The Delaware Dam Safety Program works to reduce the risk of failure of dams and to prevent injuries, property damage, and loss of reservoir storage due to dam failure. It oversees the design and construction, operation and maintenance, and inspection of regulated dams in Delaware.

Delaware’s Dam Safety Law (7 Del. Code, Chapter 42) and Dam Safety Regulations (7 DE Admin. Code, 5103) provide for proper design, construction, operation, maintenance, and inspection of regulated dams in Delaware.

The law requires permitting, inspections and preparation of emergency action plans (EAPs) and Operation and Maintenance (O&M) plans for publicly owned dams with a high or significant hazard potential. A dam’s hazard potential classification depends upon the threat to downstream communities and infrastructure in the event of a dam failure and is not related to the condition of a dam.

Classifying Potential Downstream Hazards

Delaware uses a Hazard Potential Classification system for dams that is based on federal dam safety guidelines published by FEMA.

The hazard potential classification of a dam is determined by the impact that a failure would have on the population, infrastructure and development located downstream, not on the condition or size of the dam. These hazard potential classifications are:

High Hazard Potential Dam — Any dam whose failure or misoperation will cause probable loss of human life.

Significant Hazard Potential Dam — Any dam whose failure or misoperation will cause possible loss of life, economic loss, environmental damage, disruption of lifeline facilities, or can impact other concerns.

Low-hazard Potential Dam — Any dam whose failure or misoperation is unlikely to cause loss of human life but may cause minor economic and/or environmental losses.

Dam Inspections

Owners of regulated dams in Delaware are required to conduct informal inspections of their dams at least quarterly, and regular visual inspections at least once each year for high hazard dams and once every two years for significant hazard dams. Regular inspections must be performed by a Delaware-licensed professional engineer, and a comprehensive written report must be prepared and submitted to the DNREC Dam Safety Program for each inspection.

Regular inspections for state-owned, regulated dams are performed jointly by professional engineers from the DNREC Dam Safety Program and the DelDOT Dam Preservation Program.

Emergency Action Plans

An Emergency Action Plan (EAP) is a written plan that identifies emergency conditions at a dam and specifies pre-planned actions to minimize loss of life and property damage in the event of a potential dam failure. Every regulated dam in Delaware is required to have an EAP prepared by the dam owner and approved by the DNREC Dam Safety Program. EAPs have been prepared for all state owned, regulated dams.

Water Level Monitoring at State-Owned Dams

Since 2015, the Dam Safety Program has continued the water level monitoring project to install and maintain continuous water level monitors at state owned dams. The instrumentation provides near real-time monitoring and alerts of pond/lake water levels.

Being able to remotely monitor the water levels in these ponds has greatly improved the efficiency and response time in managing these dams to prevent overtopping and failure. This information is also accessible to the public with an internet connection.

The US Geological Survey (USGS) installed and publishes data from monitoring gauges at four dams:

The Delaware Environment Observing System (DEOS) at the University of Delaware installed and publishes data from monitoring gauges at 32 publicly-owned dams:

Delaware Dam Inventory

A comprehensive inventory of dams in Delaware was performed between 2006 and 2008. Using information from previous inventories performed in 1974 and 1981, and an update in 2003, over 300 potential dam sites were reviewed and 86 structures were considered to be dams of interest. Sixty-three of those dams were classified as being potentially regulated. Since 2008 however, further, more in-depth review of each dam has reduced the number of regulated dams to the current 45.

The National Inventory of Dams (NID) is a database, maintained and published by the US Army Corps of Engineers, documenting dams in the United States and its territories. It contains information about a dam’s location, size, purpose, type, last inspection and regulatory facts for dams that meet their criteria. The NID lists 83 regulated and unregulated dams in Delaware.

Related Topics:  dam, drainage, drainage and flooding, Health and Safety, safety, watershed, waterways