Although the Cedar, Shell Rock, Wapsipinicon, Upper Iowa, Turkey and Yellow rivers all harbor strong populations of this feisty fish, the Maquoketa is likely the best Iowa river for smallmouths. The reason? Water quality is relatively good on the Maquoketa, and the river has an abundance of the fish's beloved rocks and boulders. Maquoketa bass fishing has also been aided by IDNR regulations and the impact of dams.

"Smallmouth bass can be found in the Maquoketa all the way from the Backbone Dam to the river's confluence with the Mississippi River at Green Island. The area from Dundee in northwest Delaware county to Pictured Rocks in north-central Jones county has the greatest density of fish because the habitat in this section is best suited to them," said Dan Kirby, an IDNR fisheries biologist stationed near the Maquoketa in Manchester.

This stretch also boasts several dams. The best known is the one that creates Lake Delhi, but several towns along the river also have dams of varied heights. "Dams help this fish in two ways. Slack water above the dam causes sediment to drop to the bottom. Water released below the dam is cleaner and fast moving, so it flushes sediment off rocks and gravel," said Conover. The Maquoketa also has enough water velocity and bends to naturally keep sediment flowing downstream to the Mississippi and maintain the hard bottom that smallmouths require.

Kirby has detailed data on smallmouth numbers and the best places to fish. "Before the late 1970s," he said, "we didn't have much information about smallmouths in the Maquoketa until biologist Vaughan Paragamian conducted extensive research over a multiyear span. We now have a point of reference that stretches back almost 30 years.

"Iowa State University students and biologists recently revisited the sites he studied. Although all their data haven't been released, it's safe to say that current bass populations are similar to those from the early 1980s."

Perhaps the most studied stretch of the river is the catch-and-release area below the Delhi Dam. Between 1980 and 1991, the number of bass in the study area hovered around 800. Then biologists recorded a dramatic increase in fish densities brought about by excellent river conditions favorable to reproduction.

"Many of these strong year-classes survive to older ages because they aren't harvested in the catch-and-release area," said Kirby. "Between 1995 and 2005, there were between 1,534 and 2,375 fish in the study area." That's nearly triple the 1980 population, and anglers have enjoyed the Maquoketa bass bulge. According to Kirby, the bass from these golden years are gradually dying off, and fish numbers have declined somewhat for a few years; they're now increasing in the catch-and-release area.