NOAA Coastal Ocean Program

Decision Analysis Series No. 22

ENVIRONMENTAL AND 

AESTHETIC IMPACTS OF 

SMALL DOCKS AND PIERS

Workshop Report: Developing a ScienceBased Decision Support Tool for Small Dock 

Management, Phase 1: Status of the Science

Ruth Kelty and Steve Bliven

January 2003
DECISION ANALYSIS SERIES

The Decision Analysis Series has been established by 

NOAA’s Coastal Ocean Program (COP) to present 

documents for coastal resource decision-makers which 

contain analytical treatments of major issues or topics.

To learn more about the COP or Decision Analysis 

Series, please write:

NOAA Coastal Ocean Program

1305 East-West Highway

Silver Spring, Maryland 20910

phone: 301-713-3020

fax: 301-713-4044

web: www.cop.noaa.gov
Science for Solutions

NOAA’s COASTAL OCEAN PROGRAM

Decision Analysis Series Number 22

ENVIRONMENTAL AND AESTHETIC IMPACTS OF 

SMALL DOCKS AND PIERS

Workshop Report: Developing a Science-Based Decision Support 

Tool for Small Dock Management, Phase 1: Status of the Science

Ruth Kelty

Steve Bliven

January 2003

U.S. DEPARTMENT OF COMMERCE

Donald L. Evans, Secretary

National Oceanic and Atmospheric Administration

Vice Admiral Conrad C. Lautenbacher, Jr., U.S. Navy (Ret.), 

Undersecretary for Ocean and Atmosphere

National Ocean Service

Jamison S. Hawkins, Acting Assistant Administrator

National Centers for Coastal Ocean Science

Gary C. Matlock, Director
Report Authors

Ruth Kelty, National Centers for Coastal Ocean Science

Steve Bliven, Bliven and Sternack

Workshop Participants

Clark Alexander, Skidaway Institute of Oceanography

Rick Ayella, Maryland Department of the Environment

David Blatt, Connecticut Department of Environmental Protection

Steve Bliven, Bliven & Sternack

Jerry Brashier, Mississippi Division of Marine Resources

Dave Burdick, Jackson Estuarine Laboratory, University of New Hampshire

Alison Castellan, NOAA Ocean Service, Office of Ocean and Coastal Resource Management,

Richard Chinnis, South Carolina Dept. of Health & Env. Control, Office of Coastal Resource Management

Rick Crawford, Nautilus Environmental Services

Torrance Downes, Connecticut River Estuary Regional Planning Agency

Judy Gates, Maine Department of Environmental Protection, Division of Land Resource Regulation

Andrea Geiger, Coastal States Organization

Truman Henson, Massachusetts Office of Coastal Zone Management

Mike Johnson, NOAA Fisheries Service, Northeast Regional Office

Ruth Kelty, NOAA Ocean Service, National Centers for Coastal Ocean Science

Dave Killoy, US Army Corps of Engineers, New England District

Mike Ludwig, NOAA Fisheries Service, NE Fisheries Science Center

Regan Maund, Urban Harbors Institute, University of Mass., Boston

Bill Moyer, Delaware Dept. of Natural Resources & Environmental Control, Division of Water Resources

Ed Reiner, US EPA Region 1

Steve Resler, New York Department of State

Steve Rumrill, South Slough National Estuarine Research Reserve

Denise Sanger, South Carolina Div. of Nat. Res., Mar. Res. Div., Mar. Res. Research Institute

Deborah Shafer, US Army Corps of Engineers, Waterways Experimental Station

Richard Smardon, SUNY -ESF Syracuse

Susan Snow-Cotter, Massachusetts Office of Coastal Zone Management

Ron Thom, Battelle Marine Sciences Laboratory

Peddrick Weis, UMDNJ - New Jersey Medical School

This publication should be cited as: Kelty, R.A. and S. Bliven. 2003. Environmental and Aesthetic 

Impacts of Small Docks and Piers, Workshop Report: Developing a Science-Based Decision Support 

Tool for Small Dock Management, Phase 1: Status of the Science. NOAA Coastal Ocean Program 

Decision Analysis Series No. 22. National Centers for Coastal Ocean Science, Silver Spring, MD. 69 pp.

This publication does not constitute an endorsement of any commercial product or intend to be an 

opinion beyond scientific or other results obtained by the National Oceanic and Atmospheric 

Administration (NOAA). No reference shall be made to NOAA, or this publication furnished by 

NOAA, in any advertising or sales promotion which would indicate or imply that NOAA 

recommends or endorses any proprietary product mentioned herein, or which has as its purpose 

an interest to cause directly or indirectly the advertised product to be used or purchases because 

of this publication.
Note to Readers

Environmental and Aesthetic Impacts of Small Docks and Piers is the proceedings from a January 2003 

workshop sponsored by the National Centers for Coastal Ocean Science (NCCOS). The workshop,

which focused on the status of the science, is the first of a series designed to support the development of 

a science-based decision support tool for small dock management. Future workshops will synthesize 

information on regulatory, non-regulatory, and construction tools available to improve the management, 

and reduce the environmental impacts, of small docks and piers.

The NCCOS provide a focal point through which NOAA, together with other organizations with 

responsibilities for the coastal environment and its resources, can make significant strides toward finding 

solutions to critical problems. By working together toward these solutions, we can ensure the 

sustainability of these coastal resources and allow for compatible economic development that will

enhance the well-being of the Nation now and in future generations.

A specific objective of the NCCOS is to provide the highest quality of scientific information to coastal 

managers in time for critical decision-making and in formats useful for these decisions. To this end, the 

Decision Analysis Series was developed by the Coastal Ocean Program to synthesize information on 

issues of high priority to coastal managers. As a contribution to the Decision Analysis Series, this report 

provides a critical synthesis of the potential consequences of the construction, presence, and use of small 

docks and piers on the coastal environment. A list of other available documents in the Decision Analysis 

Series can be found on the last page of this report.

As with all of its products, the NCCOS is interested in ascertaining the utility of Environmental and 

Aesthetic Impacts of Small Docks and Piers, particularly in regard to its application to the management 

decision process. Therefore, we encourage you to write, fax, call or email us with your comments.

Please be assured that we will appreciate these comments, either positive or negative, and that they will 

help us direct our future efforts. Our contact information is below.

Gary C. Matlock, Ph.D.

Director

National Centers for Coastal Ocean Science

1305 East-West Highway, Silver Spring, Maryland 20910

phone: 301-713-3020 fax: 301-713-4353 email: nccos.webmaster@noaa.gov

web: https://coastaloceanscience.nos.noaa.gov

TABLE OF CONTENTS

Introduction 1

The Workshop 3

Background Paper 4

Workshop Agenda 17

Summary of the workshop 

Management Context 18

Panel on Impacts to Vegetation from Docks 20

Panel on Impacts from Contaminants Related to Docks 30

Panel on Impacts from Associated Boating Use 35

Panel on Impacts to Navigation and Riparian Uses 40

Panel on Impacts to Aesthetics and Quality of Life Issues 41

Managers’ Response 53

Recommendations 55

Research Needs 58

Bibliography resulting from the workshop 58

An online bibliography has been posted on the NCCOS web site.

Future Steps 59

Appendix 1. Attendees’ contact information 60
1

INTRODUCTION

Statement of Problem

Few issues confronting coastal resource

managers are as divisive or difficult to manage as 

regulating the construction of private recreational

docks and piers associated with residential

development. State resource managers face a 

growing population intent on living on or near the 

coast, coupled with an increasing desire to have 

immediate access to 

the water by private 

docks or piers. 

The numbers of

requests for permits 

to construct docks,

and the numbers of 

docks constructed

and used throughout 

the nation’s coastal

areas, have

increased in recent

years (e.g. see Fig. 

1). A strong

economy, the associated increase in

discretionary spending, increasing boat sales, 

and limited mooring and public docking facilities 

all contribute to the trend. These docks and the 

vessels using them impact:

• natural resources and their use,

• aesthetic values, including natural and

development area characteristics, and

• public access and uses of shoreline and

nearshore areas.

Coastal managers and others have indicated

there is a need for better understanding of the 

individual and cumulative effects of residential docks 

and the uses associated with them. Ideally, this

improved understanding would result in better aquatic 

management that ensures that additional docks: (1) 

do not harm the environment, (2) provide waterfront 

property owners reasonable access to the water if 

they choose to have it, and (3) do not adversely

affect public access,

navigation, or other

uses of the aquatic

environment.

The Coastal Zone

Management Act of

1972 (CZMA)

encourages states to

“exercise their full

authority over the lands 

and water in the coastal 

zone.” In this broadly 

stated goal, the CZMA 

recognizes the need for 

each state to develop a coastal management

program tailored to its unique needs and

circumstances. Nearly all coastal states and

territories have responded by developing programs 

that include various means of regulating and

managing docks and piers.

Dock authorizations are now the single most

frequently sought permit from coastal managers.

Among a significant segment of the public, there is a 

perceived “right” to have a dock. For example, 90% 

of coastal South Carolina residents surveyed in 2001 

want a dock, 86% felt docks increased their property 

value, and 73%

thought they should be 

allowed to build one

(Felts et al. 2001).

Many people consider 

private residential

docks a normal and

characteristic part of

the coastal landscape 

and often do not

understand why they

must undergo a long

and arduous permit

review process.

Others, however,

consider docks a

80

581

710 701

765

623 655

812

717

816

0

100

200

300

400

500

600

700

800

900

1982199219941995199619971998199920002002

year

permits issued in SC

Figure 1. Increase in permits issued for dock construction in South Carolina.
2

threat to public values and the environment, and 

question why they are allowed at all. As coastal 

areas are developed and the number of permit 

requests increases, coastal managers are

looking for a rational, science-based decisionmaking tool to guide their regulatory decisions.

As with other coastal activities, the construction 

and use of private residential docks can create a 

range of impacts—depending on both

geographically site-specific factors and the

perspective of the observer. There is

considerable evidence that docks shade, alter 

patterns of water flow, introduce chemicals into 

the marine environment, and impact public

access and navigation. The vessels using

docks also affect resources and human uses to 

varying degrees. However, scientific

investigations and resulting literature quantifying 

the biological effects associated with individual 

and cumulative impacts are limited.

Furthermore, the existing literature is not well 

known or understood by the general public.

Background to the workshop

State and local governments in Alabama,

Connecticut, Georgia, Massachusetts, New

Hampshire, Rhode Island, and South Carolina 

are currently reviewing or revising the manner in 

which they manage docks and piers. In

November 2000, a one-day workshop on dock 

and pier science and management was held as 

part of the Northeast Regional Coastal Zone

Management Program Manager’s Meeting.

Southern and Caribbean managers expressed 

interest in a similar workshop at their 2001

regional meeting. In response, OCRM hosted a 

special session at the Coastal Zone ‘01 conference in 

Ohio on management of docks and piers. This was 

followed by a cover story in the fall issue of NOAA’s 

Coastal Services magazine.

Feedback from these initial efforts indicates that state 

managers see a need for credible, relevant, and high 

quality scientific analysis of the issue. They have 

asked NOAA’s National Ocean Service for further

assistance in developing the proposed tools and

expressed a willingness to help with the workshops 

and assessments. 

The workshop described in this document is an initial 

step in this effort—an effort to assess the state of

knowledge about the impacts of small docks on both 

the natural environment and human uses thereof.

Further efforts may explore various means currently 

available to minimize or alleviate the various impacts, 

as well as their economic and social costs. Finally, 

funding and support will be sought for a similar

working session on the regulatory and non-regulatory

tools available for management of docks.

NOAA’s Coastal Services Center (CSC) is presently 

conducting an assessment of laws, regulations, and 

policies pertaining to dock management for the

southeastern U.S. (the states of North Carolina,

South Carolina, Georgia and Florida). Over time, it is 

hoped that this effort will be expanded to include 

many of the remaining 29 coastal states and

territories and to compile the information into a

searchable database. Such a system would facilitate 

state-to-state interaction and comparisons, allowing 

managers to see how similar regions have dealt with 

specific permitting issues.
3

THE WORKSHOP

On 22–23 January 2003, NOAA's National Centers for Coastal Ocean Science hosted a workshop at the 

University of Massachusetts Boston to review the available scientific knowledge about the impacts of 

small, recreational docks. Twenty-two scientists and eight managers representing the Southeast, Gulf 

Coast, Mid-Atlantic, Northeast, Great Lakes, and Pacific regions discussed what is known (and not 

known) about how docks and associated boating activities individually and collectively impact vegetation, 

sediments and sedimentation, contamination, navigation and public trust rights and interests, and

aesthetics/quality of life.

The workshop focused on relatively small, recreational docks associated with residential use. These 

generally consist of a pile-supported walkway leading from the shore into the water and often have a float 

at the water end of the structure. Floats may be bottom anchored or held in place by piles. The 

structures may be used for boat landings, fishing, relaxing, or similar uses.

Workshop Objectives

• Synthesize existing scientific information on 

direct, cumulative, and secondary effects of 

small docks on the coastal environments 

and their users.

• Identify gaps in research results related to 

the impacts of small docks.

• Assess susceptibility of regions to the

negative impacts associated with docks.

Desired Outcomes

• A summary of existing scientific knowledge 

that can help managers guide the

implementation, development, or revision of 

federal, state, and local dock regulations.

• Identification of key elements needed by 

managers to effectively evaluate permit

requests or develop area-wide plans.

• Identification of gaps in research on the

environmental, social, and economic

impacts of small docks.

• Development of a work plan to formulate 

assessment protocols needed to guide

management actions, including a prioritized 

listing of research needs.

Workshop Products

The desired outcomes of the workshop were

intended to be reflected in the following specific 

products discussed in this document:

• A report summarizing the state of existing 

scientific knowledge pertaining to the

impacts from small docks,

• A bibliography of publications pertaining to 

the science and management of small

docks, and

• A prioritized list of research needs. 

Discussion Topics

Workshop discussions were designed to

address the following topics:

• vegetation,

• contaminants,

• boating impacts, 

• navigation, and

• aesthetics.

These discussions led to a series of

recommendations for consideration by those

involved in residential dock and pier regulation,

construction, and use.
4

Background Paper

Developing a Science-Based Decision 

Support Tool for Small Dock Management:

Status of the Science

Document prepared by:

Steve Bliven, 

Bliven and Sternack Phone: (508) 997-3826

49 Plains Field Drive Fax: (508) 997-3859

South Dartmouth, MA 02748 E-mail: Bliven@attbi.com
5

Introduction

Purpose of the document:

The following document is intended to provide a general background for participants at the workshop on 

“Developing a Science-Based Decision Support Tool for Small Dock Management: Phase I: Status of the 

Science” to be held on 22–23 January 2003 at the University of Massachusetts Boston. It is not intended 

to be a comprehensive survey of the literature related to small docks and their impacts; only as an 

introduction to the various topics to be discussed.

Definition of small docks for the purpose of this paper and workshop:

The focus at the workshop will be on small, recreational docks designed for residential use. They 

generally consist of a pile-supported walkway leading from the shore into the water and often have a float 

at the water end of the structure. Floats may be bottom anchored or held in place by piles. The 

structures may be used for boat landings, fishing or similar uses.

Purposes of the Workshop

1. To synthesize existing scientific information on direct, cumulative, and secondary effects of small 

docks on the coastal environments and their users,

2. To identify gaps in research results related to the impacts of small docks, and

3. To assess susceptibility of regions to the negative impacts associated with docks.

Desired Outcomes:

• A summary of existing scientific knowledge that can help managers to guide the implementation, 

development, or revision of federal, state, and local dock permitting processes to include 

identification of key elements needed by managers to effectively evaluate a permit request or in 

the development of an area-wide plan.

• Identification of gaps in research on the environmental, social, and economic impacts of small 

docks. Development of a work plan to formulate assessment protocols needed to guide 

management actions, including a prioritized listing of research needs.

Workshop Products:

• A report summarizing the state of existing scientific knowledge pertaining to the impacts from 

small docks,

• A bibliography of publications pertaining to the science and management of small docks,

• A prioritized listing of research needs, and 

• A check-list of known impacts from small docks.
6

Impacts on Vegetation

Vegetation is critical as a food source, habitat, and protection against erosion—both on the shore or 

marsh and submerged below the water line.

Impacts to plant productivity generally occur in one of two ways:

• Short-term construction impacts

• Chronic impacts from shading

Construction Impacts

Activities during construction can destroy plants either above the tide line (e.g., Spartina or Distichlis) or 

below (e.g., Zostera or Halodule) by pulling them from the substrate or destroying their root system. The 

peat beds underlying salt marshes can be compacted through the improper use of heavy equipment.

Although these impacts are seemingly evident, limited research appears to have been done on the longterm impacts of these activities.

In sea grass beds, the installation of pilings may have immediate impacts as well as cause long-term

changes. Installation through “jetting” with high-pressure hoses typically disturbs a surrounding area—

depopulating grasses there prior to construction. Once areas are depopulated, the presence of pilings 

may lessen chances of regrowth. Beal, Schmit, and Williams (1999) suggest that changes in seagrass 

communities in the vicinity of pilings may be caused by the modification of currents, sediment deposition, 

attraction of bioturbators, and leaching from chemically treated wood. Shafer and Robinson (2001) 

tracked the regrowth of Halodule wrightii beneath docks in St. Andrew Bay, FL. They noted bare areas 

from 35–78 inches in diameter around pilings, even though the docks had been constructed at various 

times, suggesting that regrowth is affected by the presence of pilings. The authors found that where piles 

were installed using low-pressure jetting techniques there was, “little or no sand deposition around the 

pilings and the remaining seagrasses around the pilings looked healthy and had good growth around the 

piling.”

Sanger and Holland (2002) noted a path along each side of one new dock where vegetation had been 

almost totally destroyed, presumably during construction. Resurveying the site 15 months later the 

researchers found that S. alterniflora had recolonized the area and substantial recovery had occurred.

Chronic Shading Impacts

Both marsh grasses and sea grasses have adapted to living in extended periods of sunlight. Their

photosynthetic pathways vary from many terrestrial plants allowing them to be highly productive in their 

natural settings. Shading can have significant impacts on the health and productivity of these plants.

Shaefer and Robinson (2001) indicate that light levels of 13–14 percent of mean daily surface irradiance 

(SI) are necessary for survival of the seagrass Halodule wrightii. Shaefer (1999) also found that seagrass 

densities were 40–47 percent less in areas shaded at levels of 16–19 percent SI. The summary of a 

NMFS Technical Memorandum (Kenworthy and Haunert, 1991) noted that “the light requirements of 

temperate and tropical seagrasses are very similar” requiring “at least 15 to 25 % of the incident light just 

for maintenance.” Research by Koch and Beer (1994) indicate that light levels of 300 to 500 _Em-2

s

-1

 are 

necessary for Zostera survival in Long Island Sound and Narragansett Bay.

