Climate Resilience is the ability to prepare for, recover from and adapt to the impacts of climate change. The City of Kent is strengthening its climate resilience and sustainability practices through proactive and intentional planning efforts.

Stormwater & Drainage

Functioning stormwater and drainage systems are crucial to strengthening our resilience to changes in the climate, ensuring the City of Kent is capable of handling increased rainwater and mitigating flooding.

The city works diligently to implement maintenance standards for our stormwater drainage system and facilities. These maintenance standards are developed for efficient conveyance, storage, and treatment of stormwater before it is discharged to surface or ground waters.

This helps to reduce localized flooding, decrease instances of erosion, and allow treatment processes to function properly. As a result, the city continues to ensure that these facilities are full-functioning and properly maintained and will prevent and/or reduce stormwater pollution.

The city's Design and Construction Standards and Surface Water Design Manual outline maintenance standards for all stormwater treatment and flow control facilities, and establish criteria for identifying deficiencies and needs.

Any development or construction site that disturbs one acre or more of soil must develop a Stormwater Pollution Prevention Plan (SWPPP) as part of its stormwater compliance requirements. The SWPPP includes specific Best Management Practices (BMPs) for reducing or eliminating pollution originating from a construction site, most often in the form of dirty stormwater.

Drainage Master Plan (DMP)

The Drainage Master Plan includes an evaluation of watersheds and drainage basins as well as analysis of open channel components (receiving water) for insufficient capacity. It also determines and prioritizes projects needed to reduce flood risks, improve water quality, enhance fish passage and instream and riparian habitats, and efficiently serve planned growth in a cost–effective way.

Stormwater Management Action Plan (SMAP)

The Stormwater Management Action Plan contains policies that promote compact development, with a smaller footprint, reduced impervious surfaces, natural areas within the urban core, and improved water detention, all of which will help local communities meet the Growth Management Act's goals of accommodating growth while protecting the environment. 

The SMAP development will include consideration of the following strategies...

• Capital projects including regional facilities
• Land acquisition and/or conservation easements
• Land use or zoning code adjustments
• New critical area designations
• Protected, enhanced, or restored riparian buffers
• Enhanced public stormwater drainage system maintenance
• Education and outreach

The City of Kent developed a process to assess and prioritize which receiving waters would most benefit from the implementation of a SMAP and selected one high priority receiving water.

The city chose to focus on the Mill Creek basin, with the Lower Mill Creek basin being the priority catchment area for the SMAP. The city will further narrow the focus area within the Lower Mill Creek basin using new water quality monitoring data, existing illicit discharge data, and further assessing source control properties and potential pollutants. 

Flood Hazard Planning

The city’s flood hazard planning considers off-site erosion and accretion or flood damage that might occur as a result of stabilization or protection structures or activities.

Flood hazard management planning employs nonstructural approaches to minimizing flood hazard when possible, and the city gives preference to nonstructural solutions.

Where structural solutions are rebuilt to mitigate flooding, fish-friendly structures such as setback levees are implemented. In the Lower Green River for example, every opportunity is taken to set back levees and revetments to the maximum extent practicable.

Flooding Mitigation

The city’s goals while operating and maintaining stormwater infrastructure are to help protect the environment by reducing flooding, reducing demand on public stormwater drainage systems, support healthy streams and rivers, and cultivating healthier, more sustainable communities.

The city has completed a number of major flooding reduction and drainage projects over the last several years, and continues to make significant improvements to our stormwater system to reduce flood risk in the Kent Valley.

Flooding Reduction Projects

Mill Creek Reestablishment Project

Currently moving through the federal permitting process, this project will remove accumulated sediment to increase water storage capacity and reduce flood risk while improving habitat for fish and wildlife in Mill Creek.

The project includes relocating a portion of Mill Creek to meander through wetland areas, wetland mitigation efforts and the planting of additional native vegetation. This project will substantially reduce flood levels at James St. and 76th Ave. S. in the valley when it is implemented, and divert Mill Creek runoff away from homes and businesses and into wetland property north of James St.

