Gov. Pritzker signs HB5070 into Law, Limiting the Pollution Control Board’s Future Regulations

By Drew Nishioka and Craig Thedwall

On June 26, 2026, Illinois Governor J.B. Pritzker signed House Bill 5070 into law. The legislation, now Public Act 104-0510, took effect immediately. It is a significant amendment to the Illinois Environmental Protection Act (the “Act”) that changes how environmental regulations may be revised in Illinois. The legislation is intended to prevent the Illinois Pollution Control Board (the “Board”) from weakening existing Illinois environmental standards, even when federal regulations become less stringent. HB 5070 effectively establishes a “regulatory floor” that preserves existing state environmental protections regardless of federal legislative or administrative changes.

Federal environmental statutes such as the Clean Water Act, the Safe Drinking Water Act, and the Resource Conservation and Recovery Act allow states to administer federally authorized environmental programs if their state programs satisfy applicable federal requirements. Historically, Illinois has typically maintained environmental regulations that are identical or substantially similar to federal EPA regulations. When the U.S. Environmental Protection Agency amended federal regulations, the Illinois Pollution Control Board frequently updated Illinois regulations to maintain consistency. Illinois law permitted the Board to do this by using an expedited process known as “identical in substance” rulemaking to incorporate specified federal regulatory changes into Illinois law.

The practical effect of HB 5070 is that once the Board has adopted a particular level of environmental protection, it generally cannot later lower that level through adopting more lenient federal rules through “Identical in substance” rulemaking. HB 5070 prevents the Board from using that expedited process to adopt a federal standard that is less stringent than an existing Board regulation. Under the new law, a federal revision is considered less stringent only when, on a provision-by-provision basis, it directly and substantively reduces environmental or public-health protections by:

• eliminating or increasing a numerical emission, discharge, or concentration limit;
• eliminating or narrowing a specific prohibition or restriction; or
• eliminating or weakening an identified performance, design, or technology-based requirement.

The law does not completely prohibit the Board from adopting a less stringent standard. Instead, the Board must use the ordinary rulemaking procedures established by the Illinois Environmental Protection Act and the Illinois Administrative Procedure Act rather than the expedited identical-in-substance process.

The new restrictions apply to specified federally authorized and delegated programs and standards involving ambient air quality, underground injection control, certain Clean Water Act and NPDES requirements, public drinking water, hazardous waste, underground storage tanks, and municipal solid-waste landfills. An unanswered question is what happens when Illinois is required by federal law to revise regulations as a condition of maintaining its federally-delegated environmental programs.

In practical terms, weaker federal standards cannot automatically be incorporated into Illinois regulations through expedited rulemaking. Existing Illinois standards will remain in place unless the Board undertakes the more extensive, regular rulemaking process required by the new law. The legislation reflects a policy decision that Illinois should maintain environmental protections already adopted, even if federal policy changes over time with changes in federal administrations. Illinois environmental regulations may increasingly exceed federal minimum requirements. If U.S. EPA relaxes federal standards, Illinois regulations may remain unchanged, creating situations where regulated Illinois facilities must comply with stricter Illinois requirements than those applicable in neighboring states that adopt the more lenient federal regulations. This may require Illinois-specific compliance programs, permitting strategies, and operational procedures. Illinois facilities should closely monitor future Board rulemakings to determine how the Board interprets this new statute, particularly when considering amendments to regulations that incorporate federal standards by reference.