Holistic Antidegradation Review and Limited APA Fact-Finding Duties: Commentary on Save Our Springs Alliance v. TCEQ

Holistic Antidegradation Review and Limited APA Fact-Finding Duties:
Commentary on Save Our Springs Alliance, Inc. v. TCEQ & City of Dripping Springs

I. Introduction

The Supreme Court of Texas’s decision in Save Our Springs Alliance, Inc. v. Texas Commission on Environmental Quality and the City of Dripping Springs, No. 23‑0282 (Tex. Apr. 11, 2025), sets an important precedent in Texas environmental and administrative law. The Court addresses two core issues:

  1. How “antidegradation” must be evaluated under Texas’s surface water quality standards. Specifically, whether Tier 2 antidegradation review is:
    • a parameter-by-parameter exercise (every material change in a numeric pollutant level is essentially fatal), or
    • a holistic, whole-water-body assessment of overall “water quality” informed by both numeric and narrative criteria.
  2. How detailed TCEQ’s factual findings must be under the Texas Administrative Procedure Act (APA). Must TCEQ’s final order include a highly granular “statement of underlying facts” for its antidegradation determinations?

Save Our Springs Alliance (SOS), an environmental group active in Central Texas, challenged TCEQ’s issuance of a permit allowing the City of Dripping Springs to discharge up to 822,500 gallons per day of highly treated wastewater into Onion Creek, a high‑quality Hill Country stream feeding into the Edwards Aquifer region. The dispute narrowed, by the time the case reached the Supreme Court, to:

  • whether the predicted reduction in dissolved oxygen (DO) at the discharge point—from at least 6.44 mg/L to about 5.0 mg/L—constituted “degradation” under Tier 2, and
  • whether the permit was invalid because the final agency order allegedly lacked sufficient “underlying facts.”

The Court affirms the court of appeals and upholds the permit. In the process, it crystallizes two key rules:

  • Antidegradation is assessed at the level of overall water quality, not as a mechanical parameter-by-parameter veto.
  • The APA’s “underlying facts” requirement applies only to findings stated in statutory language; standards codified solely in agency rules do not, by themselves, trigger that heightened findings obligation.

II. Summary of the Opinion

A. Holding on Antidegradation Review

The Court holds that TCEQ’s practice of conducting a qualitative, whole-water-body assessment of “degradation” under Tier 2 of the Texas Surface Water Quality Standards is lawful:

  • “Degradation” is defined by rule as “a lowering of water quality by more than a de minimis extent.”
  • The focus is on water quality as a whole, not on each individual “water-quality parameter” (such as DO, phosphorus, or nitrogen) in isolation.
  • Numeric changes in a parameter are relevant, but not dispositive; they must be evaluated in context to determine whether overall water quality has been lowered more than de minimis.

Consequently:

  • A projected drop in DO from >6.44 mg/L to 5.0 mg/L at the discharge point does not automatically constitute “degradation”.
  • Nor does an increase in nutrients (phosphorus and nitrogen) automatically mean degradation; the question is whether these changes, singly or together, materially lower overall water quality.

Because substantial evidence supports TCEQ’s determination that:

  • Onion Creek’s site‑specific DO criterion (24‑hour mean of 5.0 mg/L) will be met, and
  • Overall water quality and existing uses will be maintained, and any lowering is no more than de minimis,

the Court rejects SOS’s attacks on both Tier 1 (existing uses) and Tier 2 (antidegradation) compliance.

B. Holding on APA “Underlying Facts” Requirement

The Court also rejects SOS’s argument that the permit is void because TCEQ failed to provide an adequate “statement of underlying facts” under Texas Government Code § 2001.141(d). It holds that:

  • Section 2001.141(d) requires underlying facts only when a finding is “set forth in statutory language.”
  • Texas Water Code § 26.027 is a broad grant of authority allowing TCEQ to deny a permit that would violate any state or federal law or rule; it does not impose mandatory, statutorily-defined criteria for permit issuance.
  • The antidegradation criteria appear in agency rules (30 Tex. Admin. Code § 307.5), not in statutory text; therefore, they do not, by themselves, trigger § 2001.141(d).
  • SOS also waived its detailed-findings objection by failing to raise specific complaints about omitted findings in its motion for rehearing before TCEQ.

