Clean Water Act – An Overview


In 1948, Congress adopted the Federal Water Pollution Control Act, 33 U.S.C. §§ 1251-1387.  In 1972, that law was significantly amended.  The 1972 law and its subsequent amendments are commonly known as the Clean Water Act (“CWA”). The objective of the CWA is “to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.”  The CWA operates by requiring National Pollution Discharge Elimination System (NPDES) permits for “point source” discharges of pollutants into navigable waters, authorizing water quality standards for surface waters, assisting with funding for construction of municipal sewage treatment plants, and planning for control of nonpoint source pollution.

The Environmental Protection Agency (“EPA”) is the primary agency tasked with implementing and enforcing the CWA, although it also works in conjunction with state environmental agencies and the U.S. Army Corps of Engineers (“Corps”). While EPA is responsible for implementing the majority of the CWA, the Corps is in charge of issuing permits for discharges of dredged and fill material into waters of the United States. Permits for all other pollutant discharges are granted by EPA.

National Pollutant Discharge Elimination System

The NPDES system requires a permit before any pollutant can be discharged from a point source into a water of the United States. Discharging a pollutant from a point source into a water of the United States without a valid NPDES permit is a violation of the CWA and can result in fines and a responsibility to mitigate any damage. It is therefore important to know when a NPDES permit is required and when it is not. To do so, it is necessary to define the terms “discharge of a pollutant,” “point source,” and “waters of the United States,” and to examine a recent decision from the United States Supreme Court.

Discharge of a Pollutant

Under the CWA, the phrase “discharge of a pollutant” is defined as “any addition of any pollutant to navigable waters from any point source,” and “any addition of any pollutant to the waters of the contiguous zone or the ocean from any point source.” In other words, a discharge of a pollutant occurs when a pollutant is introduced into either a navigable water, or the ocean including the contiguous zone which is the 24 nautical mile stretch of ocean between the coastline and territorial seas over which states maintain control. The term “pollutant” is then broadly defined to include “dredged spoil, solid waste, incinerator residue, sewage, garbage, sewage sludge, munitions, chemical wastes, biological materials, radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt and industrial, municipal, and agricultural waste.” Adding any of those substances into a navigable water or the ocean from a point source requires a NPDES permit.

Point vs. Nonpoint Source

It is important to understand the difference between a point source and a nonpoint source because a NPDES permit is only required for pollutants that are discharged from a point source.

Under the CWA, a point source is defined as “any discernible, confined and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, or vessel or other floating craft.” The term does not include agricultural discharges and return flows from irrigated agriculture. Although the CWA definition provides examples of things that fall under the category of point source, it is not an exhaustive list. So long as something is a “discernible, confined and discrete conveyance,” it could be considered a point source.

A nonpoint source is defined to mean any other source of water pollution that does not meet the legal definition of point source. A common nonpoint source of pollution is runoff carried into water through rainfall or snowmelt. Additions of pollutants into waters covered by the CWA from nonpoint sources do not require NPDES permits. Nonpoint sources are typically left to the individual states to regulate through mandatory or voluntary mandates.

Waters of the United States

The term “waters of the United States” is key to the CWA because it determines which waters are protected by the Act and which are not. Only discharges of pollutants into a water of the United States (“WOTUS”) are covered by the CWA and therefore  can be federally regulated, potentially requiring a NPDES permit.

The CWA prohibits the discharge of any pollutant from a point source into navigable waters. The term “navigable waters” is then further defined as “the waters of the United States, including the territorial seas.” However, the CWA does not define the term “waters of the United States.” Instead, the term is defined by EPA through regulations.

WOTUS has had a variety of different regulatory definitions in the decades since the CWA was passed. For a detailed look at the past definitions of WOTUS,  . The most recent WOTUS definition was finalized in 2020. Known as the Navigable Waters Protection Rule (“Navigable Waters Rule”), the definition established four clear categories of jurisdictional waters, and specific exclusions of water features that have not typically been regulated under the CWA. The four types of waterbodies which are indisputably WOTUS under the Navigable Waters Rule include: (1) territorial seas and traditional navigable waters; (2) perennial and intermittent tributaries of such waters; (3) certain lakes, ponds, and impoundments of jurisdictional waters; and (4) wetlands adjacent to other jurisdictional waters. Introducing a pollutant from a point source into any waterbody that fits into any of the above categories will likely require a NPDES permit.

