e. oversized pipes)
underground detention
(i.e. oversized pipes)
underground detention
'i.e. oversized pipes)
underground detention
'i.e. oversized pipes)
underground detention
'i.e. oversized pipes)
water quality inlets
water quality inlets
Number of
BMPs
1
2
2
1
]
2
1
^
j
2
2
1
17
3
4
10
3
2
2
24
24
22
9
14
18
8
>
j
2
3
1
1
2
1
Acres Treated
Treated
10.00
17.40
27.60
0.69
0.16
0.86
0.34
1.67
2.11
0.67
0.25
18.54
4.15
3.51
11.27
2.30
1.10
2.40
21.42
25.87
26.65
7.46
12.46
19.19
12.85
1.45
12.00
9.75
0.74
2.51
2.53
9.40
Year
1988
1991
1992
1991
1988
1989
1990
1991
1992
1993
1994
1988
1989
1990
1991
1992
1993
1988
1989
1990
1991
1992
1993
1994
1995
1988
1990
1991
1992
1993
1988
1990
19
-------
Data from all jurisdictions are converted to MS Excel format before being imported into an MS
ACCESS 2.0 database. This BMP database is part of the Chesapeake Bay Information
Management System (CIMS). For Watershed Model segments that contain portions of more
than one state, the data are aggregated into one model segment by adding the acres associated
with each model BMP in each model segment. When all the BMP tracking data has been
processed, it is then applied in the Phase IV Watershed Model (Figure H. 1.1, Box C).
Section H.1.3 Land Use Conversions (Figure H.I.I, Box D)
Box A.
Federal cost
share data
BoxB
State BMP data
BoxC
State BMP data
sets
BoxD
Land use data set
development
Some BMPs involve a change in land use, for example - highly erodible land (HEL) in cropland
is retired and converted to pasture. Land use conversions are a significant portion of BMP
nutrient reductions in the Chesapeake Bay Watershed and are simulated directly in the Phase IV
Watershed Model as a change in land use area. Data for land use conversions of conventional
tillage to conservation tillage are developed through county level CTIC data for each simulation
year. Other land use conversions such as forest buffers and urban forestry are tracked in the state
BMP data bases.
For those land use conversions tracked throughout the watershed, including signatory and
nonsignatory states, the primary data sets consist of information from Conservation Technology
Information Center. Other data include land use change BMPs tracked through state
implementation grants and USDA Farm Services Agency's BMP installations. Table H.I. 14
lists those categories that create land use changes.
20
-------
Table H.I.14 BMP Practices resulting in a Land Use Change
BMP Type
Land Use Change
Conservation Reserve Program (CRP)
forest conservation
forest/grass buffers
tree planting
conventional tillage/conservation tillage
cropland to pasture
pervious urban to forest
cropland to forest/pasture
cropland/pasture to forest
conventional tillage to conservation tillage
Land use Conversions from Conventional Tillage to Conservation Tillage
In the Phase IV Watershed Model, conservation tillage is tracked on an annual basis to reflect
increases or decreases that occur in tillage management. Acreage in conservation tillage for each
of the six Chesapeake Bay basin states was obtained through the Conservation Technology
Information Center (CTIC). CTIC provides annual data sets for each state showing the acres of
cropland planted using conservation tillage.
CTIC collects these data in an annual survey conducted on a county-by-county basis by USDA
Natural Resources Conservation Service offices, and soil and water conservation districts to
track tillage systems used on annually planted crops. The acreage for "Total Cropland Planted"
and "Total Cropland Planted Using Conservation Tillage" major data categories is tracked by the
CTIC surveys and used by the Chesapeake Bay Program. Within this CTIC data set,
conservation tillage is further broken down into the following major data subcategories; "15-30
Percent Residue Tillage," "Under 15 Percent Residue Tillage," "Mulch Tillage," and "No-Till
Tillage." Tillage methods and acreage for the following crop types are estimated by the annual
surveys: corn full season and double cropped; small grain fall and spring seeded; soybeans full
season and double cropped; cotton; grain sorghum full season and double cropped; forage crops;
and other crops.
Once the Chesapeake Bay Program obtains these data, a CTIC software program (CEDAR) is
used to organize the data into a new data set that includes "Total Tillage" (all acres planted,
including those planted by conservation tillage) and "Conservation Tillage" (all acres planted
using conservation tillage) for each county. This data set includes the following crops: corn full
season; small grain fall and spring seeded; soybeans full season; cotton; grain sorghum full
season; forage crops; and other crops. To eliminate double counting of acres, the double cropped
acres are not included in this data set. Forage is included, since at the planting stage it responds
more like tilled cropland in the first season of growth.
This data set is normalized to the cropland areas represented in the Phase IV Watershed Model
by adding all acres of the above crops for both "Total Tillage" and "Conservation Tillage," and
then dividing "Conservation Tillage" by "Total Tillage" to get "Percent Conservation Tillage"
for each county. This percent value is then used to adjust conservation and conventional tillage
within each county of the Chesapeake Bay Program Land Use data set. This adjustment is made
within the data set by multiplying the "Percent Conservation Tillage" by the total cropland (less
21
-------
hayland) for each county to get the acres of conservation tillage in each county. The difference
between total cropland (less hayland) and conservation tillage is the conventional tillage acres.
Both conservation and conventional tillage acres are multiplied by the percent of county in each
Phase IV Watershed Model segment. These county values are added to obtain both conservation
and conventional tilled acres within each model segment.
Figure H.I.3 shows the amount of conservation tillage compared to the amount of conventional
tillage as modeled by the Phase IV Watershed Model. The Chesapeake Bay Watershed, in 1985
had more conservation tillage than conventional. By the year 2000, it is projected that
conservation tillage will have been implemented on even more acres. The trend of decreasing
conventional tillage and increasing conservation tillage practice is also evident in Figure H.I.4
on a national basis.
22
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Section H.2 IMPLEMENTATION OF NUTRIENT MANAGEMENT BMP
APPLICATION RATES AND BMP NUTRIENT REDUCTION EFFICIENCY RATES
Box A.
Federal cost
share data
BoxB
State BMP data
BoxC
State BMP data
sets
BoxD
Land use data set
development
BoxE
Compiled landuse
BMPs by
Watershed Model
Segment
The Phase IV Watershed Model simulates BMP nutrient reductions by land use conversions (i.e.
conventional tillage to conservation tillage), application of BMP nutrient reduction efficiencies,
and nutrient management. The following sections describe how the effects of BMPs are
simulated within the Phase IV Watershed Model, lists BMPs identified by current tributary
strategies, and includes the range of nutrient reduction efficiency values used within the Phase
IV Watershed Model.
Section H.2.1 BMPs Involving Land Use Conversion (Figure H.I.I, Box E)
Land use conversions within all Chesapeake Bay basin jurisdictions are accounted for through
the use of the Phase IV Watershed Model through a land use acreage change from one land use
to another. Because the Phase IV Watershed Model simulates only a total acreage value for each
model segment, any land use changes must be averaged over the total land use acreage and then
applied to the total acreage value within a model segment.
Land use conversions simulated by the Chesapeake Bay Watershed Model are forest/grass
buffers, conservation reserve program, forest conservation, tree planting, and changing
conventional tillage to conservation tillage. These land use conversions occur on the land
through the conversion of cropland to conservation reserve program acres, urban land to forest
(through forest conservation), urban land to forest (through tree planting programs), conventional
tillage to conservation tillage, and urban or cropland to forest/grass buffers. A final land use
conversion (used only by Maryland) is highly erodible land to pasture. Implemented land use
conversions cause nutrient load reductions because they change the edge-of-stream loading rate
into a lower rate thereby reducing nutrient and suspended sediment loads delivered to the Bay.
25
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Section H.2.1.1 Conservation Reserve Program
Authorized by the Amended Food Security Act of 1985, the Conservation Reserve Program
(CRP) is a voluntary program that offers annual land rental and incentive payments to farmers
establishing conservation practices and planting permanent vegetative cover for 10-15 years.
The program encourages farmers to convert highly erodible cropland to grass and trees. In 1997,
revisions were made to the Conservation Reserve Program stating thait only croplands that are
used to grow commodities, or marginal pastures that are either enrolled in the Water Bank
Program or suitable for use as forested riparian buffers are eligible for the program. In addition,
croplands must either be: highly erodible; considered cropped wetland; devoted to highly
beneficial environmental practices (i.e. riparian buffers, filter strips, etc.); subject to scour
erosion; or be in a national or state Conservation Reserve Program priority area.
In most cases, it is not possible to determine if land is converted to grass or trees, so it is assumed
that all acres are planted to grass. In Virginia, critical areas may be converted to forest through a
state program. In this case, the areas of converted cropland to forest are known, which allows
this conversion to forest to be applied in the Phase IV Watershed Model.
Section H.2.1.2 Forest Conservation
Forest conservation land use conversion is based upon estimates in the amount of forest land
saved between 1993 and 2000 as a result of Maryland's Forest Conservation Act. Incorporation
of forest conservation practices consist of a land use conversion from developed land (pervious
urban) to forest. Maryland's Forest Conservation Act helps to maintain ;and enhance forest cover
by requiring the identification of priority areas for forest retention, setting guidelines for
development that require the retention of 15-50 percent of the forested area, and replanting of
cleared areas. Priority areas are designated as 100-year flood plains, intermittent and perennial
streams and their buffers, steep slopes, and critical habitats. This BMP reduces deforestation
created by urban development by requiring that a certain percentage of developed land remain as
forested land.
The substitution of forest land for what would otherwise be urban land is best understood within
the context of how the Phase IV Watershed Model projects land use. For any year other than
1990, the year of the Chesapeake Bay Program land use data base, land use is projected forward
or backward based on population. As population increases within a model segment, urban land
use area increases proportional to the 1990 urban land use and population, and the land uses of
forest and agriculture, proportionally decrease. Forest Conservation Act BMPs reduce this
constant rate of urbanization as projected through population growth.
Section H.2.1.3 Tree Planting
The tree planting BMP includes any tree plantings on any site except those along rivers and
streams. Plantings along rivers and streams are considered riparian buffers and are treated
differently. The definition of tree planting does not include reforestation. Reforestation replaces
trees removed during timber harvest and does not result in an additional nutrient reduction or an
increase in the forest acreage.
26
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Section H.2.1.4 Conservation Tillage
Conservation tillage involves planting and growing crops with minimal disturbance of the
surface soil using a non-inversion plowing technique and maintaining a 30 percent minimum
crop residue cover on the soil surface. No-till farming is a form of conservation tillage in which
the crop is seeded directly into slits cut into the soil, therefore, no tillage of the soil surface is
needed. Minimum tillage farming involves some disturbance of the soil surface, but maintains a
minimum of 30 percent crop residue on the surface. Research has shown that with at least 30
percent of the crop residue remaining at the time of planting, the amount of erosion and resultant
nutrient loss are substantially reduced.
Conservation tillage is a land use simulated by the Phase IV Watershed Model. Conservation
tillage involves a simple land use change in the land acreage cover between conventional and
conservation tillage. Each Watershed Model segment acre in conservation tillage is determined
annually using Conservation Technology Information Center county level data.
27
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Section H.2.1.5 Forest and Grass Buffers
Buffers, which" are linear strips of vegetation along rivers and streams, help to filter' nutrients.
sediment, and other pollutants carried in runoff, as well as excess nutrients in groundwater. li
signatory States report buffer BMPs implemented in linear feet, buffers are assumed to be 100
feet wide on a streamside. Based on this buffer width, nutrient reductions in the Phase IV
Watershed Model are assumed to be two acres of upgradient land treated for each buffer acre. If
signatory States report buffer BMPs implemented as acres treated, then the buffer nutrient
reduction efficiency is directly applied to the reported land use.
Forest and grass buffers are incorporated into the Phase IV Watershed Model simulation in two
ways. Forest/grass buffers include both a land use conversion on the riparian area and a land use
load reduction from upgradient land. Forest buffer land use conversion is a change in land use
from cropland to forest. Grass buffer land use conversion is a change from cropland to
pastureland.
Buffers also reduce nutrient loads from land adjacent to, and upgradient from, the buffer.
Although soil types, vegetative type, width of buffer, and other factors alter the buffer's
effectiveness, it is assumed that an acre of forest or grass buffer reduces loads from 2 acres of
land adjacent to, and upgradient from the buffer.
The tracking of buffer BMPs is calculated according to buffer area. The Chesapeake Bay
Program Office assume one buffer acre for every 435.6 linear feet of riparian buffer (assumed to
be 100 feet wide). Land adjacent to the buffer are assumed to be cropland in Virginia, Maryland,
and Pennsylvania, and urban land in the District of Columbia, unless otherwise specified. In
Pennsylvania, Virginia, and the District of Columbia, forested buffers are estimated to reduce the
nitrogen load by 57 percent and both the phosphorus and suspended sediment loads by 70
percent on upgradient agricultural, and urban land uses. Grass buffers are estimated to reduce the
upgradient nitrogen load by 43 percent, and the phosphorus and suspended sediment loads by 53
percent.
