Laserfiche WebLink
Clarification of Cowardin Classification <br /> and Circular 39 <br /> Wetland Types 1, 1L, 2, 3 and 7 <br /> By <br /> Franklin J. Svoboda <br /> Svoboda Ecological Resources <br /> 2477 Shadywood Road, Sutie 100 <br /> Excelsior, MN 55331 <br /> (952) 471-1100 <br /> franks @ gpsinnovations.com <br /> Introduction <br /> The National Wetland Inventory (NWI) mapping process completed in Minnesota <br /> between 1979 and 1982 developed a wetlands inventory map for the state of Minnesota <br /> utilizing remotely sensed color infrared photography that was visually interpreted. The <br /> interpretation process hierarchically classified wetlands using, at the time, the recently <br /> published Cowardin classification system (Cowardin et al 1979). The wetland <br /> interpretation and classification process was ground verified using selective plots and <br /> locations but was ground truthed to only a limited extent. Consequently, the published <br /> NWI paper copies carry the disclaimer that these maps are to be used for advisory <br /> purposes only and actual classifications are to be based on ground verification. Visual <br /> interpretation from remote sensed imagery has some limitations particularly with regard <br /> to the water regime modifier. Year to year variation in precipitation cycles along with the <br /> occurrence of precipitation events at the time that the imagery was acquired, even if all <br /> acquisition occurred during the spring season, can result in variations in modifier <br /> categorization. <br /> Accurate classification becomes critical when regulatory decisions are being made with <br /> regard to the wetland type and the amount of de minimum fill that is permissible. Also, it <br /> is a matter of scientifically accurate consistency with regard to adherence to the various <br /> technical publications and regulatory guidance documents. <br /> Circular 39 was authored by Shaw and Fredine and published by the U. S. Fish and <br /> Wildlife Service (USFWS) in 1956. The intended purpose of Circular 39 was an effort at <br /> classifying and inventorying wetlands on a national scale in order to assess the wetland <br /> base and related waterfowl production potential. The classification process was never <br /> intended to serve as a classification system for wetland regulatory purposes. However, <br /> since it was the first national effort of its kind and as wetland regulatory intentions <br />