Lake Serene

September 2017 Update

​The lake connection was completed on September 8. Residents and county staff gathered at the lake on September 14 to celebrate the completion of the lake connection. SWM also confirmed that the original failed pipe is fully blocked from a cave-in.

August 2017 Update

  • Lake Connection Will Be Completed Ahead of Schedule – Snohomish County successfully sped up the permitting process. We will connect the lake to the emergency bypass system before the next rainy season! Construction starts September 5. It will take a week. 
  • Community Meeting – There will be a meeting at the Lake Serene Boat Launch from 4 – 6 p.m., Thursday, September 14, to celebrate this milestone and update the community. The public is invited to join Snohomish County officials to learn about the project and what to expect in the next phase.
  • The Next Phase (West of Serene Way) – Drainage improvements downstream of Serene Way are still in the design phase. Construction is scheduled for 2018. The county will replace degraded infrastructure to reduce flooding hazards for Lake Serene homeowners. See Proposed Project Sketch to learn more.

June 2017 Update

  • Current Lake Level (see “Lake Serene Levels” on  the Resources section of this page)
    The lake level continues to drop through evaporation and outflow from the existing failed/blocked outlet. The levels are anticipated to continue to drop as summer approaches, but could fluctuate based on rainfall. 
  • Status of Lake Connection
    We have accelerated the design and permitting for the portion of the project that connects the recently constructed system to the lake itself. Federal, local and state permit applications that are critical to an anticipated late summer 2017 construction target, have been submitted. Late summer 2017 construction is contingent on permits being issued. After the work is complete, the lake levels will be comparable to what they were prior to the failure/blockage of the original system. 
  • Status of Full Project (From Serene Way West) (see Proposed Project Sketch)
    Design of the full project (west of Serene Way) is progressing through property access permission, field survey, engineering, and geotechnical evaluation. Permits will be submitted when the design is sufficient to characterize impacts. The schedule presented to Council calls for construction in 2018-2019. The schedule is largely dependent on the time required to obtain the environmental permits and to solidify all of the needed property permissions. This will install a new sloped system that Snohomish County will maintain.

May 2017 Update - Environmental Permitting

​​This project will require federal, state and local permits and approvals. To comply with the State Environmental Policy Act (SEPA), an Environmental Checklist has been prepared and a Determination of Non- Significance issued. These documents are provided below:

April 13, 2017 Update

The emergency bypass is working as designed. Lake levels naturally fluctuate when it rains. Lake Serene received about an inch of rain over the past couple days. The lake level rose 1.3 inches and it is already receding. Despite record rainfall in February and March and heavy rain this week, the lake is still 10.5 inches below the record high.

With the public-private funding model approved by Snohomish County Council, staff are working to secure permits to construct a permanent fix that will do a better job of maintaining lake levels than the original private pipe.


akefront Property Owners Support Cost-Share Solution at Lake Serene

In February 2017, Snohomish County sent a survey to property owners on Lake Serene to help select a solution to manage high lake levels and reduce property flooding around the lake. Because of the failing, privately owned pipe, Lake Serene property owners were experiencing record high levels of water on their property. The survey showed that a cost-share option is favored by a significant majority of the lakeside property owners who responded to the survey. Of the 98 property owners, 70% responded to the survey.

Survey Results: 
  • 14% selected no action to be taken
  • 6% percent selected the private solution
  • 67% percent selected the cost-share option
  • 13% selected “other”
See details of options below.

March 14, 2017 Update

The new emergency bypass pipe has been functioning continuously since the morning of Friday, March 10. The water level of the lake has dropped approximately 2.7 inches since the new outlet was engaged. We have installed flow measurement sensors so we can monitor the lake outflow rates and make adjustments as necessary to prevent damage to the downstream drainage system. The crew will is now focusing on site restoration.  

Currently the lake water surface elevation is 8.2 inches below the highest level on record occurring on 2/17/2017.

