Spatial and Temporal Patterns of Best Management 

Practice Implementation in the Chesapeake Bay 

Watershed, 1985–2014

Scientific Investigations Report 2018–5171

U.S. Department of the Interior

U.S. Geological Survey

Spatial and Temporal Patterns of Best 

Management Practice Implementation in 

the Chesapeake Bay Watershed, 1985–2014

By Andrew J. Sekellick, Olivia H. Devereux, Jennifer L.D. Keisman, Jeffrey S. 

Sweeney, and Joel D. Blomquist

Scientific Investigations Report 2018–5171

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DAVID BERNHARDT, Acting Secretary

U.S. Geological Survey

James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2019

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Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials 

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Suggested citation:

Sekellick, A.J., Devereux, O.H., Keisman, J.L.D., Sweeney, J.S., and Blomquist, J.D., 2019, Spatial and temporal patterns of Best Management Practice implementation in the Chesapeake Bay watershed, 1985–2014: U.S. Geological 

Survey Scientific Investigations Report 2018–5171, 25 p., https://doi.org/10.3133/sir20185171.

ISSN 2328-0328 (online)
iii

Acknowledgments

The authors wish to thank the Chesapeake Bay Program (CBP) for their extensive work compiling Best Management Practice (BMP) information and providing model output in a variety of 

formats. Lillian Gorman Sanisaca of the U.S. Geological Survey (USGS) assisted in processing 

data and assembling tables for this report. Andrew LaMotte (USGS) also provided valuable 

assistance compiling the metadata for this report.

v

Contents

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................2

Purpose and Scope ..............................................................................................................................2

Methods...........................................................................................................................................................4

Reporting of Best Management Practice (BMP) Implementation ...............................................4

Estimation of Changes in Nutrient Loads Due to Best Management Practices (BMPs)..........6

Watershed Model ........................................................................................................................6

Isolation Scenarios......................................................................................................................6

Estimating Load Reduction for Each Best Management Practice (BMP)..........................7

Spatial Patterns of Best Management Practice (BMP) Implementation in 2014................................7

Temporal Patterns of Best Management Practice (BMP) Implementation.......................................11

Estimated Effect of Best Management Practices (BMPs) on Nutrient and Sediment Loads.........15

Summary and Conclusions.........................................................................................................................24

References Cited..........................................................................................................................................25
vi

Figures

1. Map showing chesapeake Bay watershed including River Input Monitoring

stations and major watersheds and subregions .....................................................................3

2. Maps showing A, conservation till, B, pasture fencing, and C, cover crop

implementation intensity in 2014 using reported implementation and land-use

information from the Chesapeake Bay Program Phase 5.3.2 model..................................10

3. Maps showing estimated 2014 percent reduction in A, total nitrogen, B, total

phosphorus, and C, total sediment due to Best Management Practices

in the Chesapeake Bay watershed..........................................................................................12

4. Graphs showing estimated A, total nitrogen load, B, total phosphorus load,

and C, total sediment load from 1985 through 2014 for the No Action scenarios,

which do not include Best Management Practices, and the Progress

scenarios, which do include BMPs.........................................................................................13

5. Graphs showing estimated reduction in A, total nitrogen load, B, total

phosphorus load, and C, total sediment load due to Best Management

Practices from 1985 through 2014............................................................................................14

6. Graphs showing estimated A, total nitrogen reduction, B, total phosphorus

reduction, and C, total sediment reduction by Best Management Practice

category on agricultural lands in 2014 ....................................................................................16

7. Graphs showing estimated A, total nitrogen reduction, B, total phosphorus

reduction, and C, total sediment reduction by Best Management Practice

category on developed lands in 2014 ......................................................................................19

8. Graphs showing estimated A, total nitrogen reduction, B, total phosphorus

reduction, and C, total sediment reduction from agricultural Best

Management Practices from 1985 through 2014 in the Chesapeake

Bay watershed ............................................................................................................................22

9. Graphs showing estimated A, total nitrogen reduction, B, total phosphorus

reduction, and C, total sediment reduction from developed land Best

Management Practices from 1985 through 2014 in the Chesapeake

Bay watershed ............................................................................................................................23
vii

Tables

1. List of Best Management Practice categories evaluated in model.....................................5

2. Estimated reduction of nutrients to streams due to Best Management

Practices and land use in Chesapeake Bay watershed subregions in 2014 ......................8

3. Implementation of Best Management Practices in the Chesapeake

Bay watershed in 2014.................................................................................................................9

4. Estimated reduction of nutrients to streams in Chesapeake Bay watershed

subregions due to Best Management Practices in 2005 and 2014 using

Progress and No Action Chesapeake Bay Program Phase 5.3.2 model scenarios.........14

5. Agricultural land Best Management Practice estimated mass

reduction per unit of implementation in the Chesapeake Bay watershed........................18

6. Developed land Best Management Practice estimated mass reduction

per unit of implementation in the Chesapeake Bay watershed..........................................21

Conversion Factors

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

Area

acre 4,047 square meter (m2)

Mass

pound, avoirdupois (lb) 0.00045359 metric ton

pound, avoirdupois (lb) 0.4536 kilogram (kg) 

pound per cubic foot (lb/ft3) 0.01602 gram per cubic centimeter (g/cm3)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F = (1.8 × °C) + 32.

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C = (°F – 32) / 1.8.

Datum

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Spatial and Temporal Patterns of Best Management 

Practice Implementation in the Chesapeake Bay 

Watershed, 1985–2014

By Andrew J. Sekellick1, Olivia H. Devereux2, Jennifer L.D. Keisman1, Jeffrey S. Sweeney3, 

and Joel D. Blomquist1

Abstract

Efforts to restore water quality in Chesapeake Bay and its 

tributaries often include extensive Best Management Practice 

(BMP) implementation on agricultural and developed lands. 

These BMPs include a variety of methods to reduce nutrient 

and sediment loads, such as cover crops, conservation tillage, 

urban filtering systems, and other practices.

Estimates of BMP implementation throughout the Chesapeake Bay watershed were provided for each year from 1985 

through 2014 by the Chesapeake Bay Program (CBP). This 

dataset of BMP implementation is a compilation of actions 

reported by New York, Maryland, Pennsylvania, Delaware, 

West Virginia, Virginia, and the District of Columbia, and 

includes a wide array of management activities. Management 

actions vary among the jurisdictions and generally reflect the 

typical land use in each region.

The amount of implementation also varies according to 

different priorities, reporting practices, and special programs 

within each jurisdiction. For example, extensive cover crop 

implementation was reported in Maryland whereas Pennsylvania, in general, has lower levels of BMP implementation 

reported on cropland. Pennsylvania and Maryland have higher 

levels of infiltration BMPs on developed land compared to 

those in Virginia.

Conservation tillage BMPs accounted for the majority 

of reported agricultural BMP implementation in 1985. By 

2014, however, a more diverse collection of agricultural BMPs 

was reported and conservation tillage BMPs accounted for a 

smaller proportion of overall reported agricultural BMP implementation. After the year 2000, land-use change BMPs, such as 

land retirement, pasture fencing, and forest buffers, were more 

commonly reported across the Chesapeake Bay watershed.

1

U.S. Geological Survey

2

Devereux Environmental Consulting, Inc.

3

U.S. Environmental Protection Agency

Expected changes in nutrient and sediment loads in the 

Chesapeake Bay watershed due to BMP implementation were 

estimated by use of specially designed annual scenarios of the 

CBP Partnership Phase 5.3.2 Watershed Model. Nitrogen loads 

to streams were estimated to be reduced by 11 percent from 

1985 to 2014 due to the implementation of BMPs. Compared 

with 1985, phosphorus loads were estimated to be 19 percent 

lower and sediment loads were estimated to be 23 percent 

lower by 2014 due to the effects of BMPs.

Reductions in total nitrogen from 1985 to 2014 due to 

BMPs varied spatially across the watershed and were estimated to be as high as 42 percent in areas of the Eastern 

Shore of the Chesapeake Bay. Reductions in phosphorus and 

sediment also varied spatially, with the largest reductions 

occurring in the Potomac watershed upstream of Washington, 

D.C. and the Eastern Shore of Maryland, according to the 

CBP model results.

Additional model scenarios were developed to estimate 

the effect of individual BMP types. The largest estimated 

reductions in total nitrogen loads on agricultural lands in 2014 

were attributed to land retirement, animal waste management systems, and conservation tillage. The largest estimated 

reductions in total phosphorus loads on agricultural lands were 

attributed to animal waste management systems, pasture fencing, and phytase feed additives in 2014. The largest estimated 

reduction in total sediment loads on agricultural lands was 

attributed to conservation tillage, pasture fencing, and conservation plans.

Dry ponds, wet ponds, and constructed wetlands were 

reported extensively throughout the watershed. These BMPs 

accounted for about half of the reduction in nitrogen loads 

from developed land to streams, half of the phosphorus reduction, and about a third of the sediment reduction.
2 Spatial and Temporal Patterns of Best Management Practice Implementation in the Chesapeake Bay Watershed, 1985–2014

Introduction

Chesapeake Bay is the largest estuary in North America 

and a valuable ecological and economic resource. Anthropogenic pressures, including increased urbanization and more 

intensive agricultural production, have led to degraded water 

quality conditions throughout the watershed (Phillips, 2007). 

The U.S. Environmental Protection Agency (EPA) has classified Chesapeake Bay as “impaired” by sediment and nutrients, 

and implemented Total Maximum Daily Loads (TMDLs) 

for nitrogen, phosphorus, and sediment (U.S. Environmental 

Protection Agency, 2010a).

A variety of best management practices (BMPs) are often 

used to mitigate nutrient and sediment loadings in order to 

meet the TMDL regulatory requirements. These Best Management Practices (BMPs) are an important part of Chesapeake Bay restoration efforts; however, further information 

to quantify their effects on nutrient and sediment loads is/will 

be required to improve the targeting of management actions 

across the watershed. Whereas field-scale assessments of BMP 

effectiveness exist, few regional-scale estimates of the effects 

of BMPs on nitrogen, phosphorus, and sediment loads delivered to streams are available (Liu and others, 2017).

