rule curves

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Does the Canal Corporation try to minimize flood damage?

Lake-level regulation efforts are aimed at minimizing flood damage within the entire Oswego River Basin. Typically, following the navigation season, the system's water levels are lowered to provide storage for spring snowmelt and storm runoff. Prior to navigation season, water levels are raised gradually to predetermined safe levels for summer use. In the summer, levels are regulated to provide reserve capacity sufficient to contain moderate runoff. Seasonal lake levels and other important factors such as maximum and minimum navigation levels are indicated on graphs called "rule curves" that depict ideal levels for each lake.

Rule curves are the historical compromise for water level management that have been established to balance competing interests for target water levels. The rule curve process starts by establishing the top and bottom of the curves (highest tolerable level, lowest tolerable level) to avoid at all costs severe flooding or severe drought conditions. Within that range, navigation levels and municipal water supply are given the highest priorities to ensure a stable, reliable water supply throughout low water summer months. Critical habitat concerns also drive target levels toward the high side of the range to ensure against damage to delicate natural resources.

In order to avoid floods, demand for high levels must be balanced against the effects on property owners. Typically, floods are brought on by:

• Rapid spring snowmelt/runoff
• Heavy spring rains/heavy runoff
• Heavy fall rains before the winter freeze.

To deal with these acts of nature, water levels are raised/lowered within tolerable limits by season.

• FALL – At the close of the navigation season, water levels are drawn down for storage capacity anticipating spring runoff.
• WINTER – The lowest water level on the system can be achieved mindful of water supply needs.
• SPRING – Storage capacity is maintained as long as possible to accept heavy runoffs, but gradual system increases must be undertaken to ensure target levels are reached for summer low water condition needs.
• SUMMER – Competing needs must be balanced with the available water supply.

For additional information on water management of the NYS Canal System contact: Syracuse Division Canal Office, Water Management (315) 437-2741.

What agencies provide flood and flood plain management assistance?

The NYS Department of Environmental Conservation (DEC) works with the State Emergency Management Office (SEMO) to help communities plan for flood disaster.

DEC is New York State’s flood plain management agency, which provides technical assistance to the state’s 1,500 flood-prone communities to help them prevent loss of life and to mitigate flood damages. DEC and SEMO work together to train community response teams by providing instructional materials, tests and drills, and evaluation of local training programs. Fire, police and sheriff's departments, and volunteer or professional emergency squads benefit from flood preparedness training.

DEC and SEMO also provide planning guides and resource information. They help local officials develop or improve flood preparedness plans and coordinate their plans with regional, state and federal agencies. DEC is New York's coordinating agency for the Federal Emergency Management Agency (FEMA), which administers the National Flood Insurance Program. DEC helps communities understand and administer this program’s regulations.

For additional information contact NYSDEC Flood Protection Bureau at (518) 457-3157.