Flooding and Beavers

Level Level, Flooding, and Beaver Issues​

Over the past few years, we have seen increased lake levels and flooding around the lake. In particular, 165th has been closed due to flooding, and residents on 185th Ave NE have had to drive through water as Daniels Creek has backed up over the road.

In 2014, these issues worsened, and the flooding has lasted for much longer stretches. There are several issues which contribute to the flooding (small culvert on 185th, drainage ditch issues on 165th, etc.), but the main problem is beaver dams at the outlet of Cottage Lake (Cottage Lake Creek) and on Daniels Creek between 185th and the lake.

Community members and FOCL have contacted King County about the issue and I’ll try to track updates from the county on this page.

No 185th flooding this winter – we had several big storms which raised the the lake level, but it dropped back after a few days of dry weather.

185th only saw minor flooding during the worst storms again this winter (one instance where the water level was over the road). The lake level is currently a bit high and we will continue to monitor it.

09/04/15 – King County installed levellers in the dams on Daniels Creek, and repaired and installed new levelers on Cottage Lake Creek (the outlet). The water level by 185th Ave NE has dropped, and the overall lake level should also start to go down. Please contact me with questions or comments on the results.​

08/20/15 – King County will have a crew at the north end of the lake on August 24th/25th installing a pond leveler to deal with the flooding on 185th. More details soon.


08/15/15 – ​The beavers are still very active at both the north and south ends of the lake. I’ve been monitoring the dams at the outlet that control the lake level, and notching them as per our management plan. The pond levelers through the dam closest to the lake don’t seem to be moving much water (the water level is as high as the dam). I’m still hopeful that King County will have enough funding after finishing the work at the north end to improve things at the outlet.
4/25/15 – No big updates, but here’s an article that talks about living with beavers in our area:


11/09/14 – Flooding update

The good news is that the beaver family building the dam that was controlling the lake level was relocated (see update from 10/17/14) and the dam is no longer being maintained. I’ve notched the dam several times and lowered it slowly (as per best practices).

The bad news is the lake level is not any lower, and is actually higher than prior to the beaver removal after the storm at the end of October. When I went down to the dam last weekend (11/01/14), the main part of the dam was at least 24″ under water. So, although the beavers are gone, and the dam is no longer controlling the lake level, water levels are still very high. In addition, 165th has been closed due to flooding since late October.

Next steps:

  • determine what is controlling the lake level by taking a boat downstream of the beaver dam and looking for additional obstructions. It is possible the obstruction is south of 165th and causing both the high lake levels and the road flooding.
  • Contact KC Roads to find out what they plan on doing about 165th


10/17/14 – South-end beavers relocated – update from Ben:

“The good news is that we’ve caught 6 beavers at the lower Cottage Lake site – a pregnant mating pair, 1 male and female sub-adult, and 2 kits. We relocated them this afternoon to an area up Spada Lake Road, north of the town of Sultan. This site is my best research site, and I expect good things from these beavers… I’ll continue to let you know how that family does up there. The site is at about 2000′ elevation, but they have a least 2 or 3 months to really get ready for winter. ”


09/22/14 – Meeting annoucement:

Jae Huh from the King County Water and Land Resources Division has scheduled a meeting to update the community on the progress that has been made on the flooding and beaver issues around Cottage Lake.

When: October 1st, 2014 at 6:30PM
Where: The meeting will be held Leanette Bassetti’s workshop
The address is: 18512 NE 165th St
Please park next to large barn with green roof and walk east between large barn and white barn to the grey and red metal bldg.

Please RSVP to jonathanmorrison@hotmail.com we know how many chairs to bring and set-up


09/08/14 – Update on the beaver relocation from the north end of Cottage Lake:

Here’s an article on the beaver relocation for those that are interested in more details:



08/25/14 – Update from Ben on the relocation:

We were extremely successful in our trapping effort. In all, we were able to capture the mating pair, three yearlings, and a kit, totaling six beavers. The adults and yearlings are all dam builders. We had wildlife cameras out at about half of the traps. … We hope to relocate the family sometime this coming week if all goes to plan. They are currently doing well in our husbandry facility. As of now, we are thinking of placing them at a site on Forest Service property at the headwaters of Money Creek, near Skykomish.

