Table Of ContentSecond Edition
CREATING
FRESHWATER
WETLANDS
Donald A. Hammer
LEWIS PUBLISHERS
Boca Raton New York London Tokyo
Acquiring Editor: Neil Levine
Project Editor: Suzanne Lassandro
Marketing Manager: Greg Daurelle
Direct Marketing Manager: Arline Massey
Cover design: Denise Craig
PrePress: Kevin Luong
Manufacturing: Sheri Schwartz
Library or Conpas Cataloging-In-Publication Data
Hammer, Donald A.
Creating freshwater wetlands I Donald A. Hammer. --2nd ed.
p. em.
Includes bibliographical references and index.
ISBN 1-56670-048-5 (alk. paper)
I. Wetlands. 2. Restoration ecology. I. Title.
QH87.3.H36 1996
639.9'5--dc20 96-32195
CIP
This book contains information obtained from authentic and highly regarded sources.
Reprinted material is quoted with permission, and sources are indicated. A wide variety of
references are listed. Reasonable efforts have been made to publish reliable data and information,
but the author and the publisher cannot a.~sume responsibility for the validity of all materials or
for the consequences of their use.
Neither this book nor any part may be reproduced or transmitted in any form or by any means,
electronic or mechanical, including photocopying, microfilming, and recording, or by any infor
mation storage or retrieval system, without prior permission in writing from the publisher.
The consent of CRC Press does not extend to copying for general distribution, for promotion,
for creating new works, or for resale. Specific permission must be obtained in writing from CRC
Press for such copying.
Direct all inquiries to CRC Press, Inc., 2000 Corporate Blvd., N.W., Boca Raton, Florida
33431.
0 1997 by CRC Press, Inc.
Lewi• Publisher< is an imprint of CRC Pre5<
No claim to original U.S. Government works
International Standard Book Number 1-56670-048-5
Library of Congress Card Number 96-32195
Printed in the United States of America I 2 3 4 5 6 7 8 9 0
Printed on acid-free paper
PREFACE TO THE SECOND EDITION
Five years have seen dramatic change in U.S. attitudes towards wetlands.
The "webb-foots" have arrived! In fact, membership in the Society of Wetland
Scientists now rivals that of many older scientific organizations. But the wide
spread attention on wetlands hasn't always been positive. On occasion in social
circumstances, I have even been reluctant to reveal my profession without
lengthy follow-up explanations that I was not involved in wetland regulations
and didn't always agree with some interpretations.
These are contentious times for wetlands and for wetland ecologists but
we finally have national attention, legislative action and hopefully, a new
national wetland policy will be forthcoming in the near future. As with most
legislation, the present versions (as will the final) represent compromise that
certainly won't please all webb-foots but it's a start. Future Congresses will
doubtless make additional changes when the Clean Water Act comes up for
renewal. But it seems very unlikely those changes will ever return to a national
policy of wetland drainage.
Most encouraging, the past five years have seen a considerable number of
wetland creation projects with much greater success than some earlier ones.
Appearance of reports of less than 100% of some species, group, coverage or
some other measure in the created system after 4 to 5 years as compared with
a reference wetland should not be discouraging. Other reports show virtually
the same conditions in the new and the reference wetland in similar intervals.
Much depends on the type of wetland and the techniques used by those creating
the new system or restoring a previously existing wetland. After all, 4 to 5
years is merely an Augenblick, a micro-moment, a nano-second in geological
time. Of course, the new wetland with only 80% of the natural after 5 years
is very likely to have close to I 00% after I 0 to 15 years. Though I've worked
in wetlands for almost my entire career, I am still amazed at how quickly
many created wetlands approach conditions in the natural systems. The expo
nential increase in the number of species and diversity of many created wet
lands during the early stages will doubtless taper off as its diversity approaches
that of the reference wetland. But isn't that the pattern of normal succession
in any wetland system? And isn't that our goal?
Furthermore, the dramatic changes that have occurred in the agricultural
sector in the last five years are most heartening. We appear to be close to "no
net loss" and may even be approaching "net gains" in total wetland resources
largely because of agricultural policy reversals.
Though some disagree, I believe that one positive aspect of pending leg
islation is the codification of wetland mitigation banking. Mitigation banking
is a fact and a rapidly growing phenomenon but current legal uncertainties
hinder broader acceptance and implementation. Successful mitigation banking
will require appropriate guidelines including technical expertise, long-term
financial guarantees, and judicious location of wetland banks to optimize
functional values. Mitigation banking not only provides a mechanism to
replace continual losses of often degraded, "postage-stamp" wetlands but
carefully locating banks in watersheds will enhance the value of wetland
benefits. Enhanced functional values coupled with improved understanding
will lead to broader realization and acceptance of the value of wetlands. And
I can't think of any better method to increase our wetland resources than to
provide a profit motive for those that would do so. If someone can generate
income from creating, restoring, and protecting wetlands our need for protec
tive regulations will decline precipitously.