In a field study conducted in Waquoit Bay, Falmouth/Mashpee and Nantucket Harbor, Burdick and Short 

(1999) found that the most significant factors affecting shading impacts on eelgrass from boat docks with 

plank decking are height of the structure above vegetation, orientation of the dock (north-south versus 

east-west) and dock width. The National Marine Fisheries Service suggests that spacing between 

decking planks on the order of an inch or two has little effect on shading impacts. (Michael Ludwig, 

NMFS, Personal Communication).
7

Kearney et al. (1983) studied impacts to marsh grasses from walkways/docks. They assessed the 

impacts from “all the structures” within Connecticut’s major salt marsh regions, collecting data on 

vegetation density and height beneath and adjacent to the structures, and the physical dimensions of the 

docks (width, height, plank width and spacing between planking—they did not include orientation). They 

found that dock height was the only statistically significant variable. They further reported that the 

vegetation density of low marsh grasses (Spartina alterniflora) was affected less by shading than high 

marsh grasses (S. patens and Distichlys spicata). The opposite trend was noted in vegetation height—

possibly due to etiolation. No measures of biomass were taken. Docks less than 30–40 cm (12–16

inches) above the marsh shaded out all vegetation in all of the study sites. A subsequent effect of the 

shading was reported to be accelerated soil erosion beneath structures passing over S. alterniflora at the 

edge of the marsh.

The NMFS (Colligan and Collins, 1995) assessed dock impacts on vegetation in Connecticut, Rhode 

Island, and Massachusetts with the results compiled in a “Pre-publication copy—not for distribution”. This 

study cast some doubt on the methodology and statistical analyses of Kearney et al (1983) but, because 

it has not been released in a final form, it is difficult to evaluate the results.

Maguire (1990) measured the effects of shading by open pile structures on S. alterniflora density in a 

fringe marsh in the York River Estuary (VA). The docks ranged in length between 15–20 m (~50–65 feet) 

and .6 m–2.4 m (2–8 feet) wide. A computer program was developed to calculate the total number of 

hours of shading produced by each structure based on height, width and orientation of the structure.

Based on the information from this program, correlation coefficients between shade duration and 

vegetation density were calculated These displayed a wide range (+ 0.03 to –0.93 with 60% falling 

between –0.70 and –0.93. The author attributes the wide range to a threshold phenomenon and that “a 

more refined measurement that can account for temporal differences in light intensities reaching 

vegetation as well as the response of the plant to the light that it receives may result in greater predictive 

powers.” The computer program developed as part of this project appears to hold promise as a predictive 

tool. Unfortunately, no electronic copies of the program remain (the text of the program is available) and 

it is written in Pascal. To be effective the program would have to be rewritten in a contemporary, and 

more user-friendly format.

Sanger and Holland (2002) assessed impacts from 32 docks in the Charleston, SC area on S. alterniflora.

The structures represented a range of lengths, orientations, and ages. The researchers noted that the 

plants under the docks were often taller than those adjacent to the dock. They suggested that this might 

be affected by fecal material from birds resting on the structures. Reviewing the data of Maguire (1990) 

the authors noted that the orientation of the docks did not seem to affect density.

Sanger and Holland (2002) then compared the area of marsh affected by docks to the total area within 

creek systems and across the state. Using the numbers of docks present in 1999, their findings resulted 

in an estimate of reduction in plant densities of between 0.03–0.72% of the total amount of S. alterniflora 

within local creek settings. Projected to total possible build-out of similarly sized docks in the creeks, 

these figures increase to 0.18–5.45% decrease in marsh grass. Expanded to the area of S. alterniflora in

the eight coastal counties in the state at projected year 2010 dock numbers at the maximum size 

presently allowable under regulation, an estimated density reduction of between 0.03–1.98% could be 

attributed to dock impacts.

As noted above, Maguire (1990) produced a program to predict the amount of shading over a season that 

would result from a dock of any given size. Burdick and Short (1998) prepared estimates of impacts to 

Zostera from docks of specific height, width, and orientation. They did not attempt to develop a process 

to assess the impacts from other sizes and orientation.

Questions for consideration:

1. Are the light level thresholds for maintenance or additional growth known for marsh grasses to a level 

of certainty to make defensible decisions?
8

2. Is it known which parameters of the dock structure are critical to predict impacts to vegetation—either

marsh grasses or seagrasses?

3. Is there a tool available, or could one be developed to predict the impacts of specific structures, given 

the design parameters?

4. The existing studies of marsh grasses looked at vegetation density and/or height. No measures of 

biomass were recorded. To provide a prediction of energy source to the food web (as opposed to 

appropriate habitat or erosion control), is this an important factor? If so has any research been done 

on this topic?

Bibliography:

Beal, J.L., B.S. Schmit, and S.L. Williams. 1999 “The effects of dock height and alternative construction 

materials on light irradiance (PAR) and seagrass Halodule wrightii and Syringodium filiforme cover.”

Florida Department of Environmental Protection, Office of Coastal and Aquatic Managed Areas (CAMA).

CAMA notes.

Burdick, D.M. and F.T. Short. 1998. “Dock Design with the Environment in Mind: Minimizing Dock 

Impacts to Eelgrass Habitats.” An interactive CD ROM published by the University of New Hampshire, 

Durham, NH.

Burdick, D.M. and F.T. Short. 1999. “The Effects of Boat Docks on Eelgrass Beds in Coastal Waters of 

Massachusetts.” Environmental Management, 23 (2): 231–240.

Colligan, Mary and Cori Collins. 1995. “The Effect of Open-Pile Structures on Salt Marsh Vegetation”. 

NOAA/NMFS Habitat and Protected Resources Division. Pre-publication copy–not for distribution. 44p.

McGuire, H.L. 1990. “The Effects of Shading by Open-pile Structures on the Density of Spartina

alterniflora.” Unpublished Master’s Thesis from the Virginia Institute of Marine Science. 

Kearney, V., Y. Segal and M.W. Lefor. 1983. “The Effects of Docks on Salt Marsh Vegetation”. The 

Connecticut State Department of Environmental Protection, Water Resources Unit, Hartford, CT. 06106.

22p.

Kenworthy, Judson W. and Daniel E. Hauners (eds.) 1991. “The Light Requirements of Seagrasses;

proceedings of a workshop to examine the capability of water quality criteria, standards and monitoring 

programs to protect seagrasses.” NOAA Technical Memorandum NMFS-SEFC-287. NMFS Beaufort 

Laboratory, Beaufort, NC 28516-9722.

Koch, E.W. and S. Beer. 1996. “Tides, light and the Distribution of Zostera marina in Long Island Sound, 

USA.” Aquatic Biology. 53: 97–107.

Sanger, DM and AF Holland. 2002. “Evaluation of the Impacts of Dock Structures on South Carolina 

Estuarine Environments.” SC Department of Natural Resources, Marine Resources Division Technical 

Report Number 99. Charleston, SC.

Shaefer, D. 1999. “The Effects of Dock Shading on the Seagrass Halodule wrightii in Perdido Bay, 

Alabama.” Estuaries 22 (4): 936–943.

Shaefer, D. and J. Lundin. 1999. “Design and Construction of Docks to Minimize Seagrass Impacts.”

US Army Corps of Engineers WRP Technical Note VN–RS–3.1 June 1999. Available at 

www.wes.army.mil/el/wrtc/wrp/tnotes/vnrs3-1.pdf

Shaefer, D and J. Robinson. 2001. “An evaluation of the use of grid platforms to minimize shading 

impacts to seagrasses.” WRAP Technical Notes Collection (ERDC TN-WRAP–01–02. US Army 

Engineer Research and Development Center, Vicksburg, MS. Available at www.wes.army.mil/el/wrap.
9

Impacts from Contaminants

Small docks and piers in coastal waters, either pile supported or floating, are not apt to have a 

measurable effect on levels of dissolved oxygen or temperature. Such structures are generally too small 

and, except in the most closed of lagoons or canals, the movement of coastal waters is sufficient to avoid 

such impacts.

The most common contaminant-related concern related to docks is leaching from preservatives applied to 

pilings or floats in locations that come into regular contact with water.

Oil based preservatives containing creosote (CRT) or pentachlorophenol (PCP), applied to the surface of 

wood materials, leach readily and have demonstrated toxic effects. Most states have banned their use in 

aquatic settings.

Wood pressure-treated with a chromated copper arsenate (CCA) is the most commonly used material for 

pilings and decking for small docks. The form of CCA most often seen is comprised of 47.5% hexavalent 

chromic oxide, 18.5% curpic oxide, and 34% arsenic pentoxide. Research has shown that in fact some 

leaching does occur in saline waters (Weis et al., 1991,1992). There has been extensive study of the 

toxicity of these compounds in the marine environment that suggests that the degree of toxicity depends 

on the chemical form as it reaches the target organism. The forms will change over time and in response 

to sediment types, amounts of organic material present, oxygen levels and water movement (Luoma and 

Carter, 1991).

Laboratory studies by Weis et al. (1991, 1992) have shown that leachate from CCA -treated wood can be 

toxic to estuarine species. Leaching decreases by about 50% daily once the wood is immersed in 

seawater. Approximately 99% of the leaching occurs within the first 90 days (Cooper, 1990, Brooks 

1990; in Sanger and Holland, 2002).

Elevated concentrations of metals from CCA-treated woods can be found in organisms living on treated 

pilings and in the areas near to the pilings (Wendt et al., 1996; Weis and Weis, 1996) Field studies by 

Weis et al. (1998) found elevated concentrations of metals in fine sediments adjacent (within 1 meter) of 

bulkheads constructed of CCA -treated material. At a limited number of sites elevated concentrations 

could be seen at greater distances. In an unpublished “grey literature” study prepared for the New Jersey 

Department of Environmental Protection however, Weis and Weis (1998) did not observe “any evidence 

that CCA dock pilings are a source of metal contaminants in the Navesink/Shrewsbury Rivers.” Pedrick 

Weis reported similar findings at a Massachusetts Coastal Zone Management workshop in 2000. Sanger 

and Holland (2002) report that, “it is unlikely that the bioaccumulation of dock lechates by marine biota is 

having or is likely to have an impact on living resources in South Carolina estuaries and tidal creeks.”

Reasons given are that the leaching generally occurs only when the dock is new, that the size of the area

around the dock that might be affected is small, and high rates of tidal flushing will dilute and flush any 

accumulations in the water column.

Questions to consider:

1. Are there demonstrated impacts from preservatives used for the protection of wooden portions of 

small docks? If so, what are the impacts?

2. Are there other contaminants of concern can be linked to small docks (as opposed to impacts 

from associated boating which will be discussed later)?

Bibliography:

Brooks, K.M. 1996. “Evaluating the environmental risks associated with the use of chromated copper 

arsenate-treated wood products in aquatic environments.” Estuaries 19(2A):296–305.

Cooper, P.A. 1990. “Leaching of CCA from Treated Wood.” Proc. Canadian Wood Preservation 

Association II: 144–169.
10

Luoma, S.N. and Carter, J.L. 1991. “Effects of trace metals on aquatic benthos.”. in Newman, M.C. and 

McIntosh, A.W., Eds., “Metal Ecotoxicology: Concepts and Applications”, Chelsea, MI., Lewis Publishers, 

p. 261–300.

Sanger, D.M. and A.F. Holland. 2002. “Evaluation of the Impacts of Dock Structures on South Carolina 

Estuarine Environments.” SC Department of Natural Resources, Marine Resources Division Technical 

Report Number 99. Charleston, SC.

Weis, P., J.S. Weis, and L.M. Coohill. 1991. “Toxicity to Estuarine Organisms of Leachates from 

Chromated Copper Arsenate Treated Wood.” Archives of. Environmental Contamination and Toxicology. 

20: 118–124.

Weis, P., J.S. Weis, A. Greenberg, and T.J. Nosker. 1992 “Toxicity of Construction Materials in the 

Marine Environment: A Comparison of Chromated-Copper-arsenate-Treated Wood and Recycled 

Plastic.” Archives of Environmental Contamination and Toxicology. 22: 99–106.

Weis, J.S. and P. Weis. 1996. “The effects of using wood treated with chromated copper arsenate in 

shallow water environments: a review.” Estuaries 19:306–310.

Weis, J.S. and P. Weis. 1998. “Effects of CCA Wood Docks and Resulting Boats on Bioaccumulation of 

Contaminants in Shellfish Resources: Final Report to DEP.” A report to the NJ DEP.

Wendt, P.H., R.F. Van Dolah, M.Y. Bobo, T.D. Mathews, and M.V. Levisen. 1996. “Wood Preservative 

Leachates from Docks in an Estuarine Environment.” Archives of Environmental Contamination and 

Toxicology, 31:71–79.

Boating Impacts

Most small docks are associated with boat traffic. Being situated at the interface between land and water, 

at least a portion of each dock is in the intertidal zone and extends through shallow areas. In many cases 

this leads to potential environmental impacts. In 1994, a workshop on the impacts of boating was held at 

the Woods Hole Oceanographic Institution. The results are summarized in Crawford et al. (1998). A 

number of potential boating-related impacts were discussed. While noting that there were adverse 

impacts, the presentations revealed that there were limited quantitative data available that could be used 

as the basis for management decisions—although it was agreed that sufficient data exist to “substantiate 

the inference that recreational ... motor boat traffic is far from a benign influence on aquatic and marine 

environments.” No differentiation was made between general boating activities and that taking place in 

the vicinity of docks.

A second symposium on the topic, “Impacts of Small Motorized Watercraft on Shallow Aquatic Systems” 

was held in 2000 at Rutgers. The results of this symposium were published in Kennish (2002).

Both workshops identified several issues of concern regarding boating activity including:

• Impacts to submerged aquatic vegetation,

• Contamination from fuel discharges,

• Erosion on shorelines, and

• Resuspension of bottom sediments and turbidity.

Impacts to submerged bottom vegetation.

Boat propellers can directly damage submerged aquatic vegetation in shallow waters (Thayer et al., 1975; 

Kruer, 1998; Burdick and Short, 1999); impacts that may take years to heal. Thallasia sp., for example,
11

can take four to six years to recolonize a prop scar (Kruer, 1998). Damage to the plants and their 

rhizome system often leads to both reduced habitat and destabilized sediments.

Contamination from fuel discharges:

Outboard motors associated with boating have long been associated with contamination of waterways.

Milliken and Lee (1990) provide a good summary of the early literature. Two-cycle engines release up to 

20% unburned fuel along with exhaust gases (Moore, 1998). Moore (1998) compared the PAH output 

from a two-cycle outboard engine with that from a four-cycle engine. Discharge from the two-cycle

contained five times as much PAH as from the four-cycle. Most of this difference was due to a reduction 

in discharge of 2- and 3-ring compounds—those that are generally considered acutely toxic—in the fourcycle. However, he found little difference between the levels of discharge of 4- and 5-ring compounds—

those generally related to chronic toxicity. Albers (2002) notes that PAH concentrations in the water 

column are “usually several orders of magnitude below levels that are acutely toxic”, but those in 

sediments may be much higher.

PAHs related to boating activities probably accumulate in bottom sediments (Sanger et al. 1999) where 

they may be stirred up by boat traffic (Albers, 2002). However, Sanger and Holland (2002) were not able 

to distinguish PAHs from dock-related activities from other anthropogenic sources.

Erosion on shorelines:

Many studies have related boat wakes with shore erosion (e.g., Zabawa et al. 1980; Camfield et al. 1980;

Hagerty et al., 1981). Most of these relate to boats moving at or near hull speed through waterways.

There was little found in the literature that pertained specifically to boats maneuvering near docks or 

landing areas.

Resuspension of bottom sediments and turbidity:

Running a motorized boat through shallow waters produces two distinct types of wake: 1) the surface bow 

wake that can lead to erosion of the shoreline as discussed above and 2) a pressure wave formed 

beneath the boat hull that can impact the bottom (Crawford, 1998). Crawford (1998) describes two 

components that make up the pressure wave; a low frequency wave caused by the motion of the hull 

through the water and higher frequency waves produced by the action of the propeller. The pressure 

wave does not fan out as does the surface wake and consequently has localized impacts. It is also a 

greater in slow-moving hulls, modern planning hulls have a far lesser impact on bottom sediments 

(Crawford, 1998; Hartge, 1998). Hartge (1998) also compared prop-driven boats with those that were 

water-jet propelled and noted no major differences between the amount of resuspension of sediments; he 

did note that slow-moving, heavy laden boats caused more turbidity than lighter, faster-moving boats.

Passage of slow-moving boats in shallow waters over fine sediments will produce turbidity, but Crawford

(1998) found in Waquoit Bay, MA that this was a short-term phenomenon. Ambient light sufficient for 

maintenance of eelgrass was restored within 10 minutes of the passage of a vessel. The suspension of 

bottom sediments also appears to be related to the presence of the odor of hydrogen sulfide.

Investigating impacts of bow waves from personal watercraft, Anderson (2000) found a wide range of 

settling times of resuspended sediments. Depending on the nature of the sediments, settling times 

ranged from 7 seconds to approximately 10 minutes.

Boats operating in the vicinity of docks are generally moving slowly so such impacts may be particularly 

significant to these areas, although this does not appear to be demonstrated in the literature reviewed for 

this paper.

“Prop dredging” is a specialized form of sediment suspension in which the propeller or water jets of a 

vessel are used to move sediments out of a particular area; either as a purposeful action or as a byproduct of boating use. This typically occurs where docks are of insufficient length to reach water depths 

appropriate to vessels being docked (Ziencina, 2002, pers. com.). This may lead to the loss of 

seagrasses in the vicinity of a dock (Burdick and Short, 1999) either through physical disruption of the 

vegetation or though burial by sediments.
12

Questions to consider:

1. What boating impacts have been sufficiently defined that they can form the basis of defensible 

management decisions?

2. What other impacts should be evaluated?

3. Are the impacts of boating as related to docks significantly different from those of general boating? If 

so, what are the differences and what is known about them?

Bibliography:

Albers, P.H., 2002. “Sources, fate, and effects of PAHs in shallow water environments: a review with 

special reference to small watercraft.” In “Impacts of Motorized Watercraft on Shallow Estuarine and 

Coastal Marine Environments.” Journal of Coastal Research Special Issue 37. Michael Kennish, ed.

Anderson, Franz. 2000. “Effect of Wave-wash from Personal Watercraft on Salt Marshes”. A final report 

submitted to the NOAA/UNH Cooperative Institute for Coastal and Estuarine Environmental Technology 

(CICEET).

