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

+ 47.59909 N
- 122.33136 W

+ 47°  35' 56.72"
- 122° 19' 52.90"


Erosion Hazards

Description | Contacts | Attribute Information | Constraints

Data layer thumbnail image


Layer name: ERODE
Subject category: enviro
Title: Erosion Hazards
Feature Count: 0
Feature Type: Polygon
Abstract: The Sensitive Ares Ordinance (SAO) defines significant erosion hazard areas as those soils in King County that may experience severe to very severe erosion hazard. The SAO adopts the soils definition in the U.S. Department of Agriculture Soil conservation Service (SCS) 1973 King County Coil Survey and the current draft of the Snoqualmie Pass Area Soil Survey (ND).
Purpose: Defines significant erosion hazards for unincorporated areas of King County per the County Sensitive Areas Ordinance
Status: Complete
Updated: None planned
Time period of content: (single date,as YYYYMMDD):: 19900101
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: Washington state, King County, WA, Pacific NW,
Theme Keywords: natural resoures, environmental, enviro, environment,
Lineage: Available
Supplemental Information: Erosion is a natural process of wearing away of land surfaces by falling and running water, wind and glacier scour. Of these geologic forces, erosion by running water is by far the most important within the Puget Sound Basin. The susceptibility of any soil type to erosion depends upon the physical and chemical characteristics of the soil, in addition to its protective vegetative cover, topographic position (slope length and gradient), the intensity of rainfall, and the velocity of runoff water. Whereas erosion is the wearing away of material, sedimentation or deposition is the accumulation of eroded matter where water carrying sediment is slowed. The effects of sedimentation are most pronounced where streams enter Puget Sound and in lowland lakes, ponds, wetland, and stream channels. The natural geologic processes of erosion and sedimentation are frequently accelerated by land use modifications and urban development. The erosion hazard maps show areas of King County where soils are particularly susceptible to increased erosion as a result of development. The regulations in the Sensitive Areas Ordinance for erosion hazards pertain to timing and methods of clearing for development. In general, clearing is restricted to the period between April 1 and November 1. There are two exceptions: 1) clearing of up to 15,000 square feet on individual lots, and 2) timber harvest pursuant to an approved forest practice permit. Clearing for roads and utilities shall occur first with subsequent clearing on individual lots permitted after approval of the associated building permit. A vegetation management plan is required for clearing on individual lots. An erosion control plan is required for all development proposals within erosion hazard areas. Please refer to the Sensitive Areas Ordinance and administrative rules for more details on the regulations.


Maintained by:
Permitting GIS Program Manager
Primary: King County GIS Center, GIS Data Team Lead, 206-263-4867
(How to e-mail a County contact)
Secondary: KCGIS Center; This mailbox is monitored during business hours.

Attribute Information

_HAZARD_hazard type
_EDIT_DATE_editi date


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.