This edition goes beyond the general guidelines and philosophies of the
first edition, providing considerably more detail on specific techniques useful
in creating a wetland. Although titled Creating Freshwater Wetlands, the
methods and approaches are just as important in any wetland restoration
project. The variety of expertise and information needed for a successful
project is wide and certainly beyond the scope of a single effort so the
Appendices have been substantially expanded. But three aspects are crucial
to developers of a new wetland or those attempting a restoration project: the
absolute requirement for appropriate hydrology or hydroperiod, an understand
ing that wetlands are complex, dynamic systems that often need deliberate
management to supply the disturbance factor and finally, a little patience.
Expecting to precisely duplicate a system that has developed over the eons in
5 to I 0 years is unrealistic. We have the ability to accelerate development so
the new system resembles the natural one in much less than eons and the
rapidly increasing database on creating and restoring techniques will increase
our abilities. With the right hydrology and limited management, over time, the
new system will gradually become indistinguishable from the reference wet
land. Follow the guidelines and techniques herein, provide a little guidance to
early succession, and sit back and enjoy the gradual development of one of
the most fascinating ecosystems on the planet.
D. A. Hammer
Norris, Tennessee
10 May 1996
PREFACE
Brian Lewis conceived of this little handbook as a supplement to the 1988
conference proceedings Constructed Wetlands for Wastewater Treatment, and
at his urging, I finally committed to begin compiling the information.
As a student I was fortunate in working on several National Wildlife
Refuges, and in one case, my research benefited from the historical information
on wildlife populations in old annual reports. However, in digging out infor
mation on snapping turtles from the earliest days of the refuge, I discovered
the tremendous wealth of information on methods developed to restore and
create the marsh that I believed was largely natural. Later I discovered similar
knowledge in the earliest reports from virtually every refuge and management
area that I visited.
Since many of our "natural" wetlands today were in fact restored or even
created, I have been surprised when colleagues state that we know so little
about wetlands that we can't restore or create one as mitigation or for any
other reason. In fact, the predominant conclusion from most recent wetland
meetings would be our total ignorance of basic wetland ecology. Certainly we
don't know everything about wetlands - they might not be as fascinating to
some of us if we did - but to conclude that we lack the information to restore
or create many types of wetland is to ignore or negate a considerable body of
information gathered by competent, dedicated scientists and managers over
many years.
Doubtless some will respond that this information only applies to marshes.
Certainly much of it does, but some is also available for other types, because
bogs, swamps, sloughs and fens were included in wildlife refuges and man
agement areas. But more importantly, marshes are precursors, early succes
sional stages for many other wetland ecosystems. If we can create a healthy
marsh and then allow it to progress along the successional gradient to another
wetland type, are we not well on the way to creating the bog or swamp that
is the project goal? And do we know how to create a marsh and allow it to
transition? Of course we do. We simply do not supply the disturbance factor
that is critical to maintaining the site in the early marsh stage.
Although today's society places considerable importance on natural and
created wetlands, it was not always so. While most of past society had little
use or regard for "dark and dismal swamps," and wetland drainage was national
policy, a few conservationists began raising the alarm over lost wetlands as
early as the tum of the century. Extensive drainage projects coupled with the
severe drought of the 1930s caused calamitous declines in North American
waterfowl populations. Alarmed duck hunters, many wealthy and influential
in society, initiated legislation taxing sport hunters to support wetland acqui
sition, management and research, which provided the basis for the National
Wildlife Refuge System and comparable state wildlife management areas.
Faced with a dearth of water and wetland habitats but charged with restoring
waterfowl populations, early managers slowly developed methods to create
and restore natural wetland ecosystems to enhance waterfowl habitats through
out the country.
Creation of various public works programs (CCC, WPA, etc.) concurrent
with the drive to restore waterfowl provided heretofore unheard of funding
and manpower resources in the newly emerging field of wildlife management.
