Ditch Maintenance and Small Drainage Capital Resolutions

What's the latest?

The City's Stormwater Division Project Manager will start the project in May 2024. We anticipate pursuing work in summer 2024.

2024 Project Areas

Planned neighborhoods include:

• Cimaron
• NE 16th Street
• SE 8th Street
• Tree Farm

How will the community be involved?

The City will notify affected residents by mail or door hanger when construction is anticipated. 

Ditch and Drainage Maintenance FAQs 

If you have questions, please read the Frequently Asked Questions below. If you need to talk with the project manager, please use the contact information at the bottom of this page.

WHY ARE THERE DITCHES IN MY NEIGHBORHOOD?

The City incorporated in 1999 and inherited the many neighborhoods previously constructed under the jurisdiction of King County. Older neighborhoods were developed to the standards at that time which included ditches to convey stormwater from homes and roadways to stormwater ponds and outfalls.

Ditches help reduce flooding, erosion, and pollution caused by stormwater runoff. After runoff enters the ditch, some infiltrates into the ground and the rest flows into a nearby stormwater pond or natural waterbody. For ditches to function properly, they must be clean and clear so runoff can flow unobstructed to the drainage system. Culverts and ditches full of dirt or debris can cause water to back up and potentially create flooding.

WHO OWNS THE DITCHES?

Ditches lining City roadways are in the public right-of-way. Like roadways, ditches are owned by the public and maintained by the City on their behalf. There are occasions where a Homeowner’s Association may be responsible for maintenance of the ditches and stormwater facilities in their neighborhood. This responsibility is assigned by the documents that created the subdivision and is typically noted on the map of the subdivided land on file with the King County Assessor's office.

WHO IS RESPONSIBLE FOR CLEANING THE CULVERT UNDER MY DRIVEWAY?

Maintenance, repair, and replacement of culverts under access to private property is the responsibility of the property owner. Although the culvert is located within public right-of-way, the purpose of the culvert is to facilitate access by the property owner to their private property. The City will clean and repair driveway culverts when conducting neighborhood ditch maintenance to ensure the drainage system will function properly. However, culverts should be regularly cleaned and maintained by the property owner to reduce the potential for flooding.

CAN THE CITY INSTALL PIPES AND SIDEWALKS TO REPLACE THE DITCHES?

Ditches are most commonly replaced when development subdivides land to create new lots to build a new neighborhood. Development is required to install infrastructure to current City standards which includes piping and treating stormwater and installing roadway improvements like sidewalks. The City can pursue projects to fill in sidewalk gaps that may cause ditches to be replaced with pipes, however, this typically occurs on arterial roadways as part of a non-motorized improvement and not through local neighborhoods.

CAN I PIPE OR FILL THE DITCH IN FRONT OF MY HOUSE?

Generally no, ditches must remain open because they are an efficient means of providing conveyance for stormwater runoff. Allowing individual properties to pipe the system has a high potential to cause a maintenance problem. The installation of pipe and sidewalk is a significant change to infrastructure that would also increase the cost to maintain the current stormwater system. 

WHAT DOES THE CITY DO TO MAINTAIN NEIGHBORHOOD DITCHES?

The City conducts a proactive ditch and drainage maintenance program to clean neighborhood ditches. The work includes removing excess sediment in the ditches, cleaning culverts under roadways and driveways, and stabilizing with grass to prevent erosion. Where ditches are steeply sloped, the City may place rock instead of grass as called for in the original design, or use other measures to prevent dirt from flowing downstream.

WHY IS GRASS USED TO STABILIZE DITCHES? CAN I INSTALL ROCK INSTEAD?

Grass-lined ditches filter and absorb pollutants in the runoff before the water is conveyed to a catch basin or stormwater pond. If you fill a portion of the ditch with yard debris, such as branch cuttings or grass clippings, or if you add rocks or beauty bark, it can cause flooding, damage the neighborhood stormwater pond, and add pollutants to streams and lakes.

HOW DOES THE CITY DECIDE WHICH AREAS TO WORK ON?

The City completed a ditch condition assessment in 2019, following King County guidelines to prioritize areas needing more immediate attention. The evaluation included criteria such as the amount and type of vegetation present, whether the vegetation requires maintenance such as mowing, and the amount of sediment filling the culverts.

Based on these scores, neighborhoods were prioritized for maintenance. Upon selecting the neighborhood(s) for each year’s work (approximately two to four linear miles of ditch line), the neighborhood’s stormwater system is reviewed to understand the most important connections in the system. These connections are vital and work on these may include removing private pipes and re-opening ditch segments. Whenever this kind of work is deemed necessary, the City project manager will attempt to contact you prior to commencing work.

To request ADA accommodation, including materials in a format for the visually impaired, call 425-295-0563. Persons with impaired hearing may call Washington Relay Service at 711. Persons with speech disability may call TTY at 877-833-6341.