Rapid Wetland Assessment Method for Alaska DOT

The Alaska DOT wants a Rapid Wetlands Functional Assessment method that can be used on linear projects in the state. Currently, Alaska does not have a standardized rapid wetlands functional assessment method. In fact, much of Alaska has not been mapped for inclusion in the National Wetlands Inventory (NWI). Along with my colleagues, I have written a draft rapid wetlands assessment method. We looked at the methods used by the State of Montana and Washington as a place to start, since they deal with many of the same issues we do in Alaska. The point of using these assessments is to guide compensatory mitigation when a project will disturb existing wetlands. Alaska has such an abundance of wetlands that, until now, the need to mitigate was not pressing. As development expands, wetlands in the populated areas are disappearing. The rapid functional assessment will give the AK DOT a tool to preserve and protect wetlands for the future.

The method we developed incorporates Cowardin coding along with HGM class. Each of the assessment parameters is scored by a matrix that is supported and guided by documentation (plant lists, endangered and threatened species lists, irreplaceable wetland types, etc.). We also included a section on how to determine the assessment area, as well as sections on sediment/nutrient/toxicant retention and removal and sediment/shoreline stabilization.

Developing a method that can be used for the entire state of Alaska is challenging, as there are several widely varying ecotypes or ecoregions in the state. Southeast Alaska is characterized by coastal mountains that host Hemlock-Sitka Spruce forests. The soils of the region are prone to erosion when deforested and have garnered special attention due to the difficulty of applying the AK color change (AK Regional Supplement to the Corps of Engineers Wetland Delineation Manual, 2007) criteria to wetlands delineation. The boreal forest reaches from South Central AK through the Interior, on up to the Brooks Range. Much of the region has discontinuous permafrost, intermixed with glacial features, deep peat bogs, and high mountain ranges. The Coastal Plain is a vast, treeless area underlain by deep permafrost which perches surface water, causing the region to be very wet. Add to this diversity the enormous scale and variance of the Alaska coastline and it is easy to understand why it is difficult to create a single rapid assessment method for the whole state.

The Alaska Rapid Wetlands Assessment Method is still is draft form, but we hope to be able to implement it by the end of the year. We expect that in the earliest applications, any problems in the method will come to light and we will be able to revise and improve the method.