It is assumed that a certain percentage of stream miles within urban pervious and urban
impervious land uses are impractical for buffer implementation. These assumptions are included
in the Phase IV Watershed Model by removing 100 percent of the urban impervious and 50
percent of the urban pervious stream miles from buffer eligibility.
In Maryland the efficiencies of forest or grass buffers are estimated for each tributary basin as
described in Table H.2.1.
28
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TABLE H.2.1 Maryland's Nutrient Reduction Efficiencies for Forest or Grass Buffers
Basin
Upper Potomac
(Model Segments 160, 175, 180,210,
730, 740, 750)
Middle Potomac
(Model Segments 220, 540, 890)
Lower Potomac
(Model Segments 910, 920, 990)
Patuxent
(Model Segments 330, 340, 500)
Patapsco/Back
(Model Segments 480, 490, 660, 760,
860)
Upper Western
(Model Segments 510, 870, 880)
Lower Western
(Model Segments 470, 850)
Upper Eastern
(Model Segments 370, 380, 390, 450,
800,810,820,830)
Lower Eastern
(Model Segments 410, 420, 430, 780,
840)
Choptank
(Model Segments 400, 770)
Buffer Type
forest
grass
forest
grass
forest
grass
forest
grass
forest
grass
forest
grass
forest
grass
forest
grass
forest
grass
forest
grass
% TN
Efficiency
48
36
51
38
56
42
56
42
56
41
49
37
56
42
58
43
66
49
59
44
%TP
Efficiency
36
53
70
53
70
53
70
53
70
53
70
53
70
53
70
53
70
53
70
53
29
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Section H.2.2 BMPs Involving Nutrient Reduction Efficiencies (Figure H.I.I, Box G)
Box A
Federal cost
share data
Box B
State BMP data
Box C
State BMP data
sets
Box D
Land use data set
development
I
Box E
Compiled landuse
BMPs by
Watershed Model
Segment
Box F
Modify scenario
land uses with
land use BMPs
Box G
Apply BMP
efficiency rates and
nutrient application
rates
Within the Phase IV Watershed Model, BMP nutrient reduction efficiencies are applied tc
nitrogen, phosphorus, and suspended sediment nutrient loads (Figure H.I.I, Box G, page 2)
Nutrient reduction efficiencies associated with the implementation of BMPs throughout the
Chesapeake Bay signatory states are listed in Table H.2.2.
Table H.2.2 Chesapeake Bay Watershed Model BMP Matrix With Associated Nutrient
Reduction Efficiencies
Category (Units)
urban1
urban - stormwater
management"
Type of Watershed
Model BMP
erosion and sediment
control (BMP 11)
extended detention
(dry) (BMP 12)
retention ponds (wet)
(BMP 12)
stormwater
wetland (one step)
(BMP 12)
pond-wetland
system (series)
(BMP 12)
SWM conversions
(dry->retention)
(BMP 12)
sand filters (BMP 12)
Reduction
Efficiency
N (%)
33
25
32
25
29
32
30
Reduction
Efficiency
P (%)
50
20
46
47
64
46
45
Reduction
Efficiency
TSS (%)
50
20
46
47
64
46
80
1 acres treated
'' acres protected
30
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Category
urban - septic
systems3
urban - septic
systems^
urban1
agriculture SCWQ4
Dlan implementation
agriculture5
agricultural barnyard
runoff control
agriculture"
resource protection &
watershed planning -
streambank
protection1
Type of Watershed Reduction Reduction
Model BMP Efficiency Efficiency
N (%) P (%)
septic pumping 5 0
(BMP 13)
septic connections 55 0
(BMP 15)
septic denitrification 50 0
(BMP 14)
nutrient 1 7 22
management
(residential) (BMP 16)
cropland (conventional/ 1 0/4 40/8
conservation tillage)
(BMP 1)
hayland 4 8
(BMP 1)
pasture (BMP 2) 20 14
animal waste 80 80
management systems
(AWMS) (dairy/beef/
swine) (BMP 4)
AWMS (poultry) 14 14
(BMP 4)
supplemental (added 10 10
to existing waste
management system)
(BMP 4)
full system (total 75 75
barnyard control)
(BMP 4)
grazing land protection 50 25
(rotational grazing)
(BMP 9)
stream protection 75 75
with fencing (BMP 7)
Reduction
Efficiency
TSS (%)
0
0
0
0
40/8
8
14
-
_
_
-
.
75
1 acres treated
acres protected
soil conservation water quality plan
J number of systems
' tons of manure reduced
-------
Category
resource protection &
watershed planning -
streambank
protection1
(continued)
resource protection &
watershed planning1
buffers'
cover crops'
Water Quality Model
BMPs6
Water Quality Model
3MPs - shoreline
jrotection6
Water Quality Model
BMPs - combined
sewer overflows'
Type of Watershed
Model BMP
stream protection
w/o fencing
(BMP 7)
stream restoration
(non-tidal)
(BMP 7)
forest harvesting
practices (BMP 5)
forested (BMP 1)
grassed (BMP 1)
cover crops (cereal
grain) (BMP 3)
marine pumpouts
(installation)
structural shore
erosion control
nonstrucrural shore
erosion control
treatment
conversion
(CSO->sewer)
Reduction
Efficiency
N (%)
40
75
50
48-65
35-50
34-51
95
75
75
15
95
Reduction
Efficiency
P(%)
40
75
50
70
53
10-20
95
75
75
30
95
Reduction
Efficiency
TSS (%)
40
75
50
70
53
10-20
75
75
30
95
1 acres treated
' nutrient load pound reduction
32
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The simulation of a land use, for example pastureland, within a particular Watershed Model
segment is not a simulation of all of the different types of pasturelands, but a single
representative average pasture within that Watershed Model segment. BMP nutrient reduction
efficiencies applied to pasturelands are represented with this average value and applied as a
percent reduction to the portion of pastureland treated with that BMP. This BMP nutrient
reduction efficiency represents a percent reduction in nutrient loading, which results from
applying a BMP to the land use. Equation 1 shows this process, where a hypothetical pasture
rotation BMP had a total nitrogen reduction efficiency of 10 percent, was applied to 100 aces of
pasture in a Watershed Model segment, which had a total of 1,000 acres of pastureland. The
reduction applied to the average pastureland simulated by the Phase IV Watershed Model would
then be:
10 percent BMP efficiency * 100 acres treated = overall 1 percent TN (1)
1,000 acres total reduction for the
average simulation
of pasture
Section H.2.2.1 Urban BMPs
Urban BMPs simulated within the Phase IV Watershed Model are erosion and sediment control,
extended stormwater detention (dry), pond-wetland systems, stormwater wetlands, retention
ponds, stormwater retention structure conversions (dry to wet), sand filters, septic systems
(pumping, connections, and denitrification), and urban nutrient management. The following
section describes each of these BMPs.
Section H.2.2.1.1 Erosion and Sediment Controls
Erosion and sediment controls, including sediment ponds and silt fencing, are applied to
construction sites. The Chesapeake Bay Watershed Model assumes that some portion of the
urban land use is in a transitory construction phase at all times. Erosion and sediment controls
reduce the high nutrient and suspended sediment loads during the transitory construction phase.
Erosion and sediment controls have been in place throughout the Chesapeake Bay basin prior to
the 1985 reference year, but are counted as an efficiency reduction in tributary strategies because
of the substantial refinements of erosion and sediment reduction techniques, permit inspections,
and practice implementation since 1985 throughout the Chesapeake Bay basin. The jurisdictions
have also increased implementation of erosion and sediment controls since 1985.
Erosion and sediment controls primarily protect off-site areas from sediment runoff and nutrient
pollution. There are numerous technologies that allow for the reduction of sediment from
erodible lands. By retaining the soil on-site, nutrients attached to the sediment are prevented
from leaving the disturbed area, thus reducing off-site impacts.
Incorporation of erosion and sediment controls result in the reduction of suspended sediment and
nutrient loads from pervious urban land. Erosion and sediment controls are estimated to reduce
-------
nutrient loads from urban acres by 33 percent for total nitrogen and 50 percent for both tote
phosphorus and sediment.
Section H.2.2.1.2 Stormwater Management Systems
Stormwater management systems include extended detention areas (dry basins or ponds]
retention ponds (wet), Stormwater wetlands (one step), pond-wetland systems (series)
Stormwater retrofits, Stormwater conversions (conversion from dry to retention), and sand filters
Nutrient reduction is not the only benefit of Stormwater management systems: they also reduc<
sediment transport, and control peak runoff flows. New development areas in Virginia an
required to have Stormwater management systems, but for a majority of the Bay basin, thes<
Stormwater management systems are for peak flows only and focus on protecting downstrearr
banks from erosion rather then on water quality issues. The only place where stormwatej
management system water quality controls are required for new developments within the Ba>
Watershed are in Chesapeake Bay Preservation Act areas in Virginia. These stormwatei
management practices such as retention ponds with adequate storage and ponds which have
extended detention (1 year - 24 hour design criteria) can provide significant pollutant removal.
especially when coupled with wetlands components.
Stormwater management BMPs are incorporated into the Phase IV Watershed Model by
applying nutrient reduction percentages to nutrient loads from pervious and impervious land
areas. These reductions apply to the nutrient and suspended sediment load from land acres
affected by Stormwater management BMPs. The estimated percentciges for each Stormwater
management system follow:
Management System
Extended detention
(dry basins or ponds)
Retention ponds
(wet)
Stormwater wetlands
(one step)
Pond-wetland systems
(series)
TN reductions(%) TP & TSS reductions(%)
25 20
32 ' 46
25 47
29 64
Stormwater retrofits may be extended detention retention ponds, Stormwater wetlands, or other
water bodies designed to address peak flows and nonpoint source nutrient loads generated on
existing urban land developed before Stormwater management systems were required. Retrofits
provide the same reductions as new Stormwater management practices and may be designed to
address Stormwater flows and/or nutrient and sediment control.
Stormwater conversions increase nonpoint source pollution reductions from areas served by dry
basins. Dry basins, without extended detention, are designed to control peak flows and provide
relatively few water quality benefits. A Stormwater conversion changes a detention basin to a
retention pond. For a Stormwater conversion, the estimated nutrient and suspended sediment load
34
-------
reductions are: 32 percent for total nitrogen loading, and 46 percent for both total phosphorus
and total suspended sediment loading.
Sand filters are also used for the reduction of urban nutrient loads. It is estimated that sand
filters reduce the total nitrogen load by 30 percent, the total phosphorus load by 45 percent, and
the total suspended sediment load by 80 percent.
It is not possible to decrease the flow intensity in the Phase IV Watershed Model. Therefore,
some beneficial effects of stormwater practices are not accounted for in the tracking systems.
These ancillary benefits include reduction in stream channel erosion and urban stream habitat
restoration.
Section H.2.2.1.3 Onsite Wastewater Management Systems
For onsite waste water management systems (OSWMS), commonly called septic systems,
nutrient reductions are achieved through three types of management practices. These practices
are frequent maintenance and pumping, connection of OSWMS to sewage treatment systems,
and OSWMS denitrification. For all of these septic system BMPs, the nutrient reduction
efficiency is applied only to nitrogen as it is assumed that phosphorus is entirely treated by
OSWMS.
Public education promotes onsite wastewater management system maintenance and informs
people how these systems impact the Chesapeake Bay. Whenever septic tanks are pumped and
septage removed, the onsite wastewater management system has an increased capacity to remove
settable and floatable solids from the wastewater (Robillard and Martin, 1990a). Septic tank
pumping promotes biological digestion of a portion of the solids and allows for storage space for
the remaining undigested solid portion of the wastewater. OSWMS effluent flows out of septic
tanks and into an underground soil adsorption system (field). The pumping of septic tanks is one
of several measures that can be implemented to protect soil adsorption systems from clogging
and failure (Robillard and Martin, 1990b). This measure reduces the nitrogen loads by an
estimated 5 percent. The level of BMP implementation is reported by signatory states as the
number of systems implemented. A ratio is formed of the number of pumpouts reported and the
total number of septic systems. If a system fails, soil adsorption fields are often unable to
adequately filter and treat wastewater, consequently non-treated septic system effluent can drain
directly into ground and surface water sources.
Septic system nutrient load simulations are incorporated into the Phase IV Watershed Model as a
percent reduction of the OSWMS nitrate load. This is accomplished by reducing the OSWMS
nitrate load in a Watershed Data Management file in proportion to the amount of edge-of-stream
nitrate load attenuated with OSWMS BMPs.