County of Maui

Recently, the United States Supreme Court has broadened what types of actions may require NPDES permits. In COUNTY OF MAUI, the Court concluded that a NPDES permit was required “where there is a direct discharge from a point source into navigable waters or when there is the functional equivalent of a direct discharge.” The case concerned discharges of pollutants made from a wastewater reclamation facility into groundwater, which carried the pollutants about half a mile into the Pacific Ocean. Although the wastewater facility was making discharges of pollutants from a point source, groundwater is not typically considered a water of the United States under the CWA, so the operators of the wastewater facility did not apply for a NPDES permit before making the discharges. Ultimately, the Court determined that the discharges from the facility had served as the functional equivalent of direct discharges into the Pacific Ocean due to the small amount of time it took for the pollution to reach the Ocean through the groundwater, and the short distance the pollutants had to travel. Additional factors the Court considered to determine whether the discharges were the functional equivalent of a direct discharge included the nature of the material through which the pollutant traveled, the extent to which the pollutant was diluted while traveling, the amount of pollutant that entered the Pacific Ocean compared to the amount of pollutant that left the facility, the manner by which the pollutant entered the Pacific Ocean, and the degree to which the pollutant maintained its identify.

It is currently not clear how much this ruling from the Supreme Court will affect how the CWA is administered going forward. However, it is clear that in some instances, an action that results in a pollutant entering a water of the United States may require a NPDES permit even if the action is not a direct discharge from a point source into a navigable water.

NPDES Permits & Nonpoint Source Pollution Control

NPDES permits are typically issued by EPA. However, states may receive authorization from EPA to issue NPDES permits to industries and municipalities, and to enforce permits. Most states have been authorized to administer the NPDES permit program. EPA administers programs for the remaining states and keeps an up-to-date list of the states with NPDES permitting authority here.

There are two types of NPDES permit, individual and general. An individual permit is issued to a single discharger to cover site-specific conditions and are issued directly to the individual discharger. General permits are written and issued to cover multiple dischargers with similar operations and types of discharges. Those permits are issued to no one person in particular, but instead allow multiple dischargers to obtain coverage under the permit after it is issued. Obtaining coverage under a general permit tends to be quicker than an individual permit because coverage under a general permit typically occurs immediately while coverage under an individual permit may take six months or longer.

NPDES permits set measurable limits on the amounts of pollutants allowed to be discharged. The limits may be based either on technology (“technology limits”) or water quality standards, and they are written so that they cannot be attained simply by dilution of the wastewater. Permits may also contain best management practices (“BMP”) requirements. These are the best known and most practical methods for reducing pollution levels in a particular industry.

Dredged and Fill Material Permits

Section 404 of the CWA regulates the deposit of dredged and fill material into any WOTUS, including wetlands. “Dredge” is material that is excavated from a WOTUS, and “fill material” refers to any material used to replace an aquatic area with dry land, or to change the bottom elevation of a water body. Section 404 permits are issued by the U.S. Army Corps of Engineers (“Corps”), although the EPA has the authority to veto a 404 permit.

Generally, a 404 permit will only be issued if: (1) no practicable alternative exists that is less damaging to the aquatic environment, or (2) the nation’s waters would not be significantly degraded. In other words, when someone applies for a 404 permit, they have to show that steps have been taken to avoid direct impacts to wetlands, streams, and other aquatic resources; that all potential impacts have been minimized; and that compensation will be provided for any unavoidable impacts.

Like NPDES permits, 404 permits can be issued either individually or generally. Additionally, certain activities are exempted from the 404 program. Exempted activities include certain farming, ranching, and forestry practices which do not alter the use or character of the land; some construction and maintenance activities; and activities which are already regulated by states under other provisions of the CWA.