Thus, TCEQ’s final order—which included 142 findings of fact, 22 conclusions of law, and express adoption of the Executive Director’s extensive responses to public comment—satisfied the APA.

III. Factual and Procedural Background

A. The Permit and Onion Creek

Dripping Springs, a rapidly growing city in Hays County, held an existing land-application permit for treated wastewater, requiring effluent to be disposed of via irrigation on designated fields. To accommodate growth and to implement a 100% beneficial reuse program (e.g., irrigating parks, medians, golf courses), the City applied in 2015 for a permit to discharge up to 995,000 gallons per day into Walnut Springs and Onion Creek.

Key features:

  • Onion Creek is a classified segment under the Texas Surface Water Quality Standards, designated for:
    • high aquatic life use, and
    • a site-specific DO criterion of 5.0 mg/L (24-hour mean).
  • It is a high-quality “fishable/swimmable” water (Tier 2 protected).
  • The watershed supports endangered species such as the Barton Springs Salamander, triggering consultation with U.S. Fish & Wildlife Service (USFWS).

B. TCEQ’s Technical Review and EPA Involvement

Once the application was deemed administratively complete, TCEQ conducted a technical review under Texas Water Code § 5.553 and its water quality rules (30 Tex. Admin. Code ch. 307). That review included:

  • DO modeling using QUAL‑TX to predict post-discharge DO concentrations.
  • Analysis of nutrient loading (total phosphorus (TP) and total nitrogen (TN)).
  • Consideration of narrative criteria (e.g., avoiding excessive algal growth) and numeric criteria (e.g., DO, bacteria).

TCEQ’s Executive Director (ED) concluded that more stringent effluent limits than the City initially proposed were necessary. The draft permit was modified to include:

  • Very low TP and TN limits.
  • Stricter DO requirements.
  • A disinfection requirement (eventually upgraded by settlement to UV disinfection).

With those controls in place, TCEQ’s modeling showed DO would not drop below 5.0 mg/L under worst-case conditions. EPA, which must review state-issued discharge permits under the Clean Water Act’s National Pollutant Discharge Elimination System (NPDES) scheme, initially raised questions but ultimately withdrew its objections, explicitly finding:

  • any changes in the receiving water would be “de minimis (i.e., less than noticeable),”
  • “no significant degradation of water quality” would occur, and
  • “existing uses will be maintained in Onion Creek.”

C. Public Comment, Contested Case, and Settlement

Public interest was intense. The ED received over 1,000 comments and issued 160 written responses, many addressing antidegradation concerns. Numerous parties (including SOS) requested a contested case hearing at the State Office of Administrative Hearings (SOAH).

Before trial, most protestants settled with the City and TCEQ, extracting additional protections such as:

  • Reducing the permitted maximum discharge from 995,000 to 822,500 gallons per day.
  • Using UV disinfection instead of chlorine.
  • Not discharging until flows exceed 399,000 gallons per day.
  • Expanding infrastructure to maximize land application and minimize actual discharges.

These commitments—some incorporated in the permit and others enforceable by settlement—made the permit one of the stringest municipal discharge permits in Texas. After settlement, SOS remained the sole active protestant.

D. SOAH Hearing and ALJ’s Proposal for Decision

At SOAH, once TCEQ’s administrative record was admitted, Government Code § 2003.047(i‑1) created a prima facie case that:

  • the draft permit met all applicable state and federal requirements, and
  • would protect human health, safety, the environment, and property.

SOS attempted to rebut this presumption with expert testimony arguing that:

  • increased TP and TN would spur algal blooms, reduce DO, and harm aquatic life;
  • a City model predicting a DO dip to 4.87 mg/L showed violation of the Onion Creek DO criterion; and
  • any DO reduction exceeding 10% was per se “degradation” under Tier 2.