The seven major jurisdictions in the Chesapeake Bay 

report BMP implementation to the Chesapeake Bay Program (CBP) annually. The major jurisdictions are New York, 

Maryland, Pennsylvania, Delaware, West Virginia, Virginia, 

and the District of Columbia (fig. 1). The CBP has agreed 

upon a set of BMPs that are considered effective for reducing 

nitrogen, phosphorus, and sediment loads. The CBP and the 

U.S. Geological Survey (USGS) have collaborated to develop 

a deterministic model (the Phase 5.3.2 Watershed Model) to 

quantify how water quality in the Chesapeake Bay watershed

responds to changes in watershed and airshed management 

actions as well as changes in nutrient sources and other factors 

(U.S. Environmental Protection Agency, 2010b).

The effectiveness of BMPs and individual BMP types has 

not been extensively studied or quantified in the Chesapeake 

Bay watershed. The evaluation of BMP implementation data, 

including the spatial locations, temporal patterns, and their 

modeled effects on nitrogen, phosphorus and sediment that 

is delivered to streams, provide much needed insight on the 

effectiveness of management strategies. The USGS has collaborated with the CBP to assess the amount of BMP implementation over time and estimate the changes in water quality 

attributable to these management actions.

Purpose and Scope

This report describes the spatial and temporal patterns of 

BMP implementation across the Chesapeake Bay watershed 

from 1985 through 2014. Methods to estimate the effect of 

BMP implementation on nitrogen, phosphorus, and sediment 

loads also are described. Additionally, the effect of individual 

BMP types on nutrient loads is estimated.

The CBP selected 2017 as a midpoint assessment of 

the TMDLs. The TMDLs were designed to have all jurisdictions implement reduction strategies by 2025, so that the bay 

will attain its water-quality goals. The midpoint assessment 

period was designated to assess progress in meeting reduction 

strategy goals and to evaluate recent science that may indicate 

necessary changes to those strategies (U.S. Environmental 

Protection Agency, 2010a).

A companion dataset to this report is available at (https://

doi.org/10.5066/P9OVU9PX) and includes detailed descriptions of BMP types as well as tables of model output at a 

selection of spatial scales (Devereux and others, 2018).
Introduction 3

80°

38°

40°

42°

78°

76°

Major watersheds and subregions

Appomattox

Choptank

James

Mattaponi

Pamunkey

Patuxent

Potomac

Rappahannock

Susquehanna

Eastern Shore

Western Shore

Chesapeake Bay

PENNSYLVANIA

MARYLAND

DELAWARE

0 10 20 30 40 50 MILES

0 10 20 30 40 50 KILOMETERS

50 100 MILES

0 50 100 KILOMETERS

0

80°

75°

45°

40°

38°

42°

NEW YORK

D.C. WEST

VIRGINIA

VIRGINIA

NJ

Chesapeake Bay

DE

River Input Monitoring stations

Susquehanna River at Conowingo, MD

Potomac River at Chain Bridge, DC

James River at Cartersville, VA

Rappahannock River near Fredericksburg, VA

Appomattox River near Matoaca, VA

Pamunkey River near Hanover, VA

Mattaponi River near Beulahville, VA

Patuxent River near Bowie, MD

Choptank River near Greensboro, MD

EXPLANATION

WEST 

VIRGINIA

VIRGINIA

WASHINGTON,

D.C.

NEW YORK

76°

42°

40°

38°

76°

80°

78°

76°

Base from U.S. Geological Survey, 1:2,000,000,

State boundary digital line graph, Albers 

Equal-Area Projection, NAD 1983

Chesapeake Bay

watershed

boundary

Chesapeake Bay

watershed

boundary

ATLANTIC OCEAN

MARYLAND

PENNSYLVANIA

Figure 1. Chesapeake Bay watershed including River Input Monitoring stations and major watersheds and subregions.
4 Spatial and Temporal Patterns of Best Management Practice Implementation in the Chesapeake Bay Watershed, 1985–2014

Methods

Reporting of Best Management Practice (BMP) 

Implementation

The seven major jurisdictions in the Chesapeake Bay 

watershed (New York, Maryland, Pennsylvania, Delaware, 

West Virginia, Virginia, and the District of Columbia) began 

reporting estimates of BMP implementation to the CBP in the 

late 1990s, and have provided estimates of all BMP implementation for each year from 1985 through 2014. CBP BMP 

data include State and Federally funded implementation data 

as well as practices funded by non-governmental organizations 

and voluntary implementation (Hively and others, 2013). The 

reporting for each year consists of all BMPs in the Chesapeake 

Bay watershed that were considered effective for that year, 

including active BMPs that have been installed in prior years. 

Structural BMPs, like animal waste management systems, 

can reduce pollutant runoff for many years. Other BMPs, like 

urban filtering practices, must be inspected and maintained 

each year to be effective (U.S. Environmental Protection 

Agency, 2010b). Approximately 150 different types of BMPs 

were reported in 2014. For this report, the CBP provided BMP 

implementation data that were submitted by jurisdictions for 

assessment using the Phase 5.3.2 Watershed Model. The data 

were from annual scenarios for 1985 through 2014.

The various BMP types were grouped into 55 BMP categories for evaluation, and included BMPs for both agricultural 

and developed land (table 1). The categories were determined 

by the similarity of the BMPs. For example, there are approximately 100 different types of agricultural cover crops that 

represent various planting dates, planting methods, and crop 

types (U.S. Environmental Protection Agency, 2010b). Planting dates are early, standard, or late, and reflect the planting 

time in relation to the first killing frost. The timing affects the 

successful establishment of the crop. The planting methods 

include drilled, aerial, or other, and can affect how well the 

seeds germinate. Cover crop types include various varieties 

such as rye, wheat, tillage radish, and many more. The various 

types of cover crops are presumed to have a similar effect on 

water quality in the Phase 5.3.2 Watershed Model. For the purposes of this report and the analysis methods used, evaluating 

each cover crop type individually did not result in an improved 

understanding of BMP implementation trends or their effects 

on water quality. The types of cover crops reported vary in 

large part by each state’s ability to track that level of detail. 

All cover crops were therefore grouped into a single category 

to more clearly evaluate their expected effect on nutrient and 

sediment loads to streams. Similar grouping occurred for several other agricultural and developed BMPs.

BMPs were reported at multiple spatial scales including counties, watersheds, and states. The jurisdictions have 

different reporting methods and are not necessarily consistent 

among states, BMPs, or reporting years. The CBP compiles 

most of the annual reported BMP implementation at the landriver segment modeling unit (average size 26.2 square miles) 

that is used in the CBP Partnership Phase 5.3.2 Watershed 

Model (U.S. Environmental Protection Agency, 2010b). Animal data in the CBP model originates from the U.S. Department of Agriculture, National Agricultural Statistics Service 

and is only available at the county scale. Therefore, the BMPs 

that impact manure nutrients, such as animal feed additives or 

animal waste management systems, are compiled at the county 

scale. Depending on the type of BMP, implementation may 

be reported in a variety of units, including acres, animal units 

(1,000 pounds of live animal), feet, or pounds.

The CBP BMP data require careful interpretation. In 

some major jurisdictions, there are BMPs with large shifts in 

the levels of reported implementation from year to year. These 

can reflect changes in reporting standards rather than changes 

in the actual practice implementation. Changes in reporting occur as the jurisdictions change their tracking systems, 

improve their understanding of the BMP functions in the 

context of the modeling system, and as the BMPs themselves 

are re-evaluated and re-defined. In addition, the establishment 

of the Chesapeake Bay TMDL in 2010 resulted in a revision 

of reported BMP implementation from 2006 by the jurisdictions in the Chesapeake Bay watershed (Wastewater Technical 

Workgroup, 2013). An increase in reported implementation 

from 2006 to 2014 may be a result of revised interpretation 

of historical records in addition to increased implementation. 

Although changes in reporting standards and evaluating processes have occurred during the multi-year compilation of the 

CBP BMP data, the dataset is thorough and extensive, and can 

be used to estimate the effect of BMPs on water quality.

All BMPs types are periodically reevaluated by the CBP 

Partnership expert panels, which can result in changing names 

and definitions. For this analysis, all BMP implementation 

types were related to the closest equivalent of the 2014 BMP 

definitions. For example, the nutrient management BMPs used 

in this analysis are the efficiency versions of Tier 1, enhanced, 

and decision nutrient management BMPs (U.S. Environmental 

Protection Agency, 2010b).

An estimate of the intensity of BMP implementation 

for the year 2014 for each land-river modeling segment was 

calculated by dividing the amount of reported implementation 

of selected BMPs as reported in the Phase 5.3.2 Watershed 

Model by the available land acres of the relevant land use. For 

example, acres of cover-crop implementation were divided by 

acres of cropland, and acres of pasture fencing were divided 

by acres of pasture land.
Methods 5

Table 1. List of Best Management Practice (BMP) categories evaluated in model.

Agricultural land BMPs Developed land BMPs

Alternative crops Abandoned mineland reclamation

Alum Bio-retention

Animal waste management systems Bio-swales

Barnyard runoff control Combined sewer overflow connections

Commodity cover crops Dry ponds

Conservation plans Erosion and sediment controls

Conservation tillage Filtering practices

Cover crops Forest buffers

Dairy precision feeding Forest Conservation Act

Dirt and gravel roads Impervious surface reduction

Enhanced nutrient management Infiltration

Forest buffers Permeable pavement

Grass buffers Retrofit stormwater management

High residue tillage Shoreline management

Horse pasture management Stream restoration

Land retirement Street sweeping

Loafing lot management Stormwater management—era 02 to 10

Manure transport Stormwater management—era 85 to 02

Mortality composting Tree planting

Off stream watering, without fences Urban nutrient management commercial applicators

Pasture fencing Urban nutrient management, do-it-yourself

Phytase feed additive Urban nutrient management plan

Precision agriculture Vegetative open channels

Precision rotational grazing Wet pond/wetland

Stream restoration

Streamside forest buffers

Streamside grass buffers

Tier 1 nutrient management

Tree planting

Water control structures

Wetland restoration
6 Spatial and Temporal Patterns of Best Management Practice Implementation in the Chesapeake Bay Watershed, 1985–2014

Estimation of Changes in Nutrient Loads Due to 

Best Management Practices (BMPs)

Watershed Model

The CBP Partnership Phase 5.3.2 Watershed Model was 

used to evaluate the effects of BMPs on water quality. The 

model, in part, assists CBP decision-makers in estimating the 

collective actions needed to achieve State and Federal waterquality standards necessary to restore the health of Chesapeake 

Bay. The model is built through community and participatory 

input and used for decision-support purposes by the jurisdictions in the Chesapeake Bay watershed. It is designed to 

address questions of how Chesapeake Bay water quality will 

respond to changes in watershed and airshed management 

actions (U.S. Environmental Protection Agency 2010b).

