Numeric Criteria Development

The information presented below gives a summary of state progress towards the development of numeric criteria. The information comes from EPA’s “State Adoption of Numeric Nutrient Standards (1998-2008)” report, current water quality standards, program activity measures, and nutrient criteria development plans. Links to the Connecticut’s Nutrient Criteria Plan and state water quality standards are also provided.

• Existing Numeric Criteria
• Links to the Plan and Criteria
• Milestone Information

Existing Numeric Criteria

S = Statewide    W = For selected waterbody    N ⁄ A=Not Applicable

Note: See Statewide Criteria and Site-specific Criteria tabs for more information.

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Links to Numeric Nutrient Criteria Plan and Existing Nutrient Criteria

Plan:

• Nutrient Criteria Development Plan for the State of Connecticut 2004

WQS: Connecticut Water Quality Standards
Connecticut Department of Energy & Environmental Protection: Water Quality Standards Exit

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Milestone Information

Milestone information updated July 2012.

TN: Total Nitrogen; TP: Total Phosphorus

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Statewide Criteria

The information on this tab shows EPA-approved nutrient criteria for Connecticut’s waterbodies. The language presented below comes directly from state water quality standards and applies to all waterbodies within the state (unless a waterbody type or designated use is noted). Criteria applicable to specific waterbodies within the state can be found on the “Site-specific Criteria” tab. For more information, refer to the Connecticut water quality standards.

The following information reflects Connecticut’s water quality standards posted to the Water Quality Standards Repository as of May 2011 (EPA-approved February 2011).

Inland Surface Water Classifications and Criteria

Class AA¹ and Class A² Criteria

¹ Class AA Designated Uses: These surface waters are designated for: existing or proposed drinking water supplies; habitat for fish and other aquatic life and wildlife; recreation; and water supply for industry and agriculture.

² Class A Designated Uses: These surface waters are designated for: habitat for fish and other aquatic life and wildlife; potential drinking water supplies; recreation; navigation; and water supply for industry and agriculture.

Class B Criteria³

³ Class B Designated Uses: These surface waters are designated for: habitat for fish and other aquatic life and wildlife; recreation; navigation; and industrial and agricultural water supply.

Lake Trophic Categories¹
The ranges of Total Phosphorus, Total Nitrogen, Chlorophyll-a, and Secchi Disk Transparency appearing in Table 1 below are assessed collectively to determine the trophic state of a lake. In addition to water column data, the trophic state of a lake is determined by the percentage of the surface area covered by macrophytes in accordance with Table 2 below. For the purpose of determining consistency with the WQS, the natural trophic state of a lake is compared with the current trophic state to determine if the trophic state of the lake has been altered due to excessive anthropogenic inputs. Lakes in advanced trophic states which exceed their natural trophic state due to anthropogenic sources are considered to be inconsistent with WQS.

¹ These are not numeric nutrient criteria values, but are intended to supplement the narrative criteria.

Oligotrophic
May be Class AA, Class A, or Class B water. Low in plant nutrients. Low biological productivity characterized by the absence of macrophyte beds. High potential for water contact recreation.

Mesotrophic
May be Class AA, Class A, or Class B water. Moderately enriched with plant nutrients. Moderate biological productivity characterized by intermittent blooms of algae and/or small areas of macrophyte beds. Good potential for water contact recreation.

Eutrophic
May be Class AA, Class A, or Class B water. Highly enriched with plant nutrients. High biological productivity characterized by frequent blooms of algae and/or extensive areas of dense macrophyte beds. Water contact recreation opportunities may be limited.

Highly Eutrophic
May be Class AA, Class A, or Class B water. Excessive enrichment with plant nutrients. High biological productivity, characterized by severe blooms of algae and/or extensive areas of dense macrophyte beds. Water contact recreation may be extremely limited.

Coastal Waters Classifications and Criteria

Class SA⁴ Criteria

⁴ Class SA Designated Uses: These surface waters are designated for: habitat for marine fish, other aquatic life and wildlife; shellfish harvesting for direct human consumption; recreation; industrial water supply; and navigation.

Class SB⁵ Criteria

⁵ Class SB Designated Uses: These waters are designated for: habitat for marine fish, other aquatic life and wildlife; commercial shellfish harvesting; recreation; industrial water supply; and navigation.

Site-specific Criteria

The information on this tab shows EPA-approved site-specific nutrient criteria for Connecticut’s waterbodies. Criteria on this page apply only to the waterbodies listed below. Criteria applicable to all waterbodies within the state are found on the “Statewide Criteria” tab. For more information, refer to the Connecticut water quality standards.

The following information reflects Connecticut’s water quality standards posted to the Water Quality Standards Repository as of May 2011 (EPA-approved February 2011).

None.