The Administrative Law Judge (ALJ) issued a 45‑page Proposal for Decision, finding:

  • The permit complied with Tier 1 and Tier 2.
  • TP, TN, and DO limits in the revised permit were adequate to protect existing uses and avoid degradation.
  • TCEQ had correctly applied its antidegradation rules.
  • SOS’s experts were less persuasive and lacked experience with the specific Texas standards and models.
  • Crucially: SOS’s “parameter‑by‑parameter” legal theory misread TCEQ’s rules; what matters is a “lowering of water quality by more than a de minimis amount,” not every numerical increase or decrease in a parameter.

After making minor amendments to the ALJ’s findings (as allowed by Dyer v. TCEQ), TCEQ issued a final order approving the permit, including 142 findings of fact and 22 conclusions of law and adopting the ED’s responses to public comment.

E. Judicial Review and Appeal

SOS sought judicial review in district court. The trial court:

  • accepted SOS’s parameter-by-parameter view,
  • held that the permit violated Tier 1 and Tier 2 as a matter of law based on undisputed increases in TP, TN, and the predicted DO drop, and
  • reversed and enjoined TCEQ’s order.

The El Paso Court of Appeals reversed, in a split decision, upholding the permit. The majority:

  • affirmed TCEQ’s whole-water, qualitative antidegradation approach, and
  • held that substantial evidence supported TCEQ’s findings under that approach.

The dissent would have found Tier 1 and Tier 2 violations, emphasizing projected nutrient increases and adopting an essentially parameter-centric analysis that the ALJ and majority had rejected.

The Supreme Court granted review to resolve the proper construction and application of Texas’s antidegradation rules and the APA findings issue.

IV. Detailed Analysis

A. Legal Framework and Precedents

1. Statutory and Regulatory Framework

  • Clean Water Act; state primacy.
    • The federal Clean Water Act (33 U.S.C. §§ 1251–1389) sets national goals, including “restor[ing] and maintain[ing] the chemical, physical, and biological integrity of the Nation’s waters.”
    • States implement the Act through water quality standards and permitting, subject to EPA approval and triennial review (33 U.S.C. § 1313(c)).
  • Texas Surface Water Quality Standards.
    • Texas Water Code § 26.023 authorizes TCEQ to set water-quality standards; TCEQ’s standards appear in 30 Tex. Admin. Code ch. 307.
    • Section 307.5 sets out the antidegradation policy, including Tier 1, Tier 2, and Tier 3 protections.
    • Section 307.10 (Appendix A) provides segment-specific criteria, including Onion Creek’s high aquatic life use and 5.0 mg/L DO criterion.
  • Permitting authority.
    • Texas Water Code § 26.027 gives TCEQ authority to issue or deny permits to discharge waste into state waters and to refuse permits that would violate any state or federal law or rule.
    • Sections 5.553–5.557 and Government Code § 2003.047 govern contested-case hearing procedures and the “prima facie” effect of TCEQ’s record in SOAH proceedings.
  • Implementation Procedures (IPs).
    • TCEQ’s Procedures to Implement the Texas Surface Water Quality Standards (RG‑194, June 2010) operationalize the standards in permitting.
    • EPA has approved relevant parts of the IPs for Clean Water Act purposes; some sections (not relevant here) remain unapproved.
    • The IPs discuss parameters of concern, modeling techniques, narrative criteria, assimilative capacity, and qualitative antidegradation evaluation.

2. Judicial Review and Standard of Review

Judicial review is under the APA (Tex. Gov’t Code ch. 2001) and the Water Code (§ 5.351). Key precedents:

  • Substantial evidence standard.
    • Mireles v. DPS, 9 S.W.3d 128 (Tex. 1999); Ammonite Oil & Gas Corp. v. RRC, 698 S.W.3d 198 (Tex. 2024): substantial evidence is a reasonableness or rational basis test, not correctness review.
    • The court may not substitute its judgment for the agency on factual matters committed to agency discretion (Gov’t Code § 2001.174).
  • Presumption of validity and deference.
    • NEISD v. Riou, 598 S.W.3d 243 (Tex. 2020); PUC v. Texas Industrial Energy Consumers, 620 S.W.3d 418 (Tex. 2021): agency decisions come to court cloaked with a presumption of validity; the challenger bears the burden.
  • Arbitrary and capricious review.
    • City of El Paso v. PUC, 883 S.W.2d 179 (Tex. 1994); PUC v. Gulf States Utils., 809 S.W.2d 201 (Tex. 1991): an agency acts arbitrarily if it ignores mandatory factors, considers irrelevant ones, or reaches an utterly unreasonable result.

