HOPKINTON-EVERETT LAKES

HOPKINTON LAKE - CONTOOCOOK RIVER - Merrimack River Basin - Hopkinton, NH

DRAINAGE AREA: 382 sq.mi. (Net)
426 (Gross)
Combined HOP-EVT: 446 (Net)
490 (Gross)

PERMANENT POOL: 220 Acre Recreation Pool
Elev = 380.0 Ft NGVD

DAM
Type: Rolled earth and rock
Length: 790 Feet
Top Elev = 437.0 Ft NGVD

FLOOD CONTROL STORAGE

• Hopk Only: Capacity: 70,100 Acre Feet
  3.4 Inches of Runoff
  Area at Crest: 3,700 Acres
• Comb Hop-Evt: Capacity= 161,500 Acre Feet
  6.8 Inches of Runoff (Net)
  Area at Crest: 6,600 Acres

CONTROL WORKS
Type: 3 Square Conduits (2-FC; 1-Forebay)
Size: 11'x11' square
Length: FC-124 Ft; Forebay-128 Ft
Invert Elev = 366.0 Ft NGVD
Capacity (Full Pool): 14,000 cfs
Gates (Type): Hydraulic Slide
Number: 6 (4 FC; 2 Forebay)
Size: 12' H x 6' W
Channel Capacity = 7000 cfs

SPILLWAY
Type: Ogee Weir
Length: 300 Feet
Elev = 416.0 Ft NGVD

SPILLWAY DESIGN FLOOD

• Original Design Criteria:
• Rainfall Excess = 18.2 inches
• Initial Pool Level = Full
• Flood Control Outlet Gates = Operable
• Peak Inflow = 195,000 cfs
• Peak Outflow = 106,000 cfs
• Max. Pool = 430 ft-NGVD
• Freeboard = 5.0 ft
• Current HMR 51 & 52 Criteria:
• Rainfall Excess = 20.9 inches
• Initial Pool Level = Full
• Flood Control Outlet Gates = Operable
• Peak Inflow = 201,400 cfs
• Peak Outflow = 113,400 cfs
• Max. Pool = 430.6 ft-NGVD
• Freeboard = 4.4 ft

RECREATIONAL FACILITIES: Elm Brook Park with 110 picnic tables with grills, 4 group picnic shelters, beach, parking bathrooms, water, ballfield, playground, and boat ramp.

TOTAL COST: $21,180,000 combined total

PLACED IN OPERATIONS: October 1962

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