Rivers and Streams, Characteristics - Hydro-Environmental Analysis: Freshwater Environments - page 17

FIGURE 2.3 The cow patrol. (Reprinted from a cartoon by Bill Suddick, Toronto; text modiied from origi-
nal. With permission.)
The foregoing description also demonstrates that it is the characteristics of a river or a stream that
affect our perception of its quality as well as the approaches that are used to manage and regulate
that river or stream. In 1972, the Federal Water Pollution Control Act Amendments (also known as
the Clean Water Act [CWA]) were enacted “to restore and maintain the chemical, physical, and bio-
logical integrity” of all “waters of the United States,” which of course includes rivers and streams.
The CWA requires that each state establish the beneicial uses for all waters within the state and
the allowable concentrations of speciic pollutants in order to protect those beneicial uses (numeric
standards). But, the CWA also allows the establishment of narrative standards, which are statements
of unacceptable conditions in and on the water. Thus, conditions perceived as unacceptable may
result in a river or a stream not meeting the standards established by the CWA.
Differences in the management or regulation of a river may also occur based on whether or not
that river is considered navigable. For example, Section 10 of the Rivers and Harbors Act of 1899
stipulates that the U.S. Army Corps of Engineers (COE) regulate all structures that work in, or
affect, the navigable waters of the United States. The determination of whether a waterbody is a
navigable water of the United States is also made by the COE. That determination may also impact
the management of rivers and streams or other waterbodies that are connected to, and impact on,
the navigable waterways. As will be discussed later, the connectivity to navigable waterways may
impact whether or not wetlands are protected under Section 404 of the CWA. Under this section, the
COE controls and permits the discharge of dredged and ill material in navigable and other waters.
Rivers are not static systems. The water levels, which impact the characteristics of rivers and
streams, may continually vary in response to storms, runoffs, and groundwater inlows and may
impact how rivers and streams are managed and regulated. For example, the protection of navigable
waterways under the Rivers and Harbors Act extends to structures below the mean high-water line
in tidal waters, or the ordinary high water level in nontidal waters. The high water level is typically
estimated based on a high low that would be expected to occur only once in every 100 years. The
100-year return low is also often used to establish, for lood insurance purposes, 100-year lood
inundation area, or Special Flood Hazard Area. In addition to high lows and water levels, low lows
are often critical such as for water quality or environmental impacts. Many agencies are involved in
establishing low-low criteria for rivers and streams, protective, for example, of aquatic life or the
water supply.