Upper Mill Creek Dam

The Upper Mill Creek Dam provides flood risk reduction in the area spanning from Earthworks Park to Central Avenue and from Titus Street to James Street. This area includes the Kent Senior Activity Center, Mill Creek Middle School and a number of homes and businesses along Mill Creek.

James St. Stormwater Pump Stations

Completed in 2020, these pump stations divert peak stormwater surface flows directly into the Green River to mitigate flooding. James St. is a known problem area and has a tendency to flood during extended periods of rain.

While the James St. Pump Station was not built to handle larger storm events or extremely wet seasons, the city has made improvements and has plans in place to mitigate water over roadways and flooding caused by larger storms in a more comprehensive way through a series of projects.

City crews perform maintenance all year to ensure the system works properly.

• Inspecting and cleaning catch basins and pipes
• Removing built up sediment
• Cleaning detention and filter vaults
• Replacing manhole and catch basin castings
• Replacing damaged and failing pipe
• Installing new catch basins and pipe

The Kent Valley is prone to flooding, which is why during flood events, city crews work tirelessly to respond and react to problems that arise around the city. Staff performs maintenance all year to ensure that when the rains come, the system works properly.

You can also help to minimize localized flooding by keeping the storm drains near your home clear of debris.  If you see a clogged storm drain, use a rake, shovel or stick to clear the drain. If this doesn't help, report the blockage via our KentWorks app or by calling 253-856-5600.

Green River Levee

Multiple levee improvement and flood reduction projects have been built along the Green River. Several of these projects near completion include the Lower Russell Levee, and Downey Farmstead Restoration.

The projects seek to meet or exceed Federal Emergency Management Agency (FEMA) accreditation standards as well as providing habitat restoration work along the levees with native plants, fish habitat, and invasive species removal.

Other river improvement projects built over the last 15 years include the Riverview Park Side Channel, the Leber Backchannel, portions of the Horseshoe Bend Levee, the Foster Park Levee, the Hawley Road Levee, and portions of the Lower Russell, Boeing and Briscoe/Desimone Levees. Future projects underway include Boeing Levee and habitat improvements, and Signature Pointe Levee and Milwaukee II Levee improvements.

Spills & Pollution

Pollutants are any material that enters the stormwater drainage system other than rainwater. Preventing and mitigating the spread and impacts of spills and pollution in the city can prevent damage to our environment and improve resiliency.

Pollutants are generally common household cleaners, vehicle fluids and wash water, paint, dirt and pet waste. Polluted water is harmful to plants, animals and humans alike, and we all need clean water to survive. Everyone must to do their part to keep pollutants out of our waterways.

A spill is a release of a pollutant, that causes an imminent threat to human health, the environment or the stormwater drainage system. When a spill reaches the public stormwater drainage system, it becomes an illicit discharge, and the responsible parties can be liable for fines and the cost of cleanup. 

Some common sources of spills are...

• Vehicle accidents that release fluids
• Poor management practices
• Accidental spills
• Intentional discharge of pollutants that could enter the storm system

Kent City Code (KCC) Chapter 7.14 – Illicit Discharges, provides very specific information on what can and cannot be discharged into the city's stormwater system. The code also supports actions for compliance through inspections, monitoring, and required use of stormwater best management practices to prevent pollutants from entering the public stormwater drainage system and waters of the state, such as rivers, lakes, and streams.

National Pollution Discharge and Elimination System (NPDES)

The NPDES is a permit-based water quality program implemented under the authority of the Federal Clean Water Act. 

The primary goal of NPDES is to reduce the amount of pollution that reaches streams, lakes, wetlands, oceans, and all other water bodies by regulating stormwater runoff. Visit the U.S. Environmental Protection Agency and WA Department of Ecology for more information on the federal and state programs.

