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 Arkansas’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 Arkansas 2008

WQS: Arkansas Water Quality Standards
Arkansas Department of Environmental Quality Governing Regulations: Water Division Exit

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Milestone Information

Milestone information updated May 2012.

TN: Total Nitrogen; TP: Total Phosphorus

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Statewide Criteria

The information on this tab shows EPA-approved nutrient criteria for Arkansas’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 Arkansas water quality standards.

The following information reflects Arkansas’s water quality standards posted to the Water Quality Standards Repository as of November 2010 (EPA-approved April 2009).

Chapter 4: General Standards

Reg. 2.401 Applicability
The general standards outlined below are applicable to all surface waters of the State at all times. They apply specifically with regard to substances attributed to discharges, nonpoint sources or instream activities as opposed to natural phenomena. Waters may, on occasion, have natural background levels of certain substances outside the limits established by these criteria, in which case these criteria do not apply.

Reg. 2.402 Nuisance Species
All waters shall be free from substances attributed to man-caused point or nonpoint source discharges in concentrations that produce undesirable aquatic life or result in the dominance of nuisance species.

Reg. 2.406 Color
True color shall not be increased in any waters to the extent that it will interfere with present or projected future uses of these waters.

Reg. 2.407 Taste and Odor
Taste and odor producing substances shall be limited in receiving waters to concentrations that will not interfere with the production of potable water by reasonable water treatment processes, or impart unpalatable flavor to food, fish or result in offensive odors arising from the waters or otherwise interfere with the reasonable use of the water.

Chapter 5: Specific Standards

Reg. 2.501 Applicability
The following specific standards shall apply to all surface waters of the state at all times except during periods when flows are less than the applicable critical flow. Streams with regulated flow will be addressed on a case-by-case basis to maintain designated instream uses. These standards apply outside the applicable mixing zone. Waters may, on occasion have natural background levels of certain substances outside the limits established by these criteria, in which case these criteria do not apply to the naturally occurring excursions.

Reg. 2.509 Nutrients
Materials stimulating algal growth shall not be present in concentrations sufficient to cause objectionable algal densities or other nuisance aquatic vegetation or otherwise impair any designated use of the waterbody. Impairment of a waterbody from excess nutrients are dependent on the natural waterbody characteristics such as stream flow, residence time, stream slope, substrate type, canopy, riparian vegetation, primary use of waterbody, season of the year and ecoregion water chemistry. Because nutrient water column concentrations do not always correlate directly with stream impairments, impairments will be assessed by a combination of factors such as water clarity, periphyton or phytoplankton production, dissolved oxygen values, dissolved oxygen saturation, diurnal dissolved oxygen fluctuations, pH values, aquatic-life community structure and possibly others.¹ However, when excess nutrients result in an impairment, based upon Department assessment methodology, by any established, numeric water quality standard, the waterbody will be determined to be impaired by nutrients. 

¹ The following criteria may be used in the interpretation of the narrative standard:
Reg. 2.503 Turbidity, Reg. 2.504 pH, Reg. 2.505 Dissolved Oxygen

Site-specific Criteria

The Information on this tab shows EPA-approved site-specific nutrient criteria for Arkansas’ 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 Arkansas water quality standards.

The following information reflects Arkansas’s water quality standards posted to the Water Quality Standards Repository as of November 2010 (EPA-approved April 2009).

None.