Wetland

Key Takeaways

• A wetland is ground inundated or saturated by surface water or groundwater often enough and long enough to support plants adapted to saturated soil, such as a marsh, swamp, or bog.
• Wetlands are the most common protected environmentally sensitive area, and protection usually arrives as a buffer of undisturbed ground around the wetland rather than a ban on developing the whole parcel.
• In Washington, RCW 36.70A.030 lists wetlands first among critical areas, and RCW 36.70A.060 requires every county and city to adopt development regulations that protect them.
• Discharging dredged or fill material into a wetland can require a federal section 404 permit from the Army Corps of Engineers, which is separate from any local critical areas approval.

What It Means

A wetland is ground that stays wet. More precisely, it is land inundated or saturated by surface water or groundwater at a frequency and duration sufficient to support a prevalence of vegetation adapted to life in saturated soil. Marshes, swamps, and bogs are the familiar examples, but plenty of wetlands look like ordinary damp pasture for most of the year and only reveal themselves in a wet spring.

Three things decide whether a spot is a regulated wetland: hydrology, hydric soils, and wetland plants. A qualified consultant delineates the edge in the field, then a rating system sorts the wetland by how much function and value it provides. That rating drives the buffer, the strip of undisturbed ground the owner must leave between the wetland and any building, driveway, or lawn. A wetland rarely makes a parcel worthless, but it moves the building envelope, and it can cut the lot count a proposed Subdivision can fit. For a buyer, the practical question is never only whether a wetland exists, it is how wide the required Buffer Zone is and what is left to build on.

How It Works in Washington

In Washington, wetlands are regulated on three tracks at once. First, the Growth Management Act treats them as Critical Areas. RCW 36.70A.030 defines wetlands as areas inundated or saturated by surface water or groundwater at a frequency and duration sufficient to support a prevalence of vegetation typically adapted for life in saturated soil conditions, RCW 36.70A.170 requires counties and cities to designate critical areas, and RCW 36.70A.060 requires them to adopt development regulations that protect those areas. RCW 36.70A.172 adds that local governments shall include the best available science in those policies and regulations, and WAC 365-190-090 points them to the wetland rating system developed jointly by the Department of Ecology and the United States Army Corps of Engineers.

Second, a wetland tied to a shoreline picks up the Shoreline Management Act, chapter 90.58 RCW. RCW 90.58.030 pulls wetlands associated with streams, lakes, and tidal waters into the shorelands the act governs. Third, the federal layer sits on top. WAC 173-27-050 notes that a section 404 permit under the Federal Water Pollution Control Act generally applies to any project that may involve discharge of dredge or fill material to any water or wetland area, and RCW 90.48.260 designates the Department of Ecology as the state water pollution control agency for all purposes of that federal act.

Example

Trevor is under contract on a 5-acre parcel in Thurston County at $265,000, planning a four-lot short plat. His feasibility period is 45 days, so he hires a wetland consultant for $3,200. The delineation finds a 0.6-acre wetland near the middle of the property, and the county's critical areas ordinance assigns that rating a 110-foot buffer.

Once the buffer ring is drawn, the wetland plus its buffer swallow about 2.1 acres, leaving roughly 2.9 acres of usable ground (5.0 - 2.1 = 2.9). At the county's one-acre minimum lot size, Trevor can plat two lots, not four. He runs the math again: at $265,000 across four lots he was paying $66,250 per finished lot, but across two lots the same purchase price is $132,500 per lot, which erases his margin. Trevor uses the feasibility contingency to renegotiate the price or walk away.

Common Mistakes and Exam Traps

• A wetland does not have to hold standing water year round. Ground saturated only seasonally still qualifies if it supports vegetation adapted to saturated soil.
• Finding a wetland does not make a parcel undevelopable. It normally sets a buffer and moves the building envelope, and mitigation can allow limited work inside it.
• The local critical areas ordinance and the federal section 404 permit are separate approvals. Clearing the county does not clear the Army Corps of Engineers.
• Wetlands are one of five critical area categories in Washington, alongside aquifer recharge areas, fish and wildlife habitat conservation areas, frequently flooded areas, and geologically hazardous areas.