“Representing a large company with a significant manufacturing base in Illinois, I greatly value the numerous benefits of having an IERG membership. Given the regulatory complexity in the state, IERG staff and members collaborate to derive technical understanding and provide technically defensible input into the state regulatory process. In my opinion, no other organization does this better than IERG. IERG staff are conveniently located in both the Chicago and Springfield areas, are knowledgeable on member issues, environmental matters and regulations, and completely bring members into any important development as-needed. Caterpillar has been an IERG member since the organization’s inception in 1985, and our continuous membership for nearly 40 years is a testament to IERG’s reputation for being the premiere environmental industry organization in the state.”
Brad M. Stevenson, MBA CHMM Corporate EHS Technical Manager
Kelly Thompson Kelly Thompson is the Executive Director at the Illinois Environmental Regulatory Group. She served as IERG's Project Manager for five years. Prior to joining IERG, she served as Executive Director at the Association of Illinois Soil and Water Conservation Districts from 2012 to 2017. Prior to that she worked as a GIS Analyst with Tetra Tech. Kelly also interned at IEPA – Bureau of Water during Graduate school. Kelly earned a Bachelor’s in Geography from Eastern Illinois University and received a master’s in environmental studies from University of Illinois – Springfield. Kelly has xperience in Association management, environmental policy, research and data collection, fundraising, event planning, leadership and public relations.
Trejahn Hunter Trejahn Hunter is Legal Counsel at the Illinois Environmental Regulatory Group. Trejahn is a New York native residing in Chicago who enjoys fishing, hiking, and exploring the outdoors. Trejahn also likes to watch sports and trade in the stock market. He received his law degree from the University at Buffalo. In his practice as an attorney, Trejahn incorporates values learned from the natural world including resourcefulness, resilience, and adaptation. He is grateful to be in the environmental field and a member of the IERG team!
Marissa Wesley Marissa Wesley is a Policy and Research Analyst at the Illinois Environmental Regulatory Group. Marissa’s tasks focus on monitoring and tracking Federal and Illinois environmental rulemakings and policies. Marissa joined IERG as a Graduate Intern at the beginning of 2024 while completing her master’s degree in environmental studies at the University of Illinois- Springfield and has a bachelor’s degree in biology from the University of Illinois- Chicago. She continues her education by pursuing Geographic Information Systems (GIS) Certification and is working on incorporating visual mapping for internal analysis. Previously, Marissa had several years of experience in the childcare industry, strengthening her patience, dependability, and flexibility. Marissa hails from Chicago and enjoys family time with her husband and two kids.
Marisa Thompson Marisa Thompson is Project Manager at the Illinois Environmental Regulatory Group. Marisa received her Bachelor of Science in Public Health from Belmont University in 2021. Before joining IERG, Marisa was a Tribal Consultant managing about 125 projects at a time with a 2–3-month lifecycle at EBI Consulting. Prior to that, she was an environmental scientist writing Phase I Environmental Site Assessments at EBI as well as Terracon. Marisa believes in IERG’s mission to create a more collaborative environmental regulatory landscape and is proud to be a part of the organization!
Tara Bosaw Tara Bosaw is the Office Manager at the Illinois Environmental Regulatory Group. Tara is dedicated to ensuring smooth-running and efficient office space. Prior to joining IERG, she served as the Aquatic Program Director for the YMCA of Springfield from 2014 to 2021 where she focused on customer relations and customer service training. Tara supports the office and staff and assists with event planning and execution. Tara enjoys interacting with members and the public and contributing to the growth of IERG.
Toby Frevert Mr. Frevert has provided environmental consulting services to the Illinois Environmental Regulatory Group and its members since January 2008. His professional experience encompasses over 45 years of environmental work in various programmatic areas including both air and water media. Prior to his work with IERG, Mr. Frevert was employed by the Illinois Environmental Protection Agency in various capacities, ultimately serving as Manager of the Division of Water Pollution Control. In this capacity, he was responsible for planning, monitoring, permitting, and other regulatory aspects of Illinois’ statewide water quality programs mandated pursuant to State and Federal laws. His responsibilities included direction and oversight of staff performing functions encompassing development and support of water quality standards and source control regulations, permitting and compliance oversight of regulated entities, monitoring and assessment of water quality conditions of Illinois’ streams, lakes and rivers. Mr. Frevert has participated in numerous State, interstate, and Federal initiatives providing expertise on policy, strategy, and technical aspects of water and air quality initiatives. Subsequent to his tenure at IEPA, Mr. Frevert has been providing environmental consulting services to business and local government entities on a variety of environmental issues. He also serves as a Commissioner of the Ohio River Valley Sanitation Commission, an interstate water quality Agency established through State and Federal legislation in 1948 to coordinate water quality protection for the Ohio River. He was appointed as an Illinois Commissioner in December 2009, served as Commission Chairman in 2013-14, and continues to serve and currently serves on numerous Commission committees and initiatives.
Mr. Sutton's career spans over 43 years addressing complex environmental issues, with 29 of those years spent with the IEPA as well as in environmental consulting. As a consultant, Don manages complex air pollution control/management projects for several national and international manufacturers. His expertise includes permitting, compliance assurance review, program development, BACT review, PSD review, MACT compliance, system evaluation, negotiation, and interaction with USEPA and state regulatory agencies. Mr. Sutton has provided comprehensive air quality services for numerous sectors, including but not limited to heavy equipment manufacturing, pipelines, oil and gas exploration, surface coating operations, grain industry, ethanol plants, steel mills, and the asphalt industry. Don is a licensed professional engineer and holds a Bachelor of Science in Thermal and Environmental Engineering and a Master of Science in Environmental Engineering.