Kent complies with NPDES by maintaining a current Western Washington Phase II Municipal Stormwater Permit administered by the Washington State Department of Ecology.

The permit requires the city to implement a Stormwater Management Plan that includes implementing programs to protect water quality including illicit discharge detection and elimination, source control program for existing development, and controlling runoff from new development, redevelopment, and construction sites. Visit City of Kent National Pollutant Discharge Elimination System, (NPDES) Program for more information on these programs and others required under the NPDES permit.

Source Control Program

Businesses are required to prevent the pollution of stormwater.  Rain falling on a business property can collect a number of different contaminants, including dirt, oil, fertilizers, pesticides, litter and assorted chemicals and metals.

This polluted storm runoff flows into storm drains and ditches that lead to streams, lakes, and wetlands. Preventing pollution cuts costs, avoids expensive cleanups, and protects a business from fines.

Source control best management practices (BMPs) prevent pollutants from entering stormwater runoff by controlling them at the source. Some source control BMPs are operational, such as checking regularly for leaks and drips from equipment and vehicles and covering materials that have potential to add pollutants to surface water if rainwater comes in contact with the materials.

Structural BMPs prevent rainwater from contacting materials that will contaminate stormwater runoff such as providing a covered area or berm to prevent clean stormwater from entering work or storage areas. In contrast, treatment BMPs are structures that treat stormwater to remove contaminants.

In 2023 the city began implementing a Source Control Program to require the use of source control BMPs to prevent and reduce pollutants in runoff from publicly and privately owned institutional, commercial, multi-family, and industrial sites which have the potential to release pollutants to the public drainage system based on the business processes and practices performed at the facility.

City staff inspect these facilities to ensure that BMPs are in place to protect water quality. These inspectors also provide education and technical assistance to assist the business owners/managers and staff in implementing  BMPs for their facilities.

The Source Control Program includes the following four elements...

• The use of operational, structural and treatment source control BMPs.
• Inspections of pollutant generating sources at publicly and privately owned institutional, commercial, and industrial sites to enforce implementation of required BMPs to control pollution discharging into the public stormwater drainage system.
• Application and enforcement of local ordinances at sites, identified as having the potential to release pollutants into the public stormwater drainage system, including sites with discharges authorized by a separate NPDES permit.
• Practices to reduce polluted runoff from application of pesticides, herbicides, and fertilizers from the sites identified in the inventory.

Reporting Pollution

You can report a spill or an illicit discharge by using the KentWorks app or portal, or by calling our spill hotline at 253-856-5600.  

An illicit discharge is any release of a non-stormwater substance into the stormwater drainage system and/or waterways; this can include common household cleaners, car fluids and wash water, paint, garbage, dirt, yard and pet waste.

We have staff available to respond 24/7, and you can reach our dispatch any time after hours by calling 253-856-5600 and selecting option 1. If a spill looks flammable, call 911 immediately. Kent City Code (KCC) Chapter 7.14 provides very specific information on what can and cannot be discharged into the city's stormwater system.

The code also supports actions for compliance through inspections, monitoring, and required use of stormwater best management practices to prevent pollutants from entering the public stormwater drainage system and waters of the state, such as rivers, lakes, and streams.

Controlling Runoff

All development and construction projects within the City of Kent, both public and private, are required to use erosion and sediment control best management practices, (BMPs) to reduce or eliminate the discharge of pollution originating from a construction site, most often in the form of dirty stormwater. 

Erosion and sediment control practices are continuously inspected during construction to ensure proper function and protection of water quality. These inspections are performed by a State approved Certified Erosion and Sediment Control Lead (CESCL). 

Sewer Water Discharge

Storm water, surface water, ground water, cooling water and industrial processes that have been polluted as determined by the engineer for a project and King County, the Department of Natural Resources (DNR) and DNR Wastewater Treatment Division are required to be discharged to the city sewer main through an approved pretreatment system and metering method.

Chemicals & Pesticides