Using an average water flow of 75 gallons/person-day (gpd) 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., a total nitrogen concentration of about 39 mg/1 at the edge of the septic field is calculated.
This concentration compares favorably with Salvato (1982) who calculated onsite wastewater
35
-------
management system total nitrogen concentrations of 36 mg/1. It is assumed that between th<
edge of septic system field nitrate loads and edge-of-river nitrate loads represented in the Phas<
IV Watershed Model are primarily: (1) attenuated in anaerobic saturated soils with sufficien
organic carbon" (Robertson, Cherry, et. al., 1991; Robertson and Cherry, 1992), (2) attenuated b)
plant uptake (Brown and Thomas, 1978), or (3) attenuated in the primary through quaternar>
streams before the main river reach. Overall, the total attenuation is assumed to be 60%
Consequently, 40 percent of the septic system nitrate load for each model segment as reported ir
Maizel, et. al. (1997) is input to the major river reaches simulated by the Phase IV Watershed
Model. Given the previously mentioned assumptions of a 60 percent reduction, edge-of-rivei
loads from OSWMS are 23 mg/1 of total nitrogen. Further attenuation of the OSWMS loads
delivered to the Bay occurs through nutrient dynamics in the river reaches.
The connection of onsite wastewater management system to sewage lines is particularly effective
in reducing OSWMS nutrient loads. Information used to estimate this option includes the
number of septic systems that local governments have identified as connected to sewer systems
since the base year of 1985. Septic connections reduce total nitrogen load by an estimated 55
percent which approximates an edge-of-river OSWMS nitrate load delivered to a tertiary
treatment plant.
Denitrification in OSWMSs is accomplished through a sand mound system with effluent
recirculation. The nitrogen load is reduced by 50 percent when denitrification is incorporated in
septic systems.
Section H.2.2.1.4 Onsite Wastewater Management System Loading
Onsite wastewater management system loading information per Watershed Model segment is
extracted from the National Center for Resource Innovation (NCRI) data (Maizel et al., 1997).
The NCRI report (Maizel et al., 1997) provides estimates of human population and people served
by septic disposal within a Watershed Model segment. Estimates of population using septic
disposal through time is calculated by multiplying the ratio of the total population to the total
population using septic systems by the population estimates for Chesapeake Bay Watershed
Model segments (Table H.2.4 and Table H.2.5). These data in coordination with Watershed
Model segment area values are used to simulate Watershed Model segment OSWMS loads (per
acre and per person) to the Bay.
The septic nutrient loads are included in the HSPF simulation as a continuous time series
Watershed Data Management file that inputs OSWMS nitrate (pounds/day) to model segment
river reaches or to the tidal Bay. The use of a Watershed Data Management file for
incorporation of septic nitrate allows for this attenuation factor to easily be changed on a model
segment basis. For above fall line Watershed Model segments, OSWMS nitrate loads are input
directly into the stream reach. For below fall line Watershed Model segments, there is no stream
reach, so estimated OSWMS nitrate loads are delivered directly to the tidal Bay.
36
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Section H.2.2.1.5 Urban Nutrient Management
Urban areas are divided into pervious and impervious urban areas within the Chesapeake Bay
Watershed Model. Pervious urban areas account for suburban areas, parks, lawns, and areas in
which water is able to percolate through the soil. Alternatively, impervious urban land are areas
such as roads, paved lots, and rooftops where water is unable to percolate through the soil
profile. These lands use groups are derived from Chesapeake Bay Program Land Use (CBPLU)
categories and are described in Watershed Model Appendix E: Watershed Land Uses and Model
Linkages to the Airshed and Estuarine Models. The following equations use Chesapeake Bay
Program Land Use estimates to calculate the two categories of urban areas:
(2)
Pervious Urban = (CBPLU High Intensity Urban * 0.15) + (CBPLU Low Intensity Urban * 0.6)
+ (CBPLU Herbaceous Urban * 0.9) + (CBPLU Urban * 0.9)
+ (CBPLU Exposed * 0.6)
(3)
Impervious Urban = (CBPLU High Intensity Urban * 0.85)+(CBPLU Low Intensity Urban* 0.4)
+ (CBPLU Herbaceous Urban * 0.1) + (CBPLU Urban * 0.1)
+ (CBPLU Exposed * 0.4)
Generally, on a portion of pervious urban acres including some lawns, golf courses, and portions
of park land, intensive turf management practices are applied. For these areas, an estimated
recommended fertilizer application is 130 pounds of nitrogen/acre. A portion of the pervious
urban areas has little or no turf maintenance and only has fertilizer applied once every three
years, if at all. These areas may include lawns, medians of highways, roadside rights of way, and
portions of parks. Considering the differences in the amount of fertilizer applied to various types
of pervious land and the limitation of the use of the various types of urban land use averaged to
represent a single urban land use, an average fertilizer application of 50 pounds of
nitrogen/acre/year is applied to all pervious land within the Phase IV Watershed Model.
Figure H.2.1 shows how fertilizer nutrient application rates are determined for pervious urban
areas. Fertilizer is usually applied during the spring and early fall. For this reason, the timing of
fertilizer applications are split into eight periods each with a distribution of 10 days. These
applications begin on the following days and last for 10 days; March 9, April 9, May 9, June 9,
July 9, August 9, September 9, and October 9. The application rates of fertilizer, both NC>3 and
NH4, are illustrated in Figure H.2.2.
With the implementation of tributary strategies, urban nutrient management leads to a reduction
of urban fertilizer applied. Urban nutrient management involves public education (targeting
urban/suburban residents and businesses) to encourage reduction of excessive fertilizer use. The
CBP Nutrient Subcommittee's Tributary Strategy Workgroup has estimated that urban nutrient
management reduces nitrogen loads by 17 percent and phosphorus loads by 22 percent.
43
-------
Figure H.2.1 Determining Fertilizer Nutrient Application Rates For Pervious Urban Areas
Pervious urban area based on
land use classification
Estimate of nutrient fertilizer
applications rates for intensive
turf management areas
Assumptions of nutrient fertilizer
applications frequencies
Calculation of
nutrient fertilizer
application rates
per acre
Calculation of
nutrient fertilizer
applications rates
and the time of
applications
Determination of
the amount of
nutrient fertilizer
applied for nitrogen
and phosphorous
for each
application event
for each Model
Segment
Assumptions for nutrient fertilizer
application amount in
pervious urban areas
44
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Section H.2.2.2 Agriculture/Silviculture BMPs
The types of agricultural/silvicultural BMPs included in the Chesapeake Bay Watershed Mode
simulations are: cropland nutrient management, soil conservation water quality plar
implementation, animal waste BMPs, barnyard runoff control, rotational grazing, streambanfc
protection, forest harvesting BMPs, nutrient management plans, forested and grass buffer strips,
and cover crops. The following describes the agricultural/silvicultural BMPs simulated within
the Phase IV Watershed Model.
Section H.2.2.2.1 Cropland Nutrient Management
Cropland nutrient management is simulated (for each Watershed Model segment) through the net
pound reduction of fertilizers applied to conventional tillage, conservation tillage, and hayland
acres (Figure H.I.I, Box G, page 2). Fertilizer reductions are enacted as a part of cropland
nutrient management in order to only apply nutrients at rates that ensure adequate soil fertility
for crop production, thus reducing the availability of excess nutrients to runoff waters. The
Phase IV Watershed Model accounts for these cropland nutrient management practices by
simulating "edge-of-stream" nutrient loading according to the reduction of fertilizer nutrients
applied to the land. The nutrient management application rates are implemented on the land
according to the appropriate agronomic rate for each crop, with a minimum reduction of 10
percent. These nutrient application pound reductions are determined by a Watershed Model
segment Cropland Mass Balance (Figure H.2.3) and vary between Watershed Model segments.
For this mass balance, Watershed Model segment-specific maximum nutrient fertilizer
reductions are determined from an analysis of available nutrients versus expected crop uptake.
Nutrient reduction efficiencies range from 5-39 percent for nitrogen and 5-35 percent for
phosphorous when calculated from nutrient fertilizer pound reductions.
For each Watershed Model segment, cropland nutrient management reductions are simulated
using the percentage of acres under nutrient management. For example, if nutrient management
is implemented on 100 percent of the cropland acres in a given Watershed Model segment and an
estimated reduction of 60 pounds/acre nitrogen is realized, then the fertilizer reduction would be
60 pounds/acre for nitrogen for all acres under nutrient management. However, if only 25
percent of the acres are under nutrient management, the resulting fertilizer reduction would be 60
pounds/acre multiplied by 25 percent or 15 pounds/acre.
Section H.2.2.2.2 Soil Conservation and Water Quality Plan
Soil conservation and water quality plans are comprehensive plans that address natural resource
management concerns on agricultural lands and utilize Best Management Practices to control
erosion and runoff. A USDA professional and/or a Soil Conservation District employee assists
in developing these plans at the request of a landowner. They work with farmers to determine
which BMPs and/or systems are needed to address specific erosion and/or runoff problems on
their farms. Together these practices control erosion (within acceptable levels) in a manner
compatible with the farm operation and cropping systems. Soil conservation and water quality
plans are based on current farming objectives and should be reviewed and/or revised if changes
46
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occur. Nutrient reductions are only one of many benefits derived from soil conservation and
water quality plans, other benefits include, but are not limited to, better soil quality (therefore
better crop yields), the establishment of constructed ponds, and the enhancement of wildlife and
plant habitats.
Soil conservation and water quality plans are incorporated into the Phase IV Watershed Model
through a reduction of sediment loss from conventional and conservation tillage, and pasture and
hay croplands. These plans reduce nutrient and suspended sediment loading from each land use.
The effectiveness of soil conservation and water quality plans varies between land uses.
Therefore, reductions in nutrient and suspended sediment loads vary between land uses.
The estimated reductions by landuse as effected by soil conservation and water quality plans
follows:
Landuse
Conventional tillage
Conservation tillage
Hayland
Pastureland
TN reductions(%)
10
4
4
20
TP & TSS reductions(%)
40
8
8
14
Section H.2.2.2.3 Animal Waste Management Systems
Agricultural livestock and farm animals produce manure, and consequentially nutrient flow in to
water supplies which directly impact the Chesapeake Bay water quality (Ritler and Scarbourgh,
1996; Evanylo, 1995). Understanding such an influence is important in modeling nutrient loads
from land uses to the Bay, both from surface and subsurface flow (Johnson and Parker,-1993).
Nutrients in manure are a vital resource and can be collected for application to cropland (Krider,
1992; Graves 1986).
Manure from agricultural livestock may either be voided in confined areas or unconfined areas
(Gilbertson, 1979). Within the Phase IV Watershed Model, manure voided in unconfined areas
is assumed to occur in pasturelands. The effect of confined animal waste management systems
are calculated by adjusting the percentage of manure between two types of confined groups
(confined/susceptible to runoff and confined/susceptible to runoff with BMPs able to be
implemented). This calculation allows for some of the animal waste to always be susceptible to
runoff (assuming that the BMP efficiency of animal waste and confinement systems is never 100
percent efficient).
Confined animal waste management system calculations are incorporated into Watershed Model
input files by adjusting manure acres per Watershed Model segment. A manure acre is defined
as 145 Animal Units (AUs) in the confined/susceptible to runoff grouping. Figure H.2.4 outlines
how manure acres are obtained and later incorporated into the Phase IV Watershed Model. The
Phase IV Watershed Model simulates the effect of Animal Waste System Best Management
Practices (AWSBMP) through a reduction in manure acres. These manure acres are areas of
48
-------
Figure H.2.4 Calculating Manure Acres And Their Incorporation Into The Watershed Model
Animal population by
county for four animal
types
Calculation of animal
units for each
animal type
Calculation of the number of
animals equal to 1000 pounds
Calculation of adjusted
animal units
(for each animal type)
Assumptions of time spent in
confined areas for each animal type
Sum of all adjusted
Animal Units for all
animal types
Division of total
adjusted animal units
by the comprised
animal density
Assumptions of comprised animal
density (145 animal units/acre)
Assumptions of
decreased Manure Acres
due to BMPs *
Calculation of the
number of Manure
Acres within a
Model Segment
Watershed Model uses
Manure Acres to
simulate runoff (with
set nutrient
concentration (mg/l))
to streamflow from
manured areas
* Not used during Reference Watershed Model simulations, but was applied for BMPs in
Watershed Model Progress simulations.