Burdick, D. M. and F. T. Short. 1999. “The Effects of Boat Docks on Eelgrass Beds in Coastal Waters of 

Massachusetts.” Environmental Management, 23(2): 231–240.

Camfield, F. E., R.E.L. Ray and J.W. Eckert. 1980. “The Possible Impact of Vessel Wakes on Bank 

Erosion.” Prepared by USACOE, Fort Belvoir, Virginia, for US Department of Transportation and US 

Coast Guard, Washington, D.C. Report No. USCG–W–1–80 114 pp. NTIS No. ADA-083-896.

Crawford, R. 1998. “Measuring Boating Effects of Turbidity in a Shallow Coastal Lagoon”. In “The 

Environmental Impacts of Boating: Proceedings of a workshop held at Woods Hole Oceanographic 

Insititution, Woods Hole, MA December 7–9 1994.” Technical Report WHOI-98-03. R. Crawford, N. 

Stolpe and M.Moore. Eds.

Crawford, R. N.Stolpe and M. Moore, Eds. 1998. “The Environmental Impacts of Boating: Proceedings 

of a workshop held at Woods Hole Oceanographic Insititution, Woods Hole, MA December 7–9 1994.” 

Technical Report WHOI-98-03

Hagerty, D. J., M.F. Spoor and C.R. Ullrich. 1981. “Bank Failure and Erosion on the Ohio River.”

Engineering Geology, 17:141–158.

Kennish, Michael J., (Editor). 2002. “Impacts of Motorized Watercraft on Shallow Estuarine and Coastal 

Marine Environments.” Journal of Coastal Research Special Issue 37.

Kruer, Curtis. 1998. “Boating Impacts On Seagrass Habitats In Florida.” In “The Environmental Impacts 

of Boating: Proceedings of a workshop held at Woods Hole Oceanographic Insititution, Woods Hole, MA

December 7–9 1994.” Technical Report WHOI-98-03. R. Crawford, N. Stolpe and M.Moore. Eds.

Hartge, P. 1998. “Boating Induced Turbidity.” In “The Environmental Impacts of Boating: Proceedings of 

a workshop held at Woods Hole Oceanographic Insititution, Woods Hole, MA December 7–9 1994.” 

Technical Report WHOI-98-03. R. Crawford, N. Stolpe and M.Moore. Eds.

Milliken, A. S., and V. Lee. 1990. Pollution impacts from recreational boating: A bibliography and 

summary review. Rhode Island Sea Grant. P 1134. RIU-G-90-002. 26 pp.

Moore, Michael. 1998. “Aromatic Hydrocarbons: Two-Cycle vs. Four-cycle.” In “The Environmental

Impacts of Boating: Proceedings of a workshop held at Woods Hole Oceanographic Insititution, Woods 
13

Hole, MA December 7–9 1994.” Technical Report WHOI-98-03. R. Crawford, N. Stolpe and M. Moore. 

Eds.

Sanger, D.M., A.F. Holland and G.I. Scott. 1999. “Tidal creek and salt marsh sediments in South 

Carolina Coastal Estuaries. I. Distribution of trace metals.” Archives of Environmental Contamination 

and Toxicology 37:936–943.

Sanger, DM and AF Holland. 2002. “Evaluation of the Impacts of Dock Structures on South Carolina 

Estuarine Environments.” SC Department of Natural Resources, Marine Resources Division Technical 

Report Number 99. Charleston, SC.

Thayer, G.W., D.A. Wolff and R. B. Williams. 1975. “The Impact of Man on Seagrass.” American

Scientist 63:288–296.

Zabawa, C., C. Ostrom, R. J. Byrne, J. D. Boon III, R. Waller, and D. Blades. 1980. Final report on the 

role of boat wakes in shore erosion in Anne Arundel County, Maryland. Tidewater Administration, 

Maryland Dept. of Natural Resources. 12/1/80. 238 pp

Ziencina, Mitchell. 2002. Personal Communication. Massachusetts Department of Environmental 

Protection, Lakeville, MA.

Impacts on Sediments and Sedimentation

It has been suggested that pile-supported docks may cause changes to sediments and habitats in the 

vicinity of the structure. This may occur through erosion, increased sedimentation, or resuspension and 

movement of specific particulate sizes or types. Three principal impacts from docks have been discussed 

in the literature or in review of proposed construction.

• Altering currents in the vicinity of the dock due to pilings disrupting flow or inducing scour in the 

immediate vicinity of the piling,

• Disrupting sediments during piling installation,

• Suspension of sediments as floats or boats attached to docks touch or approach bottom at low 

tides and lift sediments as they rise with the tide (“pumping”).

Structures placed in moving water have the capability to disrupt the water’s flow. Piles may cause 

increased flow rates immediately around the structure. These modifications in the flow of water may 

produce scour and erosion or increased deposition of sediments depending on the conditions and 

structure. Either of these may affect shellfish or wildlife habitats.

There appears to be very limited research results available on the impacts on sedimentation from small 

pile supported structures. What research has been reported was done in open ocean settings, not in 

embayments, and most focused on the morphological changes to adjacent shorelines and bottom 

topography—no information was located on the nature of sediment type change, if any, over time in the 

vicinity of pile-supported piers.

Noble (1978) assessed the impacts of 20 piers—all situated within the Southern California Bight. These 

piers ranged from 625–2,500 feet in length and 15–300 feet in width—far larger than the small 

recreational facilities under consideration here. All of the piers studied had pile spacing greater that 4 

times the diameter of the piles. Noble found that these piers “had a negligible effect” on sedimentation 

and erosion of adjacent shorelines. He notes that his results support prior findings of Johnson (1973) and 

Evert and DeWall (1975).
14

Miller et al., (1983), researching the impacts of a 1,840 foot long, 20 foot wide pier near Duck, NC on the 

Atlantic coast found that the pier produced a permanent trough under the pier reaching a maximum depth 

of 9.9 feet. Scour around individual pilings was noted to be on the order of 3.3 feet in depth. The pilings 

in this case are 30 and 36 inches in diameter spaced 15 feet on center across the pier and 40 feet on 

center along its length.

In an engineering study related to Lagoon Pond on Martha’s Vineyard, MA (Poole, 1987) suggests that, 

“At a wind angle of 90o to a 50-foot pier with 5 pilings on each side [diameter of pilings not noted–SB.] can 

[sic] produce eddy currents and flow friction 2 times the diameter of the pilings—minimally. This 

means...a 30 percent reduction in flow. The area or parallel shoreline affected by the flow reduction 

would be a factor of 2 to 3 times the pier length. Properties within 100 feet to 150 feet of a 50–foot pier 

could be subjected to wrack algae accumulation, sand deposition and shellfish population changes.” This

evaluation cites no research results and is based on predictive engineering calculations.

Anecdotal evidence suggests that the method of piling installation has varying impacts on sediments in 

the vicinity of a dock (Ziencina, 2002 pers. com.) Jetting of pilings tends to cause greater disruption than 

driving. Jetting suspends sediments and disrupts vegetation producing bare areas around pilings that 

appear to be subject to scour. Shaefer (2001) found that using a low pressure pump to produce a starter

hole and subsequent insertion of a sharpened pile with a drop hammer in a sandy area “reduces the 

physical removal and disturbance” of seagrasses in the area of the piling and results in little to no sand 

deposition around the pilings.

Observational evidence indicates that changes in sediments occur when floats settle on the bottom at low 

tide. As the floats rise they create a suction bring with it sediments. As wave action lifts and lowers the 

float, sediment is “pumped” into resuspension. Additionally wave refraction in a downward direction may 

also resuspend some sediments (Ludwig, 2003, pers. com.).

Questions for consideration:

1. What permanent impacts in sediment topography and type are produced by individual or 

collections of small, recreational, pile-supported docks—either on the open coast or in 

backwaters?

2. What are the impacts of various means of pile insertion in different settings?

3. What are the levels of impact from “pumping” due to floats settling on or near the bottom at low 

tides?

Bibliography:

Evert, C.H., and A.E. DeWall. 1975. “Coastal Sand Level Changes in North Carolina”. Draft Report, 

Coastal Engineering Research Center, US Army Corps of Engineers.

Johnson, J.W. 1973. Proposal preparation for Department of Navigation and Ocean Development.

Unpublished information.

Ludwig, Michael. 2003. National Marine Fisheries Service, Milford (CT) Laboratory.

Miller, H.C., W.A. Birekmeir, and A.E. DeWall. 1983. “Effects of CERC Research Pier on Nearshore 

Processes.” US Army Coastal Engineering Research Center. Reprint 83-13.
15

Noble, Ronald. 1978. “Coastal Structures’ Effects on Shorelines.” In Proceedings of the Sixteenth 

Coastal Engineering Conference, v. III. American Society of Civil Engineers. New York, NY.

Poole, Bruce M. 1987. “Diagnostic/Feasibility Study for Lagoon Pond Oak Bluffs, Tisbury, MA” SP 

Engineering, Inc. Salem MA

Shaefer, D and J. Robinson. 2001. “Evaluation of the use of grid platforms to minimize shading impacts 

to seagrasses.” WRAP Technical Notes Collection (ERDC TN–WRAP–01–02. U.S. Army Engineer 

Research and Development Center, Vicksburg, MS. Available at www.wes.army.mil/el/wrap.

Ziencina, Mitchell. 2002. Personal Communication. Massachusetts Department of Environmental 

Protection, Lakeville, MA.

Aesthetics/Quality of Life Impacts

From a manager’s perspective, oftentimes the publicly-held concerns related to small docks are not really 

related to the environment. They may be aesthetic in nature, a sense of over-development of the shore, 

or simply change. It is not uncommon for managers to hear very vocal outcries from one segment of the 

population while the rest remains quiet—the manager generally has no idea whether this silence means 

acquiescence or simply no opinion.

In an attempt to get a better sense of public sentiment regarding docks in South Carolina, Felts et al.

conducted surveys of the opinions of residents of coastal counties in the state (2001) and of dock owners 

(2002). Some of their major findings include:

• 75% of the residents of coastal counties feel that property owners should be able to construct a 

dock.

• 66% of the dock owners feel that docks should be regulated but only 50% of the residents feel the 

same way. The authors offer two possible interpretations for the stronger acceptance of 

regulation by dock owners: 1) they have their dock and would like future construction restricted or 

2) they better understand the need to manage docks as they are closer to the issue.

• 75% of the dock owners feel that the length of docks should be restricted; nearly 80% feel that 

the size should be restricted. In contrast, only 50% of the general public feels length should be 

restricted.

• Approximately 20% of both the dock owners and the general public felt that docks are harmful to 

the aquatic environment.

• 20% of the owners and 25% of the general public felt that docks detracted from the view of the 

waterbody and shoreline.

• Approximately 75% of both dock owners and the general public feel that there are not too many 

docks.

It is not clear whether these findings are transferable to other settings along the coast—other states or 

regions within those states.
16

The aesthetic appeal of docks is an individual assessment. However, techniques have evolved that 

appear to provide a reproducible or predictive assessment of the aesthetic values of an area and how 

those might change with development. As seen in Felts et al. (2001, 2002), a survey will provide some 

sense as to the feelings of the public regarding docks, although these feelings may change when applied 

to specific sites.

An assessment method applied in Blakely Harbor, WA to develop a build-out of all potential docks in the 

harbor built to full length and size by existing regulation. Calculations were then made for several public 

viewing areas around the harbor of how much of the viewshed would be impinged on by dock 

construction. The “reductions” ranged from 27% to 78%. No suggestion was provided as to public 

acceptance of these values.

Smardon (1988, 1986) and Galliano et al. (2000) have utilized assessment techniques to measure scenic 

quality based on public aesthetic values. These have been utilized in planning and land use 

management activities on public lands but are only beginning to be investigated for use as a regulatory 

tool for docks. The State of Maine is in the process of preparing regulatory standards for dock aesthetics 

(Gates, 2002, pers. com.).

Questions for consideration:

1. How significant are aesthetic/quality of life issues in regards to small docks?

2. Are there reproducible techniques to measure the aesthetic issues relating to docks and piers?

3. Are there “quality of life” or social issues other than those relating to the environment or aesthetics 

that are measurable?

Bibliography:

Best, Peter N. 2002. “Blakely Harbor Cumulative Impact Assessment.” City of Bainbridge Island (WA), 

Department of Planning and Community Development.

Felts, Arthur A., M. Freeman, M. Radic, and K. Walsh 2001. “Survey of Coastal Residents’ Perceptions 

of Docks”. Joseph P. Riley Institute for Urban Affairs and Policy Studies, College of Charleston, SC.

Prepared for the South Carolina Department of HEC.

Felts, Arthur A, and Marijana Radic. 2002. “Survey of Coastal Dock Owners’ Perceptions of Docks”. 

Joseph P. Riley Institute for Urban Affairs and Policy Studies, College of Charleston, SC. Prepared for 

the South Carolina Department of HEC.

Galliano, Steven J. and Gary M. Loeffler. 2000. “Scenery assessment: scenic beauty at the ecoregion

scale.” General Technical Report PNW–GTR-472. US Dept. Agriculture, Forest Service, Pacific 

Northwest Research Station.

Gates, Judy, Maine Department of Environmental Protection, Division of Land Use Regulation.

Smardon, R.C., J. F. Palmer and J. P. Felleman. 1986. “Foundations for Visual Project Analysis.” John 

Wiley and Sons, New York, NY 

Smardon, R. C. 1988. “Visual impact assessment for island and coastal environments.” Impact 

Assessment Bulletin 6(1): 5–24.
17

WORKSHOP AGENDA

22 January:

Opening

• Welcome to the group

• Logistical information/housekeeping information

• Charge to the group—Workshop purposes, desired outcomes, agenda

• Connection between this Workshop and future activities

• Introductions of the participants

The Management Context: Introduction to management issues and needs related to small dock 

management.

• Susan Snow-Cotter, Massachusetts Office of Coastal Zone Management 

Panel Presentations and Discussion

Panels consisted of 15-minute individual presentation, a 5-minute question period after each 

speaker, and a 20-minute discussion period following panel presentations.

Panel I: Impacts to vegetation from docks

• Dave Burdick, University of New Hampshire

• Ron Thom, Battelle Marine Sciences Laboratory, Sequim WA

• Deborah Shaefer, US ACOE, Waterways Experimental Station, Vicksburgh, MO

• Mike Ludwig, National Marine Fisheries Service, Milford (CT) Laboratory

Panel II: Impacts from contaminants related to docks

• Pedrick Weiss, New Jersey Medical School 

• Denise Sanger, South Carolina Department of Natural Resources

Panel III: Impacts from associated boating use

• Rick Crawford, Nautilus Environmental Services, Cape Cod, MA

• Steve Ressler, New York Coastal Management Program

Panel IV: Impacts to navigation and riparian uses

• Dave Killoy, New England Division, US Army Corps of Engineers

Summary discussions from first day

23 January:

Panel V: Impacts to Aesthetics and Quality of Life Issues

• Judy Gates, Maine Department of Environmental Protection

• Richard Smardon, SUNY Syracuse

• Richard Chinnis, South Carolina Office of Coastal Resource Management

Managers respond to scientific status, develop research needs and recommendations based on 

existing information

Wrap-up: General discussion of future steps

Managers meet to begin planning future steps
18

MANAGEMENT CONTEXT

Susan Snow-Cotter

Massachusetts Coastal Zone Management Office

A review of the volume and status of dock and 

pier applications on Cape Cod, one segment of 

the Massachusetts coastal zone, showed that 

over the past five years there have been

approximately 250 applications for dock

construction. Of these 195 were approved and 

63 denied. Of those 63 denials, only six

(approximately 10%) were upheld in the courts 

(Fig. 2). This suggests that managers need 

better means to review dock proposals and

make defensible decisions. For example, most 

of the denials were aimed at protecting shellfish 

and habitat but when challenged it was difficult 

to clearly demonstrate the impacts to these

resources.

Both scientists and managers recognize that 

there are significant regional differences in

resources, dock design, and impacts. However, 

state and local regulators need a science-based

framework and guidance in order to make

reasonable decisions.

Docks affect coastal conditions and uses

including:

• Navigation—docks can both promote

and hinder navigation in waterways,

• Aesthetics—cumulative impacts are the 

significant issue,

• Public access to and along waterways—

docks can promote public access to the 

waterway but may also impede lateral 

access,

• Shellfish habitat,

• Water quality—impacts result from materials 

used in construction and scouring or

resuspension of sediments around pilings

and floats, and

• Vegetative cover—docks shade vegetation in 

salt marshes and below the water.

In addition to their physical structure, the boating

associated with docks results in indirect or secondary 

effects such as prop dredging/scouring and the

release of contaminants like oil, gas, detergents, antifouling paints, etc. 

The types of information needed by managers to 

make defensible decisions include:

• A science-based understanding of the

ecological impacts from construction and use 

over time,

• Techniques for practical approaches at a

local and state level that will allow for a

comprehensive harbor by harbor planning

and regulatory approach, 

• A better understanding of the benefits of Best 

Management Practices,

• Guidance on incorporating science into

statutes, ordinances, regulations, and rules, 

and

• Techniques to factor cumulative impacts into 

the planning and permitting process.

Figure 2. About 78% of applications for docks in 

Cape Cod were approved on the first review. After 

the appeal process, less than 1% of applications 

were denied.

Docks may impede public access along the 

coast (Photo credit: S. Snow-Cotter).
19

Question & Answer Period

Q. Have you seen increased vessel size leading to proposals for larger family docks in 

Massachusetts?

A. Absolutely. Not only are the proposed docks larger, larger boats need larger “buffer zones” to 

navigate. It is important to ensure that the regulatory framework includes usage of the docks, not 

just construction.

Q. In Massachusetts, the environmental reviews are done at the local level with appeal to the state.

Is that because there are significant local concerns? This not the case in Georgia where there is 

little concern at the local level and the feeling there is that there is no need for legislation. Must 

local governments apply for ability to regulate at that level?

A. The Massachusetts Wetlands Protection Act (a state law with regulations issued by the state) 

requires local municipalities to regulate impacts to wetland resources, including shellfish habitat, 

salt marshes, land under the ocean, etc. Public trust standards are regulated at the state level, 

but there is a provision for local boards to manage that aspect as well, although few have availed 

themselves of that opportunity. Delaware has developed BMPs for docks and piers at the state 

level that will be incorporated into state land regulations. We tapped into legislators interested in 

the waterfront to help move this forward. 

Q. Were the issues involved in approving or denying pier permits mostly social/aesthetic or 

ecological?

