TCEQ Proposed Antidegradation Rule

The Texas Commission on Environmental Quality has proposed revisions to its water quality standards, including Chapter §307.5. Antidegradation. These rules apply to all wastewater discharges, including stormwater. The rule establishes the antidegradation policy of the commission which includes a three tier system:

Tier 1. Existing uses and water quality sufficient to protect those existing uses must be maintained. Categories of existing uses are the same as for designated uses
Tier 2. No activities subject to regulatory action are allowed that would cause degradation of waters that exceed fishable/swimmable quality, unless it can be shown that the lowering of water quality is necessary for important economic or social development.
Tier 3. Outstanding national resource waters are defined as high quality waters within or adjacent to national parks and wildlife refuges, state parks, wild and scenic rivers, and other designated areas of exceptional recreational or ecological significance. The quality of
outstanding national resource waters must be maintained and protected.


No discharges can lower water quality to the extent that the Texas Surface Water Quality Standards are not attained. Any discharge of wastewater that would constitute a new source or an increased source of pollution from any industrial, public, or private project or development
are required to provide a level of wastewater treatment consistent with the provisions of the
Texas Water Code and the Clean Water Act. For nonpoint sources of pollution, as necessary, cost effective and reasonable best management practices established through the Texas Water Quality Management Program are to be implemented.


Tier 1 reviews must ensure that water quality is sufficiently maintained so that existing uses are protected. All discharges that could cause an impairment of water quality are subject to Tier 1 reviews. If the existing uses and criteria of a potentially affected water body have not been previously determined, then the antidegradation review must include a preliminary determination of existing uses and criteria.

Tier 2 reviews apply to all discharges that could cause degradation of water quality where water quality exceeds levels necessary to support propagation of fish, shellfish, wildlife, and recreation in and on the water (fishable/swimmable quality). Tier 3 reviews apply to all discharges that could cause degradation of outstanding national resource waters.

Caltha LLP provides expert consulting services to public and private sector clients nationwide to address water quality standards, wastewater permitting and assessing potential impacts of chemicals in the aquatic environment.

Caltha LLP Aquatic Toxicology / WQ Standards Services Website

TCEQ Nutrient Criteria and Screening Levels

The Texas Commission on Environmental Quality (TCEQ) is proposing a methodology to calculate site-specific Nutrient Criteria and Screening Levels for reservoirs, is as a new addition to the standards rule. The result will be chlorophyll a criteria and supplemental screening values for total phosphorus and transparency which will be used to confirm if a water body is attaining the nutrient criteria. TCEQ is soliciting comments on this draft approach to derivation of criteria and screening levels in comparison to other alternative criteria, such as stand-alone criteria for chlorophyll a without supplemental screening levels.

If selected as the preferred method, TCEQ intends to use a stand-alone chlorophyll a criteria that is adjusted to be equivalent to chlorophyll a criteria with supplemental screening levels. If stand-alone chlorophyll a criteria were to be adopted, then references to supplemental screening levels for total phosphorus and transparency would be omitted in draft language in §307.2, §307.7, §307.9, and §307.10, and only the statistically adjusted stand-alone chlorophyll a criteria would appear in the final methodology.

Criteria for chlorophyll a are planned to be assessed with long-term medians of sampling data. Criteria for chlorophyll a are attained when they are not exceeded by the median of monitoring data results.

Caltha LLP provides expert consulting services to public and private sector clients nationwide to address water quality standards, wastewater permitting and assessing potential impacts of chemicals in the aquatic environment.

Caltha LLP Aquatic Toxicology / WQ Standards Services Website

Polycyclic Aromatic Hydrocarbons PAH in Stormwater Discharges

Collaborative studies by the City of Austin, TX, and the U. S. Geological Survey have identified coal-tar based sealcoat as a major and previously unrecognized source of polycyclic aromatic hydrocarbon (PAH) contamination. Several PAHs are suspected human carcinogens and are toxic to aquatic life.

Studies in Austin, Texas, showed that particles in runoff from coal-tar based sealcoated parking lots have concentrations of PAHs that are about 65 times higher than concentrations in particles washed off parking lots that have not been sealcoated. Biological studies, conducted by the City of Austin in the field and in the laboratory, indicate that PAH levels in sediment contaminated with abraded sealcoat are toxic to aquatic life and are degrading aquatic communities.

Laboratory studies included toxicity tests conducted with waters collected downstream of areas which received seal-coating, and representative control areas. These studies led the researchers to estimate that about 13% of Greater Austin area streams had PAH concentrations high enough to be toxic to benthic invertebrates.

This research has led the City of Austin to ban the use of coal-tar sealants for roads, parking lots, driveways, and other paved areas.

Caltha LLP provides expert consulting services to public and private sector clients nationwide to address water quality standards, wastewater permitting and assessing potential impacts of chemicals in the aquatic environment.

Caltha LLP Aquatic Toxicology / WQ Standards Services Website

Addressing Impaired Waters in General NPDES Permit - TCEQ Example

NPDES permits issued for discharges to impaired water typically include specific requirements so that the new or expanded discharge does not "cause or contribute to" the impairment. General NPDES permits create a special situation in which a portion of permitted discharges may be to impaired waters and the nature of the impairments may be different.

General permits for stormwater discharges are particularly problematic in addressing impaired water and antidegradation requirements. As stormwater discharge permits are revised, States will attempt to address requirements for impaired waters in a manner that would apply to a wide range of discharges. How these requirements are expressed in the permit varies widely from State-to-State.

Some States have opted to incorporate requirements which promote pollution prevention measures. As one example, the State of Texas has detected levels of selected heavy metals in surface waters which are of concern, and has promulgated numeric discharge standards for “hazardous metals” into the industrial stormwater permit. However, the Texas Commission on Environmental Quality (TCEQ) approach is to allow facilities to do a self-assessment for sources of hazardous metals and implement pollution prevention measures to avoid the higher costs of hazardous metal sampling and testing. To be exempted, facilities must certify that:

• Facility does not use a raw material, produce an intermediate product, or produce a final product that contains one of the listed hazardous metals, or
  
• Any raw materials, intermediate products, or final products which contain a hazardous metal are never exposed to stormwater or runoff, or


• Facility collects and analyses stormwater samples from the facility and the results indicate that hazardous metal(s) are not present in detectable levels.

Waivers may be obtained on a metal-by-metal basis, or on an outfall-by-outfall basis. A waiver from hazardous metals monitoring does not exempt the facility from other benchmark monitoring requirements which may apply.

[Read more about benchmark monitoring]

Caltha LLP provides expert consulting services to public and private sector clients nationwide to address water quality standards, wastewater permitting and assessing potential impacts of chemicals in the aquatic environment.

Caltha LLP Aquatic Toxicology / WQ Standards Services Website