1350 Orono Oaks Delineation - Laserfiche WebLink

Home Browse Search

in basins that are only flooded very temporarily raises a regulatory 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 aerial 35mm 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 lacking sufficient hydrology for either 5 or 12.5 percent of the growing season). The Wetland Conservation Act(WCA)determines normalcy as agricultural cropping for 6 out of 10 years (MnRules 8420.0110, Subp 53; 8420.0122 Subp.1, A and B). Typically, normalcy on agricultural lands is determined 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 abnormally wet years whereas in normal years, hydrophytic vegetation is absent. It is highly probable that the process of determination of Type 1 wetlands as jurisdictional in many cases is extending beyond the legitimate definition of Type 1 wetlands and the intent of the 1987 Manual. Does a Type 1 basin need to be flooded for 5 percent of the growing season (the lower 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 Conservation Act) applies 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 wetlands non jurisdictional. Type 1L — bottomland hardwoods — poses an equally difficult regulatory question. Tools for the evaluation of hydrology for non-cropped areas are much more data intensive and are also subject to precipitation event variability.Measurement tools for the determination of precipitation normalcy 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 days in the general latitude of the Twin Cities(5 percent of the growing season), than the area is not wetland. If water level's 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 is not. However, the standard practice of the St. Paul COE is 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 percent of the growing season are wetlands. No one has ever undertaken a scientific study to evaluate the relationship between the hydrological requirements and the presence of various wetland or non-wetland plant species.This is a critical,yet unanswered question. Some studies have been completed examining soil types and hydrological responsiveness but the link between plants and hydrology has yet to be made.Given the annual cost Svoboda Ecological Resources 1350 Orono Oaks Drive Project No.:2007-061-03 42 Ron Ridgeway