The CBP model can provide estimates of nitrogen, phosphorus, and sediment stream loads generated from sources 

such as manure, fertilizer, atmospheric deposition, wastewater, 

and urban areas. Other factors included in the model can determine the amount of each source that is transported to streams. 

These input variables were mostly estimated at the land-river 

segment scale, but county-level estimates based on compilations of available data also were used. The model generates 

annual estimates of nutrient and sediment loads at the landriver segment spatial scale for the years from 1985 to 2014. 

For this report, loads were summed from these smaller units to 

11 geographic regions across the Chesapeake Bay watershed. 

These include the watersheds for the nine River Input Modeling (RIM) stations and areas on the Eastern and Western Shore 

of Chesapeake Bay downstream from the RIM stations (fig. 1). 

The estimated loads used in this report are considered edgeof-stream and do not include in-stream processing or decay 

during movement to tidal waters. Edge-of-stream is defined as 

the edge of a large stream, typically a fourth-order stream, for 

a total of about a thousand stream segments in the model (U.S. 

Environmental Protection Agency, 2010b). This is determined 

for each stream based on streamflow and the distance to a 

monitoring station.

A variety of factors, such as groundwater lag times and 

other response lags, may not be fully represented in yearly 

model predictions. The model is intended to provide quantitative measures of progress in achieving water-quality goals in 

the distant future using the most complete dataset of reported 

BMP implementation available for the region described in this 

report. Furthermore, the wide variety of BMP actions may 

result in varied model accuracy due to the different modes 

of action of each BMP type and the interaction of soil type, 

geology, precipitation, maintenance, and other factors. The 

model may be a better predictor of the effect of one BMP type 

compared to another BMP type (U.S. Environmental Protection Agency, 2010b).

The estimated effect of BMPs on nutrients and sediment were modeled as a nonlinear cascading system (U.S. 

Environmental Protection Agency, 2010b). There were no

predetermined nitrogen, phosphorus, or sediment reductions 

for each BMP in all situations. The amount of nutrient and 

sediment reduction per unit of BMP is contingent on the land 

use it is applied to, other BMPs used in the area, and additional factors such as the amount of nutrient inputs on the land 

surface. Although there are effectiveness values for most of the 

BMPs in the CBP model, the total effect of BMPs cannot be 

calculated with these values alone. The model output can also 

be used to estimate the total summed effect of all load reductions from all BMPs by each land-use category.

The CBP model can be run for a variety of scenarios. 

For this study, “Progress” scenarios, representing an estimate 

of watershed conditions and all reported BMP implementation, were run for each year from 1985 to 2014. “Baseline” 

scenarios, also referred to as “No Action” scenarios, were also 

run for each year from 1985 to 2014. All of the conditions in 

the yearly No Action scenarios are the same as those in the 

corresponding yearly Progress scenarios, however, BMPs 

are excluded. This ensures that the full estimated effect of all 

BMPs on nitrogen, phosphorus, and sediment for each year 

from 1985 to 2014 can be calculated by subtracting the loads 

from the No Action scenario model results from the Progress 

scenario model results. A prediction of atmospheric deposition 

of nitrogen for the year 2025 (the target date for full TMDL 

implementation) was used for all scenarios to remove the 

effects of changing air quality from the study (U.S. Environmental Protection Agency, 2010a).

Isolation Scenarios

In addition to the yearly Progress and No Action scenarios, a set of 35 isolation model scenarios was designed to 

run in series to isolate the effect of individual BMPs reported 

in the 2014 Progress Review. The order and design of the 

isolation scenarios were consistent with the way that BMPs 

are credited by the CBP in the Phase 5.3.2 Watershed Model, 

and could not be generalized to other models where BMPs are 

credited differently. Each scenario builds on the next following 

the logic used in crediting the BMPs.

To ensure that the BMP effects were isolated, it was 

necessary to assume identical initial conditions for all other 

variables in a scenario. Initial conditions from the 2014 

Progress scenario of the CBP model were used and include, in 

part, 2014 model year land use, 2014 model year number of 

animals, and 2014 model year number of septic systems. The 

2014 model year land use is an estimate based on a projection of historical land-use data. The historical land uses were 

developed primarily from remote sensing data and Census of 

Agriculture information, and included changes to land use that 

resulted from BMPs, such as forest buffers and changes due to 

development (U.S. Environmental Protection Agency, 2010b).

The baseline isolation scenario does not have any BMPs 

active in the model and is identical to the No Action scenario. 

Subsequent scenarios add the various land-use change BMPs 

to the baseline scenario whereas all prior BMPs are kept in the 

subsequent scenario. Thus, the last one in the sequence has 
Spatial Patterns of Best Management Practice (BMP) Implementation in 2014 7

all land-use change BMPs included. Scenarios including feed 

additive BMPs and manure transport were added to the scenario with all land-use change BMPs following the sequence 

in the scenario list. The final scenario has all the land-use 

change BMPs, agricultural load reduction BMPs, and manure 

transport included.

BMPs that utilize reduction efficiencies or direct load 

reductions in the model were added individually to the 

scenario with the land-use change BMPs, animal BMPs, and 

manure transport. Each scenario has one efficiency or load 

reduction BMP in addition to the land-use change BMPs, animal BMPs, and manure transport. A BMP that affects developed land uses can be used in the same scenario as another 

BMP that affects agricultural land uses because neither BMP 

affects the land-use loads for the other BMP in that scenario.

Estimating Load Reduction for Each Best 

Management Practice (BMP)

The results from the isolation scenarios provided an estimated nutrient and sediment load reduction for each BMP in 

all of the 11 different geographic regions described earlier as 

well as the entire Chesapeake Bay watershed. These estimated 

reductions were the effect of individual BMP types run in 

specific scenarios, and cannot directly be used to determine the 

impact on water quality in a stream. Instead, the percent reduction by BMP in nutrient and sediment loads is used to estimate 

the expected reduction on agricultural or developed land. For 

each land-use sector, the percent reduction from a BMP from 

the isolation scenarios is multiplied by the total combined 

effect of BMPs from the Progress and No Action scenarios. 

This value can then be divided by the total amount of implementation for an estimate of pounds of nitrogen, phosphorus, 

or sediment reduced per unit of BMP implemented:

d = (a * b) / c (1)

where

d is estimate of reduction in nutrient 

and sediment load per unit of BMP 

implementation;

a is percent reduction for each BMP by sector 

as determined from the 2014 isolation 

scenarios;

b is total estimated load reduction from BMPs 

for a sector as calculated from the No 

Action and Progress scenarios for the 2014 

model year; and

c is amount of implementation credited for each 

BMP (acres, animal units, feet, or pounds) 

for the 2014 model year.

The estimate of reduction load per unit of implementation 

was developed using the 2014 model year. To determine the 

expected effect of each BMP type for each year from 1985 to 

2014, this value was multiplied by the amount of implementation and normalized by the total estimated reduction from 

BMPs by sector from the No Action and Progress scenarios 

for the same year.

This logic was consistent as long as BMPs in earlier years 

were also included in the 2014 Progress scenario, and the mix 

of BMPs and relative amount of BMPs to each other remains 

similar to the 2014 Progress scenario. A future implementation 

plan with several types of innovative practices and programs 

may not meet these criteria as there may be BMP types and 

interactions between them that can’t be accounted for with this 

method.

Spatial Patterns of Best Management 

Practice (BMP) Implementation in 2014

The Potomac River subregion, defined in this report as 

the watershed upstream of the USGS streamgage at Chain 

Bridge (fig. 1, site 2), makes up 18 percent of the total area 

in the Chesapeake Bay watershed and accounts for 32 percent of the total nitrogen reduction due to agricultural BMPs, 

38 percent of the phosphorus reduction due to agricultural 

BMPs, and 30 percent of the sediment reduction due to agricultural BMPs (table 2). Approximately 19 percent of the total 

crop area, 36 percent of the total pasture area, and 27 percent 

of the total animal feeding operation areas of the Chesapeake 

Bay watershed are in the Potomac subregion. In contrast, the 

James River subregion makes up 10 percent of the total area 

in the Chesapeake Bay watershed and accounts for only 2 percent of the total agricultural nitrogen reduction due to BMPs, 

6 percent of the phosphorus reduction, and 15 percent of the 

sediment reduction. In general, the remaining subregions were 

estimated to have a share of the total reductions in nutrient 

loads due to BMPs that are similar to their share of land area 

in the watershed.

The BMPs with the most reported acres of implementation in the Chesapeake Bay watershed in 2014 were 

conservation plans, conservation tillage, and tier 1 nutrient 

management plans (table 3). These three BMPs totaled nearly 

8,000,000 acres of implementation across the watershed and 

accounted for roughly two-thirds of agricultural BMP implementation. BMP implementation varied spatially across the 

watershed, however. BMP implementation generally reflected 

the typical land use in different regions. Implementation of 

BMPs designed to reduce nutrient and sediment loads from 

animal production were more often reported in areas with 

larger numbers of animal-based agriculture. A high intensity 

of conservation tillage is located on the Eastern and Western 

Shore of Chesapeake Bay as well as along parts of the Susquehanna River (fig. 2A). The Potomac subregion, which has a 

large amount of animal production, accounts for 42 percent 

of all pasture fencing BMP implementation (fig. 2B). Higher 

amounts of cover crops were reported in farmland throughout 
8 Spatial and Temporal Patterns of Best Management Practice Implementation in the Chesapeake Bay Watershed, 1985–2014 Table 2. Estimated reduction of nutrients to streams due to Best Management Practices and land use in Chesapeake Bay watershed subregions in 2014. [RIM, River Input Monitoring; ES, Eastern Shore; WS, Western Shore; %, percent; Ag, agricultural; N, nitrogen; P, phosphorus; S, sediment, Dev, developed; AFO, animal feeding operations] Subregion Ag N reduction (% of total) Ag P reduction (% of total) Ag S reduction (% of total) Dev N reduction (% of total) Dev P reduction (% of total) Dev S reduction (% of total) Percent of total area Percent of total crop area Percent of total pasture area Percent of total developed area Percent of total AFO Appomattox 1 2 1 0 0 0 2 1 3 1 2 Choptank 0 0 0 0 0 0 0 0 0 0 0 James 2 6 15 1 5 2 10 4 17 4 8 Mattaponi 0 0 0 0 0 0 1 1 0 0 0 Non-RIM ES 15 13 4 3 3 2 6 15 2 6 3 Non-RIM WS 7 6 9 22 28 24 16 12 7 36 8 Pamunkey 1 1 1 0 1 0 2 1 2 1 1 Patuxent 0 0 1 2 2 2 1 0 0 2 0 Potomac 32 38 30 28 28 30 18 19 36 17 27 Rappahannock 3 4 3 1 2 1 2 3 7 1 4 Susquehanna 39 29 35 43 31 38 42 45 26 32 46
Spatial Patterns of Best Management Practice (BMP) Implementation in 2014 9

Table 3. Implementation of Best Management Practices (BMPs) in the Chesapeake Bay watershed in 2014.