3. Statutory Construction and Rule Interpretation

The Court reiterates that agency rules are construed like statutes:

  • TCEQ v. Maverick County, 642 S.W.3d 537 (Tex. 2022): courts must enforce the plain text of rules without adding or subtracting requirements, especially when terms are defined in the rule itself.
  • Dyer v. TCEQ, 646 S.W.3d 498 (Tex. 2022): TCEQ may revisit the record and revise ALJ findings so long as changes are record-based and explained, underscoring agency primacy in fact-finding.

4. APA Findings of Fact and “Underlying Facts” Requirement

The leading case on the APA’s findings requirement is:

  • Texas Health Facilities Comm’n v. Charter Medical-Dallas, Inc., 665 S.W.2d 446 (Tex. 1984)
    • Gov’t Code § 2001.141(b) requires separately stated findings of fact and conclusions of law.
    • Section 2001.141(d) further requires a “concise and explicit statement of the underlying facts” only for findings “set forth in statutory language.”
    • Underlying (or “basic”) findings must be:
      • clearly stated as the agency’s own findings,
      • non-conclusory, and
      • sufficient to show that statutory criteria are met.
    • This extra requirement applies to fact findings that embody mandatory statutory criteria in the enabling act—not to every element of a multi-level regulatory scheme.

Subsequent cases like Presbyterian Hosp. N., 690 S.W.2d 564 (Tex. 1985), and W. Tex. Utils. Co. v. OPUC, 896 S.W.2d 261 (Tex. App.—Austin 1995, no writ), refine the distinction between ultimate and basic facts but preserve the core rule: underlying-facts statements are required only when a finding restates mandatory statutory language.

On preservation:

  • Hooks v. Tex. Dep’t of Water Res., 645 S.W.2d 874 (Tex. App.—Austin 1983, writ ref’d n.r.e.) and BFI Waste Sys. of N. Am., Inc. v. Martinez Env’t Grp., 93 S.W.3d 570 (Tex. App.—Austin 2002, pet. denied):
    • a motion for rehearing must specifically identify alleged omissions in findings to preserve APA § 2001.141 complaints for judicial review;
    • general, non-specific complaints do not suffice.

B. The Court’s Construction of Tier 1 and Tier 2 Antidegradation Standards

1. The Text of the Rules

Under 30 Tex. Admin. Code § 307.5(b):

  • Tier 1: “Existing uses and water quality sufficient to protect those existing uses must be maintained.”
  • Tier 2:
    • No activities “that would cause degradation of waters that exceed fishable/swimmable quality” are allowed, unless necessary for important economic or social development (an exception not invoked here).
    • “Degradation is defined as a lowering of water quality by more than a de minimis extent, but not to the extent that an existing use is impaired.”

Observations:

  • Both tiers require protection of existing uses and water quality sufficient to support them.
  • Tier 2 adds an extra layer: even if uses remain intact, one may not significantly lower water quality (beyond de minimis).
  • The rule’s definition of “degradation” focuses on “water quality,” not “individual water-quality parameters.”

The Court emphasizes this textual distinction: Tier 2 does not say “a lowering of any water-quality parameter” or “a 10% reduction in any parameter,” but “a lowering of water quality.” Under Maverick County, the Court refuses to rewrite the rule to inject parameter-by-parameter thresholds that the text does not adopt.

2. SOS’s Parameter-by-Parameter Theory Rejected

SOS’s core legal position was:

  • Tier 2 must be applied on a parameter-specific basis.
  • Any more than de minimis increase in a pollutant like TP or TN, or more than de minimis decrease in DO, is per se “degradation.”
  • In particular, a large relative decrease (over 10%) in DO is automatically degradation.

The Court rejects that construct as inconsistent with:

  • the plain language of § 307.5(b)(2);
  • the structure of the Texas Surface Water Quality Standards; and
  • TCEQ’s EPA‑approved Implementation Procedures.