A. Both. In many instances there are no defensible standards and consequently the local decisions 

may be unpredictable. This again shows the need for science-based guidance.
20

IMPACTS TO VEGETATION FROM DOCKS

Introduction

Submerged aquatic vegetation (SAV) and marsh grasses provide critical habitat, filter nutrients and 

sediments, provide nursery habitat for fish and shellfish, stabilize bottom sediments, and form the basis of 

the marine food web. Impacts to plant productivity generally occur in two ways: short-term construction 

impacts and chronic impacts from shading. Irradiance under docks falls well below the requirements for 

minimum maintenance (~3 M d-1) and full growth (= 5 M d-1) (Fig. 3). This results in reduced shoot 

density, biomass, growth, and increased height 

(probably due to etiolation), increased erosion, 

undercutting of vegetation (Burdick and Short 

1999). Susceptibility varies by species—Spartina

patens was most robust followed by Distichlis

spicata, then S. alterniflora (Kearney et al. 1983).

The significance of these shading impacts to the 

coastal ecosystem as a whole varies by region.

In South Carolina, docks existing in 1999 

reduced S. alterniflora cover by 0.03–0.72%.

Projected to a total possible build-out of similarly 

sized docks in these creeks, the decrease in 

marsh grass density was 0.18–5.45% (Sanger 

and Holland 2002). In New England and 

Florida, where coastal vegetation is already

severely impacted and reduced, the existing 

and potential loss of vegetation associated 

with dock shading is greater.

Dave Burdick

Jackson Laboratory, University of New Hampshire

In conjunction with Fred Short, Dave Burdick

investigated the impacts of docks on eelgrass 

(Zostera marina) in Waquoit Bay,

Falmouth/Mashpee, Massachusetts. They

found that the presence of small docks leads to 

fragmentation of eelgrass beds—primarily through

shading of the grasses (Fig. 4). They next examined 

physical and biological parameters to better

understand how docks impact eelgrass and,

ultimately, how to minimize those impacts.

Specifically, Burdick and Short quantified dock

characteristics (length, width, height, construction

materials, age, orientation, and design), light

reduction under the dock, and eelgrass

characteristics (shoot density, canopy height, and

bed quality under the docks). They observed which 

docks allowed the best eelgrass survival, and which 

dock characteristics are the most important predictors

of eelgrass bed quality. This allowed them to

develop dock specifications designed to allow

eelgrass to thrive under docks.

0

200

400

600

800

1000

1200

IRRADIANCE (uM/sq.m/s)

-36 -32 -28 -24 -20 -16 -12 -8 -4 0 4 8 12 16 20 24 28 32 36

DISTANCE (m)

South North

Dock

Figure 3. Irradiance under docks is below the requirements for minimum 

maintenance (~3 M d-1) and full growth (= 5 M d-1) (From Nightengale 

and Simenstad 2001, Ron Thom, pers. comm.)

Figure 4. The obvious impact of docks is 

through shading of vegetation (Photo credit: D. 

Burdick).
21

Burdick and Short found lower eelgrass density 

and greater shoot height under docks (Fig. 5).

Canopy structure (cm shoots/m2

) was lower

under the docks. They concluded that light 

levels of 15% of surface irradiance are the

minimum necessary for Zosters. Levels of

approximately 50–60% are necessary for health 

beds.

Dock orientation (north/south, east/west) is a

critical predictor of eelgrass bed quality. They 

calculated the light levels under various docks 

using the factors of height of dock, width of 

dock, and orientation and found they could

predict impacts. Using this information Burdick 

and Short produced “Dock Design with the

Environment in Mind: Minimizing dock impacts 

to eelgrass beds,” an informational CD that

allows the user to see how different dock designs will 

affect an eelgrass bed and the associated coastal 

species (Fig. 6). In this CD they provided

calculations for a limited number of scenarios; ideally 

they would like to produce a model that predicts

impacts from a larger combination of design factors.

They noted that the presence of docks in Waquoit 

Bay is not the only factor contributing to loss of 

eelgrass. Nutrient enrichment impacts eelgrass by 

promoting epiphytes that live on and shade the grass 

blades. It is not clear whether this situation made 

grasses more susceptible to impacts from docks.

This study did not address the cumulative impacts 

from eelgrass bed fragmentation. It is not clear

whether these impacts are simply additive, or

whether synergistic factors are at work.

Figure 5. Eelgrass density (A) and canopy structure (B) were significantly lower under and near docks than at 

reference sites (From Burdick and Short 1999).

0

500

1000

1500

2000

CANOPY STRUCTURE

(cm shoots/m 2)

Under Adjacent Mid Far

STATION (relative to dock)

a

b

c

b

0

100

200

300

400

500

SHOOT DENSITY (#/m 2)

UNDER ADJACENT MID FAR

b

c

b

a

Figure 6. Burdick and Short’s CD shows how dock design affects seagrasses and associated aquatic species 

and allows users to see how impacts vary with design.
22

Question & Answer Period

Q. What is the management goal articulated for eelgrass?

A. Informally, the goal is no net loss. Submerged aquatic vegetation, including eelgrass, has been 

designated as a Habitat Area of Particular Concern by several of the Fishery Management 

Councils—in part because it provides Essential Fish Habitat. 

Q. What is the correlation between the age of a dock and its height?

A. They tend to cancel one another out. Older docks mean better eelgrass because they are thinner 

and more rickety. Also, regulations for docks now require larger dimensions (i.e. wheelchair 

access) and materials that are less indestructible. The best way to calculate success is if you 

base everything on light reaching the eelgrass. This may be more direct than dealing with 

complex biological indicators.

Q. Many owners argue their docks only cover a small area and, therefore, don’t cause a problem.

How would your research address that contention.

A. To this point fragmentation and cumulative effects have not been adequately considered so it is 

difficult to tell how valid that contention is.

Ron Thom

Battelle Marine Sciences Laboratory, Sequim, WA

Ron Thom’s work was done in conjunction with 

the renovation and expansion of ferry terminal 

docks in the Pacific Northwest. Thom assessed 

the potential impacts of the planned expansion 

and worked with the company to minimize

environmental impacts during and after

construction. While commercial ferry structures 

are considerably larger than private recreational 

docks, many of the issues remain the same.

Thom quantified the

light requirements for

eelgrass (Zostera) in

the Northwest by

charting light

attenuation over depth

(the area has a 4–5

meter tidal range) and

comparing Zostera

shoot density against

depth. They found the 

highest density at 350 

micromoles PAR.

There are a number of 

techniques available to reduce shading and

increase light under docks, including grating, 

glass blocks, sun tunnels, and applying

reflective material on the underside of docks

(Fig. 7). These have been shown to be effective 

in the large ferry docks in Puget Sound.

In addition to shading, impacts on eelgrass bed

health were predicted from:

• Initial construction impacts and maintenance 

efforts

• Propeller wash (turbidity from boat traffic that 

decreased light levels), and

• Biological impacts from crabs and starfish

eating the recovering shoots and drift algae 

smothering the plants.

As part of this effort

they developed a

multiple stressor

model—a conceptual

model with mitigation as 

an end point (Fig. 8).

Thom recommended

that the ferry company 

modify the design of the 

dock to lessen the

impacts to the Zostera

bed. By building a

longer, narrower dock, 

the engineers were

able to extend the bulk 

of the structure and associated shading impacts past 

the eelgrass beds. Shading impacts were further 

reduced by incorporating light transmission

techniques. Additionally, they removed all of the

eelgrass that would have been destroyed and

maintained the shoots for restoration projects.

Vegetation near this commercial ferry in 

Washington State is impacted by shading and 

propeller wash associated with the dock.
23

Figure 7. New materials used in ferry construction in Washington State. Top left: light under glass blocks. Top 

center: Glass blocks used instead of traditional wooden planking. Top right: A sun prism. Bottom left and center: 

Metal grating on a dock and light penetration below that dock. Bottom right: A sun tunnel. (Photo credit: R. Thom).

Figure 8. Conceptual model showing how mitigation can be used to minimize construction impacts (From 

R. Thom).

UNDISTURBED

MEADOW

DISTURBANCE DURING 

CONSTRUCTION

DOCK IN PLACE

MAINTENANCE

DISTURBANCE

FERRY PROP

DISTURBANCE

LOWER

LIGHT

INCREASED

SESSILE

PREY

CONSTRUCTION

MAINTENANCE

& OPERATION 

IMPACTS EELGRASS

LOSS,

RETARDED

RECRUITMENT

LOWER PROD.,

EELGRASS LOSS,

RETARDED

RECRUITMENT

LOWER PROD.,

EELGRASS LOSS,

RETARDED

RECRUITMENT

EELGRASS LOSS,

RETARDED

RECRUITMENT

EEGLRASS

LOSS

MITIGATION MODIFY

PROCEDURES;

REPLANT

MOVE DOCK

OFFSHORE

RED. DOCK WIDTH; 

GLASS BLOCKS; 

GRATE;

FEWER PILINGS; 

REFLECTIVE

MATERIAL;

PLANT ADJACENT 

AREAS

FEWER PILINGS; 

REPLANT

REPLANT

(OVERPLANT)
24

Question & Answer Period

Q. Does eelgrass senesce (age) in the winter?

A. It continues to grow during winter but adapts to be shorter, thicker, and greener.

Q. Is the 5 mols figure for growth time dependent?

A. To be sure it would be necessary to do a carbon balance study, but generally this assumes 

summer months. Otherwise the 5 mols is based on average daily sunlight.

Q. Were the eelgrass restoration projects successful?

A. Yes, they have been successful in the Pacific NW. This type of project needs the right conditions.

We’ve found that the best way to proceed is to do environmental assessments and then establish 

plantings.

Q. Has the architectural shading model been used to predict impacts over the seasons? Could this 

be adapted as a useful tool? 

A. It’s not the ultimate answer. We need an overall eelgrass model.

Q. In the course of the survey throughout Puget Sound was drift algae a problem?

A. Yes. It gets caught up under the docks and was a problem. 

Q. Are eelgrass beds and their growth patterns comparable between the east and west coasts?

A. Yes, when water clarity is comparable.

Deborah Shaefer

US Army Corps of Engineers, Waterways Experimental Station

Dock construction has had negative impacts on 

seagrass beds in the panhandle area of Florida 

and Alabama. Up to 50 acres of seagrass were 

destroyed in the early 1990s, and it was felt that 

there was the potential for significant cumulative 

impacts. As a result, the US Army Corps of 

Engineers wanted to develop construction

guidelines and regulations. However, there was 

a lack of data supporting such guidelines.

Shaefer and Lundin therefore started by

studying the effects of docks on the seagrass 

Halodule wrightii in Perdido Bay, Alabama.

The principal sources of dock impacts were

identified as:

• impacts from shading,

• destruction of seagrasses during

construction,

• prop scarring and hull grounding,

• alteration of bottom topography and

sediment characteristics, and 

• contaminants leaching from treated wood

materials and from fuel spills.

Shaefer and Lundin examined shading and

construction impacts and experimented with

ways to minimize them. They selected docks 

with a standard set of characteristics and then

quantified seagrass loss for those docks. To

minimize variability, all of the docks in the study were:

• oriented north to south,

• four feet wide,

• four feet above mean sea level,

• four to nine years old,

• located in an area of continuous seagrass

meadows, and

• located within a one-mile stretch of shoreline.

Docks along an Alabama coastline (Photo: D. Shaefer).
25

Shaefer and Ludin observed that light (PAR)

under the docks was below the saturation rate 

between 10 am and 2:30 pm, for a total of 4.5 

hours each day. Shoot densities were 40% and 

47% lower in shaded plots at shallow and deep 

locations, respectively. Biomass was reduced 

30% and 33% in the same locations (Fig. 9). As 

in other studies of shading impacts on seagrass,

Shaefer and Lundin found that shade-stressed

plants grow to greater heights, perhaps due to 

etiolation. This suggests that seagrasses

posses mechanisms to compensate for light 

reduction. They concluded that seagrasses

under docks can be maintained and bed

fragmentation eliminated, although density and 

biomass are reduced.

A second part of the study was designed to 

evaluate the effectiveness of grated decking

material as a means of transmitting light and to 

demonstrate the possibility of low-impact

construction techniques. A series of docks were 

built with varying the heights (4’ vs. 5’) and

surface materials (traditional wood planking vs. 

1” thick reinforced fiberglass grating with 1x2”

openings). On a dock five feet above mean sea 

level, the light levels never dropped below saturation.

On a four-foot high dock they dropped below

saturation only briefly during the day. Light levels 

were much higher and seagrass grew better under 

docks with grating rather than solid wood plank

decking (Fig. 10).

The State of Florida has

prohibited roofs on terminal 

structures in an effort to

further reduce seagrass loss 

resulting from dock shading.

In an investigation of impacts 

associated with dock

construction techniques,

Shaefer noted that the high 

pressure jet pump normally

used to install dock pilings

produced a six to seven foot hole around each piling.

The resultant “halo” might remain for 10 years without 

seagrass regrowth. By sharpening the piling ends, 

using a low pressure jet to start the pilings, and a 

drop hammer to do the final installation, the size of 

the “halo” was reduced. The smaller scar size will 

make it faster and easier for seagrass to regrow.

Another way to minimize construction impacts is to 

bring construction equipment in from the water on a 

barge rather than driving heavy equipment through 

the marsh.

The Corps has adopted these techniques as

guidelines for the Southeast. Despite these being 

only guidelines, they are often followed by permit 

applicants as a way of speeding the application

review process.

0

200

400

600

800

1000

Biomass (g/sqm)

Shallow Deep

Figure 9. Biomass of the seagrass Halodule wrightii

growing under docks (green) was 1/3rd lower than 

biomass in adjacent unshaded (yellow) areas.

Figure 10. While light levels under traditional wooden plank docks (left) fell dramatically during the day, 

grated decking (right) significantly reduced the shading impact of the dock.
26

Question & Answer Period

Q. On your grid analysis – were any of the existing docks roofed?

A. No, regulatory guidelines currently prohibit construction of roofed docks.

Q. How many roofed structures might you find in a stretch?

A. This area had approximately 15 roofed structures in a one mile stretch of coast.

Q. Does grating come in different sizes?

A. Yes. It comes in different sized grates and varying thickness.

Q. Is grating acceptable for a broad range of uses (e.g., does it preclude sunbathing, high heels, is it 

hot underfoot, etc.)?

A. There have been some complaints, but it is generally well accepted.

Q. Is it an aluminum product or plastic?

A. We use fiberglass. It is the amount of light passing through that is important, not the materials 

utilized.

Q. What’s the cost of grating materials?

A. A 4’ by 8’ panel is about $500. This is approximately 20% more than wood planking for initial cost 

(not including labor) but it tends to last longer, thereby minimizing the cost differential. 

Q. Have these regulatory guidelines been taken to court yet?

A. They have been out for 3–4 years and have been tested in court. Remember that these are 

USACE guidelines. USACE can’t require, but can guide people toward this end. All of these 

guidelines are specific to North Florida. 

Mike Ludwig

National Marine Fisheries Service, NE Fisheries Science Center

Mike Ludwig presented a discussion of

experiments conducted by Mary Colligan and

Cori Collins to quantify the impacts of docks on 

the coastal environment. The study was

undertaken after the authors observed that:

• Permits for dock approval are the most

common permit requests received by

regulators.

• There is a perceived “right” to dock

construction.

• There is little in the way of defensible

management policy.

• There is no uniformity of design.

• There is little literature available about dock 

impacts to marsh grasses.

• Consequently there is little justification to 

deny permits.

Ludwig argued that the ongoing workshop was 

necessary because of our failure as managers.

While there is a Constitutional right to riparian

access, we’ve extended that to include putting in 

docks to increase property value and gain

access to deeper water. There is no absolute right to 

a dock!

Colligan and Collins collected data on marsh grass 

density and height directly under and adjacent to

each of 125 docks in Connecticut, Rhode Island, and 

Massachusetts. As noted previously, height of the 

grasses was greater under the pier, but the densities

were lower. Impacts varied by species with Spartina

alterniflora being the most affected followed by

Distichlis spicata and S. patens.

Colligan and Collins also experimented with reducing 

impacts by shifting orientation and replacing solid

planks with grid material. Orientation seemed to 

have an impact but it was not significant. Nor did use 

of grid material reduce shading - light reduction under 

the grid was almost the same as that measured

under traditional planks. This may be because in the 

northern latitudes the sun did not get high enough in 

the sky to shine through the grid (as it had in the 

Florida experiments). 
27

Erosion to areas adjacent to the dock was

increased—this was attributed to prop wash—

and there was an undercutting of the mat in the 

sub-tidal range (Fig. 11). When this happens 

the surface of the marsh slumps, falls out of its 

growing zone, and dies. These would have the 

additional benefit of providing habitat for

Spartina and would be an improvement over

bulkheads.

The conclusions of the study include:

• There are two principal impacts to plants, 1) 

density—generally lowered, and 2) height—

generally increased.

• A north-south alignment seems to particularly 

affect S. alterniflora.

• The height of docks affects different species 

differently.

• Spacing between planks appears to have no 

effect on plants.

• A grid deck may not be beneficial in higher 

latitudes.

• Docks segment wetlands and may inhibit 

wetland functions and values.

• Dock impacts include increased erosion.

Ludwig noted that the impacts of pier alignment

merits further investigation. Regulations on pier

height to width ratios may prove useful, but second 

order impacts on motile species such as birds need 

to be investigated before these are adopted. In

conclusion, Ludwig suggested that a little “intestinal 

fortitude” and the increased use of shared public 

docks as an alternative to constructing more private 

docks might better protect public resources.

Question & Answer Period

Q. It is misleading to suggest we, as regulators, can deny riparian property rights in the interest of 

the public trust because our laws are simply not there at this point. We may have failed as a 

society, but not as regulators.

A. Look at Common Law and the Constitution for the basis of these types of laws.

Figure 11. Undercutting of the vegetative mat near a dock (left) can lead to marsh slump (right) and the death of 

marsh grass (Photo credit: M. Ludwig).

Figure 12. Installation of wire mesh baskets 

filled with small stone can alleviate the 

undercutting associated with many docks. It has 

the additional benefit of providing habitat for 

Spartina and is an improvement over bulkheads.
28

Q. In some instances, in an attempt to minimize fragmentation of wetlands, long walkways to tidal 

creek have been requested, but the applicants have been denied and told to walk. Is it better to 

allow them to trample the wetland?

A. The sense is yes. It is better to allow a foot path than a walkway. In 2002 there was a case that 

was denied on this basis. Most of plant growth is done by the end of June before the major 

summer boating season. Therefore, people are probably not walking. If they do walk they should 

be encouraged to use the same path repeatedly because this flora is so delicate. 

