US Army Corps of Engineers jurisdiction over wetlands & other waters

The US Army Corps of Engineers (Corps) has jurisdiction to issue permits for discharge into wetlands and streams under Section 10 of the Rivers and Harbors Act and Section 404 of the Clean Water Act (CWA). The figure below shows the jurisdictional boundaries under each of these laws.

A graphic showing the jurisdictional boundaries for Section 10 and Section 404 in tidal and fresh water.

The west coast has two high tide levels: the high tide line or Mean Higher High Water (MHHW) and the lower high tide line or Mean High Water (MHW). In tidal waters, the Section 10 jurisdiction line is MHW and the Section 404 jurisdiction line is MHHW. In fresh water, the Section 10 jurisdiction line is the Ordinary High Water Mark (OHWM). Section 404 jurisdiction includes all areas below OHWM and any tributary rivers, streams, and adjacent wetlands of navigable waters. 

Find Corps' guidance for determining the jurisdictional boundaries by following the links below:

Section 10

The purpose of the Rivers and Harbors Act is to ensure the free flow of interstate commerce on our aquatic “highways”, or navigable waters. Navigable waters are tidally influenced waters currently or historically used to transport commerce, such as Puget Sound, Lake Washington, and the Columbia River. You will need a Section 10 permit from the Corps when you work on a structure in or over a navigable water of the US.

Check the lists of Navigable Waters in Washington State (pdf 32 kb)  on the Streams, Rivers, and Tidal Waters page of the Corps Permit Guidebook to see if the Corps has Section 10 jurisdiction of the waterbody.

Section 404

The purpose of the CWA is to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters, or Waters of the US (WOTUS). You will need a Section 404 permit to discharge dredged or fill material into a WOTUS.

Waters of the US

The Seattle District of the Corps uses the 2015 Clean Water Rule: Definition of "Waters of the United States" (2015 Clean Water Rule) (pdf 642 kb) for determining if it has jurisdiction under Section 404 of the CWA. The 2015 Clean Water Rule says the Corps has jurisdiction over discharges into:

  • Traditional Navigable Waters (TNWs) (pdf 12 kb)
  • Interstate Waters
  • Territorial Seas
  • Impoundments of “Waters of the United States”
  • Tributaries (including some ditches)
  • Adjacent waters
  • Waters with a case-specific significant nexus
  • Waters within 100-year floodplain of TNWs, interstate waters, or territorial seas
  • Waters within 4,000 feet of MHHW or OHWM of TNWs, interstate waters, territorial seas, impoundments of WOTUS, or tributaries.

The WOTUS rules keep changing. Use the Environmental Protection Agency’s Waters of the US Rulemaking website for the most recent rulemaking decisions.


Discharge means placement of material, excluding structures. Examples of discharge include:

  • Placement of fill (rock, dirt, and sandbags)
  • Mechanized land clearing
  • Grading
  • Excavation (including ditching in some instances)
  • Piling (if a form is placed in a WOTUS and wet concrete is poured into the form, the work would be regulated as fill. A pre-made concrete piling installed is not fill, it is a structure.)

Clean excavation is not considered discharge as long as there is only incidental fallback. Incidental fallback is the minor amount of material that may fall from the sides of a bucket excavator during excavation.


The 2015 Clean Water Rule defines the jurisdiction over ditches differently than the previous rule, the 2008 Rapanos decision. Under the 2015 Clean Water Rule, the Corps regulates ditches as tributaries when they meet one of these sets of criteria:

  • Perennial flowing ditches, flowing directly or indirectly into a WOTUS.
  • Intermittent flowing ditches, draining wetlands, and flowing directly or indirectly into a WOTUS.
  • Ditches, which receive water from upstream features that have bed and bank and OHWM, and which flow directly or indirectly into a WOTUS.

Many roadside ditches are exempt from Corps jurisdiction. Examples of exempted ditches include:

  • Ephemeral flowing ditches regardless of where they flow.
  • Intermittently flowing ditches that drain uplands regardless of where they flow.
  • Ditches that infiltrate or lack an outlet.

Check to see if ditches exempted from Corps jurisdiction are regulated by the Washington State Department of Ecology as waters of the state or by local agencies under city or county municipal codes.

Ditches dug in wetlands or that convey streams or tributaries are under Corps jurisdiction. If work involves moving, filling, or altering ditches, do a field assessment.

For more information on field assessment of ditches, see the ditch assessment section on the Wetland reconnaissance & assessment webpage.

Ditches and maintenance activities or emergency repairs

Highway maintenance activities or emergency repairs occurring in WOTUS (e.g. removing sediment from ditches with wetland characteristics to restore back to the original profile) may be exempt from needing Corps permits under Section 404 of the CWA, 33 CFR 323.4. See the Exemptions from Section 404 review webpage for more information on Section 404 Corps exempted activities.

    Getting a jurisdictional determination from the Corps

    If you think the Corps has jurisdiction, follow the instructions on the Section 404 & 10 Nationwide Permits webpage to apply for a permit from the Corps. The Corps will make a jurisdictional determination using the application documents.

    If you don’t think the Corps has jurisdiction, submit a Request for Jurisdictional Determination form (pdf 82 kb) and a wetland delineation to the Corps liaisons. Find instructions for preparing a wetland delineation on the Wetland reconnaissance & assessment webpage.

    Find information on the Corps’ Jurisdictional Determination process and approvals on their Approved Jurisdictional Determinations website.