The Court notes that SOS’s approach collapses “degradation” into any detectable change in a parameter, regardless of its ecological significance, which is not what the rule says. Tier 2 requires a qualitative judgment: does the discharge meaningfully lower overall water quality beyond a trivial level?

3. Role of the Implementation Procedures (2010 IPs)

The 2010 IPs are central to the Court’s analysis. They:

  • Identify numerous “parameters of concern” (DO, nutrients, bacteria, etc.).
  • Provide methods for modeling and evaluating each parameter.
  • Still expressly frame antidegradation review as a case-specific, qualitative assessment that considers the water body’s characteristics and aquatic communities.

The Court underscores that:

  • Looking at each parameter individually is a necessary step in evaluating water quality, but
  • Changes in a parameter do not mechanically equal degradation; they are inputs into a broader, whole-water judgment.

4. Assimilative Capacity and the 10% and 0.5 mg/L Examples

SOS relied heavily on portions of the IPs discussing “assimilative capacity” and significance thresholds:

  • New discharges that use less than 10% of a water body’s existing assimilative capacity are “usually not considered” to constitute potential degradation, absent unusual sensitivity.
  • New discharges that use 10% or more of assimilative capacity are not presumed to be degrading but “will receive further evaluation.”
  • The IPs also include an example where degradation is “likely to occur”: an increase in oxygen-demanding substances projected to reduce DO by more than 0.5 mg/L over a substantial distance in a water body with exceptional quality aquatic life and a unique, sensitive community.

The Court responds in several steps:

  1. DO is expressly excluded from the general assimilative-capacity screening procedure. The IPs state that the 10% screening is “not applicable to dissolved oxygen.”
  2. The 0.5 mg/L example is qualified and illustrative, not a binding legal trigger.
    • It applies only to waters with “exceptional” (not merely “high”) aquatic life use and unique, sensitive biota, which Onion Creek lacks.
    • It requires a reduction “for a substantial distance,” not merely at the discharge point.
    • The IPs themselves say these are “general guidelines,” not definitions of degradation; lower or higher changes may or may not amount to degradation, depending on context.
  3. Even when a threshold is crossed, the IPs call for “further evaluation,” not automatic denial. This underscores that numerical thresholds are screening tools, not rigid legal standards.

Thus, SOS’s attempt to turn the 10% rule or the 0.5 mg/L example into a bright-line legal definition of degradation fails both textually and structurally.

5. Clean Water Act “Integrity” Goal and EPA Guidance

SOS invoked the Clean Water Act’s overarching objective—to maintain the “chemical, physical, and biological integrity” of waters—and EPA guidance documents (including a 2005 OST memorandum) urging states to adopt significance thresholds in Tier 2 review.

The Court’s response:

  • Those goals and policy statements do not mandate a particular state implementation method (e.g., parameter-based vs waterbody-based).
  • EPA itself has recognized that:
    • its policies and guidance are non-binding, and
    • states like Texas may adopt a waterbody-by-waterbody approach, rather than parameter-by-parameter, without violating federal law.
  • Whether Texas’s rules comply with federal law is a question for EPA (which has already approved Texas’s standards and IPs), not for the state court in this state-law APA review.

Accordingly, the Court confines itself to the question: Did TCEQ follow its own Texas rules “as written”? On that question, it finds that TCEQ did.

6. Tier 1 vs Tier 2: Overlap but Not “Collapse”

SOS claimed TCEQ had “collapsed” Tier 2 into Tier 1 by focusing only on protection of existing uses. The Court rejects this, noting:

  • Tier 1 and Tier 2 overlap substantially because both protect existing uses and require maintenance of water quality sufficient to support those uses.
  • Tier 2 nonetheless adds the independent question whether water quality is being lowered more than de minimis, even absent use impairment.
  • TCEQ’s findings reflected awareness of both dimensions. For example:
    • Finding of Fact (FOF) 78 explicitly describes antidegradation review as ensuring a discharge does not “impair the uses or degrade the water quality.”
    • FOF 88 states that antidegradation requirements are satisfied because DO will be maintained at concentrations that support a healthy aquatic community and phosphorus limits will protect high-quality waters.
    • FOF 90 recites that Tier 2 review confirmed “no significant degradation of water quality” and that “existing uses will be maintained and protected.”

