The river arises in two branches: east and west. The East Branch begins just north of
East Haven. It flows southwest through Hartwellville in East Haven, then into
East Burke. The West Branch starts as several small forks in
Westmore. The
Montreal, Maine and Atlantic Railway lines follows the West Branch of the Passumpsic from West Burke until it converges with the East Branch in
Lyndonville. From Lyndonville, the river proceeds southerly through St. Johnsbury Center,
St. Johnsbury, Passumpsic, and
Barnet, and into the Connecticut River near Nine Island.
East Branch The East Branch originates about 1/2 mile southeast of Sukes Pond,
Brighton, in
Essex County. Route 114 nearly parallels it as it runs south-southeast. It soon enters
Caledonia County. It is joined by Jack Brook near Howard Brook Road in
Newark. It then turns south southwest. Just before entering
East Haven, it is joined by Mill Brook/King Brook entering from the east. It is then joined by the confluence of Bean Brook and Whetstone Brook just inside the town of East Haven, back in Essex County. It goes through Hartwellville, in the town of East Haven, then crosses into Caledonia County for good. In
Burke, a mile downstream, it is joined on the south by Flower Brook which flows mainly from the east. Duck Pond drains into it. It is followed by Route 5A and flows through East Burke. It converges with the west branch before 5A joins US Route 5.
West Branch The West Branch first exits out the west side of Newark Pond in
Newark. It flows briefly through
Barton, back into Newark, then into
Burke.
Burke Mountain The northeast and northwest sides of
Burke Mountain drain into Dish Mill Brook, thence into the
East Branch of the Passumpsic River. The southwest end of Burke Mountain drains into Mountain Brook, thence into the East Branch of the Passumpsic River. The south slopes and southeast side of Burke Mountain drain into Weir Mill Brook, thence into Bog Brook, the
Moose River, and the Passumpsic River.
Burke It proceeds south-southwest. Arcadia Brook flows into it from the north near Arcadia Lane. West Brook flows into it from the northwest near
VT 5A, which nearly parallels it from then on south. The river flows south from that point. After it crosses 5A going south southwest, another unnamed brook enters it from the east
Sutton River enters it from the southwest, near
U.S. Route 5 at
West Burke. Route 5 now nearly parallels it southbound. The river then turns south-southeast. An unnamed brook, which Brook Road parallels for a while, enters from the east.
Lyndon (west branch only) In Lyndon it passes through Folsom Village. Quimby and Calendar brooks enter from the west. The river turns south, near the Calendar Brook Road intersection with Route 5. The two branches merge near East Burke Road, just northeast of where
VT 114 intersects with US 5.
Lyndon (after two branches merge) The joined river continues south. The river turns west, even west-northwest at times. An unnamed brook enters from the north. The river turns south. Miller Run enters from the west. Miller Run Valley is a sufficiently prominent feature to be followed by Interstate 91 instead of Route 5. South Wheelock Branch enters from the west southwest just south of Riverside Court. The river proceeds to the Route 5 bridge and from there to the Vail Hydro Dam. The river runs southeast, then takes a turn west northwest, as the Sheldon River enters from the east. The river encounters the Vail Hydro Dam and runs to a gravel pit. The Little Falls, about a mile above the Great Falls, have about a descent. The river proceeds from the gravel pit and railroad tracks to the Great Falls Dam downstream. It briefly widens to pond size south of Murray Circle. It encounters the Great Falls Dam and runs downstream to the St. Johnsbury Pierce Mills Dam. Roberts Brook enters from the east. Stark Brook enters from the north and west, north of St. Johnsbury Center. A second Roberts Brook enters from the east. A third Roberts Brook enters from the west.
St. Johnsbury The river proceeds through the center of St. Johnsbury from north to south. From its valley the higher lands rise on either side to the east and west. In the southern part of the town it is joined by the Moose River at St. Johnsbury, a large stream from the east, and the Sleepers River, a smaller tributary, from the northwest. It encounters the Pierce Mills Hydro Dam. It proceeds to the Rapids after a sharp bend downstream across from the Green Mountain Trailer Park above the mall at St. Johnsbury Center. Across from the Green Mountain Trailer Park, it flows downstream to the Price Chopper store on the corner where river and the railroad come close together. From here it flows downstream to the confluence of the Moose River. It noticeably widens here after merging coming from the west. The river is often 100-200 wide as it runs south from here on. The Sleepers River runs into it. Next downstream is the Gage Hydro Dam.
Waterford The Passumpsic flows through the western corner of the town from the Gage Hydro Dam downstream to the Passumpsic Hydro Dam.
Barnet The river enters from St. Johnsbury through the corner of Waterford, in the northeastern part, and gradually turns and flows south, emptying into the Connecticut about from the northeastern corner of the town. It encounters Enerick Brook which comes from Danville and enters the Passumpsic about above the mouth of Joes Brook. Joes Brook comes from Joes Pond in Danville and flows in a southeasterly direction through the town, and enters the Passumpsic about from its mouth. Next it encounters Pass Hydro. Water Andric enters from the west and south just north of Kitchell Hill. Joes Brook flows into it. Next the river flows through East Barnet Hydro. Joes Brook enters it from the south and west just north of Barnet Center. It flows through East Barnet Hydro downstream to where the Passumpsic enters the Connecticut River from Barnet, about west of the
Comerford Dam. == Geology ==