Agricultural BMP implementation in the 

Chesapeake Bay watershed as reported to the 

Chesapeake Bay Program for the 2014 model year

Urban BMP implementation in the 

Chesapeake Bay watershed as reported to the 

Chesapeake Bay Program for the 2014 model year

BMP name Amount 

(acres) BMP name Amount (acres) 

Alternative crops 27,945 Abandoned mineland reclamation 28,291 

Barnyard runoff control 4,625 Bio-retention 2,180 

Commodity cover crops 207,002 Bio-swales 3,927 

Conservation plans 4,335,882 Combined sewer overflow connections 15,872 

Conservation tillage 2,031,703 Dry ponds 893,189 

Cover crops 423,283 Erosion and sediment controls 80,517 

Enhanced nutrient management 186,424 Filtering practices 15,177 

Forest buffers 93,857 Forest buffers 1,521 

Grass buffers 76,877 Forest Conservation Act 115,131 

High residue tillage 545,899 Impervious surface reduction 598 

Horse pasture management 1,162 Infiltration 114,222 

Land retirement 312,009 Permeable pavement 42 

Loafing lot management 419 Retrofit stormwater management 81,330 

Off stream watering, without fences 235,263 Stormwater management–era 02 to 10 78,535 

Pasture fencing 67,099 Stormwater management–era 85 to 02 130,125 

Precision agriculture 325,274 Street sweeping (efficiency) 1,534 

Precision rotational grazing 564,332 Tree planting 1,750 

Streamside forest buffers 18,009 Urban nutrient management commercial applicators 196,177 

Streamside grass buffers 18,166 Urban nutrient management do-it-yourself 426,010 

Tier 1 nutrient management 1,580,127 Urban nutrient management plan 20,260 

Tree planting 104,669 Vegetative open channels 78 

Water control structures 6,073 Wet pond/wetland 345,484 

Wetland restoration 22,799 

BMP name Amount 

(feet) BMP name Amount (pounds) 

Stream restoration 830,793 Street sweeping (pounds) 4,907,078 

BMP name Amount 

(animal units) BMP name Amount (feet) 

Animal waste wanagement systems 1,458,156 Dirt and gravel roads 1,738 

Alum 26,307 Shoreline managememt 24,627 

Dairy precision feeding 5,184 Stream restoration 450,899 

Mortality composting 41,850 

Phytase feed additive 682,876 

BMP name Amount 

(tons) 

Manure transport 103,930 
10 Spatial and Temporal Patterns of Best Management Practice Implementation in the Chesapeake Bay Watershed, 1985–2014

80°

38°

40°

42°

78°

76°

Chesapeake Bay

PENNSYLVANIA

MARYLAND

DELAWARE

VIRGINIA

0 50 MILES

0 50 KILOMETERS

EXPLANATION

A

Conservation till implementation

 intensity in 2014.

Reported acres of implementation

 per acre of crop land. 

0.00 to 0.05

0.06 to 0.12

0.13 to 0.20

0.21 to 0.30

0.31 to 0.43

0.44 to 0.59

0.60 to 0.86

No reported

 implementation

Chesapeake Bay 

watershed 

boundary

76°

76°

42°

38°

80°

78° Base from U.S. Geological Survey, 1:2,000,000, 

State boundary digital line graph, Albers 

Equal-Area Projection, NAD 1983

40°

NEW YORK

WEST 

VIRGINIA

Washington,

D.C.

80°

38°

40°

42°

78°

76°

Chesapeake Bay

PENNSYLVANIA

MARYLAND

DELAWARE

VIRGINIA

0 50 MILES

0 50 KILOMETERS

EXPLANATION

B

Pasture fencing implementation

 intensity in 2014.

Reported acres of implementation 

 per acre of pasture land. 

0.000 to 0.004

0.005 to 0.009

0.010 to 0.017

0.018 to 0.026

0.027 to 0.034

0.035 to 0.043

0.044 to 0.059

No reported

 implementation

Chesapeake Bay 

watershed 

boundary

76°

76°

42°

38°

80°

78° Base from U.S. Geological Survey, 1:2,000,000, 

State boundary digital line graph, Albers 

Equal-Area Projection, NAD 1983

40°

NEW YORK

WEST 

VIRGINIA

Washington,

D.C.

80°

38°

40°

42°

78°

76°

Chesapeake Bay

PENNSYLVANIA

MARYLAND

DELAWARE

VIRGINIA

0 50 MILES

0 50 KILOMETERS

EXPLANATION

C

Cover crop implementation

 intensity in 2014.

Reported acres of implementation 

 per acre of crop land. 

0 to 0.012

0.013 to 0.034

0.035 to 0.065

0.066 to 0.10

0.11 to 0.15

0.16 to 0.24

0.25 to 0.38

No reported

 implementation

Chesapeake Bay 

watershed 

boundary

76°

76°

42°

38°

80°

78° Base from U.S. Geological Survey, 1:2,000,000, 

State boundary digital line graph, Albers 

Equal-Area Projection, NAD 1983

40°

NEW YORK

WEST 

VIRGINIA

Washington,

D.C.

Figure 2. A, conservation till, B, pasture fencing, and C, cover crop implementation intensity in 2014 using reported implementation and 

land-use information from the Chesapeake Bay Program Phase 5.3.2 model.
Temporal Patterns of Best Management Practice (BMP) Implementation 11

the state of Maryland than in Virginia, Pennsylvania, and 

Delaware (fig. 2C).

Spatial patterns in reported implementation also can be 

identified at the jurisdictional level. These can reflect the priorities of the jurisdiction, different reporting practices, or special 

programs. Extensive cover crop implementation was reported 

in Maryland; approximately 71 percent of 423,283 reported 

cover crop acres were in Maryland (fig. 2C). Pennsylvania, 

in general, had limited reporting of BMP implementation on 

cropland. Although it accounts for approximately 41 percent 

of the crop area in the watershed, only 33 percent of the 

conservation tillage, 35 percent of the conservation plan, and 

22 percent of the tier 1 nutrient management plan BMPs were 

reported in the State. Twenty-three percent of reported pasture 

fencing BMPs were in Pennsylvania, which had 20 percent of 

the pasture land use in the Chesapeake Bay watershed.

The CBP Phase 5.3.2 Watershed Model estimated up to 

a 42-percent reduction in total nitrogen to streams due to all 

BMPs across parts of the Eastern Shore of Chesapeake Bay in 

2014 (fig. 3A). Total phosphorus and total sediment loads were 

estimated to be reduced by up to 85 percent by BMPs in 2014. 

In general, the largest reductions in nutrient and sediment 

loads were predicted on the Eastern Shore of Chesapeake Bay 

and in parts of Virginia and West Virginia. Nutrient and sediment loads in areas of the watershed that have large amounts 

of forest land use were not predicted to have reductions of 

more than 5 percent (figs. 3B and 3C). These areas were 

estimated to have relatively low loading rates in comparison to 

the rest of the watershed.

Temporal Patterns of Best Management 

Practice (BMP) Implementation

Overall, reported BMP implementation has changed 

substantially from 1985 to 2014. Agricultural BMPs reported 

as acres in the Chesapeake Bay watershed increased by 

approximately 425 percent from 1985 to 2014 and 72 percent 

from 2000 to 2014. Reported animal type BMPs increased by 

52 percent from 2000 to 2014. Only a small number of animal 

type BMPs were reported to be implemented in 1985. Acres 

of BMPs reported on developed land increased by 206 percent 

from 2000 to 2014. Few developed land BMPs were reported 

in 1985.

Implementation of BMPs from 1985 to 2014 has varied 

in different ways for each BMP type. Conservation tillage 

BMPs accounted for the majority of agricultural BMPs in 

1985 and reported implementation increased by approximately 1 percent from 1985 to 2014, however, they made up 

a much smaller proportion of the overall agricultural BMP 

implementation reported in 2014. Eighty-eight percent of the 

acres of agricultural BMPs reported in 1985 were conservation 

tillage practices. This number decreased to 26 percent by 2000 

and to 18 percent by 2014. A larger proportion of reported 

agricultural BMP implementation after the year 2000 consisted 

of land-use change type BMPs such as land retirement, pasture 

fencing, and forest buffers. Reporting of pasture fencing 

increased from 4,830 acres in 2000 to 67,099 acres in 2014. 

These BMPs were generally reported in small quantities or not 

at all prior to 2000.

Reported acres of tier 1 nutrient management plan BMPs 

decreased sharply after 2009, decreasing by 55 percent by 

2014 (Devereux and others, 2018). This may not have been 

caused by a decrease in actual implementation; consistent 

reporting standards for this BMP were not available throughout the entire time period (U.S. Environmental Protection 

Agency, 2010b). The actual level of implementation may be 

more accurately represented during these later years.