March 10, 2017 Update

The emergency bypass pipe on Lake Serene was completed today and water is passing through the outflow system. Site restoration will occur next week and the project is expected to be fully complete by mid-March. 

March 8, 2017 Update

The crew spent the day preparing the site for the installation of the final segment of pipe and the outlet structure. The preparation included creation of the work area isolation system, delivery of final materials and fittings, and installation of monitoring equipment.  On Thursday we are planning to install the final length of pipe along the boat launch and the outlet structure near the lake edge. The project is expected to be completed next week.

The lake level continues to decrease and can be seen in the graphs listed in the “resources” section of this webpage. Currently the lake water surface elevation is 5.8” below the highest level on record occurring on 2/17/2017.

March 7, 2017 Update

The crew installed the last length of the bypass along Serene Way today, including connecting to the existing catch basin. On Wednesday we are planning to install the outlet structure and final 40 feet of pipe along the boat launch. The project is expected to be completed in mid-March.

March 6, 2017 Update

Today crews worked with the water district to relocate water service lines and prepared the site for connecting to an existing catch basin along Serene Way. On Tuesday we plan to install 40 feet of pipe and connect to the existing catch basin. The project is expected to be completed in mid-March.

Weekend Update – March 4 & 5, 2017

The crews installed another 80 feet of the bypass pipe over the weekend. We expect to complete the portion along Serene Way on Monday and will then move on to installing the final 40 feet of pipe and the outlet structure near the lake’s edge. The project is expected to be completed in mid-March.

March 3, 2017 Update

Crews installed 40 feet of pipe along Serene Way today. The project is 70 percent complete as 375 of the 537 feet of pipe needed, and three of the four catch basins, have been installed. Crews will continue working through the weekend installing pipe. The project is expected to be completed in mid-March.
Currently the lake water surface elevation is 5.3 inches below the highest level on record (occurring on 2/17/2017).

March 2, 2017 Update

The crew had another productive day on site. The large catch basin at the corner of 140th and Serene Way was installed along with a section of the emergency bypass pipe. Tomorrow we plan to begin installing drain pipe along Serene Way. The project is expected to be completed in mid-March.

March 1, 2017 Update

Conditions were good today for the crew. Work on the emergency bypass pipe continued to make progress. We installed 100 more lineal feet of pipe along the boat launch. Tomorrow, we are scheduled to install a large catch basin at the corner of 140th and Serene Way (this is the third of four catch basins for the project) and begin installing pipe along Serene Way. We expect to complete the project in mid-March.

Lake level graphs are also available for both elevation and staff plate measurements and will be updated weekly.

February 28, 2017 Update

Today, crews focused on coordinating with the sewer district to complete the relocation of the sanitary sewer service line. This was a substantial effort to complete in one day as the excavation required was quite large. The crew is scheduled to continue with the emergency bypass pipe installation along the boat launch tomorrow. The project is still expected to be completed in mid-March.

Currently the lake water surface elevation is 4.3 inches below the highest level on record (occurring on 2/17/2017).

February 27, 2017 Update

Crews spent most of the day working with Alderwood Water and Wastewater District (AWWD) locating and verifying elevations of the sanitary sewer main and service line along Serene Way. Several deep holes were dug to locate the sewer lines. Tomorrow, AWWD crews are scheduled to begin relocating the side sewer which is in conflict with the new emergency bypass pipe. In addition, Snohomish County crews will continue installing pipe along the boat launch. The project is expected to be completed in mid-March.

Weekend Update – February 25 & 26, 2017

Despite the weather, work on the emergency bypass pipe continued to make progress over the weekend by installing 100 more feet of pipe and two catch basins. So far, 220 of the total 537 feet of pipe have been installed, bringing the project to 40% completed.

February 24, 2017 Update


Crews continue to make progress by installing another 60 feet of pipe, for a total of 120 feet of pipe in the ground to date. Most of the pipe has already been buried. Groundwater conditions continue to be challenging for the construction, and water quality management practices are increasing. Construction is expected to continue through the weekend, as well as next week.