Here are a couple of videos of the beavers. They aren’t very exciting, but they’ll give you an idea of the process and our husbandry facility. Feel free to share any of these.


08/11/14 – Update on meeting with Ben Dittbrenner about beaver relocation:

As mentioned in his email update, Jae Huh introduced Brooke Jones and me to Ben Dittbrenner, a researcher who is working on a study with the Tulalip Tribes that is relocating about 40 beavers into the headwaters of the Snohomish River. He came out to the site last Thursday (08/07/14), and will be back this week to attempt to live trap and re-locate the beavers that are building the dams that cause the flooding on 185th. If he is successful, we will be in a better position to reduce water levels and possibly install a pond leveler in case beavers move back into that area.

In order to attract the beavers to the live traps, Ben will be notching the two dams as the beavers have been very active in repairing damage and should come to investigate. I’ll send an update soon once we have more news from Ben.
07/31/14 – Update from Jae Huh (via email):

Dear Cottage Lake Residents,

I have received several emails recently with questions about the recent flooding of 185th Ave NE (185th), the condition of 185th/repairs, and what is being done about the flooding of 185th in the future.  I hope to address these recent emails in this summary and also provide some information on what is happening in the following days and into August.

William Kearney, a Cottage Lake resident, emailed me pictures of a flooded 185th on 7/12/14.  It had rained during the week prior to this email and the area had not seen any significant rain for weeks before this event.  Since there was no active Hydraulic Project Approval (HPA), neither King County nor the citizens were able to respond immediately to the flooding and notch/remove the beaver dams.  After some clarification regarding the HPA, Jonathan Morrison, a Cottage Lake resident, is applying for a five year HPA that will allow maintenance of the beaver dams in both the inlet channel and outlet channel.  Since this may take up to 45 days, I applied for an emergency HPA on 7/28/14 that will allow maintenance of the beaver dams for 30 days (expires 8/27/14).  On 7/29/14, a coworker and I notched/removed two beaver dams in the inlet channel and the water surface at 185th dropped about 10-12 inches.  We also notched/removed one beaver dam in the outlet channel; this dam was only impounding about an inch or two of water.

On 7/31/14, King County Department of Transportation, Roads Division Maintenance, plans to patch 185th to provide a better driving surface.  Please contact Carter Reeves (206-296-8096), Division One Maintenance Supervisor, with any question regarding this work on 185th.  The main reason for removing/notching the dams to the level we did on 7/29/14 was to provide a dry road bed for the surface repair.

Sometime in mid-August Jonathan Morrison plans to meet with Benjamin Dittbrenner about live trapping beaver.  Benjamin is a University of Washington PhD Student working on a research study with the Tulalip Tribe that will relocate beaver into the headwaters of the Skykomish River.

We expect to hear sometime in August whether the King County Flood Control District Grant submitted by King County Department of Transportation is funded.  The grant requested funds to build  a beaver pond leveler and funds to raise the road.

I would like to thank those that have been most involved up to this point.   Jonathan Morrison has been instrumental in the organization of the neighborhood meeting, working with B. Dittbrenner for trapping, applying for the HPA, and working with King County Road Services on the Flood Control District Grant.  Don Claussen has been on site with my coworkers and I to remove beaver dams several times.  Don even went out on his own to do some dam notching/removal.  Recently, Guy Baltzelle showed interest in notching/removing beaver dams.  Leanette Bassetti and her husband Bill volunteered their home to hold the neighborhood meeting and have kept an eye on the outlet channel; I believe Leanette has removed some debris from the channel as well.

If anyone is interested in helping these residents please let them know, I am sure they would appreciate your help.  When we have a long term HPA in hand, we would like to set up a time to show residents where the dams are located and how best to manage them.  If you have any questions regarding the flooding on 185th and at Cottage Lake please contact me by email or at 206-477-4874.  If your questions are regarding the condition of 185th or the proposed maintenance, please contact Carter Reeves at 206-296-8096.

