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Handbook
Streams and rivers are familiar features in the landscape of northeastern
Illinois. Drainage is their most obvious function as streams convey runoff
from the landscape, most noticeably during occasional floods.
Streams also convey the treated and untreated wastes of our urban and
agricultural landscapes. In fact, virtually the entire flow in some of our
more urban streams consists of treated wastewater during the drier times
of the year. Streams are valued as recreational amenities because of
their potential to support fishing, swimming, wildlife observation, and
boating activities. Healthy stream environments provide habitat for
diverse communities of fish, amphibians, insects, and aquatic plants.
Stream and river corridors are viewed as aesthetic amenities for
residential development and public open space and provide travel corridors
for wildlife.
Historically, however, conflicts have arisen between the various uses and
functions of streams. In particular, increased reliance on streams as
conduits for stormwater and wastewater has greatly diminished their
ability to provide recreational, habitat, water quality, and aesthetic
benefits. There are two principal causes for use conflicts involving
streams. The first is the alteration or destruction of the stream channel
and its adjacent corridor, or riparian zone. Activities such as
stream channelization or straightening destroy critical habitat features
and upset the natural balance between a stream and its floodplain that has
evolved over thousands of years.
The second cause of
stream use conflicts is the alteration of the watershed that contributes
flow to a stream. A common example is the conversion of farmland to
subdivisions and shopping centers and the corresponding increase in
impervious land surface. This can result in adverse changes to both the
quantity and quality of streamflow. These changes can consequently upset
the natural equilibrium of a stream, often resulting in channel erosion,
lost habitat, degraded water quality, and frequent flooding.
To address these use
conflicts, this handbook presents an approach for managing stream
corridors which preserves and enhances their natural functions. Improved
stream corridor management, in conjunction with better controls on
watershed development, can substantially reduce the potential for stream
degradation, loss of beneficial uses, and costly damages to property.
Improved stream management techniques also can be used to reclaim degraded
streams, restoring aesthetics, water quality, and aquatic life.
It is clear that after
decades of being ignored and abused, the rivers and streams of the region
are being seen as potential amenities. Stream corridors also are now
recognized as critical linkages in restoring the integrity and
biodiversity of the landscape and, ultimately, in enhancing the quality of
life in the region. The handbook is particularly applicable to the many
ongoing efforts to establish and restore stream-based greenways. The
Northeastern Illinois Regional Greenways Plan, developed by NIPC and
the Openlands Project, identifies over 1,000 miles of stream greenways in
the region. Stream greenways provide critical linkages to existing open
space and natural areas, thereby enhancing biodiversity.
The recommended stream
management approach uses low-cost, ecologically-sensitive techniques that
are targeted to streamside landowners. This handbook addresses a range of
common management concerns, including streamside landscaping, channel
maintenance, and streambank stabilization. It provides a framework for
improved stream corridor management but is not intended to be a definitive
design manual.
Overview of
Recommended Approach
The stream management
approach recommended in this handbook embodies several inter-related
principles.
Effective management
must address the stream and its riparian corridor as an integrated whole.
The resultant stream greenway, a linear corridor of open land, can
provide multiple, mutually-supportive functions, including habitat
protection, water quality enhancement, flood storage and conveyance, and
recreation.
Techniques
used for stream and river management systems must be multi-objective.
Techniques designed for a single purpose, without full consideration of
their effects on other functions, are destined to cause or aggravate
stream use conflicts.
Techniques
used for stream protection or mitigation should be sustainable;
that is, they should address identified problems without the need for
excessive or costly future maintenance, and with minimal adverse effects
on the surrounding environment.
Stream corridor
management should rely on natural techniques, wherever feasible.
Natural techniques are derived from systems and materials that have
evolved in nature over thousands of years. The techniques recommended in
this handbook, such as soil bioengineering methods for channel
stabilization or landscaping with native vegetation, often deviate
substantially from conventional landscaping and engineering strategies.
Recommended stream
management techniques must be cost-effective. Considering the large
network of stream channels in northeastern Illinois, the region generally
can not afford expensive solutions. Low-cost techniques are more likely to
be implemented by a higher percentage of streamside landowners.
In summary, the handbook
provides alternatives to streamside property owners that will enable them
to evaluate common stream management problems and opportunities from an
ecologically sensitive perspective. In some cases, the landowners will be
able to address their problems themselves using simple, low-cost
techniques. In other, more complicated circumstances the handbook
encourages landowners to seek professional assistance from resource
agencies or private consultants.
Handbook Overview
Stream ecosystem
dynamics: The handbook describes some of the important natural functions
of stream corridor ecosystems. Included are descriptions of watershed
relationships, stream morphology, aquatic habitat, and riparian buffer
systems.
Traditional management
approaches and their consequences: The handbook briefly describes
traditional single-purpose, "engineered" approaches to stream management
and some of the adverse consequences to natural habitats and stream
functions.
Natural management
concepts: The rationale for the use of native vegetation and natural
materials is described to serve as the basis for discussions of specific
management techniques.
Recommended
management techniques:
Appropriate,
ecologically-sensitive management techniques for addressing stream
problems and for restoring natural functions are presented. These
techniques include:
-
Streamside landscape buffers.
-
Stream channel maintenance.
-
Bank stabilization.
-
Instream habitat restoration.
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Accommodating trail access.
For each management
technique, appropriate implementation and management considerations are
addressed. Information on suggested plant lists, materials, relevant cost
factors, and maintenance is provided, where available.