49
-------
Figure H.2.5 Manure Mass Balance For
Each Watershed Model Segment
Calculate animal
populations by county
for animal types
Calculation of Total
Nitrogen (TN) and
Total Phosphorous
(TP) from manure
calculated for each
Model Segment
Manure voided from
animals in confined
areas (pounds/year)
Manure voided from
animals in
pasture (pounds/year)
Manure nutrients
susceptible to runoff
(BMPs can be applied)
Volatilization of
total nitrogen
Manure nutrients
always susceptible
to runoff
Manure nutrients never
susceptible to runoff
Simulation of runoff
from Manure Acres
to streamflow
Volatilization of
total nitrogen
Manure applied to
cropland (determined
by the acreage of crop
types and manure
application rates)
Manure in pasture
Determination of
pasture acreage
Compare manure
application rate with mass"
balance calculation on a
Watershed Model
Segment basis
Determination of the
manure application
rate to pasture
(pounds/acre/year)
50
Volatilization of
total nitrogen
-------
high concentrations of confined animals in which a large amount of nutrient load runoff occurs.
Manure acres are representative of all portions of manure management, including manure in
feedlots, production houses, processing centers, collection practices, and leakage from holding
facilities.
Manure produced in confined areas can be properly or improperly stored (Loser and Hogan
1989). Animal waste management systems are designed for the proper handling, storage, and
utilization of wastes generated from animal confinement operations. These systems include a
means of collecting wastes and wash water from confinement areas into appropriate waste
storage structures. Waste management facilities take on many forms based on the animal type
and handling method (i.e., solid, slurry, and liquid). Lagoons, ponds, and concrete tanks are used
for the treatment and/or storage of liquid wastes. Storage sheds or pits are commonly used to
store solid wastes. Adequate storage allows operators to apply manure to their land when crops
can utilize the nutrients, and when the soil and weather conditions are appropriate. Animal waste
management systems not only provide major nutrient reduction benefits, but also greatly reduce
a farmer's need for chemical fertilizers.
The influence that agricultural livestock and farm animals have on the Chesapeake Bay
Watershed is best understood by determining a mass balance of manure for each Watershed
Model segment. This manure mass balance distributes manure nutrients voided into four groups:
confined/never susceptible to runoff, confined/susceptible to runoff, confined/susceptible to
runoff with BMPs able to be implemented, and pasture (Table H.2.6). This Manure mass
balance (Figure H.2.5) uses estimated populations of animal types within each Watershed Model
segment and assumes average nutrient levels in the amounts of manure voided for each animal
type (Table H.2.7) (Palace, 1997). This mass balance includes a modification in the simulation
of pasmreland through the addition of manure in the special action block, a simulation of
ammonia volatilization, and a seasonal variation of the first-order rate constant to describe plant
uptake.
Different animal species create varied volumes of manure with distinct nutrient concentrations.
Within the Phase IV Watershed Model, four types of animals are included in manure mass
balance calculations. These animal types are beef, dairy, swine, and poultry (which include
poultry layers, broilers, and turkeys). Horse and sheep populations were not included in the
manure mass balance. To estimate the amount of manure voided in a Watershed Model segment,
an animal unit is defined as 1000 pounds of animal weight. One animal unit corresponds to 0.71
dairy cows, one beef cow, five swine, 250 poultry layers, 500 poultry broilers, or 100 turkeys.
Animal populations were derived for each Watershed Model segment from the 1992 Agricultural
Census, published by the U.S. Department of Commerce and the Bureau of the Census for the
six states within the Chesapeake Bay basin. The percentage of area in a Watershed Model
segment for each county is used to decide the proportion of animal units within a Watershed
Model segment. Figure H.2.6 shows the total animal units per county in the Chesapeake Bay
Watershed.
Animal waste management system nutrient reductions for dairy/beef/swine operations have been
estimated by the Chesapeake Bay Program Nutrient Subcommittee's Tributary Strategy
Workgroup to be 80 percent for nitrogen and phosphorus, assuming that an animal waste system
51
-------
Table H.2.6 Distribution of Total Nitrogen from Manure for Each Watershed Model
(WSM) Segment in the Manure Mass Balance Calculation for the Phase IV Watershed
Model
Animal Type
Dairy
Beef
(WSM Segment
without snow)
Beef
(WSM Segment with
snow)
Swine
Poultry (layers)
Poultry (broilers)
Turkeys
Confined
(Susceptible
to runoff)
0.20
0.00
0.04
0.20
0.01
0.01
0.01
Confined
(Susceptible
to runoff)
(BMPs can be
implemented)
0.80
0.00
0.16
0.80
0.14
0.14
0.14
Confined
(Never
susceptible
to runoff)
0.00
0.00
0.00
0.00
0.85
0.85
0.85
Pasture
0.00
1.00
0.80
0.00
0.00
0.00
0.00
Table H.2.7 Estimated Quantities of Voided Manure from Livestock and Poultry
(Normalized to 1,000 pounds of animal body weight) (Gilbertson, 1979)
Animal Type Animals/ Wet Manure Total Total
Animal Units Voided Phosphorous Nitrogen
(tons/year) (pounds/year) (pounds/year)
Dairy
Beef
Swine
Poultry (layers)
Poultry (broilers)
Turkeys
0.71
1.00
5.00
250.00
500.00
100.00
14.90
6.70
11.70
9.70
13.10
10.20
21.00
18.00
37.00
100.00
110.00
84.00
123.00
61.00
160.00
235.00
390.00
304.00
52
-------
Figure H. 2. 6
Total Animal Units By County
(1000 pounds/AU)
Animal Units
0-10,000
10,001-30,000
|30,001-100,000
Greater than 100,000
Data Source
1992 Census of Agriculture
53
-------
treats 145 animal units (or one manure acre). Using the same 145 animal unit assumption
nutrient reductions for poultry animal waste systems have been determined to be 14 percent foi
nitrogen and phosphorus. These animal waste management system BMP efficiencies are used
within the Phase IV Watershed Model to simulate the amount of nutrient reduction obtained with
these management practices.
Estimated BMP efficiencies were developed separately for livestock (primarily dairy and swine)
and poultry waste systems. Livestock manure must be stockpiled or spread daily if no storage
system is available, resulting in a high potential for nutrient pollution to ground and surface
water sources. On the other hand, poultry manure remains in the production house for a majority
of the time. Small amounts of manure are removed with each flock (approximately every seven
weeks for broilers), and the entire production house is cleaned approximately every two years.
Poultry manure is relatively dry so if it is properly stacked outside, the potential for nutrient loss
is less than that of livestock waste.
It is assumed within the Phase IV Watershed Model that dairy are in confined areas 100 percent
of the time. Dairy are further divided into the three confined groups as follows: 20 percent in
confined/susceptible to runoff, 80 percent confined/susceptible to runoff with BMPs able to be
implemented, and 0 percent confined/never susceptible to runoff.
Beef are assumed to be in pasture 100 percent of the time, except for Watershed Model segments
where snow covers the ground a large portion of the winter. These areas receiving snow tend to
have beef cattle housed in feed lots or confined areas. Within these Watershed Model segments,
it was decided that beef should be calculated in the pasture for 80 percent of the time, as opposed
to 100 percent. According to this assumption, beef are in confined areas 20 percent of the year
(4 percent of the total time in confined/susceptible to runoff, and 16 percent in
confined/susceptible to runoff with BMPs able to be implemented). This assumption is
incorporated into the Phase IV Watershed Model, based on the assumption that cattle spend 292
days a year in the field, starting March 1 and ending December 17.
Within the Phase IV Watershed Model, swine are in confined areas 100 percent of the time.
Swine are further divided into the three confined groups as follows: 1 percent in
confined/susceptible to runoff, 14 percent confined/susceptible to runoff with BMPs able to be
implemented, and 85 percent confined/never susceptible to runoff.
Throughout the Watershed Model Scenarios, it is assumed that all poultry (including poultry
layers, poultry boilers, and turkeys) are found in confined areas 100 percent of the time. Poultry
are further divided into the three confined groups as follows: 1 percent in confined/susceptible to
runoff, 14 percent confined/susceptible to runoff with BMPs able to be implemented, and 85
percent confined/never susceptible to runoff. The amount of total nitrogen in pounds per year for
each of these animal groups are presented in Tables H.2.8-H.2.11.
54
-------
Table H.2.8 Manure in All Confined Areas
Model
Segment
10
20
30
40
50
60
70
80
90
100
110
120
140
160
170
175
180
190
200
210
220
230
235
240
250
260
265
270
280
290
300
310
330
340
370
380
390
400
410
420
430
440
450
470
480
490
500
510
540
550
560
580
590
600
Cattle
(Ibs/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Dairy
(Ibs/yr)
7,412,860.77
20,222,592.93
6,171,144.32
1,440,062.40
1,023,546.70
4,916,456.66
2,315,094.50
7,994,961.58
2,849,960.38
8,705,662 44
7,427,194.61
2,730,182.08
1,660,540.52
1,348,090.20
169,339.11
952,246.82
3,800,172.50
4,114,876.79
2,982,049.73
5,529,14589
953,376.40
1,836,824.62
96,007.70
9,535.27
185,088.58
228,79641
1,230.38
1,283,631.05
653,093.29
88,400 78
918,394 17
57,327.77
120,677.81
118,124.63
93,375.90
698,781.38
83,697.71
399,939.65
326,055 85
8,301.04
53,941.46
0
3,380,971.35
550,109.10
66,937.86
52,585.01
31,514.26
0
57,993.77
525,324.65
30,914 18
20.79
247,547.01
4,394.74
Swine Poultry (layers) Poultry (broilers)
(Ibs/yr)
322,159.59
207,013.45
148,91495
844,851.76
164,450.69
526,983.66
670,308.29
3,683,503.72
360,682.36
1,543,286.86
5,057,592 49
2,044,870.19
1,295,302.63
