WATERLOO - Reminders of this summer's flooding are hard to miss.

Piles of stones form impromptu islands in rivers. Banks are scarred and stripped, sometimes to bare rock. Trees and other debris create blockades at bends.

"This is probably the most devastating flood that's ever been on the river," said Randy Logsdon, owner of Randy's Bluffton Store, a canoe rental and campground business in Bluffton near the Upper Iowa River.

For those people who rely on the river for recreation - whether a taking calm afternoon paddle or snagging a trophy trout - the deluge brought a mixed bag. Some waterways, like the Upper Iowa in Winneshiek County, saw a violent torrent that threatened to cut a new channel out of bedrock and earth. Other streams recharged and now teem with life.

In the case of the Upper Iowa, centuries of repeated flooding carved a valley from limestone hills and bluffs. The flood in June cut a little bit more, Logsdon said. In some places, the river widened by as much as 50 percent. In other places, the water deposited rocks in open fields.

"There's a lot more rock beaches than there used to be," Logsdon said.

That's a common sight wherever rivers swelled beyond their banks, said Mary Skopec, a supervisor of the watershed monitoring section at the Iowa Department of Natural Resources.

The effects on other major streams were varied. Around 47 tons of foreign material was taken out of the Cedar, Winnebago and Shell Rock rivers.

"The Cedar really took a wallop," she said.

The Iowa River saw fewer issues, in part because the Coralville Reservoir slowed the flow of water down, Skopec said.

Some of the more dramatic effects were seen on the Makoqueta River near Manchester. DNR officials had to force the river back into its banks after the floodwaters attempted to carve a new channel, Skopec said. Similar effects were seen in past floods, including in Iowa City when the Iowa River nearly turned City Park into an island by creating a new channel.

Usually, the DNR will let the river carve out its new path, Skopec said. That's because controlling the flow after a new channel develops is often too difficult.

"In most cases you are going to let the river do what the river does," Skopec said.

For paddler Peter Komendowski, that's what makes things exciting. He enjoys being able to paddle down a stream and find how things have changed, like a new set of rapids created from debris.

"They're dynamic things. It's not like you dug a concrete ditch and put water in it," he said.

Similarly, flooding has the potential to improve fishing for the region's streams and rivers by increasing the amount of habitat available for fish to live in and for insects to breed, said Brad Mullin, president of the Hawkeye Fly Fishing Association.

He warns, however, that hasn't been the uniform case across the state. The big trout fishing rivers, like the Upper Iowa, Turkey and Volga, were basically unfishable because of currents most of the summer.

"The fishing season this summer pretty much didn't exist for the eastern part of the state," Mullin said.

In flood conditions, fish like trout tend to go to deeper waters to escape the currents and debris sweeping downstream. Even more than months after the waters returned to normal levels, the fish are "still hunkering down" in those deeper pockets, which makes finding them more difficult, Mullin said.

Dan Kirby, a DNR biologist, said most river fish species aren't as bothered by flooding as other types, like lake fish. That's due in part to the fact their bodies are conditioned for river currents, so they can handle the additional flow of water. Lake species, especially bluegills and largemouth bass, tend to be stressed more because their bodies can't cope with fast water.

Usually the species tend to weather floods without much of a dip in their populations. In fact, populations for some species, like channel catfish, can explode after waters recede.

"The fish world doesn't seem to be as negatively affected by flooding as the human world," Kirby said.

The result was evident to some anglers in Black Hawk County. Fishing has been fantastic on the Cedar River near Gilbertville, said Nick Frost, president of the Waterloo chapter of the Izaak Walton League.

League members tell Frost the water in the area is clearer, which helps the fishing.

Gary Dusenberry, park ranger for George Wyth State Park in Waterloo, said perch fishing has also been great this summer in some of the park's lakes. George Wyth was inundated along with much of the surrounding area when the Cedar flooded. That brought mixed blessings for the park.

The waters helped "self-stock" some common breeds that perhaps depleted over the years and added some new ones, like walleye, Dusenberry said. But it may have also added less desirable breeds, like carp.

"There are positives and negatives," he said.

Dusenberry said state officials haven't been able to conduct a good survey of the fish population because bad weather interfered with their efforts earlier this summer. There have been plenty other problems though, mostly related to river cleanup.

Flooding forced garbage, which usually collects on the shores, further up on the banks, paddler Komendowski said. That will complicate clean-up efforts. In many cases, portage trails and other things used in paddling will have to be reconstructed.

Several groups have spent the better part of the summer working on clean-up efforts and stabilizing river and stream banks. Skopec said some of those clean-ups removed more than 15,000 containers of various shapes and purposes from the rivers.

Skopec said most of the hazardous chemicals were gone from the system pretty quickly after the initial flood incident, but the waters showed high levels of nutrients, like phosphorus and nitrates, all summer. She said they haven't been able to pinpoint why those lingered in the water.

Most expect the rivers to bounce right back to where they were pre-flood, with some changes, of course. And that's usually a good thing.

"There's an old adage that says fishing is always good after a flood," Mullin said.

Contact Josh Nelson at (319) 291-1565 or josh.nelson@wcfcourier.com.