Texas Administrative Code › Title 30 - ENVIRONMENTAL QUALITY › Part 1 - TEXAS COMMISSION ON ENVIRONMENTAL QUALITY › Chapter 307 - TEXAS SURFACE WATER QUALITY STANDARDS › Section 307.9 - Determination of Standards Attainment

Current through Reg. 49, No. 28; July 12, 2024
(a)
				General standards attainment sampling and assessment procedures. The procedures
				listed in this section are solely for the purposes of assessing water quality
				monitoring data to determine if water quality standards are attained in
				individual water bodies. Unless otherwise stated in this chapter, additional
				details concerning sampling procedures for the measurement, collection,
				preservation and laboratory analysis of water quality samples are provided in
				the Texas Commission on Environmental Quality (TCEQ)
Surface Water
				Quality Monitoring Procedures, Volume 1: Physical and Chemical Monitoring
				Methods
(RG-415) as amended, the most recently published edition of
				the book entitled
Standard Methods for the Examination of Water and
				Wastewater,
40 Code of Federal Regulations (CFR) Part 136, or other
				reliable sources acceptable to the commission. Laboratory accreditation
				requirements are specified in Chapter 25 of this title (relating to
				Environmental Testing Laboratory Accreditation and Certification). Unless
				otherwise stated in this chapter, additional details concerning how sampling
				data are evaluated to assess standards compliance are provided in the TCEQ
Guidance for Assessing and Reporting Surface Water Quality in
				Texas
as amended.
(b)
				Samples to determine standards attainment are collected at locations approved
				by the commission. Samples collected at non-approved locations may be accepted
				at the discretion of the commission. Samples to determine standards attainment
				in ambient water must be representative in terms of location, seasonal
				variations, and hydrologic conditions. Locations must be typical of significant
				areas of a water body. Temporal sampling must be sufficient to appropriately
				address seasonal variations of concern. Sample results that are used to assess
				standards attainment must not include samples that are collected during extreme
				hydrologic conditions such as high-flows and flooding immediately after heavy
				rains. Further guidance on representative sampling, both spatially, temporally,
				and hydrologically, can be found in the TCEQ
Surface Water Quality
				Monitoring Procedures, Volume 1: Physical and Chemical Monitoring
				Methods
(RG-415),
Surface Water Quality Monitoring Procedures,
				Volume 2: Methods for Collecting and Analyzing Biological Assemblage and
				Habitat
(RG-416), and the TCEQ
Guidance for Assessing and
				Reporting Surface Water Quality in Texas
as amended.
(c) Collection and preservation of water
				samples.
(1) For the purposes of assessing
				standards attainment, samples are collected and preserved in accordance with
				procedures set forth in the most recently published edition of the book
				entitled
Standard Methods for the Examination of Water and
				Wastewater,
the TCEQ
Surface Water Quality Monitoring
				Procedures, Volume 1: Physical and Chemical Monitoring Methods
(RG-415) as amended, 40 CFR Part 136, or other reliable procedures acceptable
				to the commission.
(2) Bacterial
				and temperature determinations must be conducted on samples or measurements
				taken at or near the surface in accordance with the TCEQ
Surface Water
				Quality Monitoring Procedures, Volume 1: Physical and Chemical Monitoring
				Methods
(RG-415) as amended. Depth collection procedures for chloride,
				sulfate, total dissolved solids, dissolved oxygen, chlorophyll
a,
and pH to determine standards attainment may vary depending
				on the water body being sampled. Standards for chloride, sulfate, total
				dissolved solids, dissolved oxygen, chlorophyll
a,
pH are
				applicable to the mixed surface layer, but a single sample taken near the
				surface normally provides an adequate representation of these parameters. When
				the water column is entirely mixed according to determinations described in
				TCEQ
Guidance for Assessing and Reporting Surface Water Quality in
				Texas
as amended, standards may apply to any sample taken in the water
				column for parameters indicated in this section.
(3) For toxic materials, numerical aquatic
				life criteria are applicable to water samples collected at any depth. Numerical
				human health criteria are applicable to the average (arithmetic) concentration
				from the surface to the bottom. For the purposes of standards attainment for
				aquatic life protection and human health protection, samples that are collected
				at approximately one foot below the water surface are acceptable for assessing
				standards attainment of numerical criteria.