In March 2024, A3 Environmental Consultants conducted a wetland delineation on a 29.5-acre site along Smith Road in Manhattan, Will County, Illinois. This project was commissioned by Atwell, LLC and Smith Land Holdings LLC, with the goal of identifying wetland boundaries and determining their regulatory status under U.S. Army Corps of Engineers (USACE) guidelines. The site featured Wilson Creek, a riverine habitat that flows south to Manhattan Creek, and an adjacent palustrine emergent wetland area.
Wetland Delineation
During the delineation, Wetland A was identified as the primary wetland on the property, covering 2.9 acres. This wetland is closely associated with Wilson Creek and its tributary drainage, which contributes to its hydrology. The dominant vegetation in this wetland included reed canary grass and smooth brome, typical of wetlands in the region. Soil samples confirmed the presence of Ashkum silty clay loam, a hydric soil, which further supported the wetland classification.
One notable feature observed during the fieldwork was a large beaver dam located just outside the western boundary of the study area, which affected the hydrology by causing water to back up into the wetland. A small portion of the wetland, around 0.2 acres, had been used for crop production in 2023, but the remainder of the wetland area had remained undisturbed.
Based on the findings, it was determined that Wetland A is likely under the jurisdiction of the USACE, given its connection to navigable waters via Manhattan and Jackson Creeks, which eventually lead to the Des Plaines River. A3 Environmental’s detailed analysis and precise mapping of the wetland boundaries will help ensure regulatory compliance for any future development on the site.
This project demonstrates A3’s ability to efficiently conduct wetland delineations in accordance with federal and state regulations while considering local ecological factors that might influence hydrology and habitat conditions.
