Water quality standards protect the District’s rivers, streams, and other surface waters. Water quality standards also allow for the restoration of our rivers and streams to support public use and the protection of fish and vegetation in our waters.
Water quality standards contain numeric limits for specific physical, chemical, biological, or radiological characteristics of water. Examples of the specific characteristics are water clarity, concentration of nutrients, oxygen levels, or levels of isotopes. Since not all requirements for water quality protection can be numerically defined, standards also include narrative requirements. These statements and numeric limits describe the water quality necessary to meet and maintain designated uses, such as swimming and other water-based recreation, public water supply, and the propagation and growth of aquatic life.
What are Water Quality Standards?
The District’s Water Quality Standards are regulations that are reviewed every three years and must have a public hearing during that triennial review. The Water Quality Standards are made up of four parts:
- Designated use such as “primary recreation” or “protection and propagation of fish, shellfish, and wildlife”
- Water quality criteria necessary to protect the designated uses
- Antidegradation requirements
- Application and implementation regulations that state which chemicals are permitted to be in the District’s waters and at what concentrations.
What is a designated use?
- A designated use is a goal for water quality. At least one designated use is given to each District river, stream, or other surface water body. Each of the District’s water bodies has at least one goal.
- The District’s designated uses are:
- Primary contact recreation – example activities are swimming, water skiing, or other activities where being fully underwater is likely to happen
- Secondary contact recreation and aesthetic enjoyment – example activities include kayaking, canoeing, or other activities on the water where it’s not likely that you’ll be fully underwater
- Protection and propagation of fish, shellfish, and wildlife – having the District’s waterways provide safe and healthy habitats for the aquatic life
- Protection of human health related to consumption of fish and shellfish – safely being able to eat the fish you catch
- Navigation – boating in motorized or non-motorized boats
What are water quality criteria?
- There are two types of water quality criteria, numeric and narrative.
- A numeric criterion is a specific concentration of a chemical that shouldn’t be exceeded. The District’s numeric criteria can be found in Section 1104.8.
- A narrative criterion is a generalized statement and normally includes the phrase “free from.” For example, Section 1104.1 in the District’s Water Quality Standards states that the District’s waters “shall be free from substances…that… float as debris, scum, oil.”
What is antidegradation?
- In the context of water quality standards, it means that the quality of the District’s rivers and streams shouldn’t get worse over time.
- The District’s water quality standards include three tiers of waters and can be found in Section 1102 of the District’s Water Quality Standards.
- Tier I – is the minimum level of water quality allowable and applies to all District waters. Tier I level of antidegradation protects the water’s existing use, which is defined as “the use actually attained in the waterbody on or after November 28, 1975.”
- Tier II – protects waters that have a better quality than Tier I waters.
- Tier III – protects waters of exceptional recreational or ecological significance and are labeled “Outstanding National Resource Waters.”
- Also in Section 1102 is Special Waters of the District of Columbia (SWDC). SWDC are any part of a District water body that has water quality better than needed for its current designated use or have scenic or aesthetic importance. Rock Creek, its tributaries, Battery Kemble Creek, and its tributaries have all been designated as SWDC.
What are some of the application and implementation regulations that are in the water quality standards?
- The District’s Water Quality Standards application and implementation section details when the District can use its discretion regarding water quality. Specifically, Section 1105 provides information on mixing zones, variances, and flow levels.
What are the governing laws and regulations for water quality standards?
- The District’s Water Quality Standards, Chapter 11 of Title 21 in the District of Columbia Municipal Regulations
- Water Pollution Control Act of 1984
- Clean Water Act
For information on the District’s socioeconomic, institutional, technological, and environmental (SITE) study, please visit SITE.
For the District’s previous water quality standards, please visit Archived Water Quality Standards.
For more information, email [email protected].