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Keuka Lake Association

― KEUKA LAKE - CALCULATING TOTAL DISCHARGE ―

Gates
  gate width gate sill max. opening
Gate 1 4.5 ft 709.1 ft 4.5 ft
Gate 2 4.5 ft 709.1 ft 4.5 ft
Gate 3 6 ft 709 ft 7 ft
Gate 4 6 ft 709 ft 7 ft
Gate 5 6 ft 709 ft 7 ft
Gate 6 4 ft 709 ft 5 ft



Total discharge is calculated by summing up the discharge produced by the opening of any of these six gates. The calculation method used are dependant on the lake elevation and, in some cases, the gate opening.



  gate opening lake elevation method
Gates 1 & 2 0.5 ft >= 709.7 ft Orifice Flow
Gates 1 & 2 0.5 ft < 709.7 ft Weir Flow
Gates 1 & 2 1.0 ft >= 710.3 ft Orifice Flow
Gates 1 & 2 1.0 ft < 710.3 ft Weir Flow
Gates 1 & 2 2 ft >= 711.5 ft Orifice Flow
Gates 1 & 2 2 ft < 711.5 ft Weir Flow
Gates 1 & 2 open full >= 714.5 ft Orifice Flow
Gates 1 & 2 open full < 714.5 ft Weir Flow
Gate 3, 4 & 5 open full >= 717.4 ft Orifice Flow
Gate 3, 4 & 5 open full < 717.4ft Weir Flow
Gate 6 0.417 ft >= 709.7 ft Orifice Flow
Gate 6 0.417 ft < 709.7 ft Weir Flow
Gate 6 0.5 ft >= 709.7 ft Orifice Flow
Gate 6 0.5 ft < 709.7 ft Weir Flow
Gate 6 open full >= 715 ft Orifice Flow
Gate 6 open full < 715 ft Weir Flow

 

WEIR FLOW

   Total Discharge (CFS) = discharge coefficient x gate width x (sq. root of [ lake level - sill elevation)3

  • discharge coefficient = 3.16 (supplied by the U.S. Army Corps of Engineers)




ORIFICE FLOW

   Total Discharge (CFS) = discharge coefficient x area x sq. root of 2gh

  • discharge coefficient = 0.61 (supplied by the U.S. Army Corps of Engineers)

  • Area

    • top of opening = gate sill + opening

    • area
      • if lake level > top of opening:
        • area = w x gate opening

      • if lake level < top of opening:
        • area = w x (lake level - gate sill)

  • g = gravity = 32.15 ft/sec. squared

  • h = average head

    • if lake level > top of opening:
    • h = ((lake level - gate sill) + (lake level - (gate sill + opening))) / 2

    • if lake level < top of opening:
    • h = lake level - gate sill



HIGH DISCHARGE FLOW EVENTS

When any of the gates are fully open and water discharge flows are high, the impact of tailwater requires an adjustment of total flow by the Submerged Flow Correction Factor. Tailwater conditions are the result of high amounts of water on the down steam side of the gates, which then restrict the amount of water passing through the gates. The following Submerged Flow Correction Factors are used for various full gate open conditions:


# of Gates Fully Open Submerged Flow Correction Factor
1 1.00
2 1.00
3 0.99
4 0.86
5 0.75

* When any the gates are fully open, the sum of the individual calculated total discharge for each open gate is then multiplied by the above appropriate Submerged Flow Correction Factor, to yield the Total Discharge for all combined gates.



The six control gates for Keuka Lake are located at the Main Street bridge in Penn Yan. The three "main" gates are made of steel and have widths of 6 feet (referred to as Gates 3, 4 and 5. There are also two "Andrews" Gates that have widths of 4.5 feet (referred to as Gates 1 and 2) and the Birkett Gate (Gate 6) which is 4 feet wide.


Keuka Lake - Woody

MISSION

Founded in 1956, the Keuka Lake Association, with over 1700 members, provides a unified voice for those who love Keuka Lake. Our mission is to preserve and protect Keuka Lake and its natural beauty for future generations.

Keuka Lake Association is a 501(c) (3) organization (a non-profit tax exempt organization under IRS rules). This distinction is defined by our service to the public and how we are mission-driven as opposed to profit-driven.

Gifts, donations and membership dues paid to our organization are used in direct service to the overall mission to preserve and protect Keuka Lake. Membership dues, donations and gifts are tax deductible to the extent permitted by law. Consult your professional tax preparer if you have specific tax related questions.