Working with Dunthorpe-Riverdale Sewer District in Clackamas County

Find out how to connect or disconnect to our sewer system, vacate an easement and more.

On this page

  1. Getting Started
  2. New Connection
  3. Repair or Reconnection
  4. Disconnection
  5. Vacating a Sewer Easement

Getting Started

We may not annex existing properties within 200 feet of a City of Lake Oswego sewer pipe. State law requires these properties to be annexed to the city to receive service. New properties may be annexed if they are more than 300 feet from a Lake Oswego sewer pipe.

You can find Lake Oswego sewer pipe locations on the city’s LOMap.

If your septic system needs repair or replacement and you are within 200 feet of a City of Lake Oswego pipe, learn about the city’s Annexation Program and Application.

If your new property is not within 300’ of a city pipe, read on to learn how we can help you.

First, contact the Dunthorpe-Riverdale Sewer District online or email us at dunthorpe@multco.us. We will research whether your property is within the district.

You can also look for your property on our map. If it’s within the blue boundary, you’re in the district.

New Connection

You may need a New Connection permit if:

  • your property is connected to a septic system and has never been connected to a public sewer system.
  • your primary residence is connected but you need to connect an accessory dwelling unit or secondary structure (like a detached shop or a pool house with toilet/shower/sinks).
  • you are building a new residence within the district.

Clackamas County will issue your building and plumbing permits and be your primary contact, due to an agreement with the district.

In the uncommon case that your property is not near one of our sewer pipes, you will work with the City of Portland  to extend a district pipe closer to your property. Portland provides this service to the district even though you’re in Clackamas County. In this case, you will pay for the extension of the pipe.

To apply:

  1. Sign up for an account in our Permit Portal.

  2. Once you’re signed up, apply for a Dunthorpe-Riverdale Sewer Connection (New) Permit.

  3. Fill out the Drainage Fixture Worksheet to determine charges that we collect for the City of Portland. Learn more about System Development Charges (SDCs

  4. Pay your fees. 

    • Permit Fee: $120
    • Sewer Line Connection Fee: $2,500
    • City of Portland SDCs: Depends on the number of plumbing fixtures. An ADU or secondary structure does not require SDCs.
       

  5. We will issue a Certificate of Public Sewer and a Sewer Connection permit. Provide this permit to the city. This is required before they will allow you to connect to our sewer pipe.

Clackamas County will be your main contact for building permits, connection to our sewer system and any inspections. We have an agreement with the county to provide these services.

Repair or Reconnection

You may need a Repair or Reconnection Permit if:

  • you need to repair your connection to our sewer system.
  • you need to temporarily disconnect and then reconnect to our sewer system due to construction.

We are only responsible for our sewer mains, not the private laterals that connect directly to your residence. 

If your repairs are completely on your property and don’t affect our sewer mains, we can provide you with a Certificate of Public Sewer and a Sewer Connection Permit. These will be required before Clackamas County issues you a permit for repairs.

Clackamas County will be your main contact for building and plumbing permits and any inspections. We have an agreement with the City to provide these services.

  1. Sign up for an account in the Multnomah County Permit Portal.

  2. Once you’re signed up, apply for a Dunthorpe-Riverdale Sewer Connection (Repair or Reconnect) Permit

  3. Pay a Permit Fee of $120.

  4. We will issue a Repair or Reconnect Permit. Provide this permit to Clackamas County, who is our service provider for building and plumbing permits.

Disconnection

You may want to permanently disconnect from our sewer if you demolish your residence. We need to know about this change to stop charging you for sewer service.

Clackamas County will be your main contact for building and plumbing permits and any inspections. We have an agreement with the county to provide these services.

  1. Sign up for an account in the Multnomah County Permit Portal.

  2. Once you’re signed up, apply for a Dunthorpe-Riverdale Sewer Connection (Disconnect) Permit

  3. We will issue you a Disconnect Permit and stop billing you for sewer service.

Vacating a Sewer Easement

You may have a public sewer easement that was created on your property many years ago where we never installed a sewer pipe.

If we can confirm this situation, we will vacate the easement.

You may have a private easement with your neighbor instead of the district. In this case, you will need to work with your neighbor to vacate the easement.

  1. Sign up for an account in the Multnomah County Permit Portal.

  2. Once you’re signed up, apply for a Dunthorpe-Riverdale Sewer Easement Vacation

  3. We will work with you to draft a quitclaim deed that removes the sewer easement from your property title.

  4. We will record the deed against your property and we will no longer have the easement.

 

Last reviewed July 29, 2026

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