A.
Stream and Lake Classifications. Streams and lakes shall be designated Type S, Type F, Type Np, and Type Ns according to the following criteria identified in WAC 222-16-030:
1.
“Type S waters” means those segments of natural waters identified as “shorelines of the State” under Chapter 90.58 RCW, including the Sammamish River and the main stem of Swamp Creek, as well as Lake Washington.
2.
“Type F waters” means segments of natural waters other than Type S waters, which are within the bankfull widths of defined channels and periodically inundated areas of their associated wetlands, or within lakes, ponds, or impoundments having a surface area of one-half acre or greater at seasonal low water and which in any case contain fish habitat.
3.
“Type Np waters” means all segments of natural waters within the bankfull width of defined channels that are perennial nonfish habitat streams. Perennial streams are flowing waters that do not go dry any time of a year of normal rainfall and include the intermittent dry portions of the perennial channel below the uppermost point of perennial flow.
4.
“Type Ns waters” means all segments of natural waters within the bankfull width of the defined channels that are not Type S, F, or Np waters. These are seasonal, nonfish habitat streams in which surface flow is not present for at least some portion of a year of normal rainfall and which are not located downstream from any stream reach that is a Type Np water. Ns waters must be physically connected by an aboveground channel system to Type S, F, or Np waters.
B.
Presumption of Fish Use. Waters having any of the following characteristics are presumed to contain suitable fish habitat, and therefore are a Type F water:
1.
Stream segments having a defined channel width of two feet or greater within the bankfull width and having a channel gradient of 16 percent or less;
2.
Stream segments having a defined channel width of two feet or greater within the bankfull width and having a channel gradient greater than 16 percent and less than or equal to 20 percent, and having greater than 50 acres in contributing basin size based on hydrographic boundaries;
3.
Ponds or impoundments having a surface area of less than one acre at seasonal low water and having an outlet to a fish stream; or
4.
Ponds or impoundments having a surface area greater than one-half acre at seasonal low water.
C.
Ditches. Ditches are artificial drainage features created in uplands through purposeful human action, such as irrigation and drainage ditches, grass-lined swales, and canals. Purposeful creation must be demonstrated through documentation, photographs, statements and/or other evidence. Ditches are excluded from regulation as streams, unless they are used by native species of fish. Drainage setbacks are required as per the City's surface water runoff policy (Chapter 13.35 KMC).
D.
Lakes and ponds, which terms can be used interchangeably and are loosely differentiated in common use by the larger size of lakes, are surface water bodies distinguished from wetlands by the presence of deep water, typically two meters (6.6 feet) or greater.
E.
Lakes, ponds and impoundments deliberately designed and created from dry sites, such as canals, detention facilities, wastewater treatment facilities, farm ponds, temporary construction ponds (of less than three years duration), and landscape amenities, are not regulated by this chapter unless they are used by native fish. Purposeful creation must be demonstrated through documentation, photographs, statements and/or other evidence. However, lakes, ponds and impoundments intentionally created from dry areas as mitigation for a critical areas impact are regulated by this chapter.
F.
Stream and Lake Buffers.
1.
The establishment of buffer areas shall be required for all development proposals and activities in or adjacent to streams and lakes. The purpose of the buffer shall be to protect the integrity, function, and value of the stream or lake and provide habitat for great blue heron and other wildlife. Buffers shall be protected during construction by placement of a temporary barricade, on-site notice for construction crews of the presence of the stream or lake, and implementation of appropriate erosion and sedimentation controls.
The following buffers are established for streams and lakes to protect functions and values:
Stream Type | Buffer Width (Feet) |
|---|---|
Type S – Swamp Creek, Lake Washington and Sammamish River | See KMC § 16.65.020 |
Type F – Little Swamp Creek | 150 |
Type F (other water bodies used by or containing habitat suitable for salmonid fish) | 100 |
Type F (water bodies used by or containing habitat suitable for fish other than salmonids) | 50 |
Type Np or Ns | 25 |
Any type stream restored from a pipe | 25 |
2.
Measurement of Buffers. Buffers shall be measured perpendicularly from the ordinary high water mark.
3.
Increased Buffer Widths. The city manager shall require increased buffer widths in accordance with the recommendations of a qualified professional and the best available science on a case-by-case basis when a larger buffer is necessary to protect stream or lake functions and values based on site-specific characteristics. This determination shall be based on one or more of the following criteria:
a.
A larger buffer is needed to protect other critical areas or their functions;
b.
The buffer has a slope greater than 30 percent or is susceptible to erosion and standard erosion-control measures will not prevent adverse impacts to the stream or lake. The buffer should be measured from the toe of the slope. In such cases, the buffer shall be increased to include the slope or the standard buffer shall be drawn from the top of the slope, whichever provides greater protection.
(Ord. 11-0329 § 3 (Exh. 1); Ord. 19-0488 § 2 (Exh. 1))