Comment: Based on our work in NC, Spartina can recolonize after being trampled, but it is a slow 

process. Orientation didn’t appear to be a factor there. A reduction of light of 71% was found 

with both tall and short docks.

Q. Did you vary grid height in your investigations? Height is a major factor. 

A. We had a limited number of investigations with all structures being between three–four feet high. 

Our grid material is thicker than some. It is Morton* safety grip planking that is designed to allow 

significant light passage. It is produced by Central Steel & Wire Company. They carry the 

Morton Open-Grip Grating, Standard Planks that I showed in the presentation. You can see the 

specifications and decking at www.centralsteel.com .

Q. Shoreline erosion in one of your slides appears to be attributed to a dock – did you look at 

orientations, etc.?

A. No. It seemed that shoreline erosion depended more on boat use and type (i.e., prop 

dredge/wash, etc.). In other words, human behavior is related to erosion impacts. Wave 

focusing could also be responsible for some erosion.

General Discussion on Impacts to Vegetation

Question to the group: Are the impacts on vegetation sufficiently well known to develop a management 

assessment tool? If so, what sort of tools would be appropriate?

Comment: Managers must determine what level of impairment is acceptable and then develop a 

mechanism to determine whether the impacts of a dock or series of docks will go beyond that 

acceptability.

Comment: In making a regulatory decision it is important to consider all of the pertinent factors—impacts

on vegetation, on navigation, on erosion/sedimentation, etc. While it is not necessary to be technically 

“perfect” it is important to show that all of the factors have been assessed. This is best done through the 

use of a checklist.

Comment: The use of a conceptual model would be useful to promote understanding between factors, 

structure, and function. This has been done for specific projects in the Pacific NW (Columbia Model).

This model could be linked to impacts on specific types of vegetative communities—submerged marsh,

submerged aquatic vegetation—and could incorporate regional differences. A level could then be added 

stating possible management options. This could be augmented by a list of management options and 

associated impacts.

Comment: A useful method is to establish guidelines that show applicants that if they build a dock that 

meets a defined set of criteria, that they will get a dock. New York has established such guidelines and 

they have successfully been defended in court. If you design your regulation around legitimate objectives 

and take a rational approach, the courts will back you.

Comment: Although we suspect that there are cumulative impacts, we really don’t have any research on 

the topic. It’s not really clear whether the problem is docks or development in general.
29

Summary and Recommendations

Shading under docks and piers is clearly documented, and associated biological impacts on aquatic 

vegetation have been quantified for some SAV and grass species. However, these impacts are species 

specific and vary with latitude. Further studies are needed to understand the impacts of dock shading on 

more species and in other geographic regions. There is also a need to identify and better quantify 

secondary effects of docks on vegetation. These include impacts to SAV beyond the footprint of 

approved docks such as the halo effect around a dock, or unpermitted “add-ons” like floating docks, roofs, 

observation decks, etc.

A conceptual model explaining the factors controlling the types and magnitude of potential impacts should 

be further developed. It will be important to define types and accuracy of information that would feed into 

this conceptual model and to identify information gaps. This led to the following recommendations:

• Develop a conceptual model.

• Prepare a synthesis paper that draws together all of the existing data.

• Develop a searchable database/website that could be a repository for relevant data.

• Develop checklists of parameters that managers should consider in the permitting process (tailored

to localities).
30

Figure 14. Copper and arsenic were elevated in algae 

growing on docks (From Weis, J.S., & P. Weis. 1994.

Arch. Environ. Contam. Toxicol. 26: 103-109

IMPACTS FROM CONTAMINANTS RELATED TO DOCKS

Summary

The most common contaminant-related concern 

associated with docks is leaching from preservatives 

applied to pilings or floats in locations that come into 

regular contact with water. Many states have banned 

the residential use of creosote or pentachlorophenol 

in aquatic settings (they leach readily and have 

demonstrated toxic effects); and consequently wood 

pressure-treated with a chromated copper arsenate 

(CCA) is the most commonly used material for pilings 

and decking for residential docks. CCA also leaches 

in saline waters (Weis et al. 1991, 1992). The degree 

of toxicity depends on both the concentration and the 

chemical form as it reaches the target organism and 

can change over time and in response to sediment 

types, amounts of organic material present, oxygen levels and water movement (Luoma and Carter 

1991). Ninety-nine percent of the leaching occurs within the first 90 days (Cooper 1990, Brooks 1990).

In areas of low water flow, elevated concentrations of chromium (Cr), copper (Cu), and arsenic (As) can 

be found in fine sediments adjacent to bulkheads constructed of CCA-treated wood and in organisms 

living on and around treated pilings (Weis and Weis 1996, Weis et al. 1998). Dilution appears to reduce 

these impacts; the bioaccumulation of dock leachates by marine biota did not impact survival of 

mummichogs, juvenile red drum, white shrimp, or mud snails in South Carolina estuaries characterized by 

higher flow rates (Wendt et al. 1996). However, tidal flushing thresholds for contaminant impacts have 

not been identified, and data does not exist to evaluate the dilution capacity of an area.

Peddrick Weis1 and Judith S. Weis2

1

Aquatic Toxicology Laboratory, Dept. of Radiology, UMDNJ, NJ Medical School

2

Dept. of Biological Sciences, Rutgers University 

When CCA-treated wood products are used in

estuaries—for dock pilings, floats, or bulkheads—

contaminants leach out of the wood. These

contaminants may be taken up by organisms living 

on the wood, transferred to consumers, enter

sediments and the benthic organisms that live

there, and/or wash away with the tides or currents. 

(Fig. 13).

Weis and Weis observed elevated levels of copper 

and arsenic in algae growing on open water docks 

in Pensacola Beach, Florida (Weis and Weis 1994, 

Fig. 14). A subsequent laboratory experiment

showed that snails fed algae grown on CCA -

treated wood became inactive in 3-4 weeks and 

eventually curled up inside their shells and died

(Weis and Weis 1992). This was supported by a 

field study showing that oysters living on bulkheads 

made of CCA-treated wood had taken up

measurable concentrations of copper and were

smaller than control populations (Weis et. al 1993).

When CCA concentrations are high enough, oyster 

digestive glands shrink.

 (Photo credit: P. Weis)
31

Contaminants have been measured in

sediments adjacent to CCA-treated wood, and 

these contaminants accumulate in animals

living in and feeding on those sediments (Weis

and Weis 1994, Fig. 15). In areas bulkheaded 

with CCA materials, fine sediments, and low 

water flows (e.g., canal communities in NJ), 

contamination may extend up to 10 meters,

although the highest levels are found within the 

first meter. Newer wood leaches more rapidly 

than weathered material and most leaching

occurs in the first few months.

There has been no evidence of trophic transfer 

from amphipods to fish or higher vertebrates, 

but species richness was depressed in areas 

with higher contaminant levels.

As almost all of the research work presented by 

Weis is with bulkheaded areas, it is unclear 

what impacts there will be from a limited

number of pilings for docks. Issues to consider 

include the area of exposed surface of CCAtreated materials, the newness of the materials 

used, the types of sediments in the area, and 

the flow of water through the system.

Alternatives to CCA-treated materials include 

recycled plastics, untreated woods, steel or

concrete.

Figure 13. Some of the contaminants leaching out of wood is taken up by organisms living on the wood, 

some is transferred to consumers, some may enter sediments and the benthic organisms that live there, 

and some is washed away by the tides or currents. (From Weis, J.S., and P. Weis 1992. J. Exp. Mar. Biol. 

Ecol. 161: 189-199.)

Figure 15. Contaminants are found in sediments and sediment 

feeders near CCA-treated woods. (From Weis, J.S., & P. Weis.

1994. Arch. Environ. Contam. Toxicol. 26: 103-109).
32

Question & Answer Period

Q. You mentioned different findings in Delaware and Pensacola Bay, Florida. Was there a 

significant difference in the tidal range between the two sites?

A. The tidal range is substantially greater in Delaware than Florida. This is key as the amount of 

water flow greatly impacts levels of copper and other contaminants concentrated in the area.

Q. Can recycled plastics be used for pilings as well as decking? 

A. They can be used for both, but they can’t be driven in with a drop hammer. There is a version 

that can be screwed in that is much less disturbing to the sediments and protects the pilings.

Q. Did you look at toxic impacts in copepods?

A. No, but we did look at trophic transfer and conduct some impact studies.

Q. Has any of your information been presented to EPA to apprise them of these environmental 

contaminants?

A. Yes, but I don’t know what their response is.

Denise Sanger

South Carolina Division of Natural Resources, Marine Resources Division, Marine 

Resources Research Institute

Denise Sanger presented research results from 

two studies: (1) a study undertaken by Priscilla 

Wendt and Robert Van Dolah, and (2) a study 

undertaken by Denise Sanger and Fred Holland.

The Wendt and Van Dolah study was published 

in Archives of Environmental Contamination and 

Toxicology in 1996. The study was designed to 

evaluate the effects of wood preservative

leachates from dock structures in South Carolina 

and was conducted in two phases. Phase one 

of the project was designed to compare creeks 

with docks to reference creeks without docks.

Three conditions were surveyed:

• The concentration of copper, chromium, 

and arsenic in sediments and oysters;

• The acute toxicity of sediments to a

marine bacterium (i.e., Microtox) and a 

micro-invertebrate (i.e., Rotifer); and 

• The physiological condition of the

sampled oysters.

One composite sediment sample and one

composite oyster sample were taken in each

creek at varying distances from the docks (<1m 

and >10m) and in reference creeks.

Concentrations of copper in oyster tissue from 

animals attached to pilings were significantly

higher than those in oysters collected away from 

the pilings and from reference sites. However, 

Wendt and Van Dolah did not find physiological 

differences between the sampled groups.

Sediment copper, chromium and arsenic

concentrations were not different among the

sediments collected near docks, greater than 10m 

away from docks and in reference areas.

Furthermore, no acute toxicity was observed.

The second phase of the Wendt and Van Dolah study 

focused on recently constructed docks. In situ

bioassays measured mortality in white shrimp, red 

drum, mud snails, and mummichog placed adjacent 

to five 4–12 month old docks after a 96 hour period.

These results were compared to mortality in animals 

placed in reference areas. A six-week study of oyster 

bioaccumulation of metal and its relationship to

Photo credit: D. Sanger.
33

growth was also conducted. There was no

decrease in survival of the four species in the 

96-hour assays. In addition, there were no

differences in the deployed oyster tissue metal 

concentrations or in their growth.

The second study, conducted by Sanger and 

Holland and published in a 2002 SCDNR/MRD 

technical report, examined cumulative impacts 

of docks. Spartina shading, sediment

contamination, and impacts on nursery habitat 

were examined in an effort to address as wide a 

range of impacts as possible within a limited 

budget. Only the sediment contamination and 

nursery habitat research in both small and large 

tidal creeks was presented at this workshop.

No new data was collected for this portion of the 

study as pre-existing data from two projects

performed at SCDNR were used. The small 

tidal creek data set was pulled from the Tidal 

Creek Project (TCP) which defined small tidal 

creeks as <20m wide. The large tidal creek data 

set utilized data from the South Carolina

Estuarine and Coastal Assessment Program

(SCECAP). Large tidal creeks were defined as 

creeks between 20m and 100m wide. The small 

tidal creek data set compared creeks with no 

development (reference) to creeks with

suburban development and no docks (suburbanno docks) to creeks with suburban development 

and docks (suburban-dock) (Fig. 16). The large 

tidal creek data set compared creeks with no 

docks (no docks) to creeks with low numbers of 

docks (low docks) to creeks with high numbers 

of docks (high docks).

In general, both the small and large tidal creek 

data sets showed: 

• CCA contaminants did not increase with

increasing numbers of docks.

• Higher levels of PAHs were measured in

creeks with suburban development and

docks, but the higher levels were probably 

due to the suburban development and not 

the docks; 

• Changes were found in the small tidal creek 

benthic community, but again this was probably 

more related to the suburban development of the 

upland; and 

• Suburban development may reduce fish and

crustacean abundances, but dock structures may 

also provide structure that attracts them.

The overall conclusions of these two portions of this 

study were: (1) chemical and biological effects were

observed with increasing impervious cover and

increasing dock numbers; and (2) docks are not the 

problem, they are a symptom of the much bigger 

problem which is development of the uplands.

Question & Answer Period

Q. What is the role of outboard motors and PAH? It seems that it could be a big issue.

A. Yes, outboards probably are a source of PAH. We did find some elevated levels of PAHs in small 

creeks with docks but the upland development masked any effect that may be due to docks.

Unfortunately, it would be hard to design a study to evaluate this question due to teasing out 

Reference

Suburban - No Dock

Suburban - Dock

Figure 16. Sites selected for the cumulative impact 

study compared reference areas in South Carolina to 

suburban areas with and without docks (from D. 

Sanger).
34

recreational boat use unassociated with docks compared to recreational boat use associated with 

docks would be difficult.

Q. Is it safe to say that CCA-treated wood has no impacts in areas of flushing, but does in areas of 

low flow?

A. That is generally what our research, combined with that of Dr. Weis, indicates. Impacts are 

greatest directly after the wood is put into the water. It should also be noted that the 

contaminants don’t just disappear. They may flow out of the system but we don’t know where 

they go and whether they are having impacts elsewhere.

Comment: Delaware has dealt with impacts of bulkheads by not allowing them anymore. There is almost 

always a better way to deal with erosion. You can replace existing ones, but in the process 

applicants are required to dig out the old one.

Q. You noted that species richness of fish and crustaceans increased in creeks with suburban 

development and docks compared to suburban creeks with no docks and reference creeks - did 

you consider species composition?

A. We did evaluate individual species in our analyses but did not look at a true shift in the fish and 

crustacean species composition which is something that could be considered in the future.

Q. Given that most of the contaminants leach out in the initial 90 days, if a permit requires that the 

CCA-treated wood be seasoned before building would this a be a useful precaution?

A. Only if the wood is in contact with water (e.g., rain). Once again, however, those chemicals must 

go somewhere.
35

IMPACTS FROM ASSOCIATED BOATING USE

Summary

Most docks are for private recreational boating accessory to private residential uses of upland areas.

Issues of concern include impacts to submerged aquatic vegetation, contamination from fuel discharges, 

increased use of vessels in shallow nearshore areas, erosion of shoreline and flats, turbidity and 

resuspension of bottom sediments, noise, and disturbance of wildlife (Crawford et al. 1998, Kennish 

2002) and interference with other uses of nearshore areas. However, these impacts are difficult to 

quantify. Based on the limited quantitative data available, scientists agreed that, motor boat traffic is far 

from a benign influence on the aquatic and marine environments, and identified quantification of boating 

impacts as a research need.

Rick Crawford

Nautilus Environmental Services, Falmouth, MA

The general topic of impacts from boating usage 

in shallow estuaries has been of interest to

managers and researchers for over three

decades. Recently there have been two

significant workshops (1994 and 2000) to review 

the state of knowledge on the subject.

Concerns commonly associated with boating

use include:

• Damage to submerged aquatic vegetation;

• Water quality contamination associated with 

discharges of PAH and other petroleum byproducts;

• Erosion of banks, marsh edge and tidal flats;

• Resuspension of sediments and resulting

turbidity;

• Impacts from noise; and 

• Disturbance of wildlife.

Because docks are in the most shallow areas of an 

embayment and are the location where refueling may 

take place and engines are started and stopped, 

impacts are apt to be particularly significant there.

Propeller scarring of vegetation and “prop dredging”

of sediments are perhaps the most obvious impacts 

in the shallow waters adjacent to docks (Fig. 17).

As a boat moves through the water there are two 

principal forces produced (also see Figure XX): 

• The primary wake (or bow wake) that is related 

to water displacement by the boat that moves 

out to the side and can cause bank erosion; 

and

• The secondary wake (or prop wash) related to 

engine and propeller effects that moves behind 

the boat and down and causes sediment

resuspension and damage to submerged

aquatic vegetation.

Figure17. Propeller and mooring chain scour marks near docks (left) and propeller wash scour marks in Waquoit 

Bay (right). (Photo credit: R. Crawford).
36

At slow speeds, such as those near a dock, it is 

the secondary wake and physical contact

between the hull and/or prop that is apt to have 

the most significant impacts. However, these

secondary wake impacts are difficult to quantify

accurately because they vary widely from boat to

boat and are based on environmental conditions.

Propeller thrust characteristics are also highly

variable, and depend on propeller size, thrust angle, 

clearance over bottom, engine power, hull shape, 

operating conditions (e.g, speed, state of the tide, 

weather, number of passengers), and operator

choices.

Although environmental damage caused by boat

operation in shallow waters can be quite obvious, 

despite the ongoing research, there has been limited 

progress in finding quantifiable, predictable impacts 

from boating uses.

Conclusions:

• Using sediment resuspension to assess

impacts is not recommended.

• Small-scale measurements are too variable,

the broader the scale the better.

• Parameters like light attenuation can be easily 

measured but the greatest impacts can be

short-term phenomena that are better

monitored with a recording device (an

expensive device).

• It is difficult to ascribe generic impacts resulting 

from a boating activity.

• More research is needed—however the

research is expensive and very time

consuming.

Question & Answer Period

Q. Considering the photographs showing clear prop scarring in vegetative beds, why do you draw 

such negative conclusions about being able to predict boating impacts?

A. Despite having visual evidence of obvious damage, it’s very hard to quantify what caused it.

Q. What kind of impacts were you trying to assess through the use of a light meter?

A. We were trying to determine how much sediment is disturbed by various boat propellers.

Q. Acoustic doppler current profilers have been used successfully in studying prop wash effects 

behind ferries. Have you tried them?

A. This kind of equipment doesn’t work well in the shallow water situations being considered here.

Q. Researchers at Texas A&M have developed a model on propeller energy and disturbance.

A. I’m not familiar with that specific model, but the problem with models is that the conditions are 

constantly changing once you’re out in the field.

Figure 18. Primary wake travels away in widening 

path; effects add to naturally occurring 

disturbances (waves). Secondary wake 

disturbance area remains narrow and limited; it is 

an unnatural disturbance (From R. Crawford).
37

Steve Resler

New York Department of State, Coastal Management Program

The management of docks and their associated 

uses, including recreational boating, involves

consideration of human uses and values - and 

that has been used to drive approaches to

managing them in New York. Generally, the 

primary purpose of private

docks, from privately owned 

upland, accessory to the

private residential use of the 

upland, is to gain private

access to the water for a

range of private purposes.

These uses may include

pedestrian access across

vegetated and other intertidal 

areas to the water and

vessels moored to the dock, 

launching of small vessels

such as canoes or kayaks,

and mooring larger vessels,

whether powered by sailor

motor).