118,845.38
146,311.24
194,616.55
492,39341
391,645.93
321,14463
310,694.79
50,912.90
223,921.69
8,725.23
18,768.86
37,997.56
69,541.06
1,240.63
91,132.65
295,841.88
79,414.32
139,784.61
35,211.53
16,623.40
35,945.64
11,761 72
208,409.68
17,443.20
251,239.32
939,231.02
201,318.09
991,424.01
36,999 71
1,558,345.31
140,794.82
19,783.98
18,925.13
161,515.00
2,961.32
16,673.59
13,279.39
68,466.39
0.77
136,863.13
1,423,526.95
(Ibs/yr)
238.86
30,389.97
1,396.21
6,575.97
6,605.97
6,855.71
2,244.39
1,489,409.28
1,873.52
227,551.04
3,250,559.82
2,685,280.77
1,231,38372
9,492.56
495,738 50
635,875.69
447,701 44
1,629,929.04
866,400.63
614,547.22
13,414.70
3,968.38
29238
346.41
72.66
110.18
136.33
169,058.98
176,778.42
41,364.93
86,679.14
5409
370.75
673.86
8.22
5,015.42
28.58
3,878.23
283,889.04
334,346.27
300,251.60
39.25
1,979,26471
79,045 74
1,23675
78519
3,369 56
154.94
589.11
1,310.66
353.92
0
478.36
1,479.72
(Ibs/yr)
500.88
83086
739.15
319,392.10
1,218.27
28,105.85
440,288.10
2,024,146.03
385.39
1,505,299.42
2,017,600.36
963,108.71
464,423.96
742,283.32
3,729,548.87
1,683,32868
44,463.15
10,467,233.30
6,173,757.54
7,063.78
200.23
26,576.79
0
0
0
95,158.54
0
194,525.15
1,792,61018
242,333.21
2,603,681.72
140,695.87
6312
56.7
486
924,194.74
322,871.43
4,325,250.39
15,246,760.10
5,440,244.44
14,667,499.31
1,061,254.22
705,919.77
1,538.59
0
17.94
78.36
2.01
29.36
62.83
0
0
48,191.41
263,997.19
Turkeys TN in Confined Areas
(Ibs/yr)
72741
1,661.31
469.3
81,921.46
334.53
1,214.14
195,185.63
975,150.11
22,682.22
431,594.87
1,541,127.58
113,621.55
166,811.26
197,534.59
3,660,889.95
29,928.15
46,114.35
11,524,395.63
6,820,604.65
208,278.49
21209
4,848.81
0
0
0
2.28
99,235.86
1,378,80411
13,517.48
22.48
0
0
0
44.5
7.73
21.91
0
10.89
30.73
0
0
0
123,033.42
7,901.05
0
68.11
637.06
364
0
91.38
0
0
18.62
0
(Ibs/yr)
7,736,487.51
20,462,488.53
6,322,663.94
2,692,803.69
1,196,156.17
5,479,616.02
3,623,120.91
16,167,170.72
3,235,583.86
12,413,394.62
19,294,07486
8,537,063.30
4,818,462.09
2,416,246.05
8,201,827.67
3,495,995 89
4,830,844.86
28,128,080.69
17,163,957.17
6,669,730.17
1,018,116.31
2,096,140.29
105,025.31
28,650.55
223,158.81
393,608.47
101,843.21
3,117,151.94
2,931,841 26
451,535.71
3,748,539.65
233,289.26
137,735.09
154,845.33
105,158.44
1,836,423.14
424,040.92
4,980,318.47
16,795,966.74
5,984,209.84
16,013,116.37
1,098,293.17
7,747,534.56
779,389.30
87,958.60
72,381.38
197,114.25
3,154.67
75,285.83
540,068.90
99,734.49
21 56
433,098.53
1,693,398.61
55
-------
Model
Segment
610
620
630
630
700
710
720
730
740
750
760
770
780
800
810
820
830
840
850
860
870
880
890
900
910
920
930
940
950
960
970
980
990
Cattle
(Ibs/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Dairy
(Ibs/yr)
33,739 42
338.94
4,609.62
0
1,144,317.87
2,472,554.19
7,207,546.03
4,616,11689
2,978,529.23
513,825.40
865,919.50
139,157.33
43,843.64
129,907.39
381,297.75
47,846.22
75,190.64
0
168,41666
51,548.69
0
0
49,601.26
0
15,514.91
62,955.97
503.09
0
0
18,457.87
32,294.00
14,810.76
5,781.55
128,003,720.33
Swine
(Ibs/yr)
10,564.61
427,633.17
3,936.80
0
22,542.18
1,921,256.45
5,339,553.40
1,451,561.49
1,064,117.24
263,084.83
145,078.66
47,625.10
110,689.41
16,446.62
125,301.87
7,689.04
29,044.69
370,591.83
7,721.16
15,235.60
2,664.92
9,516.72
1,82746
1,567.10
53,885.24
524,769.97
18.59
41,268.62
0
534,848.19
29898
21,283.14
47,539.75
38,788,759.94
Poultry (layers) Poultry (broilers)
(Ibs/yr)
74.1
0
0
0
38.86
2,309,305.86
7,185,820.38
952,254.30
259,298.93
19,660.98
400,671.60
12,904.97
1,796.26
8.96
4.65
0
121.42
0
248.98
95242
139.43
390.19
170.19
0
1,231.42
9,776.78
0
4.25
0
0
104.79
488.61
882.86
28,285,247.95
(Ibs/yr)
24,288.61
192,884.45
448.66
0
33.6
854,727.30
2,635,584.48
213,103.18
17,229.78
15,520.70
50.84
477,477.55
1,675,679.67
687
139,11473
147,705.50
506,074.84
2,181,566.16
0
0
1.81
5.06
1,358.08
0
21.14
341.18
0
0
0
0
0
1.17
30.13
87,800,791.65
Turkeys TN in Confined Areas
(Ibs/yr)
0
0
0
0
34.06
142,882.81
218,31335
179,45053
8,717 14
507,847.93
25.82
37.14
5 17
8.43
4.38
0
0
0
161.16
0
3276
91.66
0
21 65
25.99
2,303.15
0
36.1
0
0
0
1.28
249.89
28,709,042.50
(Ibs/yr)
68,666.74
620,856.56
8,995.08
0
1,166,966.58
7,700,726.62
22,586,817.64
7,412,486.39
4,327,892.32
1,319,939.84
1,411,74641
677,202.09
1,832,014.15
146,378.28
645,723.38
203,240.76
610,431.60
2,552,158.00
176,547.95
67,736.71
2,838.92
10,00363
52,956.98
1,588.76
70,678.70
600,147.05
521.67
41,308.97
0
553,306 06
32,697.76
36,584.96
54,484.19
311,587,562.36
56
-------
Table H.2.9 Manure in Areas Susceptible to Run-off (BMPs possible)
Model
Segment
10
20
30
40
50
60
70
80
90
100
110
120
140
160
170
175
180
190
200
210
220
230
235
240
250
260
265
270
280
290
300
310
330
340
370
380
390
400
410
420
430
440
450
470
480
490
500
510
540
550
Cattle
(Ibs/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
" Dairy
(Ibs/yr)
5,930,288.61
16,178,074.35
4,936,915.46
1,152,049.92
818,837.36
3,933,165.33
1,852,075.60
6,395,969.26
2,279,968.30
6,964,529.95
5,941,755.69
2,184,145.66
1,328,432.42
1,078,472.16
135,471.29
761,797.46
3,040,138.00
3,291,901.43
2,385,639.79
4,423,316.71
762,701.12
1,469,459.70
76,806.16
7,628.22
148,070.86
183,037.12
984.3
1 ,026,904.84
522,474.63
70,720.62
734,715.34
45,862.22
96,542.25
94,499.70
74,700.72
559,025.10
66,958.16
319,951.72
260,844.68
6,640.84
43,153.17
0
2,704,777.08
440,087.28
53,550.29
42,068.01
25,211.41
0
46,395.02
420,259.72
Swine Poultry (layers) Poultry (broilers)
(Ibs/yr)
257,727.67
165,610.76
119,131.96
675,881.41
131,560.55
421,586.93
536,246.63
2,946,802.97
288,545.89
1,234,629.49
4,046,073.99
1,635,896.15
1,036,242.10
95,076.30
117,048.99
155,693.24
393,914.73
313,316.74
256,915.70
248,555.83
40,730.32
179,137.35
6,980.18
15,015.09
30,398.05
55,632.84
992.51
72,906.12
236,673.51
63,531.45
111,827.69
28,169.22
13,298.72
28,756.52
9,409.38
166,727.75
13,954.56
200,991.45
751,384.81
161,054.47
793,139.21
29,599.76
1,246,676.25
112,635.86
15,827.19
15,140.10
129,212.00
2,369.06
13,338.87
10,623.51
(Ibs/yr)
33.44
4,254.60
195.47
920.64
924.84
959.8
314.21
208,517.30
262.29
31,857.15
455,078.38
375,939.31
172,393.72
1,328.96
69,403.39
89,022.60
62,678.20
228,190.07
121,296.09
86,036.61
1,878.06
555.57
40.93
48.5
10.17
15.42
19.09
23,668.26
24,748.98
5,791.09
12,135.08
7.57
51.9
94.34
1.15
702.16
4
542.95
39,744.47
46,808.48
42,035.22
5.5
277,097.06
1 1 ,066.40
173.15
109.93
471.74
21.69
82.48
183.49
(Ibs/yr)
70.12
116.32
103.48
44,714.89
170.56
3,934.82
61 ,640.33
283,380.44
53.95
210,741.92
282,464.05
134,835.22
65,019.35
103,919.66
522,136.84
235,666.02
6,224.84
1,465,412.66
864,326.05
988.93
28.03
3,720.75
0
0
0
13,322.20
0
27,233.52
250,965.43
33,926.65
364,515.44
19,697.42
8.84
7.94
0.68
129,387.26
45,202.00
605,535.05
2,134,546.41
761 ,634.22
2,053,449.90
148,575.59
98,828.77
215.4
0
2.51
10.97
0.28
4.11
8.8
Turkeys
(Ibs/yr)
101.84
232.58
65.7
1 1 ,469.00
46.83
169.98
27,325.99
136,521.02
3,175.51
60,423.28
215,757.86
15,907.02
23,353.58
27,654.84
512,524.59
4,189.94
6,456.01
1,613,415.39
954,884.65
29,158.99
29.69
678.83
0
0
0
0.32
13,893.02
193,032.57
1,892.45
3.15
0
0
0
6.23
1.08
3.07
0
1.52
4.3
0
0
0
17,224.68
1,106.15
0
9.54
89.19
5.1
0
12.79
TN Sus. Areas
(BMP possible)
(Ibs/yr)
6,188,221.69
16,348,288.61
5,056,412.07
1,885,035.86
951,540.14
4,359,816.86
2,477,602.77
9,971,190.99
2,572,005.95
8,502,181.78
10,941,129.97
4,346,723.36
2,625,441.17
1,306,451.93
1,356,585.10
1,246,369.25
3,509,411.78
6,912,236.29
4,583,062.28
4,788,057.07
805,367.22
1,653,552.20
83,827.28
22,691.80
178,479.09
252,007.91
15,888.92
1,343,745.31
1,036,754.99
173,972.96
1,223,193.55
93,736.43
109,901.72
123,364.72
84,113.01
855,845.34
126,118.73
1,127,022.70
3,186,524.68
976,138.01
2,931,777.50
178,180.85
4,344,603.84
565,111.09
69,550.62
57,330.09
154,995.31
2,396.13
59,820.48
431,088.31
57
-------
Model
Segment
560
580
590
600
610
620
630
630
700
710
720
730
740
750
760
770
780
800
810
820
830
840
850
860
870
880
890
900
910
920
930
940
950
960
970
980
990
Cattle
(Ibs/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Dairy
(Ibs/yr)
24,731.34
16.63
198,037.61
3,515.79
26,991.54
271.15
3,687.70
0
915,454.30
1,978,043.36
5,766,036.82
3,692,893.51
2,382,823.38
411,060.32
692,735.60
111,325.87
35,074.92
103,925.91
305,038.20
38,276.98
60,152.52
0
134,733.33
41,238.95
0
0
39,681.01
0
12,411.93
50,364.78
402.47
0
0
14,766.29
25,835.20
11,848.61
4,625.24
Swine Poultry (layers) Poultry (broilers)
(Ibs/yr)
54,773.11
0.61
109,490.50
1,138,821.56
8,451.69
342,106.54
3,149.44
0
18,033.75
1,537,005.16
4,271,642.72
1,161,249.19
851,293.79
210,467.86
116,062.93
38,100.08
88,551.53
13,157.30
100,241.50
6,151.23
23,235.75
296,473.47
6,176.93
12,188.48
2,131.94
7,613.38
1,461.97
1,253.68
43,108.20
419,815.98
14.87
33,014.90
0
427,878.55
239.18
17,026.51
38,031.80
(Ibs/yr)
49.55
0
66.97
207.16
10.37
0
0
0
5.44
323,302.82
1,006,014.85
133,315.60
36,301.85
2,752.54
56,094.02
1,806.70
251 .48
1.26
0.65
0
17
0
34.86
133.34
19.52
54.63
23.83
0
172.4
1,368.75
0
0.59
0
0
14.67
68.41
123.6
(Ibs/yr)
0
0
6,746.80
36,959.61
3,400.41
27,003.82
62.81
0
4.7
119,661.82
368,981.83
29,834.45
2,412.17
2,172.90
7.12
66,846.86
234,595.15
0.96
19,476.06
20,678.77
70,850.48
305,419.26
0
0
0.25
0.71
190.13
0
2.96
47.77
0
0
0
0
0
0.16
4.22
Turkeys
(Ibs/yr)
0
0
2.61
0
0
0
0
0
4.77
20,003.59
30,563.87
25,123.07
1,220.40
71,098.71
3.61
5.2
0.72
1.18
0.61
0
0
0
22.56
0
4.59
12..83
0
3.03
3.64
322.44
0
5.05
0
0
0
0.18
34.98
TN Sus. Areas
(BMP possible)
(Ibs/yr)
79,554.00
17.25
314,344.49
1,179,504.12
38,854.00
369,381.52
6,899.95
0
933,502.96
3,978,016.76
1 1 ,443,240.09
5,042,415.83
3,274,051.59
697,552.33
864,903.28
218,084.70
358,473.80
117,086.61
424,757.02
65,106.98
154,255.75
601,892.73
140,967.67
53,560.77
2,156.30
7,681.55
41,356.93
1,256.71
55,699.12
471,919.71
417.34
33,020.54
0
442,644.85
26,089.05
28,943.87
42,819.85
58
-------
Table H.2.10 Manure in Areas Always Susceptible to Run-off
Model
Segment
10
20
30
40
50
60
70
80
90
100
110
120
140
160
170
175
180
190
200
210
220
230
235
240
250
260
265
270
280
290
300
310
330
340
370
380
390
400
410
420
430
440
450
470
480
490
500
510
540
550
