Joseph and Yvonne Pronsolino, private landowners in Mendocino County, California, sought to conduct timber harvesting on lands draining to the Garcia River. The Garcia River had been listed by California under Clean Water Act § 303(d) as a waterbody impaired by excessive sediment. EPA approved the listing and, in the absence of an adequate state submission, established a sediment TMDL for the river. The TMDL quantified the maximum sediment load the river could receive and still meet applicable state water quality standards, and it apportioned that load among sources using load allocations for nonpoint sources and background conditions; because there were no relevant point sources, the TMDL did not include wasteload allocations. The Pronsolinos and associated parties challenged EPA's authority to establish a TMDL for a waterbody impaired solely by nonpoint-source runoff, arguing that § 303(d) is triggered only where point sources subject to NPDES permits are involved, and that EPA was thereby indirectly regulating their logging activities. The district court upheld EPA's authority and rejected the challenge. On appeal, the Ninth Circuit addressed whether § 303(d) requires TMDLs for waters impaired only by nonpoint sources and whether EPA may approve or establish such TMDLs, while acknowledging EPA's lack of direct regulatory power over nonpoint sources.
Does the Clean Water Act authorize and require the establishment of TMDLs for waters impaired solely by nonpoint sources, and may EPA approve or establish such TMDLs even though EPA cannot directly regulate nonpoint-source activities?
Under CWA § 303(d), states must identify waters for which technology-based effluent limitations are not stringent enough to implement applicable water quality standards and must establish TMDLs for those waters that account for seasonal variations and include a margin of safety. EPA must approve or disapprove the state's lists and TMDLs; if EPA disapproves, it must establish TMDLs itself. A TMDL represents the maximum amount of a pollutant a waterbody can receive and still meet standards, and is commonly expressed as the sum of wasteload allocations (for point sources) and load allocations (for nonpoint sources and natural background), see 40 C.F.R. § 130.2. The CWA does not confer direct regulatory authority upon EPA over nonpoint sources; instead, implementation of nonpoint-source controls occurs principally through state programs and planning under §§ 303(e) and 319. Where statutory language is ambiguous, EPA's reasonable interpretation is entitled to deference under Chevron.
Yes. Section 303(d) requires TMDLs for all impaired waters, including those impaired solely by nonpoint sources. EPA may approve or, if necessary, establish such TMDLs. However, TMDLs do not themselves regulate nonpoint sources or impose enforceable controls on landowners; implementation of nonpoint-source load allocations remains within state discretion.
Text and structure: The court focused on § 303(d)(1)(A), which requires states to identify waters for which "effluent limitations" are insufficient to implement water quality standards. Plaintiffs argued this language limited § 303(d) to point-source problems, because effluent limitations are a point-source concept. The Ninth Circuit rejected that narrow reading. The phrase functions as a trigger: after application of technology-based effluent limits to point sources, some waters may remain out of attainment due to other sources; for those waters, states must develop TMDLs. Nothing in § 303(d) confines the obligation to waters with point-source discharges. The court also relied on § 303(d)(1)(C), which requires a TMDL for "those pollutants" preventing attainment. EPA's longstanding regulations define TMDLs as the sum of wasteload allocations (point sources) and load allocations (nonpoint sources and background). The ordinary meaning of "load," coupled with the regulatory distinction between WLAs and LAs, supports including nonpoint sources within the TMDL framework. This interpretation preserves the statute's central objective—achieving water quality standards—regardless of the type of pollution. Legislative history and 1987 amendments: Congress created § 319 to encourage state programs addressing nonpoint-source pollution but did not repeal or narrow § 303(d). The two provisions work together: § 303(d) sets quantitative targets for impaired waters; § 319 and other state-law tools are the principal vehicles to achieve those targets where nonpoint sources are involved. Reading § 303(d) to exclude nonpoint-source-impaired waters would leave a regulatory gap contrary to the CWA's goal of restoring and maintaining the integrity of the Nation's waters. Federalism and implementation: The court emphasized that TMDLs are planning numbers, not self-executing commands. They do not, by themselves, impose duties on landowners or directly regulate nonpoint sources. States retain broad discretion to choose how to meet load allocations for nonpoint sources, through best management practices, forestry rules, watershed plans, or other measures. EPA's authority is to require the listing and TMDL and to review and approve them; EPA lacks direct enforcement authority over nonpoint sources under the CWA. Administrative law: Applying Chevron, the court concluded that, to the extent § 303(d) is ambiguous on whether nonpoint-source-impaired waters are included, EPA's interpretation is reasonable and consistent with the statute's text, structure, and purpose. Accordingly, EPA's approval and establishment of the Garcia River sediment TMDL were lawful.
Pronsolino is a leading case on the reach of § 303(d) and the nature of TMDLs. It clarifies that TMDLs are required for all impaired waters, ensuring no statutory gap for nonpoint-source pollution, while reaffirming the cooperative federalism model: EPA sets targets and oversees planning; states choose how to implement. For environmental and administrative law students, the case illustrates Chevron deference, textual and structural interpretation, the relationship between §§ 303(d) and 319, and the distinction between informational planning tools and enforceable regulations. It is frequently cited in Clean Water Act litigation and policy debates over watershed-based management and nonpoint-source control.
Pronsolino v. Nastri cements the principle that the Clean Water Act's water-quality framework reaches all impaired waters, regardless of the source of pollution. By upholding EPA's authority to require and, where necessary, establish TMDLs for nonpoint-source-impaired waters, the Ninth Circuit prevented a statutory gap that would have undermined the national goal of restoring and maintaining water quality.