It is not always necessary to conduct detailed 

individual site-by-site assessments of docks or 

vessels using them. Likewise a detailed

understanding of the specific types and degrees 

of impacts associated with a dock is not always 

prerequisite to developing and making

regulatory decisions. A valid and much easier 

approach, based on generally understood

resource and human use values, is through the 

designation of areas that have special or high 

value wetland or other natural resource or

character values based on physical or other

characteristics.

Based on experience, mangers understand that

docks and the uses of vessels associated with them 

have various types and levels or degrees of physical 

effects on resources and uses of them. If the overall 

objective in high value

habitat or other areas

with desired

characteristics that

should be protected is to 

protect, maintain, or

restore the viability of an 

area as a habitat, or for 

other purposes, and the 

value of the habitat or

other characteristics is

recognized and

considered in decisionmaking standards, the

effects of docks and

vessels using them can 

be regulated and in

certain instances

prohibited to prevent or minimize impairments to

important characteristics, functions and values of

important habitats and other areas.

New York has worked with municipalities to develop 

understandings of varying circumstances and needs 

relating to protection and uses of differing coastal 

areas, and to determine municipal needs and desires 

regarding docks and their uses. Public outreach

efforts are included in assessing areas and

considering the generally understood effects of docks 

and vessels, and involve community consensusbuilding regarding the protection of resources and 

areas and appropriate uses of them. This

consensus-building involves consideration of human 

values regarding docks and their associated uses, 

including the effects of vessels and other uses and 

values associated with them and with other use and 

values.

This consensus-building results in the development 

of regulatory decision-making regulatory standards

for docks and, in certain cases, the uses of vessels in 

special management areas. If a goal is developed to 

allow or encourage docks and vessels associated

with them, or to limit them, the State Coastal

Management Program provides recommendations,

suggestions, and technical assistance in developing 

the regulatory and other means for doing so,

(Photo credit: S. Snow-Cotter)

(Photo credit: S. Snow-Cotter)
38

including the means of minimizing adverse

effects in certain areas where there is a need to 

minimize those effects. This is usually done 

through area-wide or water-body based

planning, based on the unique circumstances of 

specific water bodies and resources and human 

use values associated with them.

Richard Crawford summarized some of the

adverse effects of vessels, including those using 

docks. Richard Smardon will address aesthetic 

considerations regarding docks and vessels

using them. Those and other affects discussed 

at this and other workshops are generally

understood. We do not know absolutely all of 

the many and varying types and degrees of

effects resulting from docks and vessels, and it 

is extremely difficult if not impossible in many 

circumstances to quantify those effects

absolutely. However, we can and do develop 

standards and base regulatory and other

decisions on our general understandings in

order to achieve legitimate governmental

objectives, using a wide range of available

authorities.

Private docks on publicly owned underwater

lands and in public waters, accessory to the 

private residential use of privately owned

uplands, affect public resources and areas and 

uses of them. They do not advance legislative 

public purposes or state or national coastal

management objectives. They serve only the 

personal private use of the upland property

owner, whether for general private pedestrian

access to the water or for the mooring of private 

recreational vessels, impairing publicly owned

natural resources and legitimate public uses of

nearshore areas to varying degrees. Vessels using 

or associated with docks, and the uses of vessels for 

a wide range of activities (i.e. water skiing in

nearshore areas) also have a wide range of effects, 

including the suspension of sediments in shallow

nearshore areas, erosion and scour of shoreline

areas and wetlands from vessel wakes and prop

wash, the introduction of certain pollutants in the 

water column, noise, and conflicts between other

legitimate public uses of nearshore areas.

Government allows the owners of upland property 

abutting the water some types and degrees of

impairments to, and interference with, resources and 

public uses associated with docks and vessels

associated with and using them. Government has 

considerable latitude in deciding the types and levels 

of allowable private access to and uses of publicly 

owned lands, waters, and resources, and

interference with legitimate public uses and values 

associated with public resources and uses of them.

While private upland property owners generally have 

rights to construct docks for access to the water for 

navigation, this right is limited to the minimum

necessary for access to the water for navigation.

Furthermore, this right does not always include the 

right to construct a dock and moor a vessel to it. The 

decision to allow greater encroachments into (and 

impairments to) publicly owned resources and

legitimate public uses of in-water areas and

resources through the construction and use of docks 

and vessels associated with them, is at the discretion 

of the states or other levels of government entrusted 

with the management of public resources, and the 

legitimate rights of the public to appropriate access to 

and use of those resources.

(Photo credit: S. Snow-Cotter).

Boat lifts are increasingly common in small tidal creeks 

in South Carolina (Photo credit: R. Chinnis).
39

It has been our experience in New York that 

courts do not second guess managers when

their regulatory standards and decisions are

based on legitimate governmental authorities 

and objectives, are well documented, and are 

based on logical, rational decision-making and 

understandings.

The range of legitimate governmental objectives 

related to the regulation of docks and vessels 

associated with them include:

• protecting or providing for general public

access along the shoreline and water for

legitimate public purposes (such as strolling, 

wading, swimming, shellfishing, fishing,

surfcasting, etc);

• protecting or providing for general public 

navigation, whether by canoe or kayak,

sail, or motorized vessels;

• protecting or providing for important public 

or other water-dependent uses and the

protection of natural resources;

• protecting or providing for certain

development or other characteristics,

including the maintenance or protection of 

aesthetic or cultural characteristics and

values; and

• general public safety.

In summary, we generally understand the effects of 

docks, vessels, and their uses on coastal resources, 

areas, and other human uses. We do not know 

absolutely the degree of all of their effects. However, 

the available information regarding, and our

understandings of, those effects and available

governmental authorities, have been and are

sufficient to develop regulatory decision-making

standards and make defensible regulatory decisions.

Question & Answer period

Comment: It seems quite important to make sure the public understands the differences between private 

amenities and public values and rights. This is the basis for determining what is and is not legal 

and allowable usage.

Q. How does New York regulate different uses of docks and waterways?

A. Through established authorities and principles of “traditional” land use planning and regulation, 

applying those principles to the water-side (i.e., “zoning” for different uses based on 

circumstances and desired characteristics and uses of areas).

Q. Would aesthetics always trump an individual’s desire to build a dock?

A. Not necessarily. We need information on a wide range of effects to help us make rational 

decisions. And we have available a range of regulatory authorizations and factors to consider in 

making decisions.

Q. How do you determine the public’s will?

A. We involve the public in understanding the effects of docks and their uses, defining what is 

desired, and asking whether the desired standards make sense in particular cases.

(Photo credit: S. Snow-Cotter)
40

IMPACTS TO NAVIGATION AND RIPARIAN USES

Dave Killoy

US Army Corps of Engineers, New England District

Increased development has led to increased

conflict between coastal resource users. The 

clear difference between access to water

(riparian rights) and permission to extend a

structure into the water is not always clear to 

property owners. In most cases, the land under 

the water is held in public trust by the states.

Because navigation is a public trust rights, any 

structure that encroaches into the water must be 

reviewed for navigational impacts.

In 1991, in an effort to preempt potential user 

conflicts and streamline the review process, the 

New England District of the Army Corps of

Engineers developed guidelines to minimize

dock impacts to navigation. These guidelines 

were revised in 1996 and copies are available 

from the District.

The guidelines limit the impact of docks on

navigation by:

• Prohibiting structures that extend into

Federal Navigation Projects or traditional 

navigation ways.

• Allowing a new structure where a similar

adjacent one already exists. The new

structure should not extend beyond the length of 

the existing one. Exceptions are for structures 

that improve and are available for public use (i.e.,

municipal or communal docks).

• Limiting the length of structures to less than 25% 

of the width of a waterway. Where structures 

extend from both sides of the waterway, at least 

50% of the waterway should be navigable.

Where there is no physical width constriction

(because the waterway is wide), dock length

should be limited to 600 ft.

• Discouraging the placement of a structure within 

25 feet of riparian lines (extensions of property 

lines). This establishes a minimum of 50 feet 

between docks, a distance designed to allow for 

navigation by most vessels.

• Recommending that moorings be located close to 

applicant’s property. When mooring area is far 

from the property, the location should be justified 

and the applicant should list potential impacts to 

public use of the area. 

While the guidelines were developed as a basis for 

design, and not as a regulatory policy, they have 

been adopted into local ordinances by several

municipalities in New England.

 (Photo credit: J. Brashier)
41

IMPACTS TO AESTHETICS & QUALITY OF LIFE

Summary

From a manager’s perspective, oftentimes the publicly-held concerns related to small docks are not really 

related to the environment. They may be aesthetic in nature, a sense of over-development of the shore, 

or simply change. It is not uncommon for managers to hear very vocal outcries from one segment of the 

population while the rest remains quiet.

In an attempt to get a better sense of public sentiment regarding docks in South Carolina, Felts et al.

conducted telephone surveys of the opinions of residents of coastal counties in the state (2001, n=384) 

and of dock owners (2002, n= 423).

• 75% of the residents of coastal counties felt that property owners should be able to construct a 

dock.

• 66% of the dock owners and 50% of residents felt that docks should be regulated.

• 75% of the dock owners felt that the length of docks should be restricted; nearly 80% felt that the 

size should be restricted. In contrast, only 50% of the general public felt length should be 

restricted.

• <25% of dock owners and the general public felt that docks are harmful to the aquatic 

environment or detracted from the view of the water body and shoreline.

• ~75% of dock owners and the general public feel that there are not too many docks.

It is not clear whether these findings are transferable to other states or regions within those states.

While the aesthetic appeal of docks is an individual assessment, techniques have evolved that appear to 

provide a reproducible or predictive assessment of the aesthetic values of an area and how those might 

change with development. Visual impacts assessments (VIAs) developed by Smardon (1986, 1988) 

consider landscape compatibility, scale contrast, and spatial dominance.

In contrast to the social survey method discussed above, in which respondents are asked to express their 

perception of an abstract issue over the phone, VIAs present respondents with a concrete image that 

shows how the visual landscape would be affected by a proposed change. With computer technology, 

these “post-construction” images are realistic 

and easy to make. VIAs indicate that, when 

shown two images of a shoreline, the vast 

majority of people select the same image as 

being aesthetically preferable, and results 

from these assessments are reliable and 

repeatable.

In general, aesthetic preferences are for 

open/distance water views, enhanced water 

access, historic or generic coastal 

development, water related development, 

and diverse, well maintained vegetation.

People disliked development in undeveloped 

coastal landscapes and tourist-like

commercial development (Banerjee 1987, 

Knutson et al 1993, Shannon et al. 1990, 

Smardon 1987, Steinitz 1990).

 (Photo credit: R. Smardon)
42

Aesthetic or visual impacts have been used 

as a basis for denying permit applications in 

Maine and New York. Maine’s Natural 

Resources Protection Act (Title 38 §§ 480-A

through Z), Standard 1 specifically requires 

an applicant to demonstrate that a proposed 

activity will not unreasonably interfere with 

existing scenic and aesthetic uses. Chapter 

315, which is currently in review by the State 

of Maine, explains regulatory concerns 

(including visual impacts), establishes a 

standardized procedure for evaluating visual 

impacts, and explains options to mitigate 

adverse impacts to existing scenic and 

aesthetic uses.

Broad scale socio-economic assessments are necessary to determine:

• public awareness and opinion of environmental and socioeconomic costs and benefits of the increase 

in private, residential docks and piers, 

• which coastal uses the public values and how residential docks and piers relate to those uses, and

• the human use patterns for existing docks including which dock owners use their docks and which 

have them as “porch furniture.”

These assessments probably need to be a combination of a VIA and traditional public opinion survey.

Results from these assessments will tell researchers and managers where to put emphasis in education 

and outreach efforts, and are critical to the development of regional scale dock policies. 

Richard Smardon

State University of New York, Syracuse

Richard Smardon’s presentation 

focused on the aesthetic

impacts of fixed and floating

docks and piers and associated 

boating activities (boardwalks

and promenades have their own 

impacts). For example, views 

from the shore can be open, 

have a panoramic edge, or be 

filtered. Generally the public

dislikes views being filtered

through structures (e.g. docks).

Visual impact analyses (VIAs) grow from

comparisons between existing settings and

proposed changes. This allows members of the 

public to evaluate how much change a

landscape can absorb. For example,

simulations of views may be set up to show what 

build-out will look like (Fig. 19, 20, 21). For this 

process it is important to:

• document angle of the lens used,

• note the distance to the object, 

• provide the aspect or angle of the viewer, and

• provide the location of the viewpoint where the 

picture was taken.

Sea Grant has set up a web site at

www.coastal.lic.lisc.edu/bluelake.htm that allows the 

viewer to view Great Lakes landscapes with different 

levels of home build out and docks.

Visual Perception Studies of Coastal Settings

There is no visual assessment process specifically 

designed for small docks and piers, but assessments 

 (Photo credit: J. Gates)

Figure 19. Computer simulation of a dock build out in Massachusetts. 

(Photo credit: MA Coastal Zone Management Office).
43

of coastal activities on aesthetics and visual

impact conducted by Mann (1979) and Smardon 

and Hunter (1983) come close. The Visual

Resources Assessment Process (VRAP)

designed by Smardon et al. (1988) for the US 

Army Corps of Engineers to assess visual and 

aesthetic impacts for all water resource type 

projects is also useful.

Smardon presented an overview of visual

perception studies that include coastal

structures. Interestingly, docks are listed as 

both positive and negative attributes. Critical

characteristics of docks in these cases are the 

condition of the dock (well maintained vs.

deteriorating) and the number and array of

docks compared to the visual quality and

diversity of the shoreline landscape. Methods 

and results from individual studies are

presented in Table 1 (facing page). These

assessments indicate that the public likes:

coastal development that is “generic” or

historical (i.e., “fits with the context”),

open/distance water views, and diverse but well 

maintained vegetation. Structures perceived as 

marine or water related are preferred, as are 

those that enhance water access. “Tourist-like”

development and development in an

undeveloped coastal landscape are disliked.

Two studies indicate that resident’s perceptions 

of what fits with the coastal landscape is

distinctly different from visitors: Wohlwill’s 1983 

study assessed visual perception of simulated 

levels of development on the Santa Barbara, 

CA coastline; and Zube and

McLaughlin (1978) assessed

perceptions of visitors and

residents to photos of the Virgin 

Islands coastline in St. Johns. In 

both studies, residents were more 

tolerant of coastal development if 

economic income is generated to 

benefit the community.

Other factors that affect visual

perception include the level of

existing development in an area, 

the use of proposed development, 

and age of the respondent. In

working or mixed-use coastal

areas, judgments are not clear-cut,

but visitors and residents tend to 

be more critical of coastal

aesthetics in parks and

undeveloped settings than in

developed areas. Finally, older

residents are generally more tolerant of coastal

commercial development.

The only study that specially assesses visual impact

of docks on the coastal landscape was by Felts et al 

(2001) in South Carolina. This was not a visual

perception study that asked respondents to react to 

images or photos, but was a multi-item questionnaire 

asking South Carolina residents a number of

questions about docks. The results of this study are 

discussed later in this panel.

In summary, the major aesthetic impacts of docks 

and piers are due to lack of upkeep. In addition to 

Figure 20. Side by side comparison yields different impacts. From 

Smardon & Karp 1992)

Figure 21. Cross Lake "before" image (left) vs. Cross 

Lake: Simulation. Note light/shadow + water texture 

(From Smardon & Karp 1992).
44

Table 1. Review of coastal perception studies.

Methodology Positive Attributes Negative Attributes Source

Urban Los Angles 

respondents were shown 

panoramic images and video 

clips.

water, activities, beach area inappropriate structures, 

high level of 

development

Banerjee

and Gollub 

1976

Photos of water resource 

development projects in 

varying stages were sorted 

into piles according to scenic 

quality.

beaver ponds, lakes, wildlife uncompleted projects, 

pollution, oil tanks, 

eroded banks, 

excavation

Gauger

and Wycoff 

1973

Scenic river boaters in 

Wisconsin were given 

cameras and told to 

photograph both positive and 

negative aspects of the river 

visual experience.

river scenes, trees, houses set in the 

woods, rapids, developed recreation 

areas

metal pipes, powerlines, 

bridges, abutments

Cherem

and

Traweek

1977

Preference ratings of mounted 

photos were used visual 

attributes of islands and 

shoals within the Thousand 

Island area on the St. 

Lawrence River between US 

and Canada.

visually contrasting rocks and trees, 

island form variation, varied color and 

texture, clear edges

lower relief, lower 

variety, presence of 

buildings and 

development on the 

islands and shoals

Knutsen,

Leopold,

and

Smardon

1996

In this study of landscape 

perception in Dennis 

Massachusetts on Cape Cod, 

~60 photos taken by town 

residents were sorted by the

town’s people into piles 

according to landscape type 

and scenic quality. 

void of humans, habitat degradation, private 

exploitation

Palmer

1978, 1983

Photos of representative 

coastal areas were used to 

assess perception of coastal 

areas throughout NY.

lack of development litter and debris, erosion, 

water appearance, 

presence of shoreline 

structures

Neiman

1987

For this study of views to the 

St. Lawrence River from Cape 

Vincent to Hammond, NY, 

North Country residents and 

students rated photos of 

views.

views or access to water, vegetation, 

natural landscape, rural image, water 

features, views to opposite shore, 

uniqueness, edge variety, superior or 

elevated views, fences, dirt roads

utilities, trailer parks, 

screening or blocking 

views, signage, 

excessive vegetation, 

flat topography, general 

clutter, boats and docks, 

poorly maintained areas

Smardon

et al. 1987

Photos and video were taken 

of views to the St. Lawrence 

River from the road and from 

the water from Massena to 

Ogdensburg, NY were shown 

to student subjects.

islands with vegetation, marsh and 

emergent vegetation along the shoreline, 

vegetation rising in steps, dense 

vegetation down to the water, unique tree 

forms, golf course, grass area with 

grazing livestock, boat launch, grassy 

knoll with little vegetation, stone 

breakwater.

oil tanks, rocky dike and 

industrial plant, industrial 

plant, power lines, 

shipping lock, dam, 

steep rocky shoreline 

w/little vegetation, 

causeway, power 

authority dam

Shannon

and

Smardon

1990, 1996

Visual perception of views 

taken from the loop road in 

Arcadia National Park in 

Maine was measured by 

asking for positive and 

negative characteristics.

sense of mystery (they wish to be further 

drawn into the scene), coastal 

development that is generic to the Maine 

landscape or with a distinctly “ historical” 

character, water views, long distance 

views, “folded” or multi-layered landscape 

(typically mountains and islands), diverse 

and well maintained vegetation 

distribution in the foreground and middle 

ground of the view.

developed or urbanized 

landscape, evidence of 

crowed use, touristoriented commercial 

development

Steinitz

1990
45

deteriorated structures, water quality

considerations, wildlife disturbances, and the

spacing or density of docks were important.

