Wetland Classification/ident/delineation-2007

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� 1 . . Discussion , Type 1/1L The description provided for Type 1 wetlands and the reference to the absence of wetland vegetation in basins that are only flooded very temporar�y raises a regvlatory question. One of ' the criteria for a jurisdictional wetland is the presence of hydrophytic vegetation (1987 Manual pp 16 - 26). Type 1 wetlands often are found in agricultural fields and often are determined to be jurisdictional on the basis of an aeria135mm slide review; the quality of the slides is poor under ' the very best of circumstances. . The determination of regulatory jurisdiction is based on normal circumstances or as defined by the COE, being agriculturally cropped 51 out of 100 years (i.e. by inference l�cking sufficiem hydrology for either 5 or 12.5 percent of the growing season). , The Wetland Conservation Act (WCA) determines noimalcy as agricultural cropping for 6 out of 10 years (MnRules 8420.0110, Subp 53; 8420.0122 Subp.l, A and B). Typically, notmalcy on , agricultural lands is detertnined by the review of the aforementioned low quality 35mm aerial slides and judgments are made as to whether an area is cropped or if the crops are subject to hydrological stresses. The process is highly subjective and can be biased by excessive ' precipitation that may occur early in the crop growth cycle. Field examination of these areas may indicate the presence of smartweed and some of the other , indicated species in seasonally abnorn�ally wet years whereas in norn�al years, hydrophytic vegetation is absent. It is highly probable that the proce.ss of detern�unation of Type 1 wetlands as jurisdictional in many cases is extending beyond the legitnnate definition of Type 1 wetlands and ' the intent of the 1987 Manua1. Does a Type 1 basin need to be flooded for 5 percent of the growing season (the lower 1 definitional bound for jurisdictional hydrology) or 12.5 percent (the upper definitional bound for jurisdictional hydrology) in order for hydrophytic vegetation to develop? In practice, the St. Paul District of the Corps of Engineers (COE) (also applied in practice under the Wetland I Conservation Act) appfies the 5 percent hydrological definition but if that is too short to allow the development of hydrophytic vegetation under normal conditions than the absence of hydrophytic vegetation would make those Type 1 wetlaads non jurisdictional. ' T 1L — bottomland hardwoods — ses an difficult re lato uestion. Tools for the YPe Po �1�Y 8`� rY 9 evaluation of hydrology for non-cropped areas are much mare data intensive and are also subject , to precipitation event variab�ity. Measurement tools for the determination of precipitation norn�alcy are a combination of evaluating annual precipitation and comparison to a 30-year rolling average along with extensive near ground surface early season hydrological monitoring. ' If the water levels are within 12" of the surface for less than 8.5 da.ys in the general latitude of the Twin Cities (5 percent of the growing season), than the area is not wetland if waxer levels are ' within 12" of the surface between 5 percent and 12.5 percent of the growing season (21 days in the general latitude of the Twin Cities) according to the 1987 Manual (Table 5 pg. 36), the area may be wetland but usually �s not. However, the standard practice of the St. Paul COE �s to , declare any areas that exceed the 5 percent criteria to be judged jurisdictional wetlands. Areas with water levels within 12" of the surface in excess of 12.5 percem of the growing season are wetlands. , Svoboda Ecolo 'cal Resources 218o Abin on Wa Si Sd Y Project No.2007-056-03 Orono,Minnesota '