― KEUKA LAKE - CALCULATING TOTAL DISCHARGE ―
| 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.
RELATED PAGES
Keuka Lake Water Level ManagementKeuka Lake Outlet Compact (KLOC) History
Keuka Lake - Calculating Total Discharge
USGS gauge in Dresden showing outlet water flow into Seneca Lake
Keuka Lake - Discharge Calculator
Hammondsport USGS Lake Level Gauge
Keuka Lake - Lake Level & Gate Setting History
NOAA Weather Forecast for Hammondsport
NOAA Weather Forecast for Penn Yan
Lake Level of Seneca Lake at Geneva
Cayuga Lake Level
Oswego River Basin - Downstream From Keuka
USGS Stream Flow Stations in NY
NOAA Weather Stations
Cayuga Lake Level & Oswego River Basin YouTube video - USGS hydrologist
Keuka Watershed Improvement Cooperative (KWIC) History