The Court concludes TCEQ did not ignore the distinct Tier 2 question. Instead, it recognized both existing-use protection and the separate “no more than de minimis” lowering of water quality, as the rule requires.

C. Application to Onion Creek: Modeling and Evidence

1. DO Modeling and Tier 1 Compliance

SOS argued that Tier 1 was violated because:

  • one of the City’s QUAL‑TX models predicted DO might drop to 4.87 mg/L, below Onion Creek’s 5.0 mg/L site-specific criterion.

The Court points out:

  • TCEQ’s own modeling (which it deemed more reliable) predicted DO would be maintained at or above 5.0 mg/L under critical conditions.
  • All modeling was conservatively conducted at the higher flow level of 995,000 gpd—above the 822,500 gpd ultimately authorized—so actual impacts would likely be less severe.
  • Under the substantial evidence standard, TCEQ was not required to accept the City’s lowest modeling result over its own.

Given these points, substantial evidence supported TCEQ’s Tier 1 finding that:

  • the 5.0 mg/L DO criterion would be met, and
  • existing uses in Onion Creek would be protected.

2. Tier 2 and the “De Minimis” Question

On Tier 2, the key question is whether predicted changes—especially the DO drop at the discharge point and nutrient increases—would:

  • “lower water quality” more than a de minimis amount, and
  • do so even if existing uses remain unimpaired.

The Court emphasizes that:

  • “De minimis” is not quantitatively defined by rule; it is a qualitative threshold grounded in professional judgment.
  • The ALJ and TCEQ conducted a comprehensive review of modeling, biological testimony, and site conditions, ultimately crediting TCEQ’s and the City’s experts.
  • The evidence showed that:
    • DO would quickly rebound to baseline levels downstream of the discharge point;
    • TP and TN would be kept at very low levels, not predicted to trigger harmful algal blooms;
    • a healthy aquatic community would persist, and existing uses (recreation, aquatic life propagation) would be maintained.

Because the case was a classic “battle of the experts”, the Court stresses that it cannot reweigh the evidence or substitute its own judgment. The relevant question is whether TCEQ’s conclusion that any water-quality lowering was de minimis had a reasonable basis in the record. The Court finds that it did.

D. APA § 2001.141 and the “Underlying Facts” Debate

1. Preservation: Motion for Rehearing

As a threshold matter, the Court holds that SOS’s challenge to the adequacy of fact findings was not preserved:

  • SOS’s motion for rehearing before TCEQ included only general complaints about failure to include “underlying facts.”
  • It did not specifically identify the particular findings or factual omissions it later claimed were required (such as specific baseline and post-discharge levels for DO, TP, and TN).
  • Under Hooks and BFI Waste, this lack of specificity is fatal to preserving an APA § 2001.141 objection.

Thus, as a procedural matter, SOS’s attack on missing or conclusory findings fails.

2. Substantive Reach of § 2001.141(d)

Even if preserved, the Court holds SOS’s argument fails on the merits because § 2001.141(d):

  • requires underlying facts only for findings “set forth in statutory language,” and
  • does not apply to findings stated solely in the language of agency rules.

Applying Charter Medical:

  • Statutorily mandated criteria, specified in the enabling act, trigger the underlying-facts requirement.
  • Discretionary or non-mandatory criteria in rules—adopted by the agency without legislative compulsion—do not.

The Court characterizes Texas Water Code § 26.027 as:

  • a general authorization allowing TCEQ to refuse a permit when issuance would violate any applicable law or rule; but
  • not a provision that sets out specific mandatory findings or criteria for granting a permit.

Therefore:

  • Fact findings that a particular permit satisfies antidegradation requirements—as defined in 30 Tex. Admin. Code § 307.5—are not findings “set forth in statutory language.”
  • Section 2001.141(d) does not require TCEQ to provide a detailed, parameter-by-parameter “statement of underlying facts” for each such finding.

