1. Procedures to Implement the Texas Surface Water Quality Standards
Peter Schaefer
Standards Implementation Team
The primary contact for the Procedures to Implement the Texas Surface Water Quality Standards is Mr. Peter Schaefer, Team Leader of the Standards Implementation Team.

2. What are “Implementation Procedures (IPs)”
Procedures to Implement the Texas Surface Water Quality Standards (IPs) RG-194 A guidance document that explains how TCEQ applies the Texas Surface Water Quality Standards
The Procedures to Implement the Texas Surface Water Quality Standards (IPs) are a regulatory guidance document explaining how the Texas Surface Water Quality Standards are implemented within Texas Pollutant Discharge Elimination System Permits. They cover a broad range of water quality permitting topics such as antidegradation, dissolved oxygen modeling, how to translate water quality criteria into permit limitations, procedures for calculating site specific criteria including TDS, chloride and sulfate, and how to request a variance from a water quality standard…and more.

3. Main Topics Covered in IPs
Determining Water Quality Uses and Criteria
Evaluating Impacts to Water Quality
Antidegradation
Mixing Zones and Critical Conditions
Dissolved Oxygen Modeling
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Slide showing main topics covered in document

4. Main Topics Covered in IPs (cont.)
Biomonitoring (WET)
Toxic Pollutants
TDS Screening Procedures
Stormwater Permits
Variance and Site-Specific Standard
Appendices
Other
Slide showing main topics covered in document

5. Determining Water Quality Uses and Criteria
Classified Waters
Unclassified Water
Presumed Aquatic Life Uses

6. Evaluating Impacts on Water Quality
Endangered and Threatened Species
Edwards Aquifer
Bacteria
Nutrient Screening
The following are topics proposed to be addressed in the 2018 IP Revision process. The revision process will involve stakeholder input and opportunity for public comment.
Procedures for Reasonable Potential Analysis for whole effluent toxicity testing will be revised in the IPs.
Updates to dechlorination requirements for minor municipal discharges.
Variance procedures
Thermal Evaluation Strategy for permits with temperature limits higher than segment criteria.
Updates to critical low-flow (7Q2) and harmonic mean (HM) flow data for classified segments.
Updates to classified segment ambient water quality values.
Supporting information for 316(b) rule implementation.
Updates to federally listed threatened and endangered species.
Updates to Minimum Analytical Levels (MALs).
pH screening procedures for certain entities that discharge directly to a classified segment.
Correcting errors/omissions in current IPs.

7. Antidegradation
Tier 1
Tier 2
Watershed Protection Rules

8. Mixing Zones and Critical Conditions
MZ and ZIDs
Critical Conditions
Determining 7Q2 and HM
Human Health
Diffusers

9. Dissolved Oxygen Modeling
Model Selection and Inputs
Screening Level Methods
Critical Low Flow Values for East and South Texas Streams
DO Impairments

10. Biomonitoring (WET) Chronic and 48 Hour Acute Tests 24 Hour Acute
Test Substitution
Toxicity Attributable to TDS
Ammonia Toxicity

11. TDS Screening Procedures
Flow Status
Determining Site-Specific Ambient TDS Values
Establishing TDS Permit Limits
Final Evaluation and Considerations

12. Stormwater Permits Site-Specific Conditions
Antidegradation Review of Stormwater Permit
Discharges to Impaired Waters
Discharges to Edwards Aquifer Recharge Zone
Watershed Rules

13. Site-Specific Standards and Variances
Interim Permit with Variance
Variance Extension
Site-Specific Standards
EPA Coordination
Standards Revision

14. Appendices Playa Lake Policy Endangered and Threatened Species
Critical Low-Flow Values
Segment-Specific Water Quality Values
TSS, pH, Hardness, TDS
MALs
Nutrient Screening Parameters-Reservoirs
Flow data from available USGS gaging stations are analyzed based on the latest 29 years of data. Both critical low flow data, also called 7Q2 flow, and harmonic mean flow data are calculated for Classified Segments.
The 7Q2 is defined in the Standards as “the lowest average stream flow for seven consecutive days with a recurrence interval of two years, as statistically determined from historical data.” Effluent limits in TPDES wastewater discharge permits are designed to maintain the applicable numerical water quality standards for the protection of aquatic life when instream flows are at or above the 7Q2.
Harmonic mean (HM) flow is defined in the Standards as “a measure of mean flow in a water course that is calculated by summing the reciprocals of the individual flow measurements, dividing this sum by the number of measurements, and then calculating the reciprocal of the resulting number.”
USGS gage data is provisional until data is verified and final data is released.

15. Any
Questions
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Contact Information
Peter Schaefer
Picture – Bullhide Creek in McClennan County taken during an RWA performed in June 2007.