The stability of a streambank is influenced by soil, groundwater and vegetation. Healthy, intact vegetation near streams helps reduce landslides and erosion which can negatively impact stream health. A well-vegetated riparian ecosystem can trap and store sediment and organic matter. 

Vegetation near streams provides shade which impacts stream temperature. The temperature of a stream affects the survival and productivity of aquatic species. Cool water is ideal for fish survival, growth and productivity. Reducing shade near a stream increases stream temperature.

Wood plays an important role in stream morphology (width, depth and size). Woody debris create dam pools, plunge pools, riffles, glides, undercut banks, and side channels. Different species need these different mini habitats in a stream. The wood debris changes stream velocity, traps sediment, alters stream course, and stabilizes banks. This creates complex and diverse stream environments which improve aquatic species health.

Organic matter from riparian ecosystems makes its way to streams via litter fall (leaves, moss, twigs etc.). Essential nutrients enter streams this way. These nutrients are consumed by species further down the food chain like microbes and invertebrates that are eaten by fish.

Riparian areas remove pollutants from runoff. A well-vegetated riparian ecosystem can remove excess nutrients, metals and pesticides before water enters the stream.

WDFW recommends riparian management zones in Shoreline extend 200 feet from either side of a stream. This is a large increase in regulated areas around streams which previously varied between 45-150 feet. This means that some properties that are not currently subject to the critical areas code would now be subject to the critical areas code.

Take a look at the draft map of critical areas in Shoreline which shows what a 200-foot riparian management zone looks like in the City.

Riparian management zones include limits on new development and provide protection for native vegetation and trees. If you live within 200 feet of a stream, you may be impacted by these new regulations. Importantly, you will be able to maintain your property and, in some instances, even be able to make additions to your property. If you are proposing something that will impact the stream, riparian management zone, or any other critical area you may be required to get a report from a qualified professional and mitigate any impacts. Here is a summary of what is and isn’t allowed in critical areas:

Allowed in a critical area	Not allowed in a critical area
Mow established lawn	Expand lawn area
Interior home remodel	Expanding house/deck/pool into critical area
Limited clearing of invasive species like blackberries	Planting invasive species
Take down a hazardous tree (with arborist assessment & city notification)	Take down a non-hazardous tree

The City has been drafting critical areas regulations that are consistent with the Department of Fish and Wildlife’s recommendations while also balancing the private property rights of the residents of Shoreline.

The SEPA threshold determination was issued October 2, 2025 and is open for public comment until October 16, 2025. You can submit written comments to Elise Keim, Planning manager at ekeim@shorelinewa.gov.

Planning Commission has met several times to discuss the draft code.

At the July 3, 2025 Planning Commission meeting, Commissioners were introduced to WDFW’s published guidance about riparian management zones. Based on WDFW’s guidance, Shoreline should designate the areas within 200 feet of a stream as a riparian management zone.

At the July 17, 2025 Planning Commission meeting, staff shared relevant excerpts of the Comprehensive Plan, provided an overview on what it means for a property to be impacted by critical areas, and shared how a larger riparian management zone might impact city surface water and property acquisition plans.

At the September 18, 2025 Planning Commission meeting, Commissioners were introduced to draft critical areas regulations for riparian management zones. At this meeting the draft code included the following:

• A standard 200-foot riparian management zone that can be reduced if it meets certain criteria.
• Clear standards about when a riparian management zone ends due to a road or building.
• An allowance of a small, one-time expansion of structures in a riparian management zone if it meets certain criteria.
• An updated list of allowed activities in critical areas
• Updated critical area report requirements

At the October 2, 2025 Planning Commission meeting, Commissioners were introduced to an entirely reorganized critical area code meant to be easier for property owners and city staff to use.

A public hearing in front of Planning Commission is scheduled for November 6, 2025 at 7:00pm. You can submit a public comment to Planning Commission via email at plancom@shorelinewa.gov or by attending the meeting in person at City Hall or online via Zoom.

City Council is tentatively scheduled for the following dates:

• November 24, 2025 – discussion of draft critical areas ordinance
• December 15, 2025 – action on draft critical areas ordinance

City of Shoreline - Online Interactive Mapping Site - use the layers tool in the upper right corner to turn the critical areas layers (including percent slope). More detail is visible the closer you are zoomed into an area of Shoreline.

WA Department of Ecology - Wetlands

WA Department of Fish and Wildlife – Riparian Ecosystems, Volume 1: Science Synthesis and Management Implications (2020)

WA Department of Fish and Wildlife – Riparian Ecosystems, Volume 2: Management Recommendations