The Court warns that adopting SOS’s interpretation would create an “absurd” result:

  • It would effectively require TCEQ to issue extensive, hyper-detailed findings for every conceivable state and federal law that might bear on a permit.
  • This would be “impossibly onerous” and inconsistent with the APA’s text and structure.

3. Relationship to the Prima Facie Case Statute

The Court notes that reading § 26.027 to require detailed compliance findings for every possible law or rule would also conflict with:

  • Gov’t Code § 2003.047(i‑1)‑(i‑3), which establishes that:
    • once the administrative record is admitted, a presumption arises that the draft permit meets all requirements; and
    • the protestant bears the burden of showing a specific violation of a “specifically applicable” requirement.

In other words, the agency is not starting from “factual void.” The burden is on the challenger to demonstrate noncompliance with a particular legal standard, not on TCEQ to affirmatively negate every potential basis of illegality in granular findings.

V. Complex Concepts Simplified

1. Tier 1 vs Tier 2 Antidegradation

  • Tier 1 (“Existing Uses” Protection)
    • Ensures that current uses of the water body (e.g., recreation, aquatic life habitat, water supply) are not impaired.
    • Requires water quality sufficient to protect those existing uses to be maintained.
  • Tier 2 (“Antidegradation” for High-Quality Waters)
    • Applies to waters better than the minimum “fishable/swimmable” quality.
    • Even if existing uses still function, the state generally may not allow more than a trivial lowering of water quality.
    • “Degradation” is lowering water quality “by more than a de minimis extent.”
    • States may allow degradation only if it is necessary for important economic or social development (not invoked in this case).

2. “De Minimis” and “Degradation”

  • “De minimis” means “too trivial or minor to merit consideration.”
    • In this context, very small or short-lived changes in pollutant concentrations that do not materially affect the water body’s health or uses.
  • “Degradation” in the Texas rule means:
    • overall water quality is materially worsened (not just that a number went up or down) beyond a de minimis level; but
    • not so bad that existing uses are actually impaired (that would also violate Tier 1).

3. Numeric vs Narrative Criteria

  • Numeric criteria:
    • Specific numbers that may not be exceeded (or may not fall below), e.g., “DO must be at least 5.0 mg/L on a 24-hour mean.”
  • Narrative criteria:
    • Qualitative standards like “nutrients must not cause excessive growth of aquatic vegetation that impairs uses.”
    • Require professional judgment and contextual evidence.

4. “Assimilative Capacity”

“Assimilative capacity” generally means the extent to which a water body can receive pollution without harmful effects. The IPs define it in functional, not legal, terms:

  • For many pollutants, the difference between:
    • the applicable criterion (e.g., a maximum allowable concentration), and
    • ambient water quality where conditions are better than the criterion.
  • Screening tools (e.g., “if you use less than 10% of this capacity, you are usually okay”) guide, but do not control, TCEQ’s judgment.

5. “Substantial Evidence” Standard

  • Not a question of whether the agency was “right” or whether a court would have decided differently.
  • The test is:
    • Is there some reasonable basis in the record for the agency’s decision?
    • If so, the court must uphold it, even if other evidence could support the opposite result.
  • Courts may not reweigh conflicting expert testimony; they ask whether the agency’s choice among experts was reasonable.

6. “Statement of Underlying Facts” under APA § 2001.141(d)

  • Applies only to findings expressed in statutory language from the agency’s enabling act.
  • Requires the agency to spell out the basic facts showing that statutory criteria are met.
  • Does not require granular findings for every regulatory or policy factor the agency might consider unless those are mandated by statute.

VI. Impact and Implications

A. For Environmental Litigation and Advocacy

  • Higher evidentiary burden.
    • Environmental challengers can no longer argue that any significant change in a single parameter (e.g., a 10% DO drop) automatically violates Tier 2.
    • They must present evidence—and often expert testimony—showing that such changes collectively lower overall water quality more than de minimis, with ecological consequences.
  • Focus shifts from numbers to ecological context.
    • Litigants will need to demonstrate changes in biological communities, habitat quality, or other integrative measures—not just point to model outputs.
    • Battle-of-the-experts scenarios will be harder to win for challengers under a deferential substantial evidence standard.