The results of the No Action and Progress scenarios of 

the CBP Phase 5.3.2 Watershed Model provided an estimate of 

the yearly nitrogen, phosphorus, and sediment load reduction 

due to BMPs on agricultural and developed lands from 1985 to 

2014. Changes in land use, nutrient input changes not related 

to BMPs, and wastewater-treatment improvements were represented in the 8-percent reduction in nitrogen loads to streams 

in the Chesapeake Bay watershed from 1985 to 2014 in the No 

Action scenarios. The 2014 Progress scenario was predicted 

to be 11 percent lower than the 2014 No Action scenario, 

indicating that an estimated 11-percent reduction in nitrogen 

loads to streams could be attributed due to the implementation of BMPs through 2014 (fig. 4A). Phosphorus loads to 

streams from 1985 to 2014 were estimated to have decreased 

by 21 percent due to land-use changes, nutrient input changes 

not related to BMPs, and wastewater treatments, with an additional 19-percent reduction in phosphorus estimated due to the 

implementation of BMPs (fig. 4B). Land-use changes during 

this period were estimated to account for about 1 percent of 

the reduction in sediment loads, with a further reduction of 

23 percent estimated from BMPs (fig. 4C). In 2005, BMPs 

were estimated to have reduced total nitrogen loads by 8 percent, total phosphorus loads by 10 percent, and total sediment 

loads by 16 percent, respectively, across the Chesapeake Bay 

watershed.

BMPs were estimated to have reduced nutrient and sediment loads to streams by a larger amount through 2014 than 

through 2005 in all subregions of the Chesapeake Bay watershed using the No Action and Progress scenarios (table 4). 

In some subregions, such as the Susquehanna, the change 

in estimated reductions between 2005 and 2014 were more 

pronounced than others where estimated improvements were 

minimal. Nitrogen loads in the Eastern Shore subregion were 

estimated to have been reduced 18 percent through 2005 and 

25 percent through 2014, representing a substantial increase 

in BMP implementation. In comparison, nitrogen loads to 

streams in the Susquehanna subregion were estimated to be 

reduced by 8 percent through 2005 and 9 percent through 

2014. All subregions saw marked improvement in total phosphorus and sediment loads to streams between 2005 and 2014. 

The Eastern Shore subregion improved from a 23-percent
12 Spatial and Temporal Patterns of Best Management Practice Implementation in the Chesapeake Bay Watershed, 1985–2014

EXPLANATION

A

C

EXPLANATION

B

EXPLANATION

Estimated 2014 percent reduction

 in total nitrogen due to BMPs

0 to 5

6 to 10

11 to 15

16 to 20

21 to 25

26 to 30

31 to 35

36 to 40

41 to 45

Estimated 2014 percent reduction

 in total phosphorus due to BMPs

0 to 5

6 to 10

11 to 15

16 to 20

21 to 25

26 to 30

31 to 35

36 to 40

41 to 45

46 to 55

56 to 65

66 to 75

76 to 85

Estimated 2014 percent reduction

 in total sediment due to BMPs

0 to 5

6 to 10

11 to 15

16 to 20

21 to 25

26 to 30

31 to 35

36 to 40

41 to 45

46 to 55

56 to 65

66 to 75

76 to 85

80°

38°

40°

42°

78°

76°

Chesapeake Bay

PENNSYLVANIA

MARYLAND

DELAWARE

VIRGINIA

0 50 MILES

0 50 KILOMETERS

Chesapeake Bay 

watershed 

boundary

76°

76°

42°

38°

80°

78° Base from U.S. Geological Survey, 1:2,000,000, 

State boundary digital line graph, Albers 

Equal-Area Projection, NAD 1983

40°

NEW YORK

WEST 

VIRGINIA

Washington,

D.C.

80°

38°

40°

42°

78°

76°

Chesapeake Bay

PENNSYLVANIA

MARYLAND

DELAWARE

VIRGINIA

0 50 MILES

0 50 KILOMETERS

Chesapeake Bay 

watershed 

boundary

76°

76°

42°

38°

80°

78° Base from U.S. Geological Survey, 1:2,000,000, 

State boundary digital line graph, Albers 

Equal-Area Projection, NAD 1983

40°

NEW YORK

WEST 

VIRGINIA

Washington,

D.C.

80°

38°

40°

42°

78°

76°

Chesapeake Bay

PENNSYLVANIA

MARYLAND

DELAWARE

VIRGINIA

0 50 MILES

0 50 KILOMETERS

Chesapeake Bay 

watershed 

boundary

76°

76°

42°

38°

80°

78° Base from U.S. Geological Survey, 1:2,000,000, 

State boundary digital line graph, Albers 

Equal-Area Projection, NAD 1983

40°

NEW YORK

WEST 

VIRGINIA

Washington,

D.C.

Figure 3. Estimated 2014 percent reduction in A, total nitrogen, B, total phosphorus, and C, total sediment due to Best Management 

Practices (BMPs) in the Chesapeake Bay watershed.
Temporal Patterns of Best Management Practice (BMP) Implementation 13

A

C

B

1985 1990

Year

1995 2000 2005 2010 2015

Nitrogen load, in millions of pounds

Sediment load, in millions of pounds

Phosphorus load, in millions of pounds

700

20,000

15,000

10,000

5,000

600

500

400

300

200

100

0

0

1985

1985

1990

1990

Year

Year

1995

1995

2000

2000

2005

2005

2010

2010

2015

2015

50

45

40

35

30

25

20

15

10

5

0

EXPLANATION

1985 total nitrogen load (No Action)

No Action, includes wastewater

 improvements

Progress, includes wastewater

 improvements and BMPs

1985 total phosphorus load (No Action)

No Action, includes wastewater

 improvements

Progress, includes wastewater

 improvements and BMPs

EXPLANATION

1985 total sediment load (No Action)

No Action, includes wastewater

 improvements

Progress, includes wastewater

 improvements and BMPs

EXPLANATION

Figure 4. Estimated A, total nitrogen load, B, total phosphorus load, and C, total sediment load from 1985 through 2014 for the No Action 

scenarios, which do not include Best Management Practices (BMPs), and the Progress scenarios, which do include BMPs.

reduction of total phosphorus to streams through 2005 to a 

32-percent reduction through 2014.

Across the entire Chesapeake Bay watershed, BMPs 

were estimated to have reduced total nitrogen loads to streams 

by about 49 million pounds by 2014 on the approximately 

9 million acres of agricultural land. BMPs on the approximately 5.4 million acres of developed lands were estimated 

to reduce total nitrogen loads to streams by approximately 

7 million pounds in 2014. By 2000, BMPs on agricultural land 

were estimated to reduce total nitrogen loads to streams by 

22 million pounds, whereas BMPs on developed land were 

estimated to reduce total nitrogen loads by about 4 million 

pounds (fig. 5A). Phosphorus loads to streams were estimated 

to be reduced by 2.2 million pounds by 2000 and 5.2 million 

pounds by 2014 due to BMPs on agricultural land (fig. 5B). 

Estimated sediment loads were reduced by nearly 1.6 billion 

pounds by 2000 and 3.3 billion pounds by 2014 due to BMPs 

on agricultural land. Developed land BMPs were estimated to 

reduce phosphorus loads by about 320,000 pounds by 2000 

and 1.2 million pounds by 2014, whereas sediment loads were 

estimated to be reduced by 260 million pounds by 2000 and 

560 million pounds by 2014 (figure 5C).
14 Spatial and Temporal Patterns of Best Management Practice Implementation in the Chesapeake Bay Watershed, 1985–2014

Table 4. Estimated reduction of nutrients to streams in Chesapeake Bay watershed subregions due to Best Management Practices 

(BMPs) in 2005 and 2014 using Progress and No Action Chesapeake Bay Program Phase 5.3.2 model scenarios.

[RIM, River Input Monitoring; ES, Eastern Shore; WS, Western Shore; TN, total nitrogen; TP, total phosphorus; TS, total sediment; %, percent]

Subregion

TN reduction in 

2005 due to BMPs 

(% change)

TP reduction in 

2005 due to BMPs 

(% change)

TS reduction in 

2005 due to BMPs 

(% change)

TN reduction in 

2014 due to BMPs 

(% change)

TP reduction in 

2014 due to BMPs 

(% change)

TS reduction in 

2014 due to BMPs 

(% change)

Appomattox 7 11 15 13 19 23

Choptank 16 22 23 22 33 43

James 5 7 14 7 14 25

Mattaponi 7 13 19 10 17 23

Non-RIM ES 18 23 25 25 32 39

Non-RIM WS 4 6 17 7 15 26

Pamunkey 7 9 17 10 14 26

Patuxent 7 7 24 10 15 29

Potomac 8 13 16 14 26 27

Rappahannock 9 14 20 11 20 25

Susquehanna 8 8 15 9 15 19

Chesapeake Bay 

watershed 8 10 16 11 19 23

Agricultural land use

Developed land use

60,000,000 6,000,000

3,500,000,000

3,000,000,000

2,500,000,000

2,000,000,000

1,500,000,000

1,000,000,000

 500,000,000

0

5,000,000

4,000,000

3,000,000

2,000,000

1,000,000

0

50,000,000

40,000,000

30,000,000

20,000,000

10,000,000

0

1985 1985

Year Year

1990 1995 2000 2005 2010 2015 1990 1995 2000 2005 2010 2015

1985

Year

1990 1995 2000 2005 2010 2015

A

C

B

Estimated reduction of 

nitrogen to streams, in pounds

Estimated reduction of 

phosphorus to streams, in pounds

Estimated reduction of 

sediment to streams, in pounds

EXPLANATION

Figure 5. Estimated reduction in A, total nitrogen load, B, total phosphorus load, and C, total sediment load due to Best Management 

Practices (BMPs) from 1985 through 2014.
Estimated Effect of Best Management Practices (BMPs) on Nutrient and Sediment Loads 15

Estimated Effect of Best Management 

Practices (BMPs) on Nutrient and 

Sediment Loads

The BMP isolation scenarios were used to identify the 

expected reduction in nutrient and sediment loads to streams 

by various BMP types. The largest estimated reduction in 

total nitrogen loads on agricultural lands in 2014 can be 

attributed to the land retirement BMP, with a total reduction of 7.7 million pounds, and the animal waste management system (AWMS) BMP, with an estimated reduction of 

7.6 million pounds (fig. 6A). Conservation tillage was estimated to reduce total nitrogen loads by 6.2 million pounds 

for 2014. The AWMS BMP was estimated to reduce total 

phosphorus loads to streams by the greatest amount, with a 

roughly 1.4 million-pound reduction. Other large estimated 

reductions in phosphorus were attributable to pasture fencing 

(810,000 pounds) and phytase feed additives (710,000 pounds) 

(fig. 6B). The largest estimated reductions in sediment loads 

were due to conservation tillage (1.2 billion pounds), pasture fencing (500 million pounds), and conservation plans 

(480 million pounds) (fig. 6C).