The lake level rose by about three-quarters of an inch from Thursday to today.

February 23, 2017 Update

The lake level dropped by half an inch from yesterday. We are now over two inches below the high water mark on February 17. Crews started pipe and catch basin installation today. They installed one catch basin and expect to install approximately 40 feet of pipe today. Another 60 feet of pipe is schedule to be installed tomorrow, working towards the lake, depending on ground water conditions. The projected completion date remains mid-March.

February 22, 2017 Update

Some relief is on the way for people affected by flooding around Lake Serene. Work is underway to install a temporary emergency overflow pipe. When completed in mid-March, it will begin reducing the lake level by about one-foot below the current level. This will reduce the risk of flooding to the road and it will provide some relief, but not a permanent solution, for private property flooding. Today, crews completed site preparation, including erosion control and the installation of a boom to protect water quality. They also dug test pits in the excavation area for the emergency bypass. Pipe and drainage infrastructure installation will begin Thursday. Subscribe to daily updates by clicking “Stay Informed”. 

February 21, 2017 Update

​Construction for the temporary, emergency bypass pipe on Lake Serene will break ground tomorrow, Wednesday, February 22. Public Works plans to complete construction of the temporary pipe in mid-March. Pre-construction work done today included delivery of materials, staging and pre-construction meetings with utilities and county staff. The temporary bypass pipe will prevent water from rising to a level that would flood county roads and damage public property.

February 13, 2017 Update

Snohomish County Executive Dave Somers authorized an emergency action to begin building a temporary drain at Lake Serene. The temporary drain will prevent water from rising to a level that would flood county roads. The Snohomish County Council also introduced legislation to fund a permanent fix. For details, please view the following:

February 2017 Update

At the April 2016 community meeting, Public Works introduced and explained the various options residents had available to them and the impact each had on them. Residents were presented with three options (see below) and were given the opportunity to provide feedback via comment cards.

Public Works is now seeking additional feedback from area residents via a mail-in card asking for their preferred option. Residents should have received the survey in the mail during the week of February 6 and will have until February 24, 2017 to respond. You can also download the survey and email it to David Ojala by February 24, 2017.


Lake Serene is located in unincorporated Snohomish County, west of Highway 99 between Mukilteo and Lynnwood. Public Works is working with community residents to mitigate flood risk for those located near the lake’s shoreline. Residents around the lake have been experiencing flooding during winter months or during periods of high rainfall. Snohomish County has assessed the condition of the lake’s outfall system. 
The investigation found the current outfall system in a state of disrepair. The corrugated metal pipe is rusted with visible holes and does not follow a sloped outfall. These issues, with increased rainfall, have caused the rising water levels in the lake.

Snohomish County Public Works has devised three alternatives for residences living around the lake.  
View Inside Pipe

Three Options Available

Option A: No Action
  • Because the pipe is mostly privately owned, costs for future replacement or upgrades will be the responsibility of local property owners
  • Outlet pipe may collapse, increasing flooding risk
Option B: Private Alternative
(No Snohomish County Participation)  
  • Replace existing pipe outlet from Lake Serene to Serene Way with a new 30-year service life pipe
  • Maintenance of downstream pipe systems remain private responsibility
  • Estimated project cost = $210,000 (County cost = $0; Private cost estimate = $210,000)
Option C: Snohomish County Cost Share Strategy
  • Post-project boat ramp staff level reading anticipated at: 2-year flood 5.9 feet, 25-year 6.5 feet, 100-year 6.7 feet (Staff gage level reading on January 20, 2017 was 7.5 feet)
  • Install new sloped system from Lake Serene to Beverly Park Road
  • Snohomish County will maintain the pipe system
  • Estimated total project cost = $850,000 (County cost = $550,000; Private cost = $300,000 [approximately $3,100 per parcel] paid by 95 parcels, via additional SWM service charges over a to-be-decided time frame)
    * private cost has been updated. See the February 13, 2017 Update above.

Detailed Information Presented at the April 5, 2016 Meeting