560
580
590
Cattle
(Ibs/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Dairy
(Ibs/yr)
1,482,572.15
4,044,518.59
1,234,225.86
288,012.48
204,709.34
983,291.33
463,018.90
1,598,992.32
569,992.08
1,741,132.49
1,485,438.92
546,036.42
332,108.10
269,618.04
33,867.82
190,449.36
760,034.50
822,975.36
596,409.95
1,105,82918
190,675.28
367,364.92
19,201.54
1,907.05
37,01772
45,759.28
24608
256,726.21
130,618.66
17,680.16
183,678.83
11,465.55
24,13556
23,624.93
18,675.18
139,756.28
16,739.54
79,987 93
65,211.17
1,660.21
10,788.29
0
676,194.27
110,021.82
13,387.57
10,517.00
6,302.85
0
11,598.75
105,064.93
6,182.84
4.16
49,509.40
Swine Poultry (layers) Poultry (broilers)
(Ibs/yr)
64,431.92
41,402.69
29,782.99
168,970.35
32,890.14
105,39673
134,061.66
736,700.74
72,136.47
308,657.37
1,011,518.50
408,974.04
259,060.53
23,769.08
29,262.25
38,923.31
98,478.68
78,32919
64,228.93
62,138.96
10,182.58
44,784.34
1,745.05
3,753.77
7,599.51
13,908.21
248.13
18,226.53
59,168.38
15,882.86
27,956.92
7,042.31
3,324.68
7,189.13
2,352.34
41,681.94
3,488 64
50,247.86
187,846.20
40,263.62
198,284.80
7,399.94
311,669.06
28,15896
3,956.80
3,785.03
32,303.00
592.26
3,334.72
2,655.88
13,693.28
015
27,372.63
(Ibs/yr)
2.39
303.9
13.96
65.76
6606
68.56
22.44
14,894.09
18.74
2,275.51
32,505.60
26,852.81
12,313.84
94.93
4,957 38
6,358.76
4,477 01
16,299.29
8,664.01
6,145.47
134.15
39.68
2.92
3.46
0.73
1 1
1.36
1,690.59
1,767.78
413.65
866 79
0.54
3.71
6.74
0.08
50.15
0.29
3878
2,838.89
3,34346
3,002.52
0.39
19,792.65
790.46
12.37
7.85
33.7
1.55
5.89
13.11
3.54
0
4.78
(Ibs/yr)
5.01
8.31
7.39
3,193.92
12 18
281.06
4,402.88
20,241.46
3.85
15,052.99
20,176.00
9,631.09
4,644.24
7,422.83
37,295.49
16,833.29
44463
104,672.33
61,737.58
70.64
2
265.77
0
0
0
951.59
0
1,945.25
17,926.10
2,423.33
26,036.82
1,406.96
0.63
0.57
0.05
9,241.95
3,228.71
43,252.50
152,46760
54,402.44
146,674.99
10,612.54
7,059.20
15.39
0
0.18
0.78
0.02
0.29
0.63
0
0
481.91
Turkeys TN in
(Ibs/yr)
7.27
1661
4.69
819.21
335
12.14
1,951.86
9,751.50
226.82
4,315.95
15,411.28
1,136.22
1,66811
1,975.35
36,608.90
299.28
461.14
115,243.96
68,206.05
2,082.78
2.12
4849
0
0
0
0.02
992.36
13,788.04
135.17
0.22
0
0
0
0.44
0.08
0.22
0
0.11
0.31
0
0
0
1,230.33
79.01
0
0.68
6.37
0.36
0
0.91
0
0
0.19
Always Susceptible
(Ibs/yr)
1,547,018.74
4,086,250.10
1,264,037.90
461,061.73
237,681.07
1,089,049.82
603,457.74
2,380,580 1 1
642,377.96
2,071,434.31
2,565,050.30
992,630.56
609,794.82
302,880.22
141,991 84
252,864.00
863,895.97
1,137,520.12
799,246.50
1,176,267.03
200,996.13
412,503.20
20,949.51
5,664 29
44,617.96
60,620.20
1,487.92
292,376.62
209,616.10
36,400.22
238,539.37
19,91536
27,464.58
30,821.80
21,027.73
190,730.53
23,457.18
173,527.19
408,364.17
99,669.73
358,750 60
18,01288
1,015,945.51
139,065.64
17,356.74
14,310.74
38,646.70
594.2
14,939.66
107,73546
19,879.65
4.31
77,368.91
59
-------
Model
Segment
600
610
620
630
630
700
710
720
730
740
750
760
770
780
800
810
820
830
840
850
860
870
880
890
900
910
920
930
940
950
960
970
980
990
Cattle
(Ibs/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Dairy
(Ibs/yr)
878.95
6,747.88
67.79
921.92
0
228,863.57
494,51084
1,441,509.21 1
923,223.38
595,705.85
102,76508
173,183.90
27,831 47
8,768.73
25,981.48
76,259.55
9,569 24
15,038.13
0
33,683 33
10,309.74
0
0
9,920 25
0
3,102.98
12,591 19
100.62
0
0
3,691.57
6,458 80
2,962 15
1,156.31
25,600,744.07 7,
Swine
(Ibs/yr)
284,705.39
2,112.92
85,526.63
787.36
0
4,508.44
384,251.29
,067,910.68
290,312.30
212,823.45
52,616.97
29,0f5.73
9,525.02
22,137.88
3,289.32
25,060.37
1,53781
5,808.94
74,118.37
1,544.23
3,047.12
532.98
1,903.34
365.49
313.42
10,777.05
104,953 99
372
8,253.72
0
106,96964
598
4,256.63
9,507.95
757,751.99
Poultry (layers)
(Ibs/yr)
148
074
0
0
0
0.39
23,093.06
71,858.20
9,522.54
2,592.99
196.61
4,006.72
129.05
17.96
0.09
0.05
0
1.21
0
249
952
1.39
3.9
1 7
0
12.31
97.77
0
0.04
0
0
1.05
4.89
8.83
282,852.48
Poultry (broilers)
(Ibs/yr)
2,639.97
242.89
1,928.84
4.49
0
0.34
8,547.27
26,355 84
2,131 03
172.3
155.21
0.51
4,774.78
16,756.80
0.07
1,391.15
1,477.05
5,060.75
21,815.66
0
0
002
0.05
13.58
0
0.21
3.41
0
0
0
0
0
0.01
0.3
878,007.92
Turkeys
(Ibs/yr)
0
0
0
0
0
0.34
1,428.83
2,183.13
1,794.51
87.17
5,078.48
0.26
0.37
0.05
0.08
0.04
0
0
0
1.61
0
0.33
0.92
0
0.22
026
2303
0
0.36
0
0
0
0.01
2.5
287,090.42
TN in Always Susceptible
(Ibs/yr)
288,239.11
9,104.43
87,523.27
1,713.77
0
233,373.08
911,831 29
2,609,817.07
1,226,983.76
811,381.75
160,812.34
206,207.11
42,260.68
47,681.42
29,271.04
102,711 16
12,584.11
25,909.03
95,934.03
35,231.66
13,366.38
534.72
1,908.21
10,301.03
313.64
13,892.82
117,669.40
104.33
8,254.13
0
110,661.21
6,519.64
7,223.69
10,675.89
34,806,446.87
60
-------
Table H.2.11 Manure in Areas Never Susceptible to Run-off
Model
Cattle
Dairy
Swine Poultry (layers) Poultry (broilers)
Segment (Ibs/yr) (Ibs/yr) (Ibs/yr)
10
20
30
40
50
60
70
80
90
100
110
120
140
160
170
175
180
190
200
210
220
230
235
240
250
260
265
270
280
290
300
310
330
340
370
380
390
400
410
420
430
440
450
470
480
490
500
510
540
550
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(Ibs/yr)
203.03
25,831.48
1,186.78
5,589.58
5,615.07
5,827.35
1,907.73
1,265,997.89
1,592.49
193,418.38
2,762,975.85
2,282,488.66
1,046,676.16
8,068.68
421,377.72
540,494.33
380,546.23
1,385,439.68
736,440.53
522,365.14
11,402.49
3,373.12
248.52
294.45
61.76
93.65
115.88
143,700.13
150,261.66
35,160.19
73,677.27
45.98
315.14
572.78
6.99
4,263.11
24.29
3,296.49
241,305.68
284,194.33
255,213.86
33.36
1,682,375.00
67,188.88
1,051.24
667.41
2,864.12
131.7
500.75
1,114.06
(Ibs/yr)
425.75
706.23
628.28
271,483.28
1,035.53
23,889.97
374,244.89
1,720,524.12
327,58
1,279,504.51
1,714,960.30
818,642.41
394,760.37
630,940.82
3,170,116.54
1,430,829.38
37,793.68
8,897,148.31
5,247,693.90
6,004.21
170.19
22,590.27
0
0
0
80,884.76
0
165,346.38
1,523,718.66
205,983.23
2,213,129.47
119,591.49
53.65
48.19
4.14
785,565.53
274,440.71
3,676,462.83
12,959,746.09
4,624,207.77
12,467,374.41
902,066.08
600,031 .80
1,307.80
0
15.25
66.61
1.71
24.95
53.4
Turkeys TN
(Ibs/yr)
618.3
1,412.12
398.91
69,633.24
284.35
1 ,032.02
165,907.79
828,877.59
19,279.88
366,855.64
1,309,958.44
96,578.31
141,789.57
167,904.40
3,111,756.46
25,438.93
39,197.20
9,795,736.29
5,797,513.95
177,036.72
180.28
4,121.49
0
0
0
1.94
84,350.48
1,171,983.49
11,489.86
19.11
0
0
0
37.82
6.57
18.62
0
9.25
26.12
0
0
0
104,578.41
6,715.89
0
57.9
541.5
30.94
0
77.67
in Non-Susceptible
(Ibs/yr)
1,247.08
27,949.82
2,213.96
346,706.10
6,934.96
30,749.34
542,060.40
3,815,399.61
21,199.95
1,839,778.52
5,787,894.60
3,197,709.38
1,583,226.10
806,913.90
6,703,250.72
1,996,762.64
457,537.10
20,078,324.28
11,781,648.39
705,406.06
11,752.96
30,084.88
248.52
294.45
61.76
80,980.36
84,466.36
1,481,030.00
1,685,470.17
241,162.53
2,286,806.74
119,637.47
368.79
658.8
17.7
789,847.26
274,465.01
3,679,768.58
13,201,077.89
4,908,402.10
12,722,588.27
902,099.45
2,386,985.21
75,212.57
1,051.24
740.55
3,472.24
164.34
525.7
1,245.13
61
-------
Model
Cattle
Dairy
Swine
Segment (Ibs/yr) (Ibs/yr) (Ibs/yr)
560
580
590
600
610
620
630
630
700
710
720
730
740
750
760
770
780
800
810
820
830
840
850
860
870
880
890
900
910
920
930
940
950
960
970
980
990
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
.0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Poultry (layers) Poultry (broilers)
(Ibs/yr)
300.83
0
406.6
1,257.76
62.99
0
0
0
33.04
1,962,909.98
6,107,947.32
809,416.15
220,404.09
16,711.84
340,570.86
10,969.23
1,526.82
7.62
3.96
0
103.21
0
211.63
809.56
118.52
331.66
144.66
0
1,046.71
8,310.26
0
3.61
0
0
89.07
415.32
750.43
24,042,460.76
(Ibs/yr)
0
0
40,962.70
224,397.61
20,645.32
163,951.78
381.36
0
28.56
726,518.21
2,240,246.81
181,137.70
14,645.31
13,192.60
43.21
405,855.91
1 ,424,327.72
5.84
118,247.52
125,549.67
430,163.62
1,854,331.24
0
0
1.54
4.3
1,154.36
0
17.97
290
0
0
0
0
0
0.99
25.61
74,630,672.90
Turkeys TN in Non-Susceptible
(Ibs/yr)
0
0
15.83
0
0
0
0
0
28.95
121,450.39
185,566.35
152,532.95
7,409.57
431,670.74
21.94
31.57
4.39
7.17
3.72
0
0
0
136.99
0
27.84
77.91
0
18.41
' 22.09
1,957.68
0
30.68
0
0
0
1.09
212.4
24,402,686.12
(Ibs/yr)
300.83
0
41,385.13
225,655.38
20,708.30
163,951.78
381.36
0
90.55
2,810,878.58
8,533,760.48
1,143,086.80
242,458.97
461,575.17
340,636.02
416,856.71
1,425,858.93
20.63
118,255.20
125,549.67
430,266.82
1,854,331.24
348.62
809.56
147.89
413.87
1,299.03
18.41
1,086.77
10,557.94
0
34.29
0
0
89.07
417.4
988.45
123,075,819.78
62
-------
Section H.2.2.2.4 Manure Application to Pasturelands
Within the Phase IV Watershed Model, it is assumed that all manure voided in unconfined areas
occurs in pasturelands. Figure H.2.7 presents a flowchart of the calculations used to estimate the
amount of nitrogen applied to these pasturelands. Manure application rates (pounds/acre/year)
per Watershed Model segment are calculated by dividing the amount of manure voided in
pasture by the number of pasture acres. Annual manure application rates are divided by 182.5 to
calculate manure application rates on two day intervals. Tables H.2.12 and H.2.13 list manure
nutrient application rates (on two-day and annual intervals) for total nitrogen per Watershed
Model segment. Manure nitrogen applications are split between organic nitrogen and ammonia
in a ratio of 55 to 45 percent (Reedy et. al., 1979; Donigian et al., 1991).
The application rate for each crop type per Watershed Model segment is determined from the
Phase IV Watershed Model input deck to allow for the comparison between the amount of
manure produced in collectible/confined areas and that applied to agricultural lands. Using the
total acreage for each crop type (conventional tillage, conservation tillage, and hayland) and the
respective application rates, total nutrients applied for a given crop type are calculated. Adding
the three crop types together yields the total nutrients from manure applied to cropland within a
Watershed Model segment. Figures H.2.8-H.2.10 illustrate the differences between the model
manure application rates and the rates calculated from animal unit and mass balance information
to each of the three crop types.