The average expected effect of each type of agricultural 

BMP per unit of implementation on nutrient and sediment 

loads across the Chesapeake Bay watershed also was estimated (table 5). The agricultural BMPs that were estimated 

to produce the largest reduction in total nitrogen load per acre 

of implementation were loafing lot management and barnyard 

runoff controls, with estimated reductions of 110 pounds per 

acre and 99 pounds per acre of implementation, respectively. 

The loafing lot management BMP is a practice that is designed 

to stabilize areas that are intensively used by people, animals, 

or vehicles by establishing vegetative cover, surfacing with 

suitable materials, or installing needed structures. Barnyard 

runoff control includes practices such as control of runoff 

from barnyards, roof runoff control, and diversion of clean 

water. These BMPs were not extensively reported across the 

Chesapeake Bay watershed, so their total estimated effect is 

not as substantial in comparison to other practices (Devereux 

and others, 2018). The BMPs that convert agricultural land 

to other land uses were estimated to reduce total nitrogen 

by a large amount for each acre of implementation. These 

BMPs include forest buffers, grass buffers, streamside forest and grass buffers, land retirement, and pasture fencing. 

These BMPs were estimated to reduce the total nitrogen load 

to streams from 20 to 56 pounds per acre of implementation. 

These BMPs were reported to be widespread throughout the 

watershed, and accounted for 42 percent of the total estimated 

reduction in nitrogen loads to streams due to agricultural 

BMPs through 2014. Other agricultural BMPs, such as conservation plans and conservation tillage, were estimated to reduce 

only a relatively small amount of nitrogen to streams (1 and 

3 pounds per acre of implementation), but were reported in 

large enough amounts throughout the watershed to account for 

almost 22 percent of the total estimated reduction in nitrogen 

due to agricultural BMPs.

Barnyard runoff control and loafing lot management were 

estimated to reduce total phosphorus loads by a substantial 

amount per acre of implementation (19 and 22 pounds per 

acre), however, the total effect was not estimated to be large 

due to limited implementation. Pasture fencing and streamside 

grass buffers also were estimated to be effective at reducing 

phosphorus loads to streams, with 12 to 13 pounds of phosphorus reduced per acre of implementation. Collectively, they 

accounted for about 20 percent of the total reduction in phosphorus load due to BMPs on agricultural land by 2014.

The agricultural BMPs with the largest estimated reduction in sediment loads to streams per acre of implementation 

were streamside grass buffers and pasture fencing at 9,800 and 

7,700 pounds per acre, respectively. However, the largest total 

estimated reduction in sediment loads to streams from agricultural BMPs was attributed to conservation tillage. Conservation tillage accounted for approximately 31 percent of the total 

estimated reduction in phosphorus to streams by 2014.

The implementation of certain BMPs that affect nutrients 

from animal production are reported to the CBP in animal 

units. Mortality composting was estimated to reduce nitrogen 

loads to streams by 10 pounds per animal unit, and phosphorus 

loads by 2 pounds per animal unit. Animal waste management 

systems were estimated to reduce nitrogen loads to streams by 

5 pounds per animal unit, and phosphorus loads by 1 pound 

per animal unit. Phytase feed additives were estimated to 

reduce phosphorus loads by 1 pound per animal unit.

Infiltration BMPs were estimated to account for the 

largest reduction in nitrogen loads to streams from developed 

land in 2014. Dry ponds and wet ponds also were extensively 

reported, and accounted for a large proportion of the estimated 

total nitrogen reduction by 2014 (fig. 7A). These BMPs also 

were estimated to have a large effect on phosphorus and sediment loads to streams (figs. 7B and 7C). Erosion and sediment 

controls provided the largest total reduction to phosphorus 

and sediment loads by 2014, with large additional reductions 

estimated from the abandoned mineland reclamation BMP.

BMPs on developed land vary widely in their effectiveness per unit of implementation (table 6). Bio-Retention was 

estimated to be the most effective BMP for reducing nutrients 

and sediment, reducing total nitrogen loads to streams by 

81 pounds per acre, total phosphorus loads by 11 pounds per 

acre, and total sediment by 5,200 pounds per acre of implementation. This BMP was not reported to be implemented 

substantially across the watershed, and only accounted for 

about 2.5 percent of the estimated reduction of total nitrogen 

from BMPs on developed land (Devereux and others, 2018). 

Dry ponds, wet ponds/wetlands, and infiltration BMPs 

have a relatively low estimated effectiveness, ranging from 

2.3 pounds of nitrogen reduced per acre of implementation to 

12.4 pounds per acre, but were reported to be implemented 

extensively throughout the watershed. They accounted for 

49 percent of the reduction in nitrogen loads from developed
16 Spatial and Temporal Patterns of Best Management Practice Implementation in the Chesapeake Bay Watershed, 1985–2014

Land retirement

Animal waste management systems

Animal waste management systems

Pasture fencing

Phytase feed additive

Forest buffers

Conservation plans

Conservation plans

Conservation tillage

Pasture fencing

Streamside grass buffers

Grass buffers

Tier 1 nutrient management

Tier 1 nutrient management

Land retirement

Cover crops

Forest buffers

Tree planting

Precision rotational grazing

Streamside grass buffers

Grass buffers

Alternative crops

Barnyard runoff control

Commodity cover crops

Mortality composting

Precision agriculture

Tree planting

Precision rotational grazing

Manure transport 

Enhanced nutrient management

Stream restoration

Barnyard runoff control

Precision agriculture

Manure transport 

High residue tillage 

Mortality composting

Streamside forest buffers

Streamside forest buffers

Alternative crops

Wetland restoration

Enhanced nutrient management

High residue tillage 

Off stream watering, without fences

Off stream watering, without fences

Wetland restoration

Water control structures

Cover crops

Stream restoration

Loafing lot management

Loafing lot management

Dairy precision feeding

Dairy precision feeding

Commodity cover crops

Phytase feed additive

Horse pasture management

Horse pasture management

Alum

Alum

Water control structures

8,000,000

7,000,000

6,000,000

5,000,000

4,000,000

3,000,000

2,000,000

1,000,000

1,400,000

1,200,000

1,000,000

800,000

600,000

400,000

200,000

0

0

A

B

Conservation tillage

Estimated 2014 total nitrogen reduction, 

in pounds

Estimated 2014 total phosphorus reduction, 

in pounds

Figure 6. Estimated A, total nitrogen reduction, B, total phosphorus reduction, and C, total sediment reduction by Best Management 

Practice (BMP) category on agricultural lands in 2014.
Estimated Effect of Best Management Practices (BMPs) on Nutrient and Sediment Loads 17

Conservation tillage Pasture fencing

Conservation plans Land retirement Streamside grass buffers Forest buffers High residue tillage

Precision rotational grazing

Tree planting

Grass buffers Streamside forest buffers Alternative crops

Stream restoration Off stream watering, without fences

Wetland restoration Cover crops

Barnyard runoff control

Loafing lot management

Horse pasture management Animal waste management systems Tier 1 nutrient management

Commodity cover crops Precision agriculture

Enhanced nutrient management

Manure transport 

Mortality composting

Water control structures Dairy precision feeding

Phytase feed additiveAlum

1,400,000,000

1,200,000,000

1,000,000,000

800,000,000

600,000,000

400,000,000

200,000,000

0

C

Estimated 2014 total sediment reduction, 

in pounds

Figure 6. Estimated A, total nitrogen reduction, B, total phosphorus reduction, and C, total sediment reduction by Best Management 

Practice (BMP) category on agricultural lands in 2014.—Continued

land to streams, 48 percent of the phosphorus reduction, and 

36 percent of the sediment reduction.

In 1985, the conservation tillage BMP accounted 

for nearly all of the estimated reduction in total nitrogen (95 percent), phosphorus (87 percent), and sediment 

(98 percent) loads due to BMPs on agricultural land in the 

Chesapeake Bay watershed (figs. 8A, 8B, and 8C). By the 

year 2000, conservation tillage accounted for 30 percent of 

the estimated nitrogen reduction, 9 percent of the estimated 

phosphorus reduction, and 68 percent of the estimated sediment reduction. By 2014, conservation tillage accounted 

for just 13 percent of the total estimated nitrogen reduction, 5 percent of the estimated phosphorus reduction, and 

38 percent of the estimated reduction in sediment loads. 

After the year 1997, a wider variety of agricultural BMPs 

were reported in greater numbers. Land-use change type 

BMPs became more prevalent across the watershed. In 

2014, land retirement, pasture fencing, grass and forest buffers, streamside grass and forest buffers, and tree plantings 

accounted for 44 percent of the estimated reduction in nitrogen load to streams, 31 percent of the estimated reduction in 

phosphorus load to streams, 37 percent of the estimated reduction in sediment load to streams.

The infiltration, dry pond, and wet pond BMPs accounted 

for the majority of estimated total nitrogen reductions to streams 

from 1985 to 2014 due to BMPs on developed land (fig. 9A). 

Prior to 2005, nearly all of the reduction in nitrogen was predicted to come from these three BMPs. The Forest Conservation Act (Department of Legislative Services, Office of Policy 

Analysis, 2017), which is reported in Maryland, has accounted 

for a growing proportion of the estimated nitrogen reduction 

from 2006 through 2014. Stormwater management BMPs are 

estimated to have had a slightly increased total effect over 

the study period. By 2014, they were estimated to have had a 

similar overall effect as wet ponds. Sharp increases in estimated 

phosphorus and sediment reductions after 2005 were driven by 

the erosion and sediment controls and abandoned mineland reclamation BMPs (figs. 9B and 9C). Some developed land BMPs 

fluctuated greatly from year to year. This may have been due to 

changing reporting standards or the nature of their implementation. Some BMPs are dependent on continual investment to 

remain operational, which may not always be possible.
18 Spatial and Temporal Patterns of Best Management Practice Implementation in the Chesapeake Bay Watershed, 1985–2014

Table 5. Agricultural land Best Management Practice (BMP) estimated mass reduction per unit of implementation in the Chesapeake 

Bay watershed.