05/22/14 – Update from Jae Huh (via email):

Good morning everyone,

This is a short summary to the neighborhood meeting held at Cottage Lake on May 15, 2014.  I want to thank Jonathan Morrison for organizing the meeting and Leanette Bassetti and Bill for providing the facility and refreshments.  I also want to thank Rhys Jones for volunteering his wife, Brooke, to help in the organization of the neighborhood to tackle the beaver issues.  I believe we have a great plan to deal with the beaver issues moving forward.  In summary, the neighbors and members of “Friends of Cottage Lake” (http://www.friendsofcottagelake.org/flooding) have agreed to maintain the beaver dams.  The dams will have to be notched or removed periodically (within the limits of the forthcoming maintenance HPA) to keep properties and 185th Ave NE from flooding; keeping lake levels down also provides live storage in the lake and presumably keeps NE 165th St. from flooding as often or as long as it has in the recent past.  Along with the maintenance of the beaver dams the neighbors agreed that trapping would be something they would like to pursue.  A Google search will give a list of trappers in the area.  King County is also looking into the possibility that the Tulalip Tribe may need live beavers for a project they are pursuing; I will pass on this information as soon as I receive it.  King County’s involvement will be to provide technical assistance when needed.

I have a call into Christa Heller, Washington State Department of Fish and Wildlife, Wildlife Biologist to get information on what the neighborhood group needs to do to obtain a 5 year maintenance Hydraulic Project Approval (HPA) for the maintenance of the beaver dams.  Please note the emergency HPA for the outlet channel expires today (5/22/14).  The HPA for the inlet channel expires on 5/27/14.  No work in the channel should occur after these dates until a 5 year maintenance HPA has been issued.

Jonathan Morrison will continue with the King County Flood Control District Grant application.  I will contact Jonathan in another email to help with this application.

We also discussed the condition of 185th Ave NE and the way King County Department of Transportation has determined that work on a road is guided by the tier system.  The following link shows that 185th Ave NE is a Tier 4 road http://www.kingcounty.gov/transportation/kcdot/Roads/NewServiceLevels/ServiceLevelsMap.aspx.  The following link describes each of the road tiers and the kind of response you can expect from King County Road Services Division http://www.kingcounty.gov/transportation/kcdot/Roads/NewServiceLevels.aspx.

The contact information you requested regarding Brenda Bauer, Road Services Division Director, is as follows:

Brenda Bauer, Director
King County Road Services Division
201 S. Jackson St.
Seattle, WA 98104
1-800-325-6165 toll-free
TTY: 711 Relay Service

I want to thank Don Claussen for going out with me last Monday and tackling some of the beaver dams.  We were able to notch the beaver dam just downstream of 185th Ave NE and a new dam that was built in Daniel’s Creek just downstream of the upper pedestrian bridge on the Jones’ property.  This new dam was holding back approximately 12-15 inches of water. Brooke Jones also came out to learn a little about the beaver dams.  Removing these dams lowered the water levels at 185th Ave NE further as the water receded from the shoulders of the road on both sides.  As Don pointed out, we could also tell the water levels had dropped about 5 inches of so by looking at the moisture left on the tree trunks.  The water levels dropped on both sides of the road which would indicate that the culvert is working and not completely blocked.

Thank you to those that attended the meeting and your willingness to participate in dealing with the beaver issues.  To those that showed an interest in removing the beaver dams, please contact me to set up a time that we can meet.

05/06/14 –
Meeting with WLRD on flooding and beaver issues scheduled for May 15th at 6:30pm

King County Water and Land Resources Division engineers Jae Huh and Brian Sleight have completed their study of the high water/beaver situation at the 185th Ave NE inlet and the Cottage Lake outlet.

They would like to meet with members of Friends of Cottage Lake and impacted neighbors to give their adaptive management report, and they will discuss strategies for managing water level and flow. People attending should feel free to discuss their own concerns about managing the high water and how all of us can work together to manage the flow.

