Drainage/Surface Water Standards and Forms
Are you developing in Sammamish? Drainage review may be required if applying for land use permits, building permits, or clearing and grading permits. Below are resources, checklists, and forms related to development.
Surface Water Design Manual and References
- Sammamish Addendum to the 2021 KCSWDM - revised 2024-10-01
- 2021 King County Surface Water Design Manual
- Low Impact Development Facility Information (Stormwater BMPs on individual lots)
- Stormwater Facility Information (detention facilities such as ponds, tanks, and vaults)
Note: Projects vested after October 1, 2024 shall be required to comply with the October 1, 2024 Sammamish Addendum to the 2021 KCSWDM. For more information see: https://www.sammamish.us/government/public-works/stormwater/npdes-stormwater-permit/
Find maps and GIS Data for flow control, water quality, landslide hazard drainage areas, and erosion hazard areas.
Important notice about projects permitted under earlier versions of the SWDM
Per requirements in Sammamish's Phase II Municipal Stormwater Permit (effective date August 1, 2019), projects permitted under the 2016 SWDM that applied prior to July 1, 2022 and have not started construction by July 1, 2027, and projects permitted under earlier versions of the SWDM that applied prior to January 1, 2017 and have not started construction by January 1, 2022, must be revised to comply with the current stormwater requirements as directed by state regulations. Revisions will need to be approved by the Department of Community Development.
* “Started construction” means, the site work associated with, and directly related to the approved project is at a stage where rough grading is complete or utilities are installed. For rough grading to be considered complete, elevations are within 1 foot of final design elevations.
Drainage Complaints
The drainage complaints map and list are updated and maintained by the Stormwater Team. Use this information to provide documented drainage complaints for a permit application.
If you need to Report A Spill, please use My Sammamish or call the Spill Hotline:
- Weekdays 8:30am to 5:00pm: (425) 295-0500
- Evenings and Weekends: (425) 295-0700
Surface Water Checklists, Guides, and Forms
- Simplified Drainage Review
- Simplified Drainage Review Step-by-Step Guide
- Simplified Drainage Review Building Permit Checklist
- Simplified Drainage Plan Template (PDF), Simplified Drainage Plan Template (CAD)
- Construction Stormwater Pollution Prevention Plan Template (PDF), Construction Stormwater Pollution Prevention Plan Template (CAD)
- KCSWDM Forms and Worksheets
- 8-A through 8-E: Use the King County Forms
- 8-F: Adjustment Application Form
- 8-G: Dedication and Indemnification Clause
- 8-H: Bond Quantities Worksheet, see Financial Guarantees
- 8-I: Maintenance and Defect Agreement, see Financial Guarantees
- 8-J: Declaration of Covenant
- 8-K: Drainage Release Covenant
- 8-L: Drainage Easement
- 8-M: Flow Control BMPS Covenant
- 8-N: Impervious Surface Limit Covenant
- 8-O: Clearing Limit Covenant
- 8-P: River Protection Easement
- 8-Q: Leachable Metals Covenant
Sammamish Standard Details and Templates
- Notice of Construction Activity Sign Details
- Stormwater Facility Information Form
- Single Family Residence Low Impact Development Stormwater Facility Information Form
- Stormwater Pond Sign Detail
Code References
- Title 13 - Surface Water Management
- Chapter 21.03.020 - Environmentally Critical Areas
- Chapter 21.03.030 - Low Impact Development
- Chapter 21.07.110 – Town Center Stormwater Standards