BMP name

Nitrogen reduction 

(pounds per acre of 

implementation) 

Phosphorus reduction 

(pounds per acre of 

implementation) 

Sediment reduction 

(pounds per acre of 

implementation) 

Alternative crops 30.3 0.9 767 

Barnyard runoff control 99.0 19.3 1,501 

Commodity cover crops 2.9 0.0 0 

Conservation plans 1.0 0.1 111 

Conservation tillage 3.1 0.1 605 

Cover crops 2.9 0.0 19 

Enhanced nutrient management 2.7 0.1 0 

Forest buffers 56.4 1.9 1,508 

Grass buffers 36.2 1.5 713 

High residue tillage 0.4 0.1 242 

Horse pasture management 0.0 0.2 76 

Land retirement 24.6 0.6 726 

Loafing lot management 110.1 22.1 2,145 

Off stream watering, without fences 0.5 0.1 50 

Pasture fencing 51.9 12.1 7,651 

Precision agriculture 1.8 0.1 0 

Precision rotational grazing 1.0 0.2 205 

Streamside forest buffers 20.0 1.4 1,226 

Streamside grass buffers 51.7 13.2 9,814 

Tier 1 nutrient management 1.7 0.2 0 

Tree planting 10.5 0.6 654 

Water control structures 8.0 0.0 0 

Wetland restoration 12.1 0.8 384 

BMP name

Nitrogen reduction 

(pounds per foot of 

implementation) 

Phosphorus reduction 

(pounds per foot of 

implementation) 

Sediment reduction 

(pounds per foot of 

implementation) 

Stream restoration 0.1 0.0 23 

BMP name

Nitrogen reduction 

(pounds per animal unit of 

implementation) 

Phosphorus reduction 

(pounds per animal unit of 

implementation) 

Sediment reduction 

(pounds per animal unit of 

implementation) 

Animal waste management systems 5.2 0.9 0.0 

Alum 0.0 0.0 0.0 

Dairy precision feeding 2.6 0.6 0.0 

Mortality composting 10.3 1.9 0.0 

Phytase feed additive 0.0 1.0 0.0 

BMP name Nitrogen reduction 

(pounds per ton) 

Phosphorus reduction 

(pounds per ton) 

Sediment reduction 

(pounds per ton) 

Manure transport 4.3 0.4 0.0 
Estimated Effect of Best Management Practices (BMPs) on Nutrient and Sediment Loads 19

Erosion and sediment controls

Abandoned mineland reclamation

Wet pond/wetland

Infiltration

Dry ponds

Forest Conservation Act

Stream Restoration

Bio-retention

Filtering practices

Bio-swales

Tree planting

Forest buffers

Impervious surface reduction

Vegetative open channels

Permeable pavement

Dirt and gravel roads

1,500,000

1,250,000

1,000,000

750,000

500,000

250,000

350,000

300,000

250,000

200,000

150,000

100,000

50,000

0

0

B

Stormwater management-era 85 to 02

Retrofit stormwater management

Stormwater management-era 02 to 10

Urban nutrient management plan

Street sweeping (pounds)

Street sweeping (efficiency)

Shoreline management

Combined sewer overflow connections

Urban nutrient management, do-it-yourself

Urban nutrient management, commercial applicators

Infiltration

Dry ponds

Forest Conservation Act

Wet pond/wetland

Erosion and sediment contols

Abandoned mineland reclamation

Stormwater management-era 85 to 02

Retrofit stormwater management

Stormwater management-era 02 to 10

Bio-retention

Urban nutrient management, do-it-yourself

Urban nutrient management, commercial applicators

Filtering practices

Bio-swales

Tree planting

Stream restoration

Forest buffers

Urban nutrient management plan

Impervious surface reduction

Vegetative open channels

Street sweeping (pounds)

Permeable pavement Street sweeping (efficiency)

Combined sewer overflow connections

Dirt and gravel roads

Shoreline management

A

Estimated 2014 total nitrogen reduction, 

in pounds

Estimated 2014 total phosphorus reduction, 

in pounds

Figure 7. Estimated A, total nitrogen reduction, B, total phosphorus reduction, and C, total sediment reduction by Best Management 

Practice (BMP) category on developed lands in 2014.
20 Spatial and Temporal Patterns of Best Management Practice Implementation in the Chesapeake Bay Watershed, 1985–2014

Erosion and sediment controls

Dry ponds

Abandoned mineland reclamation

Wet pond/wetland

Infiltration

Forest Conservation Act

Bio-retention

Stream restoration

Filtering practices

Bio-swales

Tree planting

Forest buffers

Impervious surface reduction

Vegetative open channels

Permeable pavement

Dirt and gravel roads

250,000,000

200,000,000

150,000,000

100,000,000

50,000,000

0

C

Stormwater management-era 85 to 02

Retrofit stormwater management

Stormwater management-era 02 to 10

Urban nutrient management plan

Street sweeping (pounds)

Street sweeping (efficiency)

Shoreline management

Combined sewer overflow connections

Urban nutrient management, do-it-yourself

Urban nutrient management, commercial applicators

Estimated 2014 total sediment reduction, 

in pounds

Figure 7. Estimated A, total nitrogen reduction, B, total phosphorus reduction, and C, total sediment reduction by Best Management 

Practice (BMP) category on developed lands in 2014.—Continued
Estimated Effect of Best Management Practices (BMPs) on Nutrient and Sediment Loads 21

Table 6. Developed land Best Management Practice (BMP) estimated mass reduction per unit of implementation in the Chesapeake 

Bay watershed.

BMP name

 Nitrogen reduction 

(pounds per acre of 

implementation) 

 Phosphorus reduction 

(pounds per acre of 

implementation) 

 Sediment reduction 

(pounds per acre of 

implementation) 

Abandoned mineland reclamation 21.4 7.2 3,569

Bio-retention 80.8 11.3 5,242

Bio-swales 15.1 1.5 606

Combined sewer overflow connections 0.0 0.0 0

Dry ponds 1.3 0.2 118

Erosion and sediment controls 7.9 4.1 2,801

Filtering practices 3.9 0.7 359

Forest buffers 15.4 1.2 403

Forest Conservation Act 7.4 0.4 137

Impervious surface reduction 3.3 1.5 590

Infiltration 12.4 1.3 528

Permeable pavement 2.6 0.4 174

Retrofit stormwater management 2.7 0.4 332

Stormwater management–era 02 to 10 2.7 0.3 266

Stormwater management–era 85 to 02 1.8 0.3 160

Street sweeping (efficiency) 0.0 0.0 3,016

Tree planting 24.0 1.3 461

Urban nutrient management, commerical applicators 0.8 0.0 0

Urban nutrient management, do-it-yourself 0.4 0.0 0

Urban nutrient management plan 0.7 0.0 0

Vegetative open channels 3.4 0.3 186

Wet pond/wetland 2.3 0.5 242

BMP name

 Nitrogen reduction 

(pounds per pound of 

implementation) 

 Phosphorus reduction 

(pounds per pound of 

implementation) 

 Sediment reduction 

(pounds per pound of 

implementation) 

Street sweeping (pounds) 0.0 0.0 0.9

BMP name

 Nitrogen reduction 

(pounds per foot of 

implementation) 

 Phosphorus reduction 

(pounds per foot of 

implementation) 

 Sediment reduction 

(pounds per foot 

implementation) 

Dirt and gravel roads 0.0 0.0 3

Shoreline management 0.0 0.0 46

Stream restoration 0.1 0.1 22
22 Spatial and Temporal Patterns of Best Management Practice Implementation in the Chesapeake Bay Watershed, 1985–2014 Estimated reduction of nitrogen to streams, in pounds

0

10,000,000

20,000,000

30,000,000

40,000,000

50,000,000

1985

Year

Year

Year

1990 1995 2000 2005 2010

A BMP Category

B

C

Estimated reduction of phosphorus to streams, in pounds

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

1985 1990 1995 2000 2005 2010

0

1,000,000,000

 500,000,000

2,000,000,000

1,500,000,000

3,000,000,000

2,500,000,000

3,500,000,000

1985 1990 1995 2000 2005 2010

Estimated reduction of sediment to streams, in pounds

Alum

Animal waste management systems

Dairy precision feeding

Phytase feed additive

Mortality composting

Manure transport

Loafing lot management

Horse pasture management

Precision rotational grazing

Pasture fencing

Off stream watering, without fences

Barnyard runoff control

Water control structures

Stream restoration

Wetland restoration

Land retirement

Streamside grass buffers

Streamside forest buffers

Tree planting

Grass buffers

Forest buffers

Tier 1 nutrient management

Enhanced nutrient management

Conservation plans

Precision agriculture

High residue tillage

Conservation tillage

Cover crops

Commodity cover crops

Alternative crops

EXPLANATION

Figure 8. Estimated A, total nitrogen reduction, B, total phosphorus reduction, and C, total sediment reduction from agricultural Best 

Management Practices (BMPs) from 1985 through 2014 in the Chesapeake Bay watershed.
Estimated Effect of Best Management Practices (BMPs) on Nutrient and Sediment Loads 23

700,000,000

600,000,000

500,000,000

400,000,000

300,000,000

200,000,000

100,000,000

0

0

0

Estimated reduction of nitrogen to streams, in pounds Estimated reduction of phosphorus to streams, in pounds Estimated reduction of sediment to streams, in pounds

1985

1985

1985

Year

Year

Year

1990

1990

1990

1995

1995

1995

2000

2000

2000

2005

2005

2005

2010

2010

2010

A

B

C

7,000,000

6,000,000

5,000,000

4,000,000

3,000,000

2,000,000

1,000,000

1,250,000

1,000,000

750,000

500,000

250,000

Combined sewer overflow connections

Stormwater management-era 85 to 02

Stormwater management-era 02 to 10

Retrofit stormwater management

Urban nutrient management plan

Urban nutrient management, do-it-yourself

Urban nutrient management, commercial applicators

Street sweeping

Impervious surface reduction

Permeable pavement

Infiltration

Filtering practices

Dry ponds

Wet pond/wetland

Vegetative open channels

Tree planting

Forest buffers

Forest Conservation Act

Stream restoration

Shoreline management

Bio-swales

Bio-retention

Erosion and sediment controls

Dirt and gravel roads

Abandoned mineland reclamation

BMP Category

EXPLANATION

Figure 9. Estimated A, total nitrogen reduction, B, total phosphorus reduction, and C, total sediment reduction from developed land 

Best Management Practices (BMPs) from 1985 through 2014 in the Chesapeake Bay watershed.
24 Spatial and Temporal Patterns of Best Management Practice Implementation in the Chesapeake Bay Watershed, 1985–2014

Summary and Conclusions

The U.S. Geological Survey (USGS), in conjunction with 

the Chesapeake Bay Program (CBP), undertook this study 

to improve the understanding of the effectiveness of waterquality management actions on nitrogen, phosphorus, and 

sediment loads to streams in the Chesapeake Bay watershed. 

