Rapid River

The Rapid River is 3.2 miles of boulder-strewn pocket water running from Middle Dam, at the outlet of the Richardson Lakes, down to Umbagog Lake — and it grows some of the largest wild brook trout left anywhere in the eastern United States. These are not stocked fish. The brookies here are sustained entirely by natural reproduction, average 14-15 inches, and run to 20-plus inches and 4-5 pounds. Landlocked salmon, naturalized in the drainage since the late 1800s and also self-sustaining, drop in from the Richardson Lakes and share the water. There's no road to the upper river, no live gauge, and no easy way in — which is exactly why the fishery still exists in the shape it does. If you want a genuine shot at a wild brook trout measured in pounds instead of inches, this is one of the last places in the East that reliably delivers.

Flows are the whole game, and they're entirely artificial. Middle Dam — owned by Brookfield Renewable, historically operated by the Union Water Power Company — meters every drop, and its job is delivering water to downstream users, not tuning the river for anglers. The Rapid fishes best in the 500-700 cfs window: enough push to hold fish in the pockets and seams, low enough to wade the edges and read the water. Around 800 cfs it gets marginal, and once it climbs past 900-1,000 cfs the river blows out — too much water, nothing wadeable, fish scattered. There is no USGS gauge and no hydrograph, so you don't read a chart before you drive up. You call the Brookfield / Safe Waters flow line at 1-844-430-FLOW or check Waterline (h2oline.com) for the daily Middle Dam release, or ask Lakewood Camps. Complicating things: the state and Brookfield deliberately run short high-flow pulses of about 1,200 cfs in late June to early July to blow out smallmouth bass nests — good for the trout over the long run, useless for fishing that week — and there are scheduled recreational whitewater release weekends in July and August that spike the river well above fishable levels. Check the release before you commit.

Getting here is the other filter. The standard approach is a boat run up Lower Richardson Lake from the South Arm — a maintained gravel road off Andover leads to the South Arm launch and campground — or you stay at Lakewood Camps at Middle Dam, the only lodge on the river and a sporting camp in continuous operation since the 1850s, which shuttles guests in by boat. From the Middle Dam side you hike a trail down the north bank to reach the pools. The lower 1.9 miles below Long Pool sees maybe 6 percent of the fishing pressure because it's even harder to get to. Smallmouth bass, illegally dumped into Umbagog in the 1980s, have colonized the lower river and Pond in the River, and they're the shadow hanging over the fishery — the reason for the aggressive flow management and the restrictive, catch-and-release, fly-only regulations. Fish it in early summer for the best combination of flows, hatches, and cool water; by August the trout stack into the coldest water near Middle Dam and into Pond in the River's depths, which is closed to protect them. Nearby, the Magalloway, Kennebago, and Androscoggin give you fallback water if the Rapid is blown out or crowded.