These impacts can be mitigated by: 

• Contrast reduction, 

• Reduction in height and size,

• Using “natural” or “traditional” materials,

• Increasing the distance between docks,

• Enhancing public access, 

• Providing interpretive sites (historic or

heritage uses), and

• Establishing setbacks along the shoreline for 

other structures.

Recreation User Perception Studies

Beaches: Beach aesthetic preference studies 

indicate a divergence in beach preference.

Higher educated older residents prefer natural 

beaches with low intensity of uses with attractive 

trees, whereas younger users prefer city

beaches with facilities and do not mind crowds 

(Cutter 1979, Peterson and Neuman 1969). In 

general, cleanliness, convenience and

aesthetics are desirable (Cutter 1979). Carls

(1974) found that greater numbers and

development reduces preference on

Massachusetts’s beaches on Cape Cod.

Boating: Tolerance to crowds and user patterns 

depends on the type of boater and whether the 

boater is a resident or visitor. Power boaters are 

most tolerant of other uses, sailing boaters are 

less tolerant, and fishing and non-motorized

boaters are least tolerant of multiple uses (Lime 

1970). Permanent residents are more

concerned about displacement, safety, litter and 

marine waste then visitors (Droggin et al. 2000).

Water Quality: Literature on 

perceptions of water quality by 

recreational users indicates

concern for impacts of boating 

activity associated with docks.

Water quality problems

commonly mentioned by

recreational users are: films of 

gas and oil, solid waste (bottles 

and cans), use of pesticides

and herbicides, sedimentation/ 

turbidity, beach pollution.

Boaters are most sensitive to 

water quality and are the first 

to notice muddy or foamy,

unusual colors and objects, green scum and

algae, sewage, and solids. Fisherman notice 

films and dead fish, and cottage owners notice

strange odors, algae, and skin irritations.

Shoreline Planning

Guidance material for coastal planning purposes and 

docks is part of the Wisconsin Sea Grant Coastal GIS 

Applications Project (Hart and Sutphin, undated and 

http://www.coastal.lic.wisc.edu/bluelake.htm). This

site includes alternate layouts for coastal planning 

with an interactive GIS/3D animated software that 

allows one to envision different coastal development 

futures under different zoning and setback

requirements. In terms of prescriptive planning and 

design guidance – the most detailed for coastal

development is the Victoria Coastal Council’s (1988) 

Siting and design principles on web site

http://www.vcc.vic.gov.au/siting/guidelines.htm

Shoreline regulations

Many states have regulations governing coastal zone 

land use (Smardon and Karp 1992) and marina siting 

and operation. Shoreline and 

water area zoning has been 

proposed, but is rarely

implemented. Only two water 

body areas (to authors

knowledge) have restrictions 

on the number of docks, or

dock length and design: Lake 

Tahoe, (Smardon 1992,

1997) and lakes in the

Adirondack Park in New York 

State (Smardon 1992).

Because of the Lucas case 

in South Carolina (see Nolan 

1997) and the threat of

takings of private property rights via regulation of

allowed coastal uses and development – one needs 

to be extremely careful in this area. 

Coastal development can impact views.

(Photo credit: R. Smardon)

Historic water structures are generally considered 

scenic, tourist-like commercial structures are disliked.

(Photo credit: J Gates)
46

Question & Answer Period

Q. How do you know that, if you follow the process and get public input, that the result (change in 

visual impact) arises from the process rather than from getting people to simply communicate?

A. The process is good for getting an iterative discussion started.

Comment: In our experience in Maine, it doesn’t matter whether it is the process or not—you get same 

result.

Q. How many view points do you use – only one?

A. No, six or seven is the magic number.

Q. Do these analyses actually lead to design changes?

Aesthetic Coastal Regulation:

State-by-State Breakdown

California Coastal Act of 1976, Cal. Res. Code, Div. 20, Art. 6 upheld by Candlestick Properties vs. 

San Francisco Bay Con. & Devel. Com. 89 Cal. Rpt. 897 (1970)

Connecticut Ch. 440 s. 22a-28

Maine Shoreline and Subdivision Control Act, Samorock LLC Rockland, Knox County Samoset 

Yaught Club L-14246-4F - permit denied on ecological & aesthetics at 

http://www.penday.org/nosamook

Maryland Title 9 s9-102 & Maryland Coastal Bays program: Ocean City Fishing Center in West 

Ocean City - ultra clean marina at http://www.mdcoastalbays.org/news/weekly14.html

Michigan Inland Lakes & Streams Act of 1972, s. 281.957

Minnesota Rules for Chapter 6105:0410 Marinas - limits locations http://www.reviser.leg.state.ms.us/

Mississippi Title 49, Ch. 27

New Hampshire Ch. 483As.1-b

New Jersey Title 13 Ch. 19

New York Tidal Wetlands Act art. 483 Ch. 25 s.010 (h)

North Carolina Ch. 13A-102

Oregon Land Conservation and Development Law, Goal 16: Estuarine Resources -regulates marinas 

in estuarine areas - http://utopia.uoregon.edu/projects/landuse/goal16.html

Rhode Island Title 2-1.13

Texas Ch. 33, ss001
47

A. Yes, often when we recommended that project proponents “soften” the structures, they do as a 

means of gaining public acceptance. In many instances aesthetics became a huge issue with the

public and were fundamental to getting these projects done.

Q. Could you do it backwards? Take developed shoreline and restore it?

A. Probably not, but that’s an interesting idea. Reactions vary. People are attached to things in the 

landscape.

Judy Gates

Maine Department of Environmental Protection, Division of Land Resource Regulation

In recent years there has been a growth in

permit applications for docks and with it an

increased expectation for all-tide access which 

means that structures must have heavier

construction and be larger in size and length.

The Maine Natural Resources Protection Act

(NRPA) (Title 38 § 480, A–Z) specifically

requires an applicant for a dock or other coastal 

structure to “demonstrate that a proposed

activity will not unreasonably interfere with

existing scenic and aesthetic uses.” The

supporting regulation, Chapter 315, has been

developed over the past year to provide a tool 

for assessing and mitigating impacts to existing 

scenic and aesthetic uses.

Maine’s DEP has found that to get the highest 

level of protection, it needs to get involved with 

the first structure in a newly developing area. In 

the past 5 years they have denied permits for 

docks proposed in places were there was no 

previous development. 

There have been several court cases that tested 

decisions under these rules, including:

• Kolsaka vs. ME—in this case a permit denial 

was overturned because it was “too vague”; 

and

• Anne Hannum vs. ME Board of

Environmental Protection—in this instance 

the proposed pier interfered with aesthetics 

and boat traffic. Additionally, there was

potential for interference with seal pupping 

and endangered terns that are about a

quarter of a mile away. The ruling was 

based on the use of the structure, not the 

structure itself.

In response to a concern that future cases will 

be lost because the NRPA standard concerning 

existing scenic and aesthetic uses is

unconstitutionally vague, Maine’s Department of

Environmental Protection developed Chapter 315.

This chapter codifies and standardizes aesthetic

concepts by

• Specifying state regulatory concerns,

• Defining visual impacts,

• Establishing a procedure for evaluating visual

impacts,

• Establishing when a visual assessment may be 

necessary,

• Explaining the components of a visual

assessment, and

• Describing avoidance, mitigation, and offset

measures that may eliminate or reduce adverse 

impacts to existing scenic and aesthetic uses.

Under Chapter 315 visual impacts will be determined 

by considering:

• Landscape compatibility of the proposed

structure;

• Scale contrast; and

• Spatial dominance.

Undeveloped coastline in Maine. (Photo credit: J. Gates).
48

This process has played out in a series of

decisions illustrated in Figures 22 - 24. In Case 

1, a large coastal resort proposed a marina for 

its users that would have blocked a public view 

of a historic breakwater and lighthouse. This 

application was withdrawn after the DEP issued 

a draft denial based on the projects impact on 

existing scenic uses. In Case 2 the proposed 

dock was allowed because it did not interfere 

with scenic values of the viewshed. In Case 3, 

DEP found that the proposed dock would

interfere with significant public scenic views and 

asked the proponent to consider other locations.

This case is particularly interesting in that there were 

no direct resource impacts from this individual dock.

However, the dock would have been located in the 

only natural fjord on the East coast and would have 

been the only dock visible for users of Acadia

National Park viewing the fjord from a popular hiking 

trail. Consequently the project was denied, but at this 

date is still within the timeframe for appeal. In this 

instance, the denial was partly based on existing

alternatives for coastal access available to the

applicant that would preclude construction of the

proposed pier. 

The resort has historically allowed the public to cross 

from a neighboring park, across the intertidal and 

subratidal to access the breakwater. This is the only 

access point to the breakwater.

From the park and beach, the public has an 

unobstructed view of the mile long breakwater and the 

lighthouse at the end, as well as a view of Owls Head 

across the bay.

Figure 22. Case 1: The application for this dock was withdrawn after visual impact assessment 

revealed that it interfered with public scenic views.

The Samoset resort is adjacent to the 100 y.o. Rockland 

Breakwater. The Resort itself has already changed the 

character of the shoreline, so looking solely at the view 

from the water and considering the developed nature of 

Rockland Harbor, visual quality might not be at issue. 

A modified photo showing the proposed marina’s 

proximity to the Rockalnd breakwater. The proposal 

placed the pier directly next to the park. Because 

the pier would have been higher than the 

breakwater, the public’s view of and access to the 

breakwater would have been impeded. Faced with 

a draft denial, the applicant withdrew. 
49

The DEP initiated development of the guidelines 

Figure 23. Case 2: The ME DEP determined that this pier (left), which had the dubious benefit of being permitted 

after it was built, did not interfere with the reason that the view was found to be scenic. As is not unusual, the party 

declaring a scenic impact was a neighbor, whose grandfathered lot potentially constituted a larger impact to the 

visual quality of the north side of the island (right). This project caused the DEP to think carefully about whose view 

they are charged with protecting, and reinforced the concept that it is the public’s view that the legislature was 

concerned with when it adopted the NRPA. 

Figure 24. Case 3: Looking toward the shore where the 

pier was proposed, it was easy to determine that the 

dock would not interfere with the visual quality of the 

shoreline any more than the existing development (top 

right). This was not the first pier proposed in the area, 

and in fact there are several along the adjacent shoreline 

(bottom left). Cumulative impact may have been an 

issue, but in this case there is a good distance between 

the piers and the additional direct impacts from this pier 

were unlikely. However, the coastal resource of concern 

is Somes Sound, the only natural fjord on the east coast.

The view in this photo (bottom right) is from the top of 

Flying Mountain, one of the most popular hikes in Acadia 

National Park. The proposed dock would be clearly 

visible from the trail and summit of Flying Mountain, 

while the existing docks are not.
50

The DEP initiated development of the guidelines 

in April 2001 and held an internal review in

October 2002. The draft rule has been posted 

and a public hearing will be held April 3, 2003, 

with public comments due by April 14.

As part of the process, a Standard Operating 

Procedure (SOP) for visual assessments was 

developed to provide consistency in decision-making

among staff and improve the decision-makers’ ability 

to document decisions. Under the new process, it is 

predicted that less than one percent of applications 

will have any additional requirements beyond what 

the law and the DEP already require. 

Question & Answer Period

Q. Have any local governments adopted this process?

A. Not yet, local governments seem to be waiting until the rules pass all of the legal hurdles.

Q. What alternatives to building a dock are considered (i.e., marina slips, moorings, etc.)?

A. We consider what applicants already hold as well as what’s available.

Q. Do you consider the objections of neighbors with scenic issues?

A. Yes, but not exclusively. We are much more concerned with the public’s view as specified in the 

preamble of the NRPA. We primarily look at the viewshed from publicly accessible viewpoints.

Q. How sensitive do you have to be to comments from self-interested commentators (realtors, 

developers) on the new rule?

A. We have spoken with them throughout this process. They’d like to see more consistency as well.

Chapter 315 is simply further guidance – the existing regulations already require applicants to 

show that their project will meet all of the NRPA standards.

Q. How does this proposed rule on visual effects work with other rules regarding ecology, etc.? Are 

the processes the same?

A. The same department considers water quality and the other factors.

Richard Chinnis

South Carolina Department of Health and Environmental Control, 

Office of Coastal Resource Management

In South Carolina permit applications have

increased ten-fold over the past 20 years, from 

80 in 1982 to over 800 in 2002. In addition, 

many docks are now designed with lifts to bring 

boats out of the water. This has had the benefit 

of keeping boats off the mud bottom but it has 

the adverse effect of allowing larger boats to 

dock in small tidal creeks (Fig. 25).

Existing regulations in South Carolina set the 

maximum length of docks at 1000 feet. State 

managers have attempted to have this

shortened to 500 feet, but legislative support is 

lacking.

Figure 25. The use of boatlifts means that now you see not 

only the dock, but the entire profile of the raised boat as 

well. (Photo credit: R. Chinnis).
51

Managers in South Carolina have the authority 

to review docks for visual impacts. To date, they 

have had a 100% success rate in denying

permits on these grounds in areas designated 

for special protection such as the Ashley River.

In one instance a project proponent subdivided 

her property and proposed 

to build a dock on each of 

seven lots. Her property 

was across the river from 

a Historic garden (Fig. 26).

After testimony to the

effect that the docks would 

degrade the visual

enjoyment of visitors to the 

public garden, the permits 

were denied.

Last year, there were 42 

appeals of dock permits.

In most cases, the

appellants were annoyed

that too many docks are being permitted without 

consideration of cumulative or aesthetic impacts.

To find out more about public

perceptions of docks, the DHEC

sponsored two public attitude

surveys that were conducted by

Felts et al. 

One sought opinions from coastal 

residents, the second from dock 

owners. Generally, people feel that 

docks add to property values. A 

court assessor claimed that a

permit alone can enhance property 

value by $300–600K. Furthermore, 

the majority (~75%) of residents of 

coastal counties felt that:

• property owners should be

allowed to build a dock,

• docks are not harmful to the 

aquatic environment,

• docks do not take away from 

views, and 

• there are not too many docks.

However, 66% of dock owners and 

50% of residents agreed that docks 

should be regulated and their size 

restricted. Half of those surveyed thought that

boating uses are harmful, and 59-76% felt that there 

are places where docks should not be built.

If they have to be regulated, most residents felt that 

regulation by local, rather

than state government is 

more appropriate.

However, local

governments do not want 

to do the regulation—they

have neither the budget

nor expertise.

Presently, docks are

limited to three feet above 

mean high tide and four

feet in width and can only 

be built on lots 75 ft wide 

or wider. Despite

resistance to restrictions

on roofs or coverings (as 

indicated in the survey), present regulations do not 

allow roofs if no one else near by has one. Where 

they are allowed the maximum is 12 ft above the 

deck level including peak of roof, weather vane, etc.

Figure 26. Proposed docks across from the historic Magnolia Gardens 

were denied because they would interfere with scenic views from the 

garden. (Photo credit: R. Chinnis).
52

Question & Answer Period

Q. Do you consider other structures in the area?

A. No, because we use dated (1986) aerial photos.

Q. In Loyd Harbor, NY, they had two assessors look at values of properties with and without docks.

The potential to have a dock (or having one) didn’t affect property value. The value of the 

waterfront lot was similar to inland lots, development pattern and services were more important.

So were the increases in property value real or perceived?

A. Analyses have not been conducted, but our opinions regarding these sorts of property value 

impact issues are based on the testimony of appraisers in court.

Q. Can you argue that a neighbor’s dock devalues surrounding property values?

A. That question was asked in the survey. The public does not think this is the case. 

Q. Is there a correlation between dredging requests and proliferation in docks?

A. Not really. We do not permit dredging in natural creeks along which most of these docks are built.

Q. Do you have a sense of the demographics of people interviewed for survey?

A. It was weighted toward white-collar college graduates. For more information take a look at the 

website. It can be downloaded from the Hot Topics section of the South Carolina Department of 

Health and Environmental Control website: http://www.scdhec.net/ocrm/.

Q. How do you deal with shading?

A. We deal with shading by requiring dock master plans that show alignment. We have some 

flexibility, but other than specific regulations we can’t do much about height and width.

Q. What are dock master plans?

A. They are part of our newer process. Any project that requires another permit (i.e., wastewater) 

from the state or federal government must provide a dock master plan according to specific 

guidelines. Applications are posted for the public on the website every week (see 

http://www.scdhec.net/ocrm/).

Q. Are dock master plans required in previously developed areas?

A. No, only since 1993 have dock master plans been required.

Q. No pictures were shown during the survey to participants? It is somewhat scary to have that 

survey out there.

A. That is correct, the survey was conducted on the telephone. We had no role in designing the 

survey—showing participants some pictures might have resulted in a different response. 
53

MANAGEMENT RESPONSE

Following the presentations, the managers were asked to respond, either commenting on how the 

material presented met their needs or to make recommendations for best use of the material. The 

following are drawn from that discussion.

Comment: This sort of workshop is taking us in 

the right direction. There is a strong need 

for research that will quantify impacts and

help managers explain why they are

approving or denying docks. Managers

need to know what species and habitats will 

be affected and whether there is the

possibility of mitigating 

the impacts.

The idea of a

conceptual model is

very welcome. Based 

on such a model,

managers could

generate an overall

plan, policy, or

guidelines to avoid

site-by-site analyses.

Scientifically backed,

broad policies add to predictability and

understanding by legislators—whose

support is critical—and the regulated

community.

Comment: Matrices have been used in some 

instances with a fair degree of success. In a 

proposed sub-division in Delaware the

developer promised a dock for each of some 

40+ lots. Rather than reviewing this many 

individual permits over time, state managers

developed a general plan that assessed the 

cumulative impacts and determined that the 

system could handle 20 docks without

unacceptable impacts. Under appeal, it was 

found that this was a reasonable approach 

and the 20-dock limit was upheld. 

Comment: Managers realize that it is difficult if 

not impossible to establish specific

thresholds or standards for all impacts.

However, the best available information on 

the various impacts will help managers

make more informed decisions on

approvable designs and on when a

proposed project should be denied.

Comment: There is little information on the topic 

of cumulative impacts. While managers have 

some sense of the impacts of individual docks, it 

is not known whether cumulative impacts are 

additive, exponential or otherwise. Additional 

research on systems where there are multiple 

docks is necessary.

