Colorado Fishing Reports ยท South Platte Basin
Below Gross Reservoir, South Boulder Creek is a canyon tailwater reached by a steep hike, which keeps the crowds down.
Looking for the latest Below Gross Reservoir river report? This page is updated by the AvidMax fly shop team with live flows, current conditions, hatches and the flies working now on the South Boulder Creek โ Below Gross Reservoir.
Current flows
Wind forecast
Below Gross Reservoir fishing report
Updated November 7, 2026.
Flows are good and steady. BWOs and midges are hatching, and fish are taking dries during the hatch. Nymph a small midge, RS2 or perdigon until the bugs start.
Load your fly box
Before you head to Below Gross Reservoir, bring: Zebra Midge #18-22, RS2 Emerger #18-22, Perdigon #18-20, Parachute Adams #18-20, Elk Hair Caddis #14-16, JuJu Baetis #18-22, Pheasant Tail Nymph #16-20, Black Beauty #20-24, Egg #14-16, Squirmy Wormie #12-14.
Flies working right now
The flies above that we have in stock right now.
Below Gross Reservoir river details
| Access | A steep hike in from the Walker Ranch Loop or the Gross Dam Road trail. |
|---|---|
| Elevation | About 7,000 ft |
| Drive from AvidMax | About 48 miles, roughly 2 hours 12 minutes from our Centennial shop |
| Best season | Spring and fall |
| Fish | Brown and rainbow trout |
| Regulations | Check Colorado Parks and Wildlife for the current rules. A Colorado fishing license is required. |
| Leaders and tippet | 9 ft leaders, 5X to 6X tippet |
| Camping | None |
| Kids | No. The canyon trail is steep. |
| Good to know | Flows depend on Denver Water releases, and the dam expansion may affect access. Check before you go. |
Fishing by season
Winter
Low releases. Midges.
Spring
BWOs.
Summer
Higher releases and caddis.
Fall
BWOs. Good fishing.
How to get there
Park at the Walker Ranch trailhead off Flagstaff Road.