The Delineation and Monitoring of the McWilliams Farm Replacement Wetland Area in Southern York County Patrick Fetich – Department of Biology, York College Introduction. Wetland areas play many roles in the environment, from habitat to water purification. The construction of replacement wetland resources is required by the Department of Environmental Protection to compensate for any destruction of a wetland area. Size, functionality, and location are attributes that are carefully analyzed and computed to determine the necessary steps to offset the impacted area. (Department of Environmental Protection, 1997) The McWilliams Farm Mitigated Wetland Area is located in Southern York County in North Codorus Township. This site was a result of a parking area needed for a section of the York County Heritage Rail Trail. The construction impacted approximately 0.76 acres of wetland area. Using specific Department of Environmental Protection guidance, a new mitigated wetland area was designed, built, allowed to grow. After a 5 year period, the site was studied and analyzed. The analysis includes a general land survey for size and condition, an examination of the hydrology, including the depth, quality, and quantity and an inspection of the vegetative conditions, which include the location, diversity and timing of specific plants. I conducted the final inspection in accordance with the conditions of the PA DEP Water Obstruction and Encroachment Act. The inspection suited the needed assessment of this mitigated wetland area to determine the effectiveness and success of the project. Objective. Determine the functionality of the compensatory wetland area based on land survey, hydrology, soil samples, and vegetation. Literature Cited. Department of Environmental Protection “Design Criteria – Wetlands Replacement/Monitoring,” Pennsylvania Department of Environmental Protection. Environmental Laboratory “Corps of Engineers Wetlands Delineation Manual,” Technical Report Y-87-1, US Army Engineer Waterways Experimental Station, Vicksburg, Miss. Hersh, Donald Mench, U.S. Dept. of Agriculture, Soil Conservation Service. Soil survey, York County, Pennsylvania. Page 159. Tiner, Ralph W. Jr “Field Guide to Nontidal Wetland Identification,” Cooperative Publication, Newton Corner, MA. Acknowledgements. I would like to thank Dr. Bruce Smith for all the advice and guidance he provided. I would also like to thank Thomas Stich of LSC Design for access to the field sites and imperative information. Lastly, I would like to thank the entire York College Biology staff for their continued support. Results. Survey Area is equal to or greater than the 1:1 ratio Approximately 35x115 meters (4000 square meters) – 0.82 acres Disrupted acreage acres Hydrology Low water levels noted – Drought conditions Soil sample holes back filled with water by next day at site indicating hydric soils and the high water table. Normal Levels - less than 1” to 21” of standing water. Soil Brown/dark gray color, very smooth texture All classified as poorly drained, Chewacla silt loam (Ck) (Hersh 1963, York County Soils Maps) No clear soil layers – Area previously farmed. Vegetation 21 of the 23 original plants were identified in the mitigated wetland site. Introduced plants were very prolific and settled. Survey Conducted a basic land survey to determine the area’s size in meters 2 as determined by the 1987 Corps of Army Engineers Manual. Sample Point Selection One random sample point was selected on each of the 5 pre-established transects. A random number chart was used to locate each of the sample points. Assessment of Each Sample Point Hydrology, vegetation and soils were examined at each sampled point. Location. The impacted site is located at Gladfelter Station on the York County Heritage Rail Trail Area. The latitude is N39º 52’ 24”; longitude is W76º 44’ 54”. Original Impacted Wetland Mitigated Wetland Hydrology Determined by the presence of inundated soils and noting the visual signs of high water on herbaceous plants. Soil Examined the soil layers, color, texture and wetness of the soil. Determined soil type using the 1987 Corps of Army Engineers Manual and pre-existing soil maps. Vegetation Identified (using Tiner, 1988) the vegetation to determined the presence or absence of the 23 wetland plants present in the original wetland. Methods. Figure 1. Comparison inventory of wetland plants found at each of the 5 transect points in correlation to original wetland area. Conclusions. The survey, hydrology, soil, and vegetation characteristics all met or exceeded the needed standards to be classified as a palustrine emergent wetland area. The results indicate that the wetland mitigation area is developing and functioning as a natural wetland area should. The mitigation site successfully compensates for the lost original wetland area in size and functionality.