Ecological Risk Assessments

Ecological Risk Assessment Program Description

The TCEQ ecological risk assessment program provides guidance and resources for regulated entities that must evaluate ecological risk at a site in one of the Remediation Division programs. According to the Texas Risk Reduction Program (TRRP) rule, some form of an ecological risk assessment is required to be conducted at all remediation sites under this rule.

What is an Ecological Risk Assessment?

The TCEQ defines an ecological risk assessment as a process that evaluates the likelihood that adverse ecological effects are occurring or may occur as a result of exposure to one or more chemicals of concern (COCs) from a remediation site. In general, the primary functions of an ecological risk assessment are as follows:

1. Determine whether actual or potential ecological risk exists at a remediation site;
2. Screen the chemicals of concern present to identify those that might pose an ecological risk, allowing for the focusing of further efforts; and
3. If necessary, determine ecologically protective concentration levels (PCLs) to be used in evaluating a response action.

Ecological Risk Assessment Resources

• Conducting Ecological Risk Assessments at Remediation Sites in Texas (RG-263). This is the TCEQ's primary ecological risk assessment guidance document and has been updated to the most recent accessibility standards. In addition, a few changes have been made to some of the technical information as described in its Introduction section. It is the parent document to the companion documents described below. The ecological risk assessment guidance has also been designed to work with a database (see below) by providing subject-matter instructions for its use, which are dispersed throughout the document in relevant locations.
• Ecological Benchmark Tables. The numeric benchmarks for surface water, sediment, and soil are provided as an Excel file. Benchmark tables last updated August 2023. Sites recently entering Remediation under TRRP should use the most current tables.
  • 2024 TCEQ Ecological Screening Benchmarks (October 2024) 
  • 2023 TCEQ Ecological Screening Benchmarks (August 2023)
  • 2022 TCEQ Ecological Screening Benchmarks (August 2022) 
  • 2021 TCEQ Ecological Screening Benchmarks (August 2021)
  • 2020 TCEQ Ecological Screening Benchmarks(August 2020)
  • 2019 TCEQ Ecological Screening Benchmarks (August 2019)
• Supporting Documentation for the TCEQ’s Ecological Benchmark Tables (RG-263b). This document discusses the sources and the derivations of the media-based, screening-level benchmarks.
• Case Study for the TCEQ's Ecological Risk Assessment Process (RG-263c). This document presents a hypothetical site and affected property, the releases of COCs from the associated facility, and how ecological risk can be evaluated through the Tier 1 Exclusion Criteria Checklist, the Tier 2 screening level ecological risk assessment (SLERA), and the ecological service analysis. The SLERA also demonstrates how the PCL Database (see below) can be used to help evaluate ecological risk and how the information can be presented to the TCEQ for review.
  • Supporting Excel Documentation for the case study includes:
    • Data tables by Media
    • Dioxin/Furan Toxic Equivalency Calculations for Birds, and Dioxin/Furan Toxic Equivalency Calculations for Mammals 
    • ProUCL Output , including Upper Prediction limits, Upper Confidence Limits and Outlier Tests.

• Ecological Protective Concentration Level (PCL) Database . The TCEQ and its contractor (West Texas A&M University) have developed a database that provides default ecological PCLs for soil and sediment for a variety of wildlife receptors and COCs. Users may adjust the default PCLs based on site-specific inputs (e.g., home range). Additionally, the database can be used as a source for assessment levels, toxicity profiles, toxicity reference values, life history information, and uptake factors (e.g., bioaccumulation factors). Instructions and options for logging in to the database can be found by clicking the question mark on the login page.
• Determining Representative Concentrations of Chemicals of Concern for Ecological Receptors (TRRP-15eco). This guidance addresses aspects of ecological evaluations currently not discussed in detail in the ecological risk assessment guidance and is intended to be used in conjunction with the ERAG. Topics addressed include: ensuring that data used in ERAs are representative and appropriate for each exposure medium, defining representative concentrations and exposure areas for various ecological exposure pathways, and evaluating potential hot spots.
• Determining PCLs for Surface Water and Sediment (TRRP-24). This guidance describes processes for developing PCLs for ecological (and human) receptors that may be exposed to surface water and sediment affected by COCs. It also provides information for developing source media PCLs for soil and groundwater that may release COCs to surface water and sediment.
• Useful Links for Developing Ecological Risk Assessments. Links to pages that have other useful information for developing ecological risk assessments.

History of the Ecological Risk Assessment Program

The TCEQ's ecological risk assessment program was established in 1995 to evaluate ecological reports submitted under various agency remediation programs (e.g., Superfund). In 1996, an Ecological Workgroup comprised of technical experts from industry, government, consulting firms, and academia was formed to assist in developing guidance that would interface with the ecological aspects of agency rules. The agency first released Guidance for Conducting Ecological Risk Assessments at Remediation Sites in Texas in 2001. This guidance provided a detailed description of how to conduct ERAs using the TCEQ's three-tiered approach. It also identified the participation and coordination processes with the Natural Resource Trustee Programs and outlined methods for establishing ecological PCLs for COCs. The 2018 versions of RG-263, RG-263b, RG-263c, and the release of the PCL Database reflect a more current state of the science and provide a significant improvement to the TCEQ’s ecological risk assessment program. The suite of guidance documents provide a comprehensive and user friendly toolbox for evaluating ecological risk in Texas.

Questions? Contact Us

For answers to your questions about these documents or the ecological risk assessment program, contact the Remediation Division at 512-239-2201. Or contact us via email at techsup@tceq.texas.gov

Related Items

Texas Risk Reduction Program