Water Quality Standards & TMDLs

One of the main objectives of the CWA is to “maintain the chemical, physical, and biological integrity of the Nation’s waters.” To help achieve that goal, the CWA implements a water quality standards-based approach for regulating water quality. Under the CWA, the EPA is tasked with developing national water quality criteria which are then used as a basis for state water quality standards. Those standards are then the legally enforceable limits which are used to evaluate water quality impairment. The CWA requires states to keep a list of all waters which have become impaired and submit that list to EPA every two years. For each water on the list, the state identifies which pollutant is causing the impairment, and then establishes a total maximum daily load (“TMDL”) of the pollutant in violation. Once a TMDL for a particular pollutant is in place on a waterbody, it sets the limit for the amount of that pollutant which can be discharged into the waterbody per day.

Water Quality Standards

Water quality standards are scientifically measurable standards that quantify the goals of the CWA and include designated uses, water quality criteria, and antidegradation policies. Designated uses are the uses of a waterbody that society would like to achieve in a location such as fishing, industrial water supply, or agricultural irrigation. Water quality criteria are the conditions necessary to achieve a waterbody’s designated uses. Finally, antidegradation policies are rules implemented by states to prevent waterbodies with higher than normal water quality from becoming impaired in the future. When assigning designated uses to waterbodies, several policies must be followed. Any use that the waterbody has achieved since November 28, 1975, even if it is not possible at present, must be included in the designated uses for that waterbody. Because the broad goals of the CWA include fishing and swimming, every waterbody must include those designated uses unless the downgrading process has been followed to allow the reduction of quality in a waterbody. Waste transport may never be a designated use. If multiple designated uses are defined for a waterbody, the designated uses requiring the highest water quality sets the standard. Designated uses may only be reduced by following a downgrade process that demonstrates that the water quality goals are unattainable because of natural background conditions, irreversible human-caused conditions, resulting substantial environmental harm, or excessive social and economic cost. Under EPA regulations, an existing use may never be removed from the designated uses for a waterbody.

The water quality criteria are the technical conditions required to reach the designated uses in a particular water body, including concentrations of pollutants, temperature, pH, and “no toxic chemicals in toxic amounts.” However, acceptable water quality criteria can also include narrative descriptions that are difficult to scientifically quantify such as no objectionable bottom deposits, no unsightly floating debris, or no nuisance odor or color. The CWA requires that water quality criteria be established based on the latest scientific knowledge.

Antidegradation policy is a required component of CWA water quality standards that states are required to adopt and enforce. These policies are designed to protect waterbodies with water quality that is higher than standards require, and prevent degradation or loss of existing uses. EPA regulations direct states to include three levels of protection in their antidegradation policies. The first level protects existing uses, and requires that the level of water quality necessary to sustain those uses be maintained. The second level requires that states maintain water quality that exceeds levels necessary to support recreation, and wildlife uses, unless a lower water quality is necessary to allow important economic or social development. Finally, the third level of antidegradation policy requires that states maintain water quality in high qualities waters that are considered “outstanding National resource[s],” including waters within national and state parks, wildlife refuges, and waters with “exceptional recreational or ecological significance.”

Total Maximum Daily Load

If a waterbody does not attain the proper water quality standards, then a strategy is implemented to reach the required standard. The most common approach is the use of a Total Maximum Daily Load (“TMDL”), which is the maximum amount of a pollutant in a particular area of an impaired waterbody that would allow the water quality standards to be met. Ideally, TMDLs are adopted on a watershed basis so that a comprehensive system of restoration and antidegradation of water quality is reached. TMDLs must be approved by the EPA, and if the EPA and the state cannot agree, the EPA may establish a TMDL through federal rulemaking. TMDLs may be established for individual waterbodies, or may cover entire watersheds that span across multiple states. Currently, the largest TMDL in the country is the Chesapeake Bay TMDL which includes waterbodies in six states and the District of Columbia.

Once a TMDL is established for a waterbody, then the allowable amount of pollutant discharge is divided among various sources as determined by the states. These allocations are called Wasteload Allocation for point sources, and Load Allocation for nonpoint sources. The Wasteload Allocation for a point source is generally included as part of a discharger’s NPDES permit.  Many methods are used under the CWA to try to meet TMDL requirements, including NPDES and section 404 permits, grants for nonpoint source pollution reduction, and a revolving loan fund for construction or improvement of water treatment plants.