Introduction to Stream Restoration - Hydro-Environmental Analysis: Freshwater Environments - page 211

8 Introduction to Stream

Restoration

8.1 INTRODUCTION
The stated objective of the Clean Water Act (CWA) was to “restore and maintain the physical, chemi-
cal and biological integrity of the Nation's waters” (United States Code title 33, Sections 1251-1387).
As discussed in Chapter 7, following the implementation of the CWA, a variety of methods were
developed to evaluate the (physical, chemical, and biological) “integrity of the Nation's waters.” The
methods developed ranged from criteria as expressed in concentration standards, to physical charac-
teristics, to the more complex indices of biotic integrity (IBI). In this chapter, we will concentrate on
the irst part of the CWA's stated objective to “restore and maintain” that integrity (e.g., Figure 8.1).
As with the variances in the methods used to deine and determine “physical, chemical, and
biological integrity,” a number of deinitions have been developed for restoration. One common
difference in the deinitions is in the stated goals of what condition, by restoration, a river should
be returned “to.” For example, the U.S. Environmental Protection Agency (U.S. EPA) (USEPA
2000) deined restoration as “the return of a degraded ecosystem to a close approximation of its
remaining natural potential .” Cairns (1991) deined restoration as the “complete structural and
functional return [of the river] to a pre-disturbance state.” Similarly, the Society for Ecological
Restoration Science and Policy Working Group (2002) indicates that restoration may be thought of
as an “attempt to return an ecosystem to its historic (predegradation) trajectory.” In addition, a vari-
ety of other terms have been associated with river restoration, such as (Shields et al. 2003a, 2008;
National Research Council 1992; Brookes and Shields 1996; FISRWG 1998):

• Rehabilitation: Activities to facilitate the partial recovery of ecosystem processes and

functions, making them useful again, such as restabilizing a riverbank

• Preservation (or protection, maintenance): Activities to maintain the current functions and

characteristics of an ecosystem or to protect it from change or loss

• Mitigation: Activity to compensate for or alleviate environmental damage, such as creating

wetlands to mitigate the loss of wetlands elsewhere

• Naturalization: Activity that results in creating a natural and sustainable environment,

although not necessarily that which existed prior to the disturbance

• Creation: Activities to create a new system that does not currently exist, such as a wetland

or a riparian zone

• Enhancement: Activities to improve some aspect of the existing system's quality, such as

riparian vegetation

• Reclamation: Traditionally used to adapt systems to human needs (such as “reclaim” or

drain wetlands), but now commonly used to refer to bringing about a stable, self-sustaining
ecosystem (but not necessarily the original ecosystem)

Restoration projects do not necessarily return a river or a stream to its undisturbed or natural
condition, because either that condition is not well described or a complete return is not feasible.
As a result, Copeland et al. (2001) suggested that a realistic goal of a restoration project should be
a partial recovery of the natural geomorphic, hydraulic, and ecological functions of the stream. In