The meeting is set for May 15, 2014 at 6:30PM and will be held in Leanette Bassetti’s workshop (Thanks Leanette!).
The address is: 18512 NE 165th St
Please park next to large barn with green roof and walk east between large barn and white barn to the grey and red metal bldg.

Please RSVP to jonathanmorrison@hotmail.com – thanks.


05/02/14 – update from ​Dan Anderson (King County Road Services)

Dear neighbors of 185th Avenue NE,

Thank you for your patience while part of 185th Avenue NE was covered by high water. We appreciate your emails and phone calls to King County and apologize for any inconvenience this may have caused you.

The Water and Land Resources division initially removed three beaver dams at the south end of Cottage Lake to bring the lake level down. The lower lake level revealed another beaver dam at the north end of the lake that was keeping water over 185th Avenue. The northern dam was partially removed and water quickly dropped below the height of the road. The beaver have not yet rebuilt the dams at the south end of the lake but have rebuilt the dam at the north end of the lake.  The county has a 30-day emergency Hydraulic Project Approval to remove dams at the north and south ends of the lake to keep water off the roadway. Crews from the Road Services Division will monitor the road and remove the dam as needed to keep the road dry.

The team at the Water and Land Resources Division will be meeting with the local community group Friends of Cottage Lake to discuss the long-term strategy for managing the beaver in the area. If you would like to be part of that meeting or have questions concerning the drainage of the lake and surrounding areas, please contact Jae Huh, Stormwater Services Section Engineer, at 206-477-4874.

You may be aware that this is not the first time 185th Avenue has flooded. This has been a recurring issue for both the neighborhood and the county. Unfortunately, the road was originally constructed on soft wetland soil that does not provide a stable base for a road. In order to adequately raise the roadway, the county would have to undertake a relatively expensive capital project, estimated to cost up to $800,000, which is not in the county’s current budget.

The county has also communicated with neighbors regarding the culvert at 185th Avenue NE, saying that it is on a list to be replaced with a larger culvert. However, examination during the recent flooding by environmental engineers indicated that replacement of the culvert without also raising the road will not provide substantial relief.

Regarding potholes, the standing water and poor subsurface conditions will continue to make long-lasting repairs to the asphalt surface difficult. Now that the water level has fallen and exposed most of the road surface, county crews have used hot-mix asphalt to fill in potholes. Proper repairs could not be done under standing water since asphalt patches do not adhere to wet pavement and rock or gravel fill would wash away. Please reach out to our 24/7 Roads Helpline to report additional potholes at 206-296-8100.

Looking forward, Road Services will continue to monitor the culvert’s condition, patch potholes on the road and work collaboratively with Water and Land Resources to see if improvements in water levels impacting 185th Avenue can be made. We do value all of our residents, and while we would like to be able to immediately rebuild all roads susceptible to flooding or in need of reconstruction, the county unfortunately cannot afford to do so because of greatly reduced financial resources. Please let us know if you have additional questions or comment. Thank you.


Dan Anderson, King County Road Services

04/28/14 – update from Jae Huh (Water and Land Resources Division)

Good afternoon everyone,

This is an update to the work Brian and I did as described in his email below.  On Thursday, the following day, the two beaver dams that Brian and I had removed had not been rebuilt.  A coworker (Craig Hislop) and I removed the 3rd beaver dam that Brian mentioned in his email below.  This beaver dam is located approximately midway between the Bassetti bridge and NE 165th Street.  Craig and I also walked the outlet channel from the Bassetti bridge towards the lake.  Craig, wearing a drysuit, was able to enter the creek just east of the Bassetti’s east property line.  From there he was able to see all the way to the lake and did not see any obstructions.  He walked downstream from this location and walked over several humps in the bottom of the channel that we assume are old beaver dams.  These humps were a couple of feet under water and not controlling the lake levels.  He continued to walk downstream until he reached a point that could be seen from either the Bassetti bridge or from the Bassetti property, confirming there were no obstructions upstream of the Bassetti bridge beaver dam all the way to the lake.