B. For TCEQ and Regulated Entities

  • Affirmation of TCEQ’s qualitative, whole-water approach.
    • TCEQ’s long-standing practice of evaluating antidegradation at the level of water quality as a whole is now solidly endorsed by the state’s highest court.
    • This grants TCEQ significant discretion to weigh competing evidence and professional judgment in antidegradation decisions.
  • Permit certainty.
    • Municipalities and dischargers that design permits with:
      • robust modeling,
      • very stringent effluent limits, and
      • consideration of narrative criteria and biological impacts
      will enjoy greater certainty that their permits will survive legal challenge.
  • Administrative efficiency.
    • The Court’s limitation on APA underlying-facts obligations avoids forcing TCEQ to generate overly lengthy, parameter-by-parameter findings for every permit.
    • Agencies can continue to issue orders with detailed—but not exhaustive—findings, relying on the presumption of validity and the challenger’s burden under Gov’t Code § 2003.047.

C. For Administrative Law in Texas

  • Clarified scope of § 2001.141(d).
    • Only statutorily mandated criteria trigger the “underlying facts” requirement; criteria appearing only in rules do not.
    • Challengers cannot bootstrap regulatory standards into “statutory language” merely because rules were adopted under a broadly worded statute.
  • Strict preservation requirements.
    • Parties must explicitly identify missing or inadequate findings in motions for rehearing to preserve such complaints for judicial review.
    • Generic or boilerplate references to “underlying facts” are insufficient.

D. For Federal–State Relations Under the Clean Water Act

  • State flexibility reaffirmed.
    • The decision highlights that states possess discretion in structuring their antidegradation implementation, subject to EPA approval, but not circumscribed by nonbinding EPA guidance.
    • Texas’s waterbody-by-waterbody approach is expressly recognized as acceptable by EPA and upheld here as a matter of state law.
  • Limited role of federal policy in state APA review.
    • The Court insists its job is to interpret Texas statutes and rules “as written,” not to independently enforce federal policy goals where EPA has already approved the state framework.

E. Potential Areas of Future Dispute

  • “De minimis” threshold.
    • The decision confirms that “de minimis” is qualitative and context-dependent; it does not set a numeric threshold.
    • Future disputes will likely focus on what combinations of parameter changes and ecological evidence cross that qualitative line.
  • Localized hotspots vs overall waterbody health.
    • The whole-water approach may raise questions about localized impacts near discharge points, especially for sensitive species or uses, even if average conditions meet criteria.
    • Future cases may clarify how much localized adverse impact can exist before overall water quality is deemed “lowered” more than de minimis.
  • Interaction with endangered species protections.
    • This case involved the Barton Springs Salamander and USFWS consultation, but the Court did not need to reach the substantive ESA issues.
    • Future litigation may explore how antidegradation analysis interacts with endangered species requirements at the state and federal levels.

VII. Conclusion

Save Our Springs Alliance v. TCEQ & City of Dripping Springs establishes two important principles in Texas law:

  1. Holistic Antidegradation Review.
    • “Degradation” under Tier 2 of the Texas Surface Water Quality Standards means a lowering of overall water quality, assessed qualitatively and contextually, not a mechanical parameter-by-parameter veto triggered by any significant numerical change.
    • Numeric criteria and modeling remain vital tools, but they are inputs into a whole-water-body judgment that also considers narrative criteria and biological evidence.
  2. Limited APA Fact-Finding Requirements.
    • The APA’s requirement for “underlying facts” applies only to findings stated in statutory language mandating particular criteria in the enabling act.
    • Antidegradation standards embedded in TCEQ rules, and broad statutory grants like Water Code § 26.027, do not trigger granular underlying-facts obligations for each parameter.
    • Parties must preserve any complaints about missing or conclusory findings with specificity in motions for rehearing.

By upholding TCEQ’s permit for Dripping Springs, the Court reinforces a deferential, legally grounded approach to environmental permitting: agencies must follow their rules as written, and challengers bear the burden to show—within that framework—that decisions lack a reasonable basis or violate specific statutory commands. For Texas water law and administrative law practitioners, this decision is a pivotal reference point on how far antidegradation protections extend and how rigorously agency fact-finding will be scrutinized in court.

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