Our Stormwater System

What is stormwater?

Stormwater is the runoff generated from rainfall or snowmelt. When the runoff doesn’t soak into the soil, it flows over impervious surfaces like roads, sidewalks, parking lots, and rooftops or even pervious surfaces like lawns. Runoff enters our wetlands and streams including Boeckman Creek, Coffee Lake Creek, and the Willamette River.

How does stormwater impact me and my property?

Stormwater runoff can impact you and your property in a number of ways if not managed properly. When stormwater flows, it can carry pollutants like trash, oil, and dirt/sediment that can harm fish, plants, wildlife, and people. The increased flow due to development (and increasing impervious surfaces) can also lead to stream erosion, flooding, and other in channel impacts.

Why do we need to manage stormwater?

We need to manage our stormwater to protect the environment, property, and support healthy watersheds for fish, wildlife, and recreation. We also need to manage stormwater to meet regulatory requirements from the Oregon Department of Environment Quality (DEQ).

How does Wilsonville currently manage its stormwater?

The Community Development and Public Works departments manage stormwater for the city. In cooperation the departments plan, regulate, operate, and administer the stormwater collection and treatment systems in Wilsonville.

A variety of standards, policies, and regulations guide the program. The City operates under a Municipal Separate Storm Sewer (MS4) permit from Oregon DEQ that requires programs and projects to be implemented to manage stormwater. This permit reflects the City’s compliance with the Federal Clean Water Act and EPA regulations.

In addition, the City has a Stormwater Master Plan that guides capital projects and programs to manage storm drainage infrastructure. In 2021, the city initiated a process to update the 2012 Stormwater Master Plan. The 2024 Stormwater Master Plan update is anticipated to be adopted in April 2024.

Other documents that detail stormwater program and project activities include the Wilsonville’s Erosion Control Program, and Public Works Standards for design and construction for stormwater and surface water management.

What is included in the 2024 Stormwater Master Plan update?

The update of the Stormwater Master Plan is a comprehensive planning document that includes project, program, and policy recommendations to improve and enhance the performance of the storm drainage infrastructure throughout the city over the next 20-year planning period. In the Plan the city identified 15 capital projects and four planning projects to improve the stormwater system, as well as six annual stormwater programs. These include:

Table ES-1. Capital Project Costs and Schedule
Project Number ^a	Project Name	Objectives Addressed^b	Estimated Cost	Implementation Schedule
Project Number ^a	Project Name	Objectives Addressed^b	Estimated Cost	Near-term (2024-28)	Mid-term (2029-33)	Long-term (2034-43)
Capital Projects
BC-1	Library Pond Retrofit	Capacity Water Quality Infrastructure Need	$1,880,000	X
BC-2	Ash Meadows Flow Mitigation	Capacity Water Quality	$2,940,000	X
BC-3- Phase 1	Wiedemann Ditch and Canyon Creek Park Retrofit, Phase 1	Capacity Water Quality	$4,860,000			X
BC-3- Phase 2	Wiedemann Ditch and Canyon Creek Park Retrofit, Phase 2	Capacity Water Quality	$7,210,000			X
BC-4	Boeckman Creek Stabilization at Colvin Lane	Erosion/Sediment Control Repair/Replacement Maintenance	$410,000	X
BC-5	Memorial Park Swale Retrofit	Water Quality Erosion/Sediment Control Maintenance	$910,000			X
BC-6	Gesellschaft Water Well Channel Restoration	Erosion/Sediment Control Maintenance	$400,000	X
CLC-1-Phase 1	Day Road Stormwater Improvements, Phase 1	Repair/Replacement Capacity	$8,020,000	X
CLC-1-Phase 2	Day Road Stormwater Improvements, Phase 2	Capacity	$3,930,000		X
CLC-2	Arrowhead Creek Culvert Replacement at Arrowhead Creek Trail	Repair/Replacement Maintenance	$290,000		X
CLC-3	Garden Acres Pond Retrofit	Capacity Water Quality	$3,780,000		X
NC-1	Frog Pond East and South Conveyance Pipe Installation	Infrastructure Need	$4,090,000	X
WR-1-Phase 1	SW Willamette Way/Morey’s Landing Stormwater Improvements, Phase 1	Capacity Water Quality	$2,310,000		X
WR-1-Phase 2	SW Willamette Way/Morey’s Landing Stormwater Improvements, Phase 2	Capacity	$1,080,000			X
WR-2-Phase 1	Miley Road Stormwater Improvements, Phase 1	Repair/Replacement Erosion/Sediment Control Maintenance	$820,000		X
WR-2-Phase 2	Miley Road Stormwater Improvements, Phase 2	Repair/Replacement Maintenance	$10,510,000			X
WR-3	Rose Lane Culvert Replacement	Capacity Maintenance	$200,000	X
WR-4-Phase 1	Charbonneau East Stormwater Improvements, Phase 1	Capacity Repair/Replacement	$600,000			X
WR-4-Phase 2	Charbonneau East Stormwater Improvements, Phase 2	Repair/Replacement Maintenance	$4,440,000			X
WR-5	Charbonneau West Stormwater Improvements	Repair/Replacement Maintenance	$10,370,000			X
City-wide Planning Projects
City-1	Flow Monitoring and Rain Gauge Installation	Capacity	$100,000	X
City-2	Hydromodification Assessment and Stream Survey	Erosion/Sediment Control	$30,000/ event	X	X	X
City-3	Porous Pavement Pilot Study	Water Quality	$100,000	X
City-4	Boeckman Creek Geotechnical Evaluation	Erosion/Sediment Control	$150,000	X
TOTAL:				$19.14M	$20.85M	$29.53M

