I. The Prohibition

Section 301(a) of the Federal Water Pollution Control Act, commonly called the Clean Water Act, provides that the discharge of any pollutant by any person shall be unlawful except in compliance with, among other sections, Section 402 of the Act.¹ Section 402 creates the National Pollutant Discharge Elimination System, the NPDES permit program: pollutants may be discharged only in accordance with the terms of a permit issued under that section.² The prohibition is fifty-four years old. The permit program has stood for the same fifty-four years.

The Act defines its operative terms at Section 502. "Discharge of a pollutant" means any addition of any pollutant to navigable waters from any point source.² "Point source" means any discernible, confined and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, or vessel or other floating craft, from which pollutants are or may be discharged.³ The list is non-exhaustive by its own terms. The words "including but not limited to" are doing the work. The conveyance is doing the rest.

II. The Discharger

The discharger this investigation concerns is precipitation. A cloud is discernible. A falling column of rain is confined by the surrounding air and discrete from the ground it has not yet reached, and it discharges, continuously, for the duration of the storm. This is not a claim about runoff, which the agency already regulates through other permittees. This is a claim about the fall itself, the addition of water to navigable waters from a conveyance in the sky, before any curb, gutter, or catch basin has touched it.

A careful reader will note that the Act was written with pipes, ditches, and concentrated animal feeding operations in mind. This investigation notes it too, and proceeds anyway, on the authority of the statute's own non-exhaustive list. The statute enumerates the conveyances Congress could picture in 1972 and then declines to close the enumeration. The investigation takes the statute at its word.

The statute contains an exclusion, and the exclusion sharpens the point. Section 502(14) provides that the term point source "does not include agricultural stormwater discharges and return flows from irrigated agriculture."³ Congress exempted the farm's stormwater. It did not exempt the sky's. When the legislature carves out the water that falls on a field after it lands and declines to carve out the water that falls on everything before it lands, the omission is the holding.

III. The Effluent

The United States Geological Survey reports that clean or unpolluted rain has a slightly acidic pH of 5.6, because carbon dioxide and water in the air react to form carbonic acid, a weak acid.⁴ In the United States, average rain pH ranges from 4.2 to 5.9.⁴ The figure of 5.6 is not the polluted case. It is the clean case, the floor of the argument, the rain at its best behavior.

In the Environmental Protection Agency's Quality Criteria for Water of 1986, the recommended ambient water quality criterion for pH ranges from 6.5 to 9.0, depending on what is protective of aquatic life and the particular system.⁵ The agency's own recommended range for the protection of freshwater aquatic life begins at 6.5. The discharger's effluent, at its cleanest, arrives at 5.6. It is below the recommended range before any pollutant is added, before any human activity touches it, in the condition the agency calls unpolluted.

Under the NPDES program, water quality criteria are translated into enforceable effluent limits in permits, with monitoring and reporting requirements to verify compliance.³ The discharger has no effluent limit, because it has no permit. It has no monitoring, because it files no discharge monitoring reports. The excursion is therefore categorical: every storm, every receiving water, the effluent below the criterion, no mixing zone requested, none granted.

IV. The Flow

The United States Geological Survey's Integrated Water Availability Assessment reports that average annual rainfall across the conterminous United States was 857 millimeters per year for water years 2010 through 2020, with 2012 the driest year at 729 millimeters and 2019 the wettest at 995 millimeters.⁶ Computed over the land area of the conterminous United States, 857 millimeters per year is approximately 5,000 billion gallons per day of discharge.¹⁰

For comparison, the Survey's estimated water use in the United States in 2015 put total withdrawals, for every use in the nation, at about 322 billion gallons per day: thermoelectric power, irrigation, and public supply accounting for ninety percent of it.⁷ The unpermitted discharger's flow is more than fifteen times the combined withdrawals of the entire country. The nation withdraws 322 billion gallons per day under every permit, contract, and water right in American law. The discharger adds 5,000 billion gallons per day under none of them.

V. The Receiving Waters

On May 25, 2023, the Supreme Court decided Sackett v. Environmental Protection Agency, holding that the Clean Water Act covers only wetlands with a continuous surface connection to bodies that are waters of the United States in their own right, endorsing the formulation that the Act reaches relatively permanent, standing or continuously flowing bodies of water described in ordinary parlance as streams, oceans, rivers, and lakes.⁸ The Court narrowed the agency's jurisdiction over the receiving waters. It did not narrow the discharge.

The discharge lands on all of them: on the streams, the oceans, the rivers, and the lakes in ordinary parlance, and on the wetlands with their continuous surface connections besides. Some of it lands on waters beyond the agency's reach, puddles and ditches the Court placed outside the statute. The jurisdictional map is the agency's problem. The discharger's coverage is complete either way.

VI. The Permit Gap

The agency reports that approximately 7,250 municipal separate storm sewer systems operate nationwide under NPDES MS4 permits.⁹ Each permit requires its holder to develop and implement a comprehensive stormwater management program with pollution prevention measures, treatment or removal techniques, monitoring, and annual reporting, to control the quality of storm water discharged to the storm drains and thence to waters of the United States.⁹ Cities file annual reports. Counties maintain best management practices. States inspect. An entire federal apparatus exists to manage the discharger's effluent after it lands.

The conveyors of the discharge are permitted. The discharger is not. The 7,250 permittees monitor, report, and implement best management practices against water that fell from the sky unpermitted, and the sky has never once submitted an annual report. The permitted world manages the rain. The rain answers to no one.

VII. The Enforcement Record

Section 309(d) of the Act subjects violators to a civil penalty not to exceed $25,000 per day for each violation.¹ The agency maintains concurrent enforcement authority alongside authorized state programs, and its enforcement history names factories, municipalities, developers, and concentrated animal feeding operations.¹ In the fifty-four-year history of the program, no enforcement action has ever named precipitation as the respondent.

Every rainy day is a separate violation, and the statute measures the penalty per day per violation. The arithmetic follows, and the agency has never done it. Section 504 gives the agency authority to act against any person causing or contributing to pollution that presents an imminent and substantial endangerment; the authority has never been exercised against a storm. The enforcement file on the largest discharger in American history is empty, and the discharges continue, daily, in every state, in every season, at 5,000 billion gallons per day.

VIII. The Compliance Impossibility

The agency could demand the permit application that Section 402 requires. The application would list, as the outfall, the sky; as the flow, 5,000 billion gallons per day; as the effluent, weather. Technology-based limits require the application of available treatment technology to the waste stream; there is no treatment technology for a storm, because the storm is not a waste stream. Water quality-based limits require the effluent to meet the criterion; the effluent cannot meet the criterion, because the criterion was written for water and the effluent is weather.

Section 308 gives the agency monitoring authority over the discharge. The sample would have to be taken from the storm, during the storm, of the storm. The public notice would run to every downstream state, which is to say, every state. The best management practice for a cloud has never been written, because the practice would have to be practiced on a cloud.

The prohibition has stood for fifty-four years. In that time the discharger has added approximately 5,000 billion gallons per day to the waters of the United States, filed no permit application, submitted no discharge monitoring report, met no effluent limit, answered no enforcement action, and trained no operator. The 7,250 permitted systems below it manage the effluent, monitor the effluent, and report on the effluent. The effluent falls anyway.

Ergo.