This is on the NH fish and game site.
New Hampshire Rivers and Streams Managed for Trout without a Closed Season
Name of Waterbody and Location
Androscoggin River: from the Dummer-Cambridge town line to the Pontook Dam. from Saw Mill Dam to the NH/ME border.
Cocheco River: from Watson Road dam in Dover downstream to head of tide.
Contoocook River: from Contoocook Lake downstream to the area marked with signs and wire in West Henniker. From a point 2,500 feet above paper mill dam in Henniker to the Lower Falls Dam in Boscawen including the Hopkinton Everett Flood Control Area. From the Lower falls Dam in Boscawen to the confluence with the Merrimack River.
Exeter River: from Rte. 121A to the Squamscott River. Isinglass River: from Route 125 bridge in Rochester downstream to confluence with the Cocheco River.
Lamprey River: from the Raymond/Deerfield town line to the head of tide.
Merrimack River: from the confluence of the Winnipesaukee River and the Pemigewasset River to the NH/MA border.
Pemigewasset River: from the closed section below Ayers Island Dam in Bristol to the Eastman Falls Dam in Franklin. From the posts 150' below the Eastman Falls Dam in Franklin to the confluence of the Pemigewasset River and the Winnipesaukee River.
Piscataquog River, South Branch: from 300 feet upstream of Lyndeboro Road bridge, downstream to first bridge on Route 13 in New Boston.
Souhegan River: from 300 feet upstream of green bridge on Old Wilton Road in Greenville to 300 feet downstream of Route 31 bridge in Wilton
Suncook River: from the Rte 126 Bridge in Barnstead to its confluence with the Merrimack River. Taylor River: west of Rte. 95.