Estimates of Best Management Practice (BMP) effectiveness 

were not extensively documented at the regional scale in the 

study area. Information on the spatial and temporal patterns of 

BMP implementation can provide context to current conditions as well as assist in understanding trends in water-quality 

loads. The CBP Partnership Phase 5.3.2 Watershed Model 

was used to evaluate a set of scenarios in order to investigate 

spatial and temporal patterns of BMP implementation in the 

Chesapeake Bay watershed. The CBP also provided reported 

amounts of various types of BMP implementation on agricultural and developed land. Year to year changes in reported 

BMP implementation may partially reflect changing reporting 

standards and the revision of historical records in addition to 

actual changes in BMP implementation. An analysis of model 

results was performed in order to estimate the expected effectiveness of BMPs at mitigating nutrient and sediment loads 

throughout the watershed. The total expected effect of different types of BMPs on nitrogen, phosphorus, and sediment 

were estimated as well as the expected effect per unit of BMP 

implementation.

Conservation plans, conservation tillage, and tier 1 nutrient management plans were identified as the BMPs with the 

most reported acres of implementation in the Chesapeake Bay 

watershed in 2014. A measure of BMP implementation intensity was defined as acres of BMP implementation per available land use. Spatial patterns of BMP implementation can 

be associated with different agricultural practices throughout 

the watershed. Areas with large amounts of animal production, such as the Potomac subregion, were found to have large 

amounts of related animal type BMPs, such as pasture fencing 

and animal waste management systems (AWMSs). In general, 

areas of high crop production tended to have large amounts 

of cover crops and conservation tillage. Additionally, each 

jurisdiction in the Chesapeake Bay watershed (consisting of 

New York, Maryland, Pennsylvania, Delaware, West Virginia, 

Virginia, and the District of Columbia) tended to focus on 

certain types of BMPs. Maryland had a higher intensity of 

reported cover crops and conservation tillage BMPs than other 

areas of the watershed. Pennsylvania had a lower intensity of 

BMPs reported on cropland in comparison to other jurisdictions. Virginia had a higher intensity of animal type BMPs.

The amount of agricultural BMPs reported as acres in 

the Chesapeake Bay watershed increased from 1985 to 2014. 

Developed land BMPs were only reported in small numbers in 

1985, but increased substantially from 2000 to 2014. Conservation tillage constituted the majority of reported agricultural 

BMP implementation in 1985 and increased slightly by 2014 

but decreased from 88 percent to 18 percent of the proportion 

of the total reported agricultural BMP implementation during

the same time period as more alternative BMP types became 

available and were reported. After the year 2000, a larger 

proportion of agricultural BMPs consisted of land-use change 

type BMPs, including land retirement, pasture fencing, grass 

buffers, and forest buffers.

By 2014, BMPs were estimated to have reduced total 

nitrogen loads to streams by approximately 49 million pounds 

on agricultural land and 7 million pounds on developed land. 

Agricultural BMPs were estimated to reduce phosphorus loads 

to streams by 5 million pounds whereas BMPs on developed 

lands were expected to reduce phosphorus loads by about 

1 million pounds. Reductions in sediment loads due to BMPs 

were estimated at 3.3 billion pounds for agricultural BMPs 

and 560 million pounds for developed land BMPs.

The largest estimated reduction in total nitrogen on 

agricultural lands by 2014 was attributed to land retirement, 

AWMSs, and conservation tillage. AWMSs were estimated 

to reduce total phosphorus loads to streams by the largest 

amount, followed by pasture fencing and phytase feed. Other 

agricultural BMPs had a marginal effect on phosphorus loads 

by comparison. Conservation tillage, conservation plans, 

and pasture fencing were estimated to have the greatest total 

effects on sediment loads to streams.

Loafing lot management and barnyard runoff controls had 

the highest estimated reduction in nitrogen and phosphorus per 

acre of implementation, but were not widely reported across 

the Chesapeake Bay watershed. Land-use conversion BMPs, 

such as forest buffers, grass buffers, streamside forest and 

grass buffers, land retirement, and pasture fencing were estimated to reduce the total nitrogen load to streams from 20 to 

56 pounds per acre of implementation. These BMPs accounted 

for 42 percent of the total estimated reduction in nitrogen 

loads to streams due to agricultural BMPs by 2014. Conservation plans and conservation tillage were estimated to reduce 

only 1 and 3 pounds per acre of implementation, respectively, 

but accounted for 22 percent of the total estimated reduction in nitrogen due to agricultural BMPs. Pasture fencing 

and streamside grass buffers were estimated to be effective at 

reducing phosphorus loads to streams with 12 and 13 pounds 

of phosphorus reduced per acre of implementation, and these 

BMPs accounted for about 20 percent of the total reduction in 

phosphorus load on agricultural land by 2014. Conservation 

tillage accounted for the largest total estimated reduction in 

sediment loads to streams.

Bio-retention was estimated to be the most effective 

BMP for reducing nutrients and sediment on developed land, 

but this BMP is not frequently used or reported in the Chesapeake Bay watershed. Although dry ponds, wet ponds and 

constructed wetlands, and infiltration BMPs have a relatively 

low estimated effectiveness, they accounted for 49 percent of 

the total reduction in nitrogen loads to streams due to BMPs, 

48 percent of the phosphorus load reduction, and 36 percent of 

the sediment load reduction.

Conservation tillage accounted for nearly all of the estimated reduction in total nitrogen, phosphorus, and sediment 

loads due to BMPs on agricultural land in the Chesapeake
References Cited 25

Bay watershed in 1985. Although the total estimated reduction in nutrients and sediment from this BMP did not change 

significantly by 2014, conservation tillage accounted for just 

13 percent of the total estimated nitrogen reduction, 5 percent 

of the total estimated phosphorus reduction, and 38 percent of 

the total estimated sediment load reduction as a wider variety 

of agricultural BMPs were reported. These included land-use 

change type BMPs, such as land retirement, pasture fencing, 

grass and forest buffers, streamside grass and forest buffers, 

and tree plantings.

The largest reductions in nitrogen, phosphorus, and sediment to streams by 2014 were predicted on the Eastern Shore 

of the Chesapeake Bay and in the Potomac subregion. A large 

amount of reported implementation of conservation tillage, 

cover crops, AWMSs, and conservation plans on the Eastern 

Shore were responsible for large estimated reductions in nutrient and sediment loads to streams. In the Potomac subregion, 

extensive implementation of pasture fencing was estimated to 

reduce nutrient loads in addition to the implementation of a 

variety of other BMPs to pasture and cropland.

References Cited

Department of Legislative Services, Office of Policy Analysis, 

2017, Forest Conservation Act and Other Forester Programs 

in Maryland, accessed June 11, 2018, at http://dls.maryland.

gov/pubs/prod/NatRes/Forest-Conservation-Act-and-OtherForestry-Programs-in-Maryland.pdf.

Devereux, O.H., Sekellick A.J., and LaMotte, A.E., 2018, 

Estimated effect of best management practice implementation on water quality in the Chesapeake Bay watershed from 

1985 to 2014: U.S. Geological Survey data release, https://

doi.org/10.5066/P9OVU9PX.

Hively, W.D., Devereux, O.H., and Claggett, P., 2013, Integrating Federal and State data records to report progress in 

establishing agricultural conservation practices on Chesapeake Bay farms: U.S. Geological Survey Open-File Report 

2013-1287, 36 p., accessed August 21, 2018, at https://doi.

org/10.3133/ofr20131287.

Liu, Y., Engel, B.A., Flanagan, D.C., Gitau, M.W., McMillan, S.K., and Chaubey, I., 2017, A review on effectiveness 

of best management practices in improving hydrology and 

water quality: Needs and opportunities: Science of the Total 

Environment, v. 601-602, p. 580-593, accessed August 21, 

2018, at http://doi.org/10.1016/j.scitotenv.2017.05.212.

Phillips, S.W., ed., 2007, Synthesis of U.S. Geological Survey 

science for the Chesapeake Bay ecosystem and implications 

for environmental management: U.S. Geological Survey 

Circular 1316, 63 p., accessed August 21, 2018, at https://

pubs.usgs.gov/circ/circ1316/.

U.S. Environmental Protection Agency, 2010a, Chesapeake 

Bay TMDL Executive Summary, accessed January 11, 

2017, at https://www.epa.gov/sites/production/files/2014-12/

documents/bay_tmdl_executive_summary_final_12.29.10_

final_1.pdf.

U.S. Environmental Protection Agency, 2010b, Chesapeake 

Bay Phase 5.3.0 Community Watershed Model: Annapolis, Maryland, U.S. Environmental Protection Agency, 

Chesapeake Bay Program Office, EPA 903S10002 - CBP/

TRS-303-10, December 2010, accessed January 11, 2017, 

at http://ches.communitymodeling.org/models/CBPhase5/

documentation.php.

Wastewater Technical Workgroup (WTWG), 2013, Minutes 

of the Chesapeake Bay Program Watershed Technical 

Workgroup Conference Call, July 8, 2013, accessed January 11, 2017, at https://www.chesapeakebay.net/channel_

files/19141/wtwg_070813_minutes_final_draft.pdf. 
For additional information, contact:

Director, MD-DE-DC Water Science Center

U.S. Geological Survey

5522 Research Park Drive

Baltimore, MD 21228

or visit our website at:

http://md.water.usgs.gov/

Publishing support provided by West 

Trenton Publishing Service Center
Sekellick and others

—Spatial and Temporal Patterns of Best Management Practice Implementation in the Chesapeake Bay Watershed, 1985–2014

—Scientific Investigations Report 2018–5171

ISSN 2328-0328 (online)

https://doi.org/10.3133/sir20185171