WEST THOMPSON DAM

QUINEBAUG RIVER - Thames River Basin - North Grosvenordale, CT

DRAINAGE AREA: 173.5 sq.mi.(Gross)
74.0 sq.mi.(Net)

PERMANENT POOL: 200 Acre Recreation Pool
Stage: 13 ft (305.0 ft NGVD)

FLOOD CONTROL STORAGE
Capacity: 25,600 Acre Feet
6.5 Inches of Runoff (Net)
Area at Crest: 1,250 Acres

DAM
Type: Rolled Earth Fill
Length: 2,550 Feet
Top Elev: 361.5 ft NGVD (69.5 ft)

CONTROL WORKS
Type: Horseshoe Conduit
Size: 12' diam
Length: 254 Feet
Invert Elev: 292.0 ft NGVD
Weir Crest: 305 ft NGVD (13 ft)
Capacity (Full Pool): 5,100 cfs
Gates (Type): Hydraulic Slide
Number: 3
Size: 5' X 9'
Channel Capacity: 2300 cfs

SPILLWAY
Type: Chute Spillway w/ Concrete Ogee Weir
Length: 320 Feet
Elev: 342.5 ft NGVD (50.5 ft)

SPILLWAY DESIGN FLOOD

Original Design Criteria:
- Rainfall Excess: 22.1 inches
- Initial Pool Level: Full
- Flood Control Outlet Gates: Operable
- Peak Inflow: 85,000 cfs
- Peak Outflow: 63,000 cfs
- Max. Pool: 356.5 ft-NGVD
- Freeboard: 5.0 ft
Current HMR 51 & 52 Criteria:
- Rainfall Excess: 24.8 inches
- Initial Pool Level: Full
- Flood Control Outlet Gates: Operable
- Peak Inflow: 98,800 cfs
- Peak Outflow: 77,700 cfs
- Max. Pool: 358.8 ft-NGVD
- Freeboard: 2.7 ft

RECREATIONAL FACILITIES: 50 Picnic tables with grills, parking areas, bathroom, water, group picnic shelter, trails, winter skating area and boat ramp.

TOTAL COST: $6,915,000

PLACED IN OPERATION: 1965