INDIANA – Underscoring Indiana’s commitment to clean water, the Indiana Department of Environmental Management (IDEM) submitted new data to the U.S. EPA this week, showing measurable improvements to the state’s rivers and streams.
As part of the report, IDEM reported 43,657 total miles of rivers and streams assessed through 2026, which, when adjusted for size, is more than any other state in the country. In addition, Indiana reported 24.49 more miles of unimpaired rivers and streams compared to 2024.
“It is important to me that we steward Indiana’s natural resources responsibly,” said Gov. Mike Braun. “We have positioned Indiana as a national leader in developing a clear picture of water quality. By investing in transparent reporting and sound science, we will continue to focus resources where they’re needed most and make meaningful progress in restoring our waterways.”
Under the federal Clean Water Act, states are required to assess and report on the condition of their waters every two years. As part of this process, the ‘303(d) List’ identifies waterbodies that are not meeting one or more designated uses defined in Indiana’s water quality standards. A waterbody is considered impaired if its water quality is not sufficient to support its intended uses. Data is measured by miles listed as impaired or unimpaired.
“Indiana has shown a deliberate track record of assessing, protecting, and working to restore our waterways,” said IDEM Commissioner Clint Woods. “With more than 62,000 miles of rivers and streams, our Office of Water Quality works every day to identify impairments and develop a restoration plan. These improvements support safer recreation, healthier streams, and stronger local ecosystems across Indiana communities.”
Historically, Indiana assesses a significantly greater variety and higher ratio of waterbodies for impairments compared to other states. Despite being a smaller state in terms of land area, in 2024, Indiana was among the top two states in the country for total miles of rivers and streams assessed for full body contact. Only Colorado (79,367 mi) provided more sampling data than Indiana (33,643 mi) according to U.S. EPA data.
The top causes of impairment were E. coli, biological impairment, and PCBs discovered in fish tissue. In most cases, improvements were driven by measured reductions in pollutants or by restored support for designated uses.
“Indiana has put a strong focus on ensuring we have a complete picture of water health across the state. Our sampling includes everything from rivers and lakes to small streams and farm ditches,” said Martha Clark Mettler, IDEM’s Assistant Commissioner of Water Quality. “While this may show more impaired waters on paper, Indiana’s commitment to detailed monitoring ensures that issues are identified, prioritized, and addressed; not overlooked.”
When a waterbody is listed as impaired, IDEM is required to establish a Total Maximum Daily Load (TMDL) to assess causes for impairments, and pollution reduction measures to establish a pathway for the waterbody to meet water quality standards.
Indiana was also the nation’s leader in submissions to the U.S. Environmental Protection Agency of documented waterbody improvements in 2025. Last year, the U.S EPA published 13 water quality Success Stories, which detail restoration efforts that have led to documented water quality improvements in Indiana. The next closest states had 10.
Success Stories are U.S. EPA-designated case studies that highlight measurable water quality improvements achieved through local partnerships and community-driven solutions in waters that didn’t meet environmental standards for contaminants such as bacteria, nutrients, or sediment due to nonpoint source (NPS) pollution. Nonpoint source pollution refers to water pollution that does not come from a single identifiable source.
To qualify as a Success Story, a waterbody must have:
- Been previously considered impaired, meaning it was too polluted to support expected activities such as swimming, fishing, or hosting certain biological communities; and
- Be partially or fully restored, show progress toward achieving water quality goals, or show other qualitative measures toward improvement.
To collect data, IDEM’s Watershed Assessment and Planning Branch follows a rigorous monitoring program that includes eight permanent monitoring networks, citizen science partnerships, and targeted sampling to identify and respond to emerging water quality issues. More information on water sampling programs is available here.