Comment: It is important 

to put proposed docks in 

their environmental

context. In South

Carolina, where there is 

a considerable amount of 

salt marsh, shading

impacts may be minimal 

when compared with the 

amount of the resources.

In other states, or even in 

particular creeks in South 

Carolina, full build-out

may not be appropriate.

Comment: There needs to be an assessment of the 

impacts of the “no build option” as well as from 

dock construction and use. If a dock is not 

permitted, the result may be additional foot traffic 

across a marsh or tidal flat or boat storage on the 

shore. We have little solid data on the impacts of 

this sort of use as compared with a dock to meet 

the same needs.

Comment: It was very useful to get a better

understanding of the validity of viewshed

analyses. This information needs to be

incorporated in project assessment and the

techniques need to be more widely disseminated.
54

Comment: There has been little peer-reviewed

information published on the topic of

shading impacts to salt marsh vegetation. It 

is important to have better information on 

this topic and perhaps more research.

There presently is no tool available to

managers to predict shading impacts.

Comment: Better outreach to the affected

community and their legislators and elected 

officials is critical. Providing defensible

science-based information can help frame

policy and regulatory decisions and lead to 

acceptance. It is often difficult to clearly 

explain and justify changes in regulatory or 

assessment processes and consequently

there is a need for clear scientific data. Along 

with any guidelines should be a clear rationale of 

what the intended goal is and on what

information decisions will be based.

Comment: There is a need for flexibility in the review 

process. By identifying and clearly stating social 

and environmental goals and putting each project 

into its context decisions will be more

understandable. This requires the development 

of critical decision points for these goals.

Comment: All of this underscores the need for the 

development of a conceptual model or matrix to 

be utilized in decision-making.
55

RECOMMENDATIONS

Coastal Planning and Regulation

• Base licensing decisions on small docks on 

impacts to habitats, water quality, and

existing uses, which include navigation,

recreation, and scenic and aesthetic

values.

• Mandate that the purpose and use of a 

dock be water dependent.

• Educate that public trust and riparian rights 

only allow waterside property owners

access to the water—the use of public

waterways for a dock is a privilege, not a 

right of ownership. There is no absolute 

right to a dock for a large boat. 

• Charge responsible application fees for the 

use of public trust lands where managers 

rely on permitting to regulate docks. Fees 

should reflect the property value increase

the dock owner will receive and a portion of 

the fees should be applied to mitigating for 

lost or damaged resources associated with 

the permitted structure.

• Incorporate results from environmental and 

socioeconomic assessments to develop

regional scale dock policies that (1) provide

incentives for home owners who elect not to have 

docks or groups of homeowners that chose a 

shared dock strategy (e.g. reduced property

taxes for short-term and permanent easements 

against a dock), and (2) include a dock mitigation 

strategy and plan that can be supported at the 

local, state, and national level.

Environmental Mitigation Strategies

• Minimize shading impacts on vegetation by 

limiting the following parameters:

- Height: maintain a four-foot minimum 

elevation over the marsh face or mean 

high water (In New England that height 

may need to be greater.)

- Width: limit the width to a

maximum of four feet (with 

exceptions for handicap

access and American

Disabilities Act issues)

- Orientation: orient as close 

as possible to North–South.

- Length: limit length to the 

minimum needed to reach

water navigable at mean

low water.

• Consider alternatives to CCA -

treated lumber in areas of low 

flushing.

• Reduce shading impacts by using grated

material as decking (especially in Southern US).

• Increase illumination under docks by

incorporating light tunnels or reflective deck

bottoms.

• Keep heavy equipment off the 

marsh face unless it is

especially designed to avoid

peat compaction. Float

construction materials in from

the water side, and work as

much as possible from the

water or existing structures.

• Avoid high pressure jetting for 

piling installation—sharpen

piling tips and make initial

insertion with low pressure

jetting or by utilizing a drop

hammer.
56

Accounting for Visual Impacts

• Consider aesthetics in the permitting

process.

• Predict aesthetic impacts reliably by

incorporating Visual Impact Assessment

techniques into the permitting process.

• Conduct public opinion surveys to establish 

general values and levels of awareness;

they are greatly improved when preceded by 

a visual characterization. (The surveys do 

not provide aesthetic valuations.)

Minimizing Impacts to Navigation

• Discourage structures that extend >25% 

across a waterway 

• Redirect structures extending into Federal 

Navigation Projects or traditional navigation 

paths.
57

RESEARCH NEEDS

Subsequent to the presentations, the managers in attendance met to discuss research needs from their 

perspective. These are summarized in the following list. No priorities were applied to the items on the 

list.

• The cumulative impacts from docks and their associated uses and how they can be avoided, 

minimized or mitigated.

• The relationship between the presence, construction, and/or use of docks and vegetative habitat 

fragmentation.

• The regional differences, if any, between impacts from docks.

• Light requirements for marsh and submerged aquatic vegetation by region.

• A method or model to predict shading impacts from proposed docks.

• Better understanding of impacts to shellfish and fisheries, habitat for shellfish and fisheries, and 

on shellfishing and fishing.

• Monitoring protocols to measure impacts from docks over time.

• Impacts of docks on sediments, sedimentation, and hydrodynamics.

• Public perceptions and understanding of the benefits and detriments of docks.

• The impacts of a no-build scenario (i.e., foot traffic, dingy storage, etc. on inter-tidal and supratidal resources.

• Better understanding of the overall effects of docks and their associated uses on: resource 

functions, characteristics, and values; development and aesthetic characteristics and values; and 

human uses of coastal areas and resources. 

Non-research needs identified by the managers included:

• Additional information on the technical aspects and capabilities of dock design and construction in 

order to minimize impacts.

• Establishment of an outreach or education plan and materials to inform the general public and 

those seeking to construct docks about potential impacts, purposes and nature of regulatory 

programs, and techniques of dock construction.

(Photo credit: D. Shafer)
58

BIBLIOGRAPHY RESULTING FROM THE WORKSHOP

During the course of preparing for and presenting this workshop an extensive bibliography was 

developed. This will be supplemented and posted on the NOAA National Centers for Coastal Ocean 

Science website: http://www.coastalscience.noaa.gov. Full references for literature cited in this report are 

included in the online bibliography.

The bibliography is searchable for the following keywords: vegetation, shading, contaminants, sediments, 

boating, recreational uses, navigation, planning, public access, recreation, and aesthetics, as well as by 

author, and title.
59

FUTURE STEPS

Prepare a peer-reviewed synthesis document on the impacts of small docks.

It was strongly suggested that there is a need for a thorough, peer-reviewed synthesis report on the state 

of the scientific knowledge related to the impacts of small docks. The background paper included in this 

proceedings provides a starting point but a much more thorough review is needed.

In addition to expanding on the material in the background paper prepared prior to the workshop, the 

synthesis document should:

• Address regional differences in affected environment, dock design and impacts

• Provide a clearer description of the nature of the problem(s)—real or perceived

• Characterize the various designs and construction of docks (i.e., the range of structures) as well as 

the activities related to dock use

• Determine impacts for each element of dock structure (e.g. pylons, etc.)

• Address both project-specific and cumulative impacts.

Develop bibliography related to the science of dock impacts.

As part of the preparation and presentation of this workshop, an initial bibliography related to docks was 

prepared. Several of the presenters submitted additional bibliographic material. This should be 

expanded and made available—possibly through a web site—for researchers and managers. Plans 

should be made to maintain the bibliography with current research.

Host additional workshops on: 

• Available technologies for dock design and construction

This workshop would bring together managers, representatives of the dock design and construction 

industry, and those familiar with new and innovative techniques and materials to help managers 

better understand the options available in dock design and construction.

• Available management techniques: regulatory and non-regulatory

A workshop providing information on the management techniques and tools available at the local, 

state, and federal level would provide a basis for refining planning and regulatory programs. This 

should include a review of the legal parameters that apply to docks and case studies of successful 

(and perhaps unsuccessful) programs. 

Prepare a state-by-state checklist of regulatory tools and programs used to manage docks and 

precedent-setting court decisions.

Present workshop findings. The following presentations are scheduled:

• Emerging Technologies, Tools, & Techniques – January 2003, Coco Beach, FL

• Southeast Coastal Program Managers’ Meeting – February 2003, Wrightsville Beach, NC

• Coastal Zone ’03 – July 2003, Baltimore, MD

• Society for Conservation Biology Annual Meeting – June 2003, in Duluth, Minnesota

Establish a dedicated web site for dock impacts and management discussion.

Develop a checklist of known and potential/implicated impacts from small docks.

Develop a conceptual model that will allow mana gers to assess the impacts of single dock 

proposals or develop a regional dock management plan.
60

APPENDIX 1: PARTICIPANTS’ CONTACT INFORMATION

Name

Address P hone Email

Clark Alexander Skidaway Institute of 

Oceanography

10 Ocean Science Circle

Savannah, GA 31411 

912.598.2329

fax:

912.598.2310

clark@skio.peachnet.edu

Rick Ayella MD Dept. of the Environment

1800 Washington Blvd

Baltimore, MD 21230

410.537.3835 rayella@mde.state.md.us

David Blatt CT Dept Environmental Protection

79 Elm Street

Hartford, CT 06106

860.424.3034

fax:

860.424.4054

david.blatt@po.state.ct.us

Steve Bliven Bliven & Sternack

49 Plains Field Drive

South Dartmouth, MA 02748

508.997.3826

fax:

508.997.3859

Bliven@attbi.com

Jerry Brashier Permitting Bureau Director

Division of Marine Resources

1309 Rosemont Drive

Gautier, MS 39553

228.374.5022

x 5028

Jerry.brashier@dmr.state.ms.us

Dave Burdick Jackson Estuarine Laboratory

University of New Hampshire

Durham, NH 03824

603.862.2175 dburdick@cisunix.unh.edu

Allison Castellan NOAA, OCRM

1305 East West Highway, Room 

11208

Silver Spring, MD 20910-3282

301.713.3155

x225

Allison.Castellan@noaa.gov

Richard Chinnis OCRM

SC Dept. Health & Env Control

1362 McMillan Ave, Suite 400

Charleston, SC 29405

843.747.4323

x 129

chinnira@dhec.sc.gov

Rick Crawford Nautilus Environmental Services

1815 Falmouth Road, Unit H-2

Centerville, MA 02632

508.790.8322 rcrawford@whoi.edu

Torrance Downes Connecticut River Estuary Regional 

Planning Agency

455 Boston Post Road

P.O. Box 778

Old Saybrook, CT 06475

860.388.3497 jhtdownes01@yahoo.com

Judy Gates Division of Land Resource Reg.

Maine DEP

17 State House Station

Augusta, ME 04333

207.287.7691 Judy.Gates@maine.gov

Andrea Geiger Coastal States Organization

Hall of States, Suite 322

444 North Capitol St, NW

Washington, DC 20001

202.508.3860 ageiger@sso.org

Truman Henson Massachusetts CZM

3195 Main Street, Route 6A

P.O. Box 220

Barnstable, MA 02630

508.362.1760 Truman.Henson@state.ma.us

Mike Johnson NMFS Northeast Regional Office

One Blackburn Drive

Gloucester, MA 01930-2298

978.281.9130

fax:

978.281.9301

Mike.R.Johnson@noaa.gov

Ruth Kelty National Centers for Coastal Ocean 

Science

1305 East-West Highway, SSMC 4, 

301.713-3020

x133 Fax 

301.713.4353

ruth.kelty@noaa.gov
61

rm. 8215

Silver Spring, MD 20910

Dave Killoy NE District

US Army Corps of Engineers

696 Virginia Road

Concord, MA 01742-2751

978.318.8490 David.H.Killoy@usace.army.mil

Mike Ludwig NMFS NE Fisheries Science 

Center

Habitat Conservation

Milford Laboratory

212 Rogers Ave

Milford, CT 06460-6499

203.882.6504 Michael.Ludwig@noaa.gov

Bill Moyer DE Dept Nat Res & Env Control

Div. Water Resources

89 Kings Highway

Dover, DE 19901

302.739.4691 william.moyer@state.de.us

Ed Reiner US EPA Region 1

1 Congress St., Suite 1100 (CMA)

Boston, MA 02114

617.918.1692

fax.

617.918.0692

Reiner.ed@epa.gov

Steve Resler NYCMP-NYS Dept. of State

41 State Street

Albany, NY 12231-0001

518.473.2470

fax:

518.473.2464

sresler@dos.state.ny.us

Steve Rumrill South Slough National Estuarine 

Research Reserve

P.O. 5417

Charleston, OR 97420

541.888.2581

x 302

fax

541.888.3250

Steve.Rumrill@state.or.us

Denise Sanger Marine Resources Research Inst.

Marine Resources Div. SCDNR

217 Fort Johnson Rd.

Charleston, SC 29412

843.953.9087 sangerd@mrd.dnr.state.sc.us

Deborah Shafer EE/W

Army Corps of Engineers

Waterways Experimental Station

3909 Halls Ferry Road

Vicksburg MS 39180

601.634.3650

fax:

601.634.3205

ShaferD@wes.army.mil

Richard Smardon SUNY-ESF Syracuse

106 Marshall Hall

1 Forestry Drive

Syracuse, NY 13210

315.470.6636/

6576

fax:

315.470.6915

rsmardon@mailbox.syr.edu

Susan SnowCotterMassachusetts CZM

251 Causeway Street, Suite 900

Boston, MA 02114-2199

617.626.1202 Susan.snow-cotter@state.ma.us

Ron Thom Battelle Marine Sciences Lab

1529 W. Sequim Bay Road

Sequim, WA 98382

360.361.3857

fax: 360-681-

3681

Ron.Thom@pnl.gov

Peddrick Weis Dept of Radiology/G-621

UMDNJ - New Jersey Medical 

School

Newark, NJ 07101-1709

973.972.4409 weis@umdnj.edu
62

OTHER TITLES IN THE DECISION ANALYSIS SERIES

1. Synthesis of Summer Flounder Habitat Parameters (K.W. Able and S.C. Kaiser, May 1994) 

2. Technology and Success in Restoration, Creation and Enhancement of Spartina Alterniflora Marshes 

in the United States [2 volumes] (G. A. Matthews and T.J. Minello, August 1994) 

3. Bibliography of Synthesis Documents on Selected Coastal Ocean Topics (E.V.Collins, M. Woods, I.C. 

Sheiffer, J. Beattie, October, 1994) 

4. Marine Eutrophication Review (K.R. Hinga, H. Jeon, N.F. Lewis, January 1995) 

5. Economic Valuation of Resources: A Handbook for Coastal Resource Policymakers (D.W. Lipton, K. 

Wellman, June, 1995) 

6. Methodologies and Mechanisms for Management of Cumulative Coastal Environmental Impacts 

(Vestal, B., A. Reiser, et al., 1995) 

7. Forestry Impacts on Freshwater Habitat of Anadromous Salmonids in the Pacific Northwest and 

Alaska - Requirements for Protection and Restoration. (M.L. Murphy, October, 1995) 

8. Watershed Restoration - A Guide for Citizen Involvement in California (W.F. Kier, December 1995) 

9. Atmospheric Nutrient Input to Coastal Areas - Reducing the Uncertainties (R.A. Valigura, W.T. Luke, 

R.S. Artz, B.B. Hicks, June, 1996) 

10. Harmful Algal Blooms in Coastal Waters: Options for Prevention, Control and Mitigation (D.F. Boesch, 

D.M. Anderson, R.A. Horner, S.E. Shumway, P.A. Tester, T.E. Whitledge, February, 1997) 

11. Change in Pacific Northwest Coastal Ecosystems (Edited by G.R. McMurray and R.J. Baily, April, 

1998)

12. Guidelines for the Conservation and Restoration of Seagrasses in the United States and Adjacent 

Waters (M.S. Fonseca, W.J. Kenworthy, and G.W. Thayer, November 1998)

13. Bering Sea FOCI Final Report 1998 (Edited by S.A. Macklin, December 1998)

14. Nutrient Enhanced Coastal Ocean Productivity in the Northern Gulf of Mexico (Edited by Wiseman, 

Rabalais, Dagg & Whitledge 1999) 

15. Characterization of Hypoxia: Topic 1 Report for the Integrated Assessment on Hypoxia in the Gulf of 

Mexico. (Rabalais, N., R.E. Turner, D. Justic, Q. Dortch, and W. Wiseman Jr. 1999)

16. Ecological and Economic Consequences of Hypoxia: Topic 2 Report for the Integrated Assessment

on Hypoxia in the Gulf of Mexico. (Diaz, R.J., and A. Solow. 1999)

17. Flux and Sources of Nutrients in the Mississippi-Atchafalya River Basin: Topic 3 Report for the 

Integrated Assessment on Hypoxia in the Gulf of Mexico. (Goolsby, D.A. W.A. Battalin, G.B. 

Lawrence, R.S. Artz, B.T. Aulenbach, R.P. Hooper, D.R. Kenney, and G.J. Stensland. 1999)

18. Effects of Reducing Nutrient Loads to Surface Waters within the Mississippi River Basin and the Gulf 

of Mexico: Topic 4 Report for the Integrated Assessment on Hypoxia in the Gulf of Mexico. (Brezonik, 

P.L. V. Bierman, Jr., R. Alexander, J. Anderson, J. Barko, M. Dortch, L. Hatch, G. Hitchcock, D. 

Kenney, D. Mulla, V. Smith, C. Walker, T. Whitledge, and W.J. Wiseman, Jr. 1999)

19. Reducing Nutrient Loads, Especially Nitrate-Nitrogen to Surface Water, Ground Water, and the Gulf 

of Mexico: Topic 5 Report for the Integrated Assessment on Hypoxia in the Gulf of Mexico. (Mitsch, 

W.J., J.W. Day, Jr., J.W. Gilliam, P.M. Groffman, D.L. Hey, G.W. Randall, and N. Wang. 1999)

20. Evaluation of the Economic Costs and Benefits of Methods for Reducing Nutrient Loads to the Gulf of 

Mexico: Topic 6 Report for the Integrated Assessment on Hypoxia in the Gulf of Mexico. (Doering, 

O.C., F. Diaz-Hermelo, C. Howard, R. Heimlich, F. Hitzhusen, R. Kazmierczak, J. Lee, L. Libby, W. 

Milon, T. Prato, and M. Ribaudo. 1999)

21. COASTAL: The Potential Consequences of Climate Variability and Change. (Edited by D.F. Boesch, 

J.C. Field, and D. Scavia. October 2000)

22. Environmental and Aesthetic Impacts of Small Docks and Piers, Workshop Report: Developing a 

Science-Based Decision Support Tool for Small Dock Management, Phase 1: Status of the Science.

(Kelty, R.A. and S. Bliven. January 2003)