Matthew K. Tieslau

Matthew K. Tieslau advises public and private clients across the Rocky Mountain Region on complex environmental and regulatory matters. His practice spans both federal and state environmental regulatory compliance, enforcement actions and litigation, federal rulemaking advocacy, permitting, environmental audits, environmental due diligence for real estate transactions, brownfield developments, water law, and liquor licensing. His clients have included state and local governments, industrial manufacturers, oil and gas operators, mines, local property owners, and ranchers.

Matt’s approach to environmental regulatory issues is a comprehensive strategy focused on seeking to ensure that complex regulatory compliance matters do not impair his clients’ mission and day-to-day operations - staying ahead of compliance obligations to ensure that business can continue as usual. His experience also includes significant state and federal rulemaking advocacy, helping clients participate in rulemaking and policy development to pursue practical, reasonable, and achievable policy.

Matt has substantial experience navigating complex compliance issues under the Clean Water Act (CWA), Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), Endangered Species Act (ESA), Energy Policy and Conservation Act (EPCA), Federal Land Policy and Management Act (FLPMA), Mineral Leasing Act (MLA), the National Environmental Policy Act (NEPA), and the Resource Conservation and Recovery Act (RCRA). He also advises on compliance and implementation matters related to building energy-use regulations in Colorado including the City and County of Denver’s Energize Denver regulation and the statewide Regulation 28 building performance standards.

Matt advises on water law matters related to water applications covering senior and junior rights, as well as exchanges and expansions, historical use quantification, and issues of state versus federal law. He also provides counsel on remediation and other water quality issues.

Matt also works on due diligence for the purchase and sale of manufacturers and retailers with liquor licenses, including national manufacturer mergers. He advises manufacturers, distributors, and food and beverage clients on local, state, and federal liquor licensing requirements, ongoing compliance, and day-to-day operations.

Concentrations

•Environmental and regulatory compliance
•Environmental auditing
•Environmental transactional due diligence
•State and federal environmental rulemakings
•Building Energy Codes and Building Performance Standards
•National Environmental Policy Act challenges
•Federal Tort Claim Act litigation
•Climate change
•Water rights transactions and litigation
•Mining
•Right-of-access
•Election law
•Liquor Licensing

Recognition & Leadership

Awards & Accolades

•Listed, The Best Lawyers in America
•'Ones to Watch,' Litigation - Environmental, 2023-2025
•'Ones to Watch,' Natural Resources Law, 2023-2025
•'Ones to Watch,' Environmental Law, 2024-2025
•Listed, The Legal 500 United States, Dispute Resolution Product Liability, Mass Tort and Class Action - Defense - Toxic Tort, 2024
•Listed, Super Lawyers magazine, Colorado Super Lawyers, 'Rising Stars,' 2023-2024
•Team Member, a Law360 “Environmental Practice Group of the Year,” 2022