a. CP numbering reflects the following drainage basins: BC = Boeckman Creek, CLC = Coffee Lake Creek, WR = Willamette River, NC = Newland Creek. City-wide planning projects are designated as “City”.

b. Primary objectives addressed are identified in BOLD.

Table ES-2. Program Costs
Project Number	Project Name	Objective(s) Addressed	Estimated Annual Cost
City-Wide Programs
P-1	Local Drainage Improvements Program	Infrastructure Need Capacity	$100,000/yr
P-2	Water Quality Retrofit Program	Water Quality Capacity	$200,000/yr
P-3	City-wide Repair/Replacement Program	Repair/Replacement Maintenance	$275,000/yr
P-4	Charbonneau Repair/Replacement Program	Repair/Replacement Maintenance	$1,920,000/yr
P-5	Riparian Vegetation Management Program	Maintenance Water Quality	$25,000/yr
P-6	Vegetative Facility Maintenance Program	Water Quality Maintenance	$25,000/yr
Annual Total			$2,545,000/yr
Note: Primary objectives addressed are identified in BOLD.

To inform and help guide the planning process, a public survey was developed in 2021.

What makes up Wilsonville’s current stormwater system?

Wilsonville has a comprehensive system to actively manage stormwater runoff.

Conveyance system:
- pipes, culverts, natural channels, and constructed channels
- 81 miles of public storm water mains; plus, approximately 43 miles of private lines
- 2,361 public manholes; plus, approximately 640 private manholes
Low impact development, green infrastructure:
Wilsonville’s required method for stormwater management, whereby stormwater runoff is controlled and treated through a system of decentralized and integrated facilities, such as rain gardens, vegetated swales, and planter boxes. In comparison, conventional stormwater management relied on an “end- of-pipe” approach, which utilized large detention ponds and other facilities not integrated into development sites.
Water quality and healthy streams and wetlands:
A variety of aquatic organisms depend on healthy streams and wetlands to support their life cycles. In Wilsonville’s streams and wetlands, such as Boeckman Creek and the Coffee Lake wetlands, Chinook salmon, steelhead, red-legged frogs, and other vulnerable species need clean water and suitable habitat.

What can residents do to help manage stormwater in their neighborhoods?

Here are a few simple things you can do to help manage stormwater in your neighborhood:

Clean up leaves and debris around storm drains
Vegetate bare ground to limit erosion and sediment transport
Pick up lawn clippings
Clean up after your pets
Dispose of contaminants properly
Clean your car at a commercial car wash
Check your car for leaking fluids and recycle motor oil

How are stormwater services paid for?

Stormwater services are paid for as part of residential and commercial utility bills.