If you want an honest report card on a river, ask a biologist what's swimming in it.
At the 2026 Great Miami Riverway Summit in Hamilton, Ohio, that's exactly what Kelsea Downs delivered. As an Aquatic Habitat Biologist with the Ohio Department of Natural Resources' Division of Wildlife, Downs spends her career tracking what lives beneath the surface of rivers like the Great Miami — and her session at the Summit, "From the Science to the Sport," laid out a quietly remarkable story: a river that was nearly lifeless a few generations ago is now one of the best fishing destinations in the state.
The Great Miami River stretches roughly 157 miles, from the outflow of Indian Lake down to its confluence with the Ohio River in Hamilton County. Its watershed drains about 3,800 square miles of southwest Ohio and is home to 1.3 million people — a mix of dense urban corridors and quiet farmland, all feeding into the same river system.
Within that watershed, Downs and her colleagues have documented 113 species of fish across 25 different families — an unusually diverse number for a river of this size. That list ranges from the foundational species that anchor the food web (minnows, suckers, and herring, roughly 50 species in total) up through sunfish, nine species of catfish and bullheads, and members of the perch family that span everything from tiny darters to trophy-sized saugeye.
If there's one species that defines the Great Miami's reputation among anglers, it's the smallmouth bass. Downs described the river as ranked #1 among Ohio's river systems for producing trophy-sized smallmouth — with a current trophy record around 24.3 inches. Anything over 18 inches earns a "Fish Ohio" trophy designation, and the Great Miami consistently produces fish well above that bar, particularly in the middle and upper reaches where the water runs clear, fast, and over the cobbled bottoms smallmouth prefer.
Since 2017, ODNR has been sampling smallmouth populations in the river alongside other regional waterways like the Stillwater, Little Miami, and Mad Rivers. What they've found is a population with strong early growth and excellent recruitment — biologist shorthand for "young fish are surviving and growing well," which is one of the clearest signs of a healthy, self-sustaining fishery.
Smallmouth aren't the only draw. The river also supports a growing population of hybrid striped bass (more than 54,000 stocked since 2020), a saugeye fishery that ranks third among Ohio rivers, walleye, largemouth and spotted bass, a notable trophy catfish fishery, and even northern pike in the river's northern stretches.
Below the lowest dam in Hamilton, the Great Miami connects directly to the Ohio River — and that connection means the occasional surprise swims upstream. Downs described several species of gar, paddlefish, bowfin, and lamprey that turn up in the lower stretches, fish that wouldn't normally be associated with an Ohio river at all.
The best example: a few years ago, an angler near the Hamilton dam caught an alligator gar — a species that had been extirpated from Ohio entirely. The most likely explanation is that it wandered up from a stocking program in Kentucky or Illinois. And just this spring, an angler fishing for saugeye near Middletown landed a hybrid crappie — a cross between black and white crappie — currently under review as a potential new Ohio state record.
None of this diversity existed by accident, and it certainly didn't exist a few decades ago. Before the 1970s, heavy industrial pollution and habitat loss left the Great Miami River with low fish diversity, dominated by only the most pollution-tolerant species. The passage of the Clean Water Act changed that trajectory — not just for the Great Miami, but for rivers across the country, the same shift that took the infamously flammable Cuyahoga River from a national punchline to a recovering ecosystem.
From the 2000s into the 2010s, the focus shifted toward habitat restoration and improved agricultural practices — soil conservation, better stormwater management — which Downs credits with measurable improvements in smallmouth bass and other populations. Today's work is increasingly about improving fish passage and habitat connectivity, with an eye toward long-term climate resilience.
The results show up in the numbers: about 58% of the watershed now meets Clean Water Act goals, with another 20% partially meeting them. It's not a finished project — but it's a dramatically different river than the one Ohio had fifty years ago.
One persistent myth Downs addressed head-on: the idea that fish from the Great Miami River are somehow unsafe, mutated, or otherwise off-limits. They're not. With the exception of a few specific stretches where carp and catfish consumption isn't recommended, most of the river supports one to two safe meals of fish per month — a fact confirmed through EPA sampling that ODNR regularly assists with.
Healthy fish communities are more than a biology footnote, they're an economic engine. Ohio ranks 10th in the nation for fishing, and roughly 1.7 million Ohioans fish each year, generating $5.5 billion in economic impact and supporting an estimated 34,000 jobs statewide. On the Great Miami specifically, anglers spend an average of $25–$40 per day — money that flows into local restaurants, lodging, bait shops, and outfitters up and down the corridor.
Downs closed her session with a simple challenge to the room: if you have a memory of fishing as a kid — a Snoopy pole, a quiet afternoon, a first catch — go make that memory again, or pass it on to someone else. The Great Miami River, she made clear, has more than earned a second look.
Want to see the data for yourself? The Great Miami River's healthiest stretches for smallmouth bass are typically in the river's middle and upper reaches, where clearer, faster-moving water creates ideal habitat. Check the Great Miami Riverway's Maps & Trails section for access points near you.