Environmental Engineering Reference
In-Depth Information
From 1970 to 1995, the U.S. Environmental Protection Agency (U.S. EPA) provided $61.1
billion in Federal Construction Grants Program funds to help fund new or upgrade existing POTWs
(Figure 5.2) to secondary or higher treatment. Secondary treatment includes a biological treatment
process for the removal of dissolved organic matter from wastewater. The treatment plants also
typically include a inal treatment to disinfect the wastewater stream prior to its discharge, thereby
treating two of the primary water quality concerns: bacterial contamination and DO impacts due
to excess organic materials. As a result, the number of people served by POTWs with secondary or
greater levels of wastewater treatment almost doubled from 1968 to 1996 (USEPA 2000a; Stoddard
et al. 2002). Case studies for nine urban waterways with historically documented water pollution
problems (the Connecticut River, Hudson-Raritan Estuary, Delaware Estuary, Potomac Estuary,
James Estuary, Chattahoochee River, Ohio River, Upper Mississippi River, and Willamette River)
indicated that following the implementation of pollution control policies as required by the CWA,
worst-case DO levels increased from 1-4 mg L -1 for most of the case study sites during the period
1961-1970 to 5-8 mg L -1 during 1986-1995 (USEPA 2000a; Stoddard et al. 2002).
In addition to construction grants, the NPDES was a major component of the CWA, requiring
all point source dischargers to obtain a discharge permit. In general, the formulation of regulations
for the implementation of the CWA provisions and the enforcement of those regulations were the
responsibilities of the U.S. EPA, but they were delegated to the states.
Also fundamental to the CWA and the establishment of permit limits is the feature requir-
ing states to develop water quality standards for waterbodies, to monitor compliance with these
standards, and to report impairments (Section 305). Water quality standards are the foundation
of the water quality-based control program and they deine the water quality goals for a water-
body. The standards also established water quality-based treatment practices for dischargers
(WQBELS). The U.S. EPA publishes standards (under Section 304(a) of the CWA) that states
can use or modify, or states can adopt criteria based on other scientiically defensible methods.
A water quality standard consists of three basic elements:
Beneicial designated uses (e.g., activities such as swimming, drinking water supply, and
oyster propagation and harvest)
Numeric criteria protective of designated uses
Antidegradation policies
8
Construction grants
CWSRF
7
6
5
4
3
2
1
0
1970
1975
1980
1985
Ye ar
1990
1995
2000
FIGURE 5.2 Annual funding provided by the U.S. EPA's construction grants and the Clean Water State
Revolving Fund (CWSRF) Program to local municipalities for improvements in water pollution control infra-
structure from 1970 to 1999 (costs reported in current year dollars). (From USEPA, Progress in water qual-
ity: An evaluation of the national investment in municipal wastewater treatment, Environmental Protection
Agency, Ofice of Water, Washington, DC, 2000a.)
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