It is not intended that this chapter repeal, abrogate or impair any existing regulations, easements, covenants or deed restrictions. However, where this chapter imposes greater restrictions, or is in conflict with any other applicable city ordinance or regulation, the provisions of this chapter shall prevail.
(Ord. 1118 § 3.1, 2001; Ord. 1464 § 1 (Exh. A (part)), 2012)
The director is authorized to adopt written procedures for the purpose of carrying out the provisions of this chapter, including procedures related to the inspection of stormwater facilities. Prior to fulfilling the requirements of this chapter, the city shall not grant any approval or permission to conduct a regulated activity including but not limited to the following:
Building permit, commercial or residential; binding site plan; conditional use permit; franchise right-of-way construction permit; grading and clearing permit; master plan development; planned unit development; right-of-way permit; shoreline substantial development permit; shoreline variance; shoreline conditional use permit; shoreline environmental redesignation; unclassified use permit; variance; zone reclassification; subdivision; short subdivision; special use permit; utility and other use permit; zone reclassification; or any subsequently adopted permit or required approval not expressly exempted by this chapter.
(Ord. 1118 § 3.2, 2001; Ord. 1464 § 1 (Exh. A (part)), 2012)
The current edition of the King County Surface Water Design Manual is hereby adopted by reference.
(Ord. 1118 § 3.3.1, 2001; Ord. 1464 § 1 (Exh. A (part)), 2012; Ord. 1577 § 2, 2016; Ord. 1809 § 5, 2024)
Stormwater and drainage features should incorporate low impact development techniques that mimic predevelopment hydrologic conditions, when technically feasible. BMPs shall be used to control runoff flows and treat stormwater for all projects. Approved BMPs are contained in the manual. The city has also adopted by reference the current edition of the King County Stormwater Pollution Control Manual (BMP manual) as now in effect or as subsequently amended. The BMP manual applies to existing facilities and activities and to new development activities not covered by the King County Surface Water Design Manual. The BMP manual describes the types of regulated activities, the types of contaminants generated by each activity, the contaminant's effect on water quality, the required source control BMPs, and the available treatment BMPs. The BMP manual includes information on design, maintenance, allowable use of alternative BMPs, and a schedule for BMP implementation.
(Ord. 1118 § 3.3.2, 2001; Ord. 1464 § 1 (Exh. A (part)), 2012; Ord. 1809 § 6, 2024)
A. 
Type C waters are those natural open ephemeral drainage courses (including where bridged, piped or culverted) that are not Type S, F, Np or Ns waters, which contain flow only during or immediately after periods of precipitation, and which flow generally less than 30 days per year.
B. 
Type C waters are regulated for the values they provide for conveyance, infiltration, water quality treatment, and flow attenuation of surface waters. It is encouraged that Type C waters be maintained in their existing natural channels to provide these functions. However, subject to conformance to all floodplain management regulations, such channel courses may be altered, piped or realigned, so long as sufficient mitigation is provided that maintains:
1. 
One-hundred-year conveyance capacity;
2. 
Infiltration capacity equivalent to that provided by the original channel either within the altered, piped, or realigned system or together with other infiltration accomplished elsewhere on the site; and
3. 
Comparable water quality treatment per the Manual either within the altered, piped or realigned system or together with other aboveground water quality measures provided for the on-site development that are accomplished elsewhere on the site.
(Ord. 1688 § 8, 2019; Ord. 1809 § 7, 2024)
Connections of conveyance systems to the storm drainage system or ground water infiltration systems which were not constructed or intended to convey precipitation runoff, or which have been converted from such usage, are prohibited, with the following exceptions:
A. 
Allowable discharges as defined in NBMC § 14.16.100;
B. 
Discharges authorized by a NPDES or state waste discharge permit;
C. 
Connections conveying effluent from an approved onsite sewage disposal system to its drainfield.
(Ord. 1118 § 3.3.3, 2001)
It is unlawful for any person to discharge contaminants into surface water and stormwater, or ground water. Contaminants include, but are not limited to, the following:
1. 
Trash or debris;
2. 
Construction materials;
3. 
Petroleum products including but not limited to oil, gasoline, grease, fuel oil, heating oil;
4. 
Antifreeze and other automotive products;
5. 
Metals in either particulate or dissolved form;
6. 
Flammable or explosive materials;
7. 
Radioactive material;
8. 
Batteries;
9. 
Acids, alkalis, or bases;
10. 
Paints, stains, resins, lacquers, or varnishes;
11. 
Degreasers and/or solvents;
12. 
Drain cleaners;
13. 
Pesticides, herbicides, or fertilizers;
14. 
Steam cleaning wastes;
15. 
Soaps, detergents, or ammonia;
16. 
Swimming pool or spa filter backwash;
17. 
Chlorine, bromine, or other disinfectants;
18. 
Heated water;
19. 
Domestic animal wastes;
20. 
Sewage;
21. 
Recreational vehicle waste;
22. 
Animal carcasses;
23. 
Food wastes;
24. 
Bark and other fibrous materials;
25. 
Collected lawn clippings, leaves, or branches;
26. 
Silt, sediment, or gravel;
27. 
Dyes (except as described in NBMC § 14.16.100, Allowable discharges);
28. 
Chemicals not normally found in uncontaminated water;
29. 
Any other process associated discharge except as otherwise allowed in this section;
30. 
Any hazardous material or waste not listed above.
(Ord. 1118 § 3.3.4, 2001)
Subject to provisions of the BMP manual, the following types of discharges shall not be considered prohibited discharges for the purpose of this chapter unless the director determines that the type of discharge, whether singly or in combination with others, is causing pollution of surface water and stormwater or ground water.
A. 
Potable water including water from water line flushing and hydrant maintenance;
B. 
Uncontaminated water from crawl space pumps or footing drains;
C. 
Lawn watering;
D. 
Dechlorinated swimming pool water;
E. 
Materials placed as part of an approved habitat restoration or bank stabilization project;
F. 
Natural uncontaminated surface water or ground water;
G. 
Flows from riparian habitats and wetlands;
H. 
Common practices for water well disinfection;
I. 
Discharges resulting from diffuse or ubiquitous sources such as atmospheric deposition;
J. 
Discharges resulting from dye testing authorized by the director;
K. 
Discharges which result from emergency response activities or other actions that must be undertaken immediately or within a time too short to allow full compliance with this chapter so as to avoid an imminent threat to public health or safety. (The director may further define qualifying activities in administrative guidance. The person responsible for said emergency response activities should take steps to ensure that the discharges resulting from such activities are minimized and ensure that future incidents are prevented to the greatest extent possible);
L. 
Other types of discharges as determined by the director.
(Ord. 1118 § 3.3.5, 2001)