How Do EPA Water Quality Standards Affect Your Business?

To protect public drinking water supplies, recreation, and fish and wildlife, the Clean Water Act (CWA) requires the Environmental Protection Agency (EPA) to establish water quality standards (WQS) for waters of the United States where appropriate and attainable.
 
Not all bodies of water are the same, of course, so EPA must consider a number of factors to determine what constitutes “acceptable” water quality in a given situation. Different habitats—lakes, ponds, rivers, streams, and wetlands—behave differently. Most waters of the United States are freshwater habitats, but some are saltwater and others are brackish (where salt- and fresh-water bodies intermingle).

EPA also considers how the water is used: What’s acceptable water quality for the local fish and wildlife population may not be acceptable for recreation or public drinking water supplies. Variables like these make establishing a single set of requirements for every water of the United States, at the very least, impractical.

So how does EPA meet the Clean Water Act mandate to establish WQS?

EPA Delegates Water Quality to the States

EPA delegates the responsibility to establish WQS to the individual states. Each state is required to establish, review, and revise (when necessary) WQS for any waters of the United States within its boundaries. EPA then reviews and approves or disapproves each state’s WQS.

Water Quality Standards consist of:

• Designated uses,
• Numeric and/or narrative criteria for each use, and
• An anti-degradation policy.

Once approved, the WQS are promulgated and enforced by the issuing state. If a state has not established WQS, or if EPA does not approve of the state’s standards, then the EPA’s national standards at 40 CFR 131, Subpart D apply in that state. See the 40 CFR 131, Subpart D WQS here.  
 

What Are Designated Uses?

The state adopts WQS for individual water bodies by first designating what uses the water might be put to. Such uses may include, but are not limited to:

• Aquatic life support
• Fish consumption
• Shellfish harvesting
• Drinking water supply
• Swimming

Since the goal of the Clean Water Act is to “restore and maintain the chemical, physical and biological integrity of the Nation’s waters,” the state will need to base its water quality standards on how well the body of water supports the assigned uses. Once the uses are identified, the state determines whether the water can support that use. This determination can range from “Fully Supporting” to “Not Attainable.”

Numeric and Narrative Water Quality Criteria

The criteria established by the state in the WQS for each body of water can be numeric, narrative, or both.

Numeric criteria are measurable physical, chemical, or biological limits based on accepted science and health data. For instance, numeric criteria can be a limit of < 3.2 ppb for lead contamination or a minimum dissolved oxygen level of 9.5 mg/L.

Narrative criteria define, rather than quantify, conditions and attainable goals. For instance, narrative criteria can be not allowing the discharge of toxic pollutants in concentrations that may affect public health or the natural aquatic environment.

What Is an Antidegradation Policy or Anti-Backsliding?

The state must also adopt an antidegradation policy to protect and maintain existing uses. “Antidegradation” is not defined in the regulations, but it is broadly interpreted as not allowing water quality to worsen to a less usable level, no matter the future economic or social development in the area around the water body. [40 CFR 131.12]

How Has EPA’s Waters of the US Definition Changed Over Time?

If you follow EPA water regulations, you may remember that in 2015, US EPA and the Army Corps of Engineers (ACoE) announced a rulemaking to expand on the definition of “Waters of the United States.” The updated definition would put more bodies of water under the scope of EPA’s Clean Water Act, including water quality standards. Read about the updated definition of “Waters of the United States” here.  

The rule took effect in August 2015, but after facing legal challenges by affected industry groups, the new definition of “Waters of the United States” was stayed nationwide by a US Court of Appeals. This stay has delayed enforcement of the updated rules until the legal challenges are settled.

How Do EPA Water Quality Standards Affect Businesses?

National Pollutant Discharge Elimination System (NPDES) permit limits, including Stormwater Discharge permit limits (40 CFR 122), National Pre-Treatment Program limits for discharging into Publicly Owned Treatment Works (POTWs) (40 CFR 403), state-level non-point source controls, and other rules or regulatory programs are designed with the intent of meeting these water quality standards. Over time, effluent limits and controls may become more or less stringent if the quality of water in the body being discharged into improves or deteriorates.

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Tags: Act, Clean, EPA, NPDES, Water, Water Quality Standards