To determine the amount of manure produced in a Watershed Model segment that is available
for collection and application to pasturelands, the following steps were taken. After manure
acres are calculated, 25 percent of the total nitrogen applied to pasture and croplands is assumed
to be volatilized. The remaining total nitrogen from both confined/properly stored and
confined/improperly stored is assumed to be collected and applied to croplands.
An application rate is calculated from the manure mass balance for each crop type. This is
primarily used as a comparison tool. An effort is made to create comparable nutrient application
rates proportional to the original nutrient application rates and consistent with the acreage of a
given crop type within a Watershed Model segment. An added difficulty is that some crop type
application rates are zero. When an application rate is zero and excess manure needs to be
applied, the application rate is determined by a proportion of nutrient application rates and crop
type acreage. Manure application rates are then compared with actual input of total nitrogen
from the Phase IV Watershed Model, based on a matrix that determines how much of a crop area
receives the specific manure and fertilizer applications.
Within the Phase IV Watershed Model, pastureland plant uptake simulations can be completed
with three simulation methods. These methods are Michaelis-Menton, yield based, and first
order simulations. Michaelis-Menton is included in the Phase IV Watershed Model for forest
simulation only. Beaulac and Reckhow (1982) suggest that pastureland nutrient export is more
like forest than it is like cropland. In other words, the pasture has a greater assimilation potential
for nutrients than does cropland. Because pasturelands are not being managed for nutrients like
cropland and yield-based plant uptake is based on growing specific sized crops, the first order
63
-------
Figure H.2.7 Method Used To Estimate
Nitrogen Applied To Pasture
Animal population by
county for four
animal types
Calculation of total
nitrogen and total
phosphorous from
manure calculated for
each Watershed
Model Segment
Determination of the
types of animals spending
time in pasturelands
Manure voided
from animals in
pasture (pounds/year)
The influence of beef
manure multiplied by
1.0 if no snow is
present; if snow is
present multiply by 0.8
Determination of the
manure application
rates to pasturelands
(pounds/acre/year)
Determination of
pasture acreage
50% Volatilization of
Ammonia simulated by
the Watershed Model
Add nutrient application
to pasturelands in soil
surface layer
(0.45 ammonia and
0.55 organic nitrogen)
Apply manure at
two day intervals
(pounds/acre/2days)
Comparison of literature
referenced and
Watershed Model
simulated pastureland
nutrient export values
-------
Table H.2.12 Breakdown Of TN Manure Applications Per 2 Days
Model
Segment
10
20
30
40
50
60
70
80
90
100
110
120
140
160
170
175
180
190
200
210
220
230
235
240
250
260
265
270
280
290
300
310
330
340
370
380
390
400
410
420
430
440,
450
470
480
490
500
510
540
550
560
580
590
600
610
620
630
650
700
710
720
730
740
750
760
770
780
800
810
820
830
840
850
860
870
880
890
900
910
920
930
940
950
960
970
980
990
Pasture
Acres
197241 72
427825 19
166774 57
82904 58
39209 33
11377655
70540 14
13115556
52940 01
113751 64
11482817
13523 79
22488 55
96781 63
197544 80
8619783
73980 78
262749 45
20510691
64782 21
12471834
26231719
1059644
6293 27
30485 59
3821365
25312 86
206758 49
240132 88
25576 39
86827 25
2679 33
14447 08
12027 71
644703
3179923
6639 97
26747 25
1130276
2847 37
1011839
234072
64410 66
37039 47
2561.81
2298 82
34407 79
98428
2547 52
72686 55
24494 42
1221 64
26051 43
23684 19
6398 95
7267 65
31471
13711 57
20243 34
16854 59
29341 79
32615 84
167395 31
14821 07
1151492
474465
270672
4563 08
14539 95
215794
8020 67
2846 15
3714 99
87363
1005 95
7333 31
2048 45
4631 52
831522
3815670
1685 97
328416
1532 51
151433
120532
20204 74
122642
Average
NH3
lb/acre/2d
0038
0036
0046
0029
0040
0048
0047
0070
0057
0069
0 109
0285
0124
0037
0035
0047
0078
0082
0076
0101
0053
0070
0076
0066
0082
0090
0027
0081
0072
0089
0068
0122
0033
0052
0026
0024
0019
0023
0081
0055
0059
0033
0084
0039
0078
0136
0018
0061
0098
0053
0077
0030
0050
0076
0073
0034
0046
0000
0104
0216
0340
0143
0049
0070
0161
0047
0043
0051
0027
0032
0018
0038
0116
0176
0054
0030
0079
0023
0029
0022
0016
0080
0013
0059
0145
0055
0045
0.069
ORGN
lb/acre/2d
0046
0044
0057
0035
0049
0058
0058
0085
0070
0085
0 133
0348
0 152
0045
0042
0058
0095
0101
0092
0123
0065
0085
0093
0080
0100
0110
0033
0099
0088
0109
0083
0150
0040
0063
0032
0029
0024
0029
0099
0068
0073
0040
0103
0048
0095
0167
0022
0075
0119
0064
0094
0036
0061
0093
0089
0042
0056
0000
0127
0264
0416
0175
0059
0086
0196
0057
0053
0062
0033
0039
0022
0047
0 141
0215
0066
0037
0097
0029
0035
0026
0020
0097
0016
0072
0177
0068
0055
0.084
TN
lb/acre/2d
0084
0080
0103
0064
0088
0106
0105
0155
0128
0154
0242
0634
0276
0082
0077
0105
0173
0183
0168
0224
0118
0155
0170
0146
0182
0200
0061
0180
0160
0198
0150
0272
0072
0115
0057
0053
0043
0052
0179
0123
0 132
0074
0188
0087
0173
0303
0039
0136
0217
0117
0171
0066
0 110
0169
0162
0076
0102
0000
0231
0480
0756
0318
0108
0156
0357
0103
0097
0113
0060
0071
0040
0085
0257
0391
0120
0068
0 176
0052
0063
0048
0036
0177
0030
0131
0321
0123
0101
0.153
65
-------
Table H.2.13 Breakdown Of TN Manure Applications Per Year
Model
Segment
10
20
30
40
50
50
70
80
90
100
110
120
140
160
170
175
180
190
200
210
220
230
235
240
250
250
265
270
280
290
300
310
330
340
370
380
390
400
410
420
430
440
450
470
480
490
500
510
540
550
560
580
590
600
610
620
630
650
700
710
720
730
740
750
760
770
780
800
810
820
830
840
850
860
870
880
890
900
910
920
930
940
950
960
970
980
990
Pasture
Acres
197241 72
42782519
166774 57
82904 58
39209 33
11377655
70540 14
13115556
52940 01
11375164
11482817
13523 79
22488 55
96781 63
19754480
8619783
73980 78
262749 45
20510691
6478221
12471834
262317 19
1059644
6293 27
30485 59
38213 65
25312 86
206758 49
240132 88
25576 39
86827 25
2679 33
1444708
12027 71
644703
3179923
663997
26747 2i
1130276
2847 37
1011839
234072
6441066
37039 47
256181
2298 82
34407 79
98428
254752
72686 55
24494 42
122164
26051 43
2368419
6398 95
7267 65
31471
13711 57
20243 34
16854 59
29341 79
3261584
16739531
14821 07
1151492
474465
270672
4563 08
14539 95
215794
8020 67
2846 15
371499
87363
1005 95
7333 31
2048 45
4631 52
831522
3815670
168597
3284 16
1532 51
151433
1205 32
20204 74
122642
Average
NH3
lb/acre/2d
6870
6579
8458
5227
7.266
8698
8617
12692
10477
12637
19844
52033
22665
6770
6317
8637
14.208
15052
13.788
18.364
9682
12762
13936
11 997
14978
16455
4995
14759
13 173
16271
12347
22355
5946
9418
4715
4334
3539
4256
14728
10119
10843
6042
15419
7150
14220
24872
3221
11 171
17831
9613
14054
5395
9043
13886
13321
6223
8393
0000
18985
39397
62066
26149
8883
12774
29304
8496
7936
9294
4943
5822
3267
6962
21 118
32 112
9836
5551
14432
4284
5203
3938
2942
14545
2.425
10757
26399
10125
8271
12562
ORGN
lb/.icre/2d
8397
8042
10338
6388
E881
10631
10532
15512
12 805
15445
24254
63 596
27 702
8275
7721
10556
17 366
1E397
16853
22445
11 833
15598
17033
14663
18306
20 111
6 105
18039
16101
19886
15091
27323
7267
11 511
5763
5297
4325
5201
18000
12368
13253
7385
18.345
8136
17 380
30 399
3937
13 653
21 794
11 750
17 177
6594
1 1 053
16972
16282
7606
10258
0000
23204
48152
75858
31 960
10857
15613
35816
10384
9699
11 350
6042
7 116
3993
8509
25811
39248
12 022
6785
17639
5235
6359
4813
3596
17778
2.9E4
13 147
32266
12 375
10 109
15353
TN
lb/acre/2d
15267
14621
18796
11615
16147
19329
19150
28203
23282
28082
44098
115629
50368
15045
14038
19194
31574
33450
30641
40809
21 515
28361
30968
26660
33284
36566
11 100
32798
29274
36157
27438
49678
13213
20929
10479
9631
7864
9457
32728
22487
24096
13427
34264
15888
31600
55272
7159
24824
39626
21 363
31 231
11989
20096
30858
29603
13829
18652
0000
42 189
87549
137 923
58109
19741
28387
65121
18879
17635
20654
10985
12938
7260
15471
46928
71360
21 858
12336
32071
9519
11563
8751
6538
32323
5.388
23904
58665
22499
18381
27915
66
-------
Figure H.2.8 Comparison of Modeled and Observed Manure Application Rates of TN
to Conventional Tillage
300
250
- Observed
-Modeled
Model Segments
Comparison of Modeled and Observed Manure Application Rates of TP to
Conventional Tillage
Model Segments
67
-------
Figure H.2.9 Comparison of Modeled and Observed Manure Application Rates of TN to
Conservation Tillage
-Modeled
- Observed
Model Segments
Comparison of Modeled and Observed Manure Application Rates of TP to
Conservation Tillage
Modeled
-«- Observed
Model Segments
68
-------
Figure H.2.10 Comparison of Modeled and Observed Manure Application Rates of TN
to Hayland
«? <$>
Model Segments
Comparison of Modeled and Observed Manure Application Rates of TP to Hayland
35 T
30
25
20
0 15
10
--Modeled
-» Observed
Model Segments
69
-------
simulation method seems to be the most appropriate for the simulation of plant uptake withir
pasturelands.
The amounts of manure nutrients applied to pasturelands are incorporated into the Phase IV
Watershed Model using AGCHEM Watershed Model input files. Ammonia volatilization rates
for manured pasturelands are simulated by the Phase IV Watershed Model and are based on a 50
percent loss of ammonia in the first twenty-four hours for unincorporated manure (Thompson et
al. 1987, Lauer et al. 1976, and Reedy et al. 1979b). After five days only 3 percent of the
original ammonia is retained. The surface layer ammonia volatilization rate is lower than the
sub-surface layer ammonia volatilization rate and is based on a 40 percent volatilization loss
after ten days. Lower layers down to and including groundwater layers simulated within the
Phase IV Watershed Model have no ammonia volatilization due to the incorporation of manure
into the soil.
Section H.2.2.2.5 Runoff Control for Animal Confinement Areas
A facility with an existing animal waste storage structure may not have runoff controls for
animal confinement areas. As a result, runoff from up-slope areas and roof flows to feedlots can
carry waste nutrients to surface water bodies. In some cases, excess runoff flows into waste
lagoons cause overflow problems. Animal confinement runoff control consists of practices such
as up-slope diversions and directed downspouts to minimize off-site water entering the facility.
In some cases, improved conditions at the confinement facility can improve animal health and
production. Both supplemental and full runoff control systems are monitored by the signatory
states. Supplemental systems are those installed in addition to a waste storage structure and full
systems are installed at a site without a preexisting storage structure.
Implementation of a full system (without a waste storage system) reduces current nutrient loads
by an estimated 75 percent for nitrogen, phosphorus, and sediment. A. supplemental system
(with a waste storage system) can reduce current nutrient loads by an additional 10 percent for
nitrogen, phosphorus, and suspended sediment beyond those reductions gained by the storage
structure.
Section H.2.2.2.6 Grazing Land Rotation
The rotation of livestock on grazing land limits the manure load and other impacts of livestock to
pasture. Benefits of this BMP include improved infiltration/runoff characteristics, healthier grass
stands, reduced need for fertilizers, and reduced erosion. It is estimated that the nitrogen and
phosphorous load is reduced by 50 percent and suspended sediment loads are reduced by 25
percent for pastures utilizing grazing rotation management. See the Stream Protection
paragraphs (below) for an explanation of how this BMP is incorporated into the pasture.