Substantial efforts in these programs were directed towards developing meth
ods to design and construct dikes and water control structures, plant and/or
seed wetlands and terrestrial vegetation, re-stock wildlife and fish populations,
manipulate water levels and manage fish and wildlife populations in the
restored or created wetland ecosystems. Probably because of the bureaucratic
penchant for documentation, most of the methods developed and tested were
reported in the "gray literature"- the annual reports for each refuge or
management area. Not surprisingly, virtually all types of wetland ecosystems
in the U.S. are encompassed. Simple examination of a distribution map for
the National Wildlife Refuges reveals refuge locations from coast to coast,
including most types of freshwater wetlands and some brackish/saltwater
systems. Restoration and creation techniques were investigated and reported
in the late 1930s, 1940s and 1950s on most of these areas.
Early managers unrestrained by the policy of not reporting "negative
results" prevalent in scientific journals today, included failures as well as
successes. Unfortunately much of this knowledge never found its way into
scientific journals and, hence, is largely unknown to the new crop of wetland
ecologists and managers. Some has not even been written down though it has
been passed along and is still in use by present managers. But that information
is still available in the files or from the staff of the local refuge or management
area office.
Unfortunately many sincere and dedicated wetland enthusiasts are unaware
of this wealth of information, or choose to disregard it - "they were only
interested in growing ducks." I am afraid I must disagree with the latter.
Techniques developed in the late 1930s and 1940s to establish or manage
Scirpus, Potamogeton, Spartina, Quercus, Larix, or Taxodium or a host of
other wetland plants need not be reinvented today, nor must we use the most
expensive methods. Though propagation and hand-planting were used, early
wetlands managers slowly discovered the growth requirements for important
species and developed methods to foster or retard vegetative types through
inexpensively manipulating water levels in appropriate seasons.
Methods developed for management of duck production, migratory or
wintering areas have successfully provided wetland habitats for innumerable
other species of wetland wildlife, fish, and plants. Ducks may have been the
priority but "they dido 't just grow ducks." In fact, many of the larger "natural"
wetlands extant today are located in refuges, management areas and a few
parks because they were restored, enhanced and, in a few instances, created
by early waterfowl managers.
Finally, my earlier experiences creating or managing wetlands with the life
support function as a primary goal, and more recent work with the water
purification function have convinced me that a wetland ecosystem that supports
diverse and abundant vertebrate populations does so because it has the com
plex, requisite structure. If the structure is present to provide significant life
support, then that system likely has the structure to provide much of the water
purification, hydrologic buffering and other important functions that we value
in wetland ecosystems. Regardless of the prime objective, designing and
constructing a wetland that will attract and support representative vertebrate
species will likely achieve the prime objective plus support many other impor
tant functional values.
This then is a small attempt to organize and present some of the information
on methods to create or restore freshwater wetlands accumulated by wetland
scientists and managers during the last 50 years. It is my hope that the reader
will interpret this volume as a general guideline and employ specific, localized
information from nearby offices of wetland and waterfowl research/manage
ment agencies before starting a project.
D. A. Hammer
Norris, Tennessee
2 March 1991
ACKNOWLEDGMENTS
As wetlands develop from early primitive forms through interim stages to
finally mature as full-blown, complex ecosystems, so do wetland ecologists.
Neither would succeed without nurturing, assistance and management. Both
need and benefit from the influences of others.
Although the number of people and wetland systems that shaped and
focused my development is too great to enumerate, a few had inordinate
influence. I've worked in wetlands from the Arctic Circle to some 30 degrees
south and on every continent except Africa and Antarctica, including extended
periods in the fresh- and saltwater systems of Maine, bottomland hardwoods
of the Southeast and fresh and saline wetlands of the Intermountain West, but
the prairie pothole marshes of my early years in North Dakota and Lacreek
National Wildlife Refuge in South Dakota had far greater impact on me than
any other wetland ecosystem. Even today, I am awed by the diversity and
almost explosive productivity of a prairie marsh in June.
Not surprisingly, most of the individuals I am most deeply indebted to
shared their love of and experience with these same systems. They include
Bob Seabloom (University of North Dakota), Bob Dahlgren and Ray Linder
(South Dakota State University), Juan Spillett and Jess Low (Utah State Uni
versity), Mal Coulter and Howard Mendall (University of Maine), and Merrill
Hammond, Jim Monnie, and John Ellis (U. S. Fish and Wildlife Service).
Finally, neither this nor any other project during the last 31 years would
have been accomplished without the interest, support, and patience of my wife,
Joan. From counting snapping turtle eggs (her small hands could reach into
the nest) to providing lunch for the whole crew at almost inaccessible field
sites, keeping the household during my extended forays, coordinating field
activities with colleagues, securing osprey or eagles so they wouldn't interfere
while I landed the aircraft, and tolerating my increasing cantankerousness with
days or weeks beyond the deadline, her dedication and assistance has been
immeasurable.
