They do stock some pools on the Rock River, like the pool below Dixon, and pools above it. Contrary to fish stories put out by some unreliable sources, the best fishing on the pool below Sterling is around Phrophetsown. That’s where the best Flathead fishing is as well. The further down river you go, the better the fishing for Crappie, Bass and Walleye. Some Walleye to migrate to the dam in the spring but most get caught and kept so they don’t spawn or return the next year.
The best Bass fishing is also around P-town. Here is what the DNR says:
“Walleye are stocked each year into the Rock River to provide a quality sport fishery for this species. Fishing is generally good below the dams and at the mouths of the tributaries. Walleye ranging in size up to and over the state record weight have been caught in recent years in the upper Rock River and the Pecatonica River, a tributary of the Rock near Rockford. A survey conducted in the fall of 2014 near Dixon found a catch rate of 1 fish/ minute with a total of 101 fish of all sizes collected in one hour, well over the target rate for stocking success. The largest collected was just over 3 pounds. Anglers regularly report catching memorable-size walleye from Sterling up through Rockford. Best fishing for walleye is in the upper Rock River, north of Rockford, however anglers sometimes report good fishing near Dixon and at Prophetstown State Park. Regulation: Walleye, Sauger, or Hybrid Walleye – Wisconsin state line downstream to the Sears and Steel dams at Milan: 6 either singly or in combination; 14” minimum length limit. Walleye, Sauger, or Hybrid Walleye — Sears and Steel dams downstream to confluence with Mississippi River, State of Illinois (Rock Island County): 6 fish daily creel with no more than 1 walleye greater than 27” in total length; 15” minimum length limit with a 20-27” protected Slot Length Limit.”
“Smallmouth bass are common and abundant in the Rock River. A survey conducted in the summer of 2014 found very large numbers of young fish, indicating an excellent spawn. The catch rate was low for the larger fish though, (> 7”) with a rate of 0.6 fish/minute, but the catch rate of 1.2 fish/minute for all sizes was within the target rate. The overall number of adult fish (>11”) collected was a little low, with only 28% of the population in this size range, but this rate has increased slightly as compared to the survey of 2013. Prophetstown had the best number of larger fish with 44% of the adult smallmouth collected in this area > 11”! With the strong year classes produced in 2012, 2013, and again in 2014, the number of larger fish should improve significantly in the near future. Best fishing areas are in South Beloit, below the dam in Dixon, and downstream of Prophetstown State Park. Regulation: 6 black bass, singly or in combination, with no more than 3 smallmouth bass in the daily creel; 14” minimum length limit for smallmouths. Note: There is a closed season on smallmouth bass. All smallmouth bass caught between April 1 and June 15 must be immediately released alive and in good condition back into the waters from which they came.”