Section H.2.2.2.7 Stream Protection (with and without fencing)
Direct animal contact with surface waters and the resultant streambank erosion are primary
causes of nutrient loss from pastures. Stream protection with fencing involves fencing narrow
strips of land along streams to exclude livestock. The fenced areas may be planted with trees or
70
-------
grass, but are typically not wide enough to provide the benefits of buffers. The implementation
of stream fencing limits the length of streambanks where animals can enter into a stream but
does not exclude animals from entering the stream within limited watering and stream crossing
areas.
Streambank fencing greatly reduces the nutrient losses from pasture, in addition to improving
streambank stability, reducing sedimentation, and creating wildlife habitat. The implementation
of two hundred and eight feet of streambank fencing results in a nutrient reduction equal to 75
percent of the load from three acres of pasture.
Stream protection without fencing involves the use of troughs or "water holes" away from
streams. In some instances, trees are planted away from the stream to provide shade for the
livestock. Research has indicated that these measures will greatly reduce the time livestock
spend in streams. Therefore, nutrient losses should decrease.
The incorporation of stream protection (both with and without fencing) into the Phase IV
Watershed Model involves a reduction of the load from pasture. To determine the total amount
that the load to pasture is reduced for the entire Watershed Model segment, "Pastureland," a new
pasture application load, is incorporated in the SPEC-ACTIONS section of the Phase IV
Watershed Model input deck.
It has been determined by the Chesapeake Bay Program Nutrient Subcommittee's Tributary
Strategy Workgroup that stream protection with fencing reduces nutrient and suspended
sediment loads to pasture by 75 percent for total nitrogen, total phosphorous, and total
suspended sediment. For stream protection without fencing the reduction is an estimated 40
percent for total nitrogen, phosphorous, and sediments. These reductions are only applied to
pasturelands within the Phase IV Watershed Model.
Section H.2.2.2.8 Forestry BMPs
Forestry BMPs focus on minimizing the environmental impacts from forest harvesting
operations, such as road building, and harvesting and thinning operations. These BMPs reduce
soil erosion and the loss of nutrients that adhere to the eroding soil particles. Timber harvesting
is a regulated activity. Additional controls are required when working in non-tidal wetlands,
stream buffers, and the Chesapeake Bay Critical Area in Maryland. Forest harvesting BMPs
could potentially be applied to all forested lands cut for timber each year. Virginia has a
silviculture law that applies to the entire state.
Forest BMPs are incorporated into the Phase IV Watershed Model by reducing the nutrient and
suspended sediment flow from the forest. It has been determined by the Chesapeake Bay
Program Nutrient Subcommittee's Tributary Strategy Workgroup that when BMPs are used
during forest harvesting operations a reduction of 50 percent of total nitrogen, total phosphorus,
and total suspended sediment loading is achieved.
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Section H.2.2.2.9 Forest and Grass Buffers
Forest and grass buffers also receive nutrient reduction efficiencies. For forested buffers, the
average reduction for nitrogen is estimated to be 57 percent, and an estimated 70 percent
reduction for phosphorous and suspended sediment.- Grass buffers have an average nutrient
reduction estimated at 43 percent for nitrogen and 53 percent for phosphorous and sediment.
Section H.2.2.2.10 Cover Crops
This BMP refers to (non-harvested) cover crops specifically designed for nutrient removal. This
BMP is more prevalent in the lower Chesapeake Basin due to the longer growing season.
Significant amounts of nitrogen may remain in the soil after harvest, regardless of yield,
especially during drought years. Nitrate nitrogen is particularly subject to leaching to
groundwater over the winter if substantial amounts are in the soil in the fall. Small grains (i.e.,
rye, barley, wheat) planted without fertilizer in late summer or early fall will greatly reduce
nitrate leaching losses. These small grains use the nitrogen as they grow, provided root growth is
sufficient to reach the available nitrogen, hence the early planting date requirement. (Proper
timing of cover crop plow-down in spring releases "trapped" nitrogen for use by the following
crop.) As with other cover crops, their use reduces phosphorus losses through reduced soil
erosion.
While nutrient reduction is the principal benefit of cover crops, the quality of the soil may also
improve in the long-term. Cover crop acres will be assumed to be in the conventional and
conservation tillage land uses, and will receive average reductions of 43 percent for nitrogen and
15 percent for phosphorus and sediment.
Section H.2.2.3 BMPs Affecting Direct Loads to Tidal Bay Waters
Within the Phase IV Watershed Model, the types of BMPs affecting direct nutrient and
suspended sediment loading to the Chesapeake Bay are marine pumpouts, tidal shoreline
protection (structural and nonstructural), and combined sewer overflows (treatment and
conversions). These BMPs reduce nutrient loads that are used as direct input into the
Chesapeake Bay Water Quality Model.
Section H.2.2.3.1 Marine Sewage Disposal Facilities
Marine sewage disposal facilities include pumpouts and portable toilet dump stations located
shore side to allow boaters to properly dispose of sewage. Boat sewage is then transported to
local wastewater treatment plants, where treatment levels vary. Marine sewage pumped to local
treatment plants is included in point source calculations. Only Maryland tracks marine pumpouts
as part of their individual tributary strategies. Two components of controlling nutrients from
boat waste are the installation of pump-out facilities and the implementation of an educational
program to encourage boaters to use existing and new pumpouts for boat waste disposal. Marine
sewage disposal facilities reduce the nitrogen load by an estimated 43 percent and the
phosphorus and suspended sediment loads by an estimated 53 percent. Currently, nutrient
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reductions from these practices are not simulated by the Phase IV Watershed Model, but are
subtracted from the final simulated Watershed Model output values.
Section H.2.2.3.2 Shoreline Protection
Tidal structural and non-structural erosion control measures stabilize the eroding shoreline, a
major source of suspended sediment and nutrient loading to the Bay. Non-structural erosion
control practices focus on the use of native vegetation to stabilize shorelines. Where wave
energy is too high for the non-structural approach, structural methods are employed, such as
stone revetments and breakwaters. Both tidal structural and non-structural erosion controls
reduce the nitrogen, phosphorus, and suspended sediment loads by an estimated 75 percent.
Similar to marine sewage disposal facility pumpouts, nutrient reductions from shoreline erosion
practices are not simulated by the Phase IV Watershed Model but are subtracted from final
simulated load output values.
Section H.2.2.3.3 Combined Sewer Overflows
Combined sewer overflows (CSOs) deliver a nutrient load to rivers and the bay during storm
events. A combined sewer system only uses a single sewer pipe network to collect storm runoff,
domestic wastewater, and industrial discharge. During dry-weather flow periods, the wastewater
treatment facility is able to process all dry weather flows. However, during storm events, the
wastewater treatment facility is unable to handle the increased flow; therefore, the excess flow
(containing sewage) is discharged directly into the water bodies through a bypass mechanism in
the conveyance system. Since high loads are a result of high flow periods, the combined sewer
overflow is extremely detrimental to nutrient reduction strategies. There is an effort to treat
water that does originate during a high flow period. Conversion of combined sewer overflows is
one effort underway to reduce nutrient loads to the tributary rivers and the Bay. The treatment
and conversion of combined sewer overflows are tracked in the tributary reductions. Treatment
of combined sewer overflows reduce the nitrogen load by an estimated 15 percent and the
phosphorus and suspended sediment loads by an estimated 30 percent. Conversion of combined
sewer overflows reduce the nitrogen, phosphorus, and suspended sediment loads by an estimated
95 percent. This number is high because it is the assumed efficiency of wastewater treatment
plants. To apply this load reduction in a Tributary Strategy Watershed Model Scenario, the
existing combined sewer overflow load must be incorporated into the Water Quality Model
(Note, to date this has only been done for the District of Columbia's combined sewer overflows).
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Section H.3 SUMMARY OF WATERSHED MODEL OPERATIONS
BoxH
Modify Model Mass
Links to reflect BMP
efficiencies, special
actions for
fertilizer/manure
changes, external
sources for point source
and atmospheric
deposition changes
Boxl
Run Watershed
Model to get
preliminary
edge-of-stream
loads
BoxJ
Post process
Watershed Model
data in order to
obtain edge-of-
stream loads
BoxK
Use ratio of edge-of-
stream loads for
Watershed Model
scenario and
calibration runs to set
sediment nutrient
release rates
BoxL
Run Watershed Model
sediment nutrient release
rates
Box M
Develop
scenario
specific transport
factors
*
BoxN
Post process
Watershed Model
nutrient management
to allocate all nutrient
and sediment loads
BoxO
Quantify BMPs not
simulated by the
Watershed Model but
used to track nutrient
reduction progress
including marine
pumpouts, shoreline
protection, or combined
sewer overflows
Box P
Post Watershed
Model scenario
documentation and
results on web site
The Phase IV Watershed Model is based upon the Hydrologic Simulation Program-FORTRAN
(HSPF) Model - Version 11 (Johanson et al., 1980). An HSPF simulation requires two types of
data files, a user control input file (UCI) and a water data management (WDM) file. The UCI
file contains simulation time and output control information, hydrological and nutrient dynamic
module control, initialization, parameterization, linkages between land and water and specific
loading information. The WDM file is a binary file that contains input time series data for
meteorological, precipitation, atmospheric deposition and point source data.
Each scenario uses unique UCI files that are modifications of the reference scenario UCI files.
The changes in the UCI files reflect the physical changes in the watershed due to estimated land
use change and reported BMP implementation. A series of FORTRAN programs read each
HSPF UCI file and generate modified files according to scenario-specific data files. All
scenarios use the same WDM files.
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Section H.3.1 Scenario Characteristic Modification
For each scenario, the reference UCI files are modified by a series of FORTRAN programs. A
UNIX script file is used to call each program in turn for each UCI. The modifications include
land use changes, loads of fertilizer and manure to crop land, manure deposited on pasture land,
changes to exported loads due to BMP implementation, and changes to point source and septic
loads.
Section H.3.2 Initial Model Run for the Edge of Stream Loads
After the synthesis of the scenario-specific UCI files is completed, a model run is performed to
produce edge-of-stream loads. The output of this model run contains daily edge-of-stream loads
for suspended solids and several species of nitrogen and phosphorus for each land use and model
segment.
Section H.3.3 Adjustment of Bed Concentration
The Phase IV Watershed Model adjusts the concentration of adsorbed ammonia and phosphate in
the bed sediment of the free-flowing rivers. This adjustment is proportional to the change in
edge-of-stream loading from all upstream sources for each particular Watershed Model segment.
These factors are determined through the comparison of the Watershed Model Reference
scenario edge-of-stream loads and those of the specific scenario being run. Once again, a
FORTRAN program is used to automatically adjust the concentrations sorbed to bed sediment
specified in the UCI files. Sediment scoured from the river bed is reduced by a similar process.
Section H.3.4 Second Model Run
The second run of the Watershed Model scenario is only necessary for those model segments
that have reaches, since the only alteration since the initial run is in the bed concentration and the
amount of sediment scoured. The in-stream concentration files are then used to determine the
loads for each reach that are delivered to the next downstream reach.
Section H.3.5 Delivery Factors
To determine the loads delivered to the Chesapeake Bay from each source within each Phase IV
Watershed Model segment, delivery factors must be developed which give the fraction of the
total load entering any particular river reach that reaches tidal waters. A pre-formatted
spreadsheet is used to calculate the delivery factors from the post-processed edge-of-stream loads
and the loads exiting each reach.
*&
Section H.3.6 Final Model Run
This model run is a twelve year simulation that applies a nutrient load to the Chesapeake Bay
Water Quality Model. The adjusted bed concentrations from the second run are used to simulate
the full twelve years, as opposed to only eight. There are a few differences between this Phase
IV Watershed Model run and the previous ones: (1) the November, 1985 storm is now included
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in the precipitation and load data, and (2) participate inorganic phosphorus loads are now
identified for linkage to the Chesapeake Bay Water Quality Model.
The final model outputs are in a tabular format with loading information about NHs, NOs,
organic nitrogen, total nitrogen, PC>4, organic phosphorus, total phosphorus, and total sediment.
This information is further broken down by land use, basin, state and above/below fall line.
Subsegmentation is used in segments that discharge directly to tidal waters. This produces
higher resolution which is more compatible with the Water Quality Model.
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Donigian, A.S. Jr., Linker, L.C., C. Chang. 1991. Chesapeake Bay Program Watershed Model Application To Calculate Bay
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Chesapeake Bay Program
U.S. Environmental Protection Agency
Chesapeake Bay Program Office
410 Severn Avenue, Suite 109
Annapolis, MD 21403
1-800-YOUR BAY
www.epa.gov/chesapeake
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