King County GIS Center
King Street Center
201 S. Jackson St.
Suite 706
Seattle, WA 98104
giscenter@kingcounty.gov

+ 47.59909 N
- 122.33136 W

+ 47°  35' 56.72"
- 122° 19' 52.90"

 

Channel Migration Areas in King County

Description | Contacts | Attribute Information | Constraints

Data layer thumbnail image

Description

Layer name: CHNLMIGR
Subject category: hydro
Title: Channel Migration Areas in King County
Feature Count: 236
Feature Type: Polygon
Abstract: Channel migration hazards for seven King County rivers: Middle White River, Raging River, Tolt River, Three Forks area of Snoqualmie River, Cedar River, Green River, and the South Fork of the Skykomish River. The Cedar River was updated April 2015, the SF Skykomish June 2017, and the Tolt July 2018. In December 2019, the Middle White River was added, the Raging River was updated, and a revision was made to the updated Cedar CMZ.
Purpose: This dataset can be use to estimate the channel migration for seven rivers: White River, Raging River, Tolt River, Three Forks area of Snoqualmie River, Cedar River, Green River, and the South Fork of the Skykomish River.
Status: Complete
Updated: As needed
Time period of content: (single date,as YYYYMMDD)::
Time period of content: (date range, as YYYYMMDD):: -
Spatial reference: WA State Plane North
FGDC Documentation: Classic or FAQ
Open Data Availability: Yes
Place Keywords: King County, WA, Pacific NW, Washington state,
Theme Keywords: rivers, hydro, channel, migration, inlandWaters,
Lineage: Available
Supplemental Information: There are several rapidly migrating river systems in King County. Studies (cited below) have been prepared by or for the King County Department of Natural Resources to map and describe areas of channel migration hazard on sections of seven King County rivers: middle White River, Raging River, Tolt River, Three Forks area of Snoqualmie River, Cedar River, Green River, and the South Fork of the Skykomish River. In each study, the maximum probable future limits of channel migration were defined using historic meander belt widths and other geomorphic features. Land within these limits is classified according to the relative degree of hazard from channel migration, based upon historic rates of channel migration and the presence of major bank protection structures that protect arterial roads and subdivisions.

Contacts

Maintained by:
King County IT, GIS Center
Primary: Todd Klinka, GIS Analyst, 206-477-4412
(How to e-mail a County contact)
Secondary: KCGIS Center; giscenter@kingcounty.gov. This mailbox is monitored during business hours.

Attribute Information

ItemDescriptionDomain
_HAZARD_Level of channel migration hazard.
MODERATEThe moderate hazard area is located between the outer boundary of severe hazard and the maximum probable limits of future migration.
POTENTIALThe area is not yet a channel migration zone, but could become one.
SEVEREThe severe hazard area includes the width of the river channel itself plus a width equal to one hundred (100) years times the average annual channel migration rate. It is assumed that channel will migrate for fifty (50) years on both sides of the present channel location during this hundred year period.


Constraints

Access: None

Use: King County data are made available with the understanding that they shall be used exclusively by the obtainer or his/her authorized agents. Digital products may not be reproduced or redistributed in any form or by any means without the express written authorization of King County.