This educational guide is based on the linked primary sources. It is not a Court publication, is not affiliated with the Court, and is not legal advice.
In brief
Overview
Petitioners contend that the Corps of Engineers and the EPA have exceeded the limits of congressional authority, arguing that the agencies are overreaching the plain text of the Clean Water Act.
According to Petitioners, petitioners assert that their wetland is hydrologically isolated from any navigable water of the United States.
Respondents argue that jurisdiction can be based on a hydrological connection, citing their brief’s discussion of such connections.
Respondents further claim that the sole basis for agency jurisdiction is the adjacency of the wetland to a non‑navigable, unnamed ditch dug for a sewer system.
According to General Clement, Corps regulations since 1975 specifically exclude the Nundane ditch and its adjacent drain from the definition of “waters of the United States.”
According to Justice Scalia, the classification of a municipal drainage ditch as “waters of the United States” is “extravagant.”
Chief Justice Roberts asked the Court to define what a “tributary” is.
Chief Justice Roberts also asked what constitutes a “hydrological connection,” including whether seepage through the ground suffices.
According to Justice Stevens, a wetland lacking a current hydrological connection could become connected after a proposed project is built.
- [1] d95e35018b57444c049c-r1-37b89618981b80a0.pdf, p. 3
- [2] d95e35018b57444c049c-r1-37b89618981b80a0.pdf, pp. 16–17
- [3] d95e35018b57444c049c-r1-37b89618981b80a0.pdf, p. 20
- [4] d95e35018b57444c049c-r1-37b89618981b80a0.pdf, p. 25
- [5] d95e35018b57444c049c-r1-37b89618981b80a0.pdf, p. 35
- [6] d95e35018b57444c049c-r1-37b89618981b80a0.pdf, p. 40
- [7] d95e35018b57444c049c-r1-37b89618981b80a0.pdf, p. 9
- [8] d95e35018b57444c049c-r1-37b89618981b80a0.pdf, p. 21
- [9] d95e35018b57444c049c-r1-37b89618981b80a0.pdf, p. 29
Background and question before the Court
Chief Justice Roberts asked how to define a tributary and what constitutes a hydrological connection, including whether seepage through the ground is sufficient.
Justice Scalia asked whether it would be sufficient to prove that a discharge ultimately reaches a tributary, implying a focus on the “discharge” test for jurisdiction.
According to Justice Stevens, justice Stevens raised the question of whether a future hydrological connection, created by the proposed project, could establish jurisdiction.
What each side argues
Petitioners
Petitioners argue that the Corps and EPA have overreached the statutory limits of the Clean Water Act, exceeding the plain text of the statute.
Petitioners maintain that their wetland is hydrologically isolated from any navigable water, and therefore lies outside the scope of the Act.
Respondents
Respondents contend that jurisdiction can be established through a hydrological connection, as reflected in their brief.
Respondents argue that the wetland’s adjacency to a non‑navigable ditch, dug for a sewer system, is the sole basis for agency jurisdiction.
According to General Clement, general Clement testified that Corps regulations since 1975 specifically exclude the Nundane ditch and its adjacent drain from the definition of “waters of the United States.”
Government representative General Clement argued that the Corps does not distinguish between man‑made and natural channels, noting that even the Erie Canal is a ditch.
According to Government, government explained that the Corps’ regulations have long ignored the presence of berms because, in most cases, they do not prevent a hydrological connection.
What happened at oral argument
Chief Justice Roberts asked the Court to define “tributary.”
According to Chief Justice Roberts, chief Justice Roberts also questioned what constitutes a “hydrological connection,” including whether seepage through the ground is sufficient.
Justice Scalia asked whether it would be enough to prove that a discharge ultimately reaches a tributary.
According to Justice Stevens, justice Stevens inquired whether a wetland lacking a present hydrological connection could become connected after the proposed project is built.
According to Justice Scalia, justice Scalia characterized the classification of a municipal drainage ditch as “waters of the United States” as “extravagant.”
According to Justice Ginsburg, justice Ginsburg noted that one of the wetlands was much closer to the water body.
- [1] d95e35018b57444c049c-r1-37b89618981b80a0.pdf, p. 9
- [2] d95e35018b57444c049c-r1-37b89618981b80a0.pdf, p. 21
- [3] d95e35018b57444c049c-r1-37b89618981b80a0.pdf, p. 8
- [4] d95e35018b57444c049c-r1-37b89618981b80a0.pdf, p. 29
- [5] d95e35018b57444c049c-r1-37b89618981b80a0.pdf, p. 40
- [6] d95e35018b57444c049c-r1-37b89618981b80a0.pdf, p. 77
What the Court decided
Why it matters
Terms to know
No glossary terms are available for this guide.
Primary sources
Read the source materials on the official site or open the immutable repository copy used for this guide.
- d95e35018b57444c049c-r1-37b89618981b80a0.pdforal argument transcript
Guide generated September 21, 2026. Automated validation accepted this version.