South Boulder Creek cuts across the middle of the Walker Ranch Loop. Lots of access to the river can be found along the trail. The trail itself is a 7.5-mile loop. If hiking, be aware of mountain bikers. Most of the time, they are courteous, follow the rules of the road, and yield to foot traffic. This is a great loop to run-fish; think Flyathon. Browns and Rainbows can be found. 

Lots of great "fishy holes" exist. A popular spot with easy access to the river can be upstream from the first bridge, right before the trail starts to climb. Another option is, If you are starting from the main TH, about ~4 miles (counter-clockwise) or so in, where the trail steeply descends to the river (stairs), or if you are coming from the other direction, cross the bridge and work the river heading upstream. It can be rewarding. 

With all the rain Boulder has been receiving this spring, it has disrupted the flows. As of June 4, 2023, this segment resembled a chocolate milkshake. As of this posting (June 6, 2023), the weather, the flows, and the clarity have improved. Drop me a line if you have any observations.

It looks like DWR increased water, which makes the flow pretty good. 

The flows are pretty good. However, it's getting cold down the canyon. Fished Sunday, Nov 13, 2022, around 1 PM; think streamers and/or nymphs to reach the fish.

The flows are quite nice and very fishable. 

Flows are decreasing daily! 

Spring run-off is in full swing. 

Had success with a Yellow Sally #16 (surface) in shallow/fast-moving water. A hopper/dropper (surface/sub-surface) combo might be rewarding for deeper holes that exist.

The main parking for the Walker Ranch TH often fills up. Additional parking can be found at the Meyers Homestead Trail. Updated info can be found on Boulder County's site. The park is open from sunrise to sunset.