While heading back to office we stopped by 185th and the asphalt pieces placed by Brian at the water surface level were no longer there.  I set a hub in the shoulder of the road at the water surface level so I could verify if the water levels had dropped during my planned visit the next day.

On Friday morning I spoke with Gary Dixon who mentioned that lake levels were down approximately 5-6 inches.  I stopped by the Bassetti property again and verified that the beaver dams had not been rebuilt.  I then went to 185th and the water surface levels had not dropped, however, I was able to confirm that the lake levels had dropped just as Gary mentioned.  Since the water level on the Jones property (blueberry farm) had also dropped, I was able to walk the inlet channel (Daniel’s Creek) most of the way up to 185th and discovered a beaver dam.  I notched this dam in several places and in about 2 hours the water over 185th was almost completely gone.  I presume I was not able to locate this dam in my previous field visits since the high water levels, created by the backwater of the beaver dams in the outlet channel, limited my access.  It is also possible that this beaver dam was completely submerged due to the backwater of the lake during my previous site visit.

Today I was told that 185th is again under water and I presume the beavers have rebuilt the dam in Daniel’s Creek.  I just spoke with Gary Dixon and he estimates that the lake level is down approximately 15 inches since Brian and I first removed the beaver dams in the outlet channel.

King County staff will be meeting this week to discuss our strategy on Cottage Lake moving forward and I will keep everyone updated.  Please let me know if you have any questions.


Jae Huh,
Engineer II
Water and Land Resources Division

​​04/23/14 – update from Brian Sleight (Water and Land Resources Division)

Jae and I met Christa Heller from WDFW at Cottage Lake today to look at the beaver problems.  Christa gave us a verbal emergency HPA to remove parts of a couple beaver dams today.  Jae and I removed the smaller dam by Leanette’s west property line that didn’t seem to be maintained by the beaver.  We also removed a large section of the dam upstream of her bridge that was definitely backing water up about 6-8 inches.  I did some recon downstream and found the dam Paul had told me about but could not get close to it.  From where I could see, it looked like it was only backing water up 3 inches or so.  We did not have time to recon towards the lake to see if there were additional dams between the bridge and the lake.  However, the little area of Leanette’s property right by her road was not going down quickly which it would have if there were another dam not too far upstream so I think that area of her property will drop at the same rate as the lake.

We stopped by 185th at the north end of the lake on our way out and placed a couple pieces of asphalt at the water line on each side of the road so Jae can tell whether there is a change when he goes back out tomorrow.  Jae will go to the dams we worked on today and see if the beaver try to rebuild them.  He will try to recon from there to the lake to make sure there are no other dams upstream and then, if he has time, will try to get to the downstream dam and remove part of it.

Jae and I removed some of the two beaver dams then went out to 165th to see if there was any effect.  Water was still just up to the fog line on the south side of the road just like it was when before we started.  We went back and removed more of the dams and when we left water had risen so it covered the south driving lane for a couple hundred feet.  We call the WLRD complaint line to inform them in case they received any calls and asked them to call the KCDOT front desk to inform them and also call the Road Maintenance Supervisor for the area to have them put water over road signs up that are already out there.  Note that while flooding an entire lane of traffic sounds bad, that only equates to a rise in the water surface at 165th of a couple inches.

I tried to estimate the flow through the beaver dam after we were done based on the approximate area and a velocity estimate.  That flow combined with a typical flow from Cold Creek is still only about 50% of a typical winter storm event flow recorded at a downstream flow gage.  I expect 165th to stay partially flooded until the lake level goes down but I don’t expect any flooding problem downstream on Cottage Creek or further down in Bear Creek.

So our first action of the adaptive management is done.  If the beavers react as we hope they will and rebuild the dam at the bridge, our next step would be to replace the existing flow leveler with a larger diameter flow leveler.  If the beavers don’t react how we want them to, we’ll re-evaluate what the next step is.