How Do I Know When I Need Wetland Delineation?

Both the U.S. Army Corps of Engineers USACOE and the Regional Water Quality Control Board (RWQCB) regulate jurisdictional Wetlands. Most wetlands contain some type of plant or animal species that is protected and therefore the property is also under the scrutiny of the California Department of Fish and Wildlife (CDFW). When developing land for something as small or large, a property owner may be at risk of fines or penalties including imprisonment for impacts to jurisdictional wetlands.

Wetlands can also be deceiving as not all jurisdictional wetlands are wet. Some jurisdictional wetlands may only hold water for 6 weeks of the year, believe it or not, that’s long enough.

Wetland Delineation

Wetland delineation comprises of site survey, which takes typically more than one visit by a qualified biologist. Plants, soils and topography are surveyed, researched and recorded to determine if areas within the property contain areas where wetlands occur. If property contains wetlands as identified by the delineation, the United States Army Corps of Engineers will determine jurisdiction. Any disturbance to the wetlands must either be avoided or mitigated.

Avoiding wetlands does not end with “going around” the perimeter of a wetland, but it is best avoided by providing a buffer around the wetland to protect the area from disturbance. Buffer distances are proposed for the onsite conditions and are project specific, but as a general rule, CDFW recommends 250 feet. This distance will vary and must be adequate to protect the wetland resource.

Delineations are best done in the spring when water is still present and plants are easier to identify. Delineations done in summer or fall will not be adequate as vegetation is dry and blooms are not present. Relying on Topography and soils data alone will not provide enough information to determine if the location has standing water for the minimum 6 weeks required. Other factors such as drought also skew results, so using a professional to determine your requirements for development is essential.