OTTER BROOK DAM

OTTER BROOK - Connecticut River Basin - Keene, NH

DRAINAGE AREA: 47 sq.mi.

PERMANENT POOL: 90 Acre Recreation Pool
Stage: 20 ft

DAM
Type: Rolled earth
Length: 1,288 Feet
Top Elev: 802.0 ft NGVD (119 ft)

FLOOD CONTROL STORAGE
Capacity: 17,600 Acre Feet
7.0 Inches of Runoff
Area at Crest: 374 Acres

CONTROL WORKS
Type: Boston Horseshoe Conduit
Size: 6' diameter
Length: 589 Feet
Invert Elev: 683.0 ft NGVD
Weir Elevation (top of logs): 701.0 ft NGVD (18 ft)
Capacity (Full Pool): 1,320 cfs
Gates (Type): Hydraulic Slide
Number: 3
Size: 2'-6"W x 4'-6"H
Channel Capacity: 650 cfs

SPILLWAY
Type: Chute Spillway
Length: 145 Feet
Elev: 781.0 ft NGVD (98 ft)

SPILLWAY DESIGN FLOOD

Original Design Criteria:
- Rainfall Excess: 21.2 inches
- Initial Pool Level: Full
- Flood Control Outlet Gates: Inoperable
- Peak Inflow: 38,000 cfs
- Peak Outflow: 34,500 cfs
- Max. Pool: 797.1 ft NGVD
- Freeboard: 4.9 ft
Current HMR 51 & 52 Criteria:
- Rainfall Excess: 24.45 inches
- Initial Pool Level: Full
- Flood Control Outlet Gates: Operable
- Peak Inflow: 64,800 cfs
- Peak Outflow: 58,500 cfs
- Max. Pool: 803.0 ft NGVD
- Freeboard: -1.0 ft

RECREATIONAL FACILITIES: 80 Picnic tables with grills, beach, parking areas, bathrooms, boat ramp, drinking water, and two group picnic shelters.

TOTAL COST: $4,132,500

PLACED IN OPERATION: April 1958