Illahee Creek Culvert - 2/6/08

A few weeks ago we asked Kitsap County to re-access the Illahee Creek culvert situation since we felt it was no longer fully functional when it filled up with sediment during the Dec 3, 2007 storm.

We received the following response back from Jon Brand, the Assistant Public Works Director:

Mr. Aho: I've taken an opportunity to review Parametrix's report, visit the site and discuss this matter with other Public Works engineers and managers. The steep gradient, geology and development patterns in the watershed all contribute to the abundant deposition of material at the culvert outlet. There is a history decades long of Public Works removing sediment from this stream. Prior to the early nineties, Public Works forces cleared the channel of debris on a monthly basis from the culvert all the way down to the beach. As environmental regulations were tightened and issues developed with the property owner, this practice ceased.

The Public Works Department views the aftermath of the December 3rd storm as a maintenance issue. The 14-foot wide concrete box culvert is in good condition and, provided that it is regularly maintained, has adequate capacity. The depth of sediment in the culvert has been monitored regularly since installation in 1999 and crews have not been directed to remove sediment. In hindsight, the County probably should have been performing regular maintenance to keep the sediment level lower. Public Works crews have been removing material from the outlet this winter and we will continue to do so until a reasonable bed elevation can be established and maintained. If resource agencies, the property owner and the public are in favor of removing sediment from the culvert outlet to the beach, the County would be interested in participating.

Your e-mails indicate that there may be funding available for replacement of the arch culvert. Given the fact that there was no monetary damage resulting from the December 3rd storm other than required maintenance, it's unlikely that the County would qualify.

I hope that I've addressed your concerns.

Jonathon Brand, P.E.
Assistant Public Works Director - County Engineer
Kitsap County Department of Public Works
360-337-5777

We responded as follows on 2/6/08:

Jon - Thank you for looking into our concerns and for your reasoned response. We who live here are hoping we don't have any more serious storms this season, as we are concerned about the culvert plugging with possible disastrous affects to Illahee Road. I'm not sure the local residents would agree to channelize the creek to Port Orchard Bay, as among many other considerations, one would then need to decide which of the recent channels to use, not to mention which one the property owner would want.

Thank you for the history of the downstream maintenance of the stream. I had not heard that the county cleared debris from the old culverts to the beach. I presume it was just debris and not sediment. Our concern is with the steadily increasing sediment deposits migrating downstream such that they are physically raising the elevation of the flood plain. The sediment load is of such a magnitude that maintenance actions as some point will become futile. Our thoughts are that a raised flood plain makes this a much more complex and difficult situation to try and resolve. We will be scheduling a brainstorming session, possibly in March when Derek Booth and Erin Nelson are available, as part of the Port of Illahee's DOE grant to come up with watershed solutions to the problems, that will likely include flood plain issues.

As for disaster funding, we were thinking the filling of the culvert indicated a failure. We now understand that to be labeled a failure in FEMA's eyes it needs to be a total failure, not an eminent one.


After the December storm we sent out a community update with photos showing the 19 inch vertical opening at the culvert. We are also monitoring the culvert on a regular basis and hope we don't have any more major storms this season. We will keep the community appraised of the results of our monitoring efforts along with any changes observed at the culvert.

Jim Aho