| (7) Assessment of chlorophyll a criteria
in reservoirs. Procedures to determine standards attainment for chlorophyll a criteria in reservoirs must be in accordance
with the TCEQ Guidance for Assessing and
Reporting Surface Water Quality in Texas as amended, including
the evaluation of multiple uses as indicated in §307.7(b)(4)
of this title. Chlorophyll a criteria
in individual reservoirs are found in Appendix F of §307.10 of
this title (relating to Appendices A - G). The data for the assessment
must be collected at the sampling stations used for calculating the
criteria, as listed in Appendix F of §307.10 of this title, or
from comparable stations in the main pool of the reservoir. Assessment
values indicated in the TCEQ Guidance for
Assessing and Reporting Surface Water Quality in Texas are
to be used for assessment purposes only and are not to be used as
water quality-based effluent limits in wastewater discharge permits
for wastewater permitting.
(8) Site-specific criteria for aquatic recreation (geometric
mean), total dissolved solids, chloride, and sulfate as established
in Appendix A of §307.10 of this title, and human health criteria
as established in Table 2 of §307.6(d)(1) of this title do not
apply in the following stream types and flow conditions:
(A) perennial streams when flows are below 0.1 cubic
feet per second;
(B) intermittent streams when less than 20% of the
stream bed of a 500 meter sampling reach is covered by pools; or when
extremely dry conditions are indicated by comparable observations
of flow severity.
(f) Biological integrity. Biological integrity, which
is an essential component of the aquatic life categories defined in §307.7(b)(3)
of this title, is assessed by sampling the aquatic community. Attainment
of biological integrity is assessed by indices of biotic integrity
that are described in the TCEQ Surface Water
Quality Monitoring Procedures, Volume 2: Methods for Collecting and
Analyzing Biological Assemblage and Habitat Data (RG-416) as
amended. Determination of attainment may account for statistical variability
to reduce uncertainty in evaluations in accordance with TCEQ Guidance for Assessing and Reporting Surface Water
Quality in Texas as amended. Primary criteria associated with
assessing the attainment of aquatic life uses are indices of biotic
integrity and criteria for dissolved oxygen. When the appropriate
aquatic life use as determined by the use-attainability study is less
stringent than the presumed high use, then the appropriate aquatic
life use and dissolved oxygen criteria are listed in Appendix D of §307.10
of this title after approval by EPA.
(g) Additional parameters. Assessment of narrative
criteria parameters must be performed in accordance with the TCEQ Guidance for Assessing and Reporting Surface Water
Quality in Texas as amended.
|
| Source Note: The provisions of this §307.9 adopted to be effective July 10, 1991, 16 TexReg 3400; amended to be effective July 13, 1995, 20 TexReg 4701; amended to be effective August 17, 2000, 25 TexReg 7722; amended to be effective July 22, 2010, 35 TexReg 6294; amended to be effective March 6, 2014, 39 TexReg 1450; amended to be effective March 1, 2018, 43 TexReg 1102 |
