Ellington, Presiding Judge. This dispute arises from a National Pollutant Discharge Elimination System (“NPDES”) permit issued in 2015 by the Environmental Protection Division (“EPD”) of the Georgia Department of Natural Resources renewing appellee Rayonier Performance Fibers, LLC’s (“Rayonier”) authorization to discharge effluent into the Altamaha River from its pulp plant in Jesup. Appellant Altamaha Riverkeeper, Inc. (“Riverkeeper”) filed in the Office of State Administrative Hearings a petition for a hearing asserting that it and its members had been adversely affected by the issuance of the permit. Following the hearing, the administrative law judge (the “ALJ”) reversed the permit. Rayonier and Richard Dunn, in his capacity as the director of EPD, sought judicial review of the ALJ’s decision. The Superior Court of Wayne County reversed the ALJ’s decision and affirmed the permit. Riverkeeper appeals following this Court’s grant of its application for discretionary appeal and argues that the superior court erred (i) by interpreting Ga. Comp. R. & Regs. r. 391-3-6-.03 (5) (c) to prohibit only “unreasonable” interference with legitimate water uses and (ii) by making factual findings about the reasonableness of the interference instead of remanding the case to the ALJ to make factual findings consistent with its order. For reasons that follow, we affirm in part, vacate in part, and remand the case with direction. The Federal Clean Water Act permits individual states to enact and administer their own waterquality programs, subject to certain federal minimum standards. See 33 USC §§ 1251, 1313; Upper Chattahoochee Riverkeeper, Inc. v. Forsyth County, 318 Ga. App. 499, 502 (1) (734 SE2d 242) (2012). Under the Georgia Water Quality Control Act, OCGA § 12-5-20 et seq. (“WCQA”), persons operating a facility that discharges a pollutant from a point source into the waters of the State must obtain an NPDES permit before any such discharge. OCGA § 12-5-30; Upper Chattahoochee Riverkeeper, Inc. v. Forsyth County, 318 Ga. App. at 502 (1). EPD administers the NPDES program within the State. See OCGA § 12523 (b) (3), (c) (15); OCGA § 12530.The Georgia Board of Natural Resources (the “Board”) is responsible for issuing regulations governing, among other things, water use classifications and water quality standards. OCGA § 12-5-23 (a) (1) (C). Many water quality standards impose numeric limits for matters such as chemical constituents, bacteria, dissolved oxygen, and pH levels, among others.[1] The rules, however, also contain non-numerical “narrative standards” that address aesthetic concerns. At issue here is the narrative standard established by Ga. Comp. R. & Regs. r. 391-3-6-.03 (5) (c), which, at the relevant time, provided: “All waters shall be free from material related to municipal, industrial or other discharges which produce turbidity, color, odor or other objectionable conditions which interfere with legitimate water uses.” The ALJ interpreted the phrase “interfere with legitimate water uses” to mean “any interference” with such uses, and concluded that such standard applies to all waterways and for all legitimate uses, without exception and without consideration of the designated use of the waterway. The ALJ further concluded that, to show interference with legitimate water uses, the “use of the river [must be] actually hindered or disrupted.” Applying that standard, the ALJ concluded that Rayonier’s effluent has the reasonable potential to cause a violation of the narrative water standard for water and color. In particular, the ALJ found that the legitimate uses of the Altamaha, such as fishing or swimming or boating, are likely to be hindered during low flow due to aesthetic objections of local residents and visitors.[2]On judicial review, the superior court found that the ALJ erred in interpreting the narrative standard. Finding EPD’s interpretation of the standard to be reasonable and in accord with regulatory and statutory purposes, the superior court held that the narrative standard protected the use of waters from unreasonable interference, rather than any interference. The superior court further found that Rayonier’s discharge does not unreasonably interfere with legitimate uses of the river and so reversed the ALJ’s decision and affirmed the issuance of the permit. 1. The Appellant contends that the superior court erred in interpreting Ga. Comp. R. & Regs. r. 391-3-6-.03 (5) (c) to prohibit only “unreasonable” interference with legitimate water uses. In reviewing an administrative agency’s decision, the “court shall not substitute its judgment for that of the agency as to the weight of the evidence on questions of fact.” OCGA § 501319 (h). See OCGA § 12-5-44 (a) (proceedings for judicial review of administrative decisions under the WCQA shall be in accordance with OCGA § 50-13-19). The superior court may, however, reverse or modify the agency decisionif substantial rights of the appellant have been prejudiced because the administrative findings, inferences, conclusions, or decisions are: (1) In violation of constitutional or statutory provisions; (2) In excess of the statutory authority of the agency; (3) Made upon unlawful procedure; (4) Affected by other error of law; (5) Clearly erroneous in view of the reliable, probative, and substantial evidence on the whole record; or (6) Arbitrary or capricious or characterized by abuse of discretion or clearly unwarranted exercise of discretion.
OCGA § 50-13-19 (h). On appeal from the superior court’s decision in an administrative appeal, this Court’s “duty is not to review whether the record supports the superior court’s decision but whether the record supports the final decision of the administrative agency.” (Citation and punctuation omitted.) Quigg v. Ga. Professional Standards Comm., 344 Ga. App. 142, 148 (809 SE2d 267) (2017). In this case, the ALJ’s final order constituted the final agency decision for purposes of judicial review. See Ga. Comp. R. & Regs. r. 391-1-2-.08. “[T]his Court conducts a de novo review of claimed errors of law in the superior court’s appellate review of an ALJ’s decision. Furthermore, the interpretation of a statute or regulation is a question of law and, thus, is also reviewed de novo on appeal.” (Citation and punctuation omitted.) Barrow v. Dunn, 344 Ga. App. 747, 749 (812 SE2d 63) (2018).At issue is the correct interpretation of the narrative standard, particularly the phrase “interferes with legitimate water uses.”In construing agency regulations, we employ the basic rules of statutory construction and look to the plain language of the regulation to determine its meaning. Nevertheless, even if words are apparently plain in meaning, they must not be read in isolation and instead, must be read in the context of the regulation as a whole. Furthermore, we must defer to an agency’s interpretation and enforcement of its own rules.
