Dam Inspections by Owners
(Periodic Maintenance Inspections)
The owner of a dam is responsible for maintaining and operating the dam in a safe condition at all times so it does not constitute a hazard to life, health, or property. Because a dam impounds water or has the potential to impound water, the owner of the dam is responsible for taking appropriate measures, including periodic inspection, maintenance, monitoring, and needed repairs. It is recommended that dam owners inspect their dam(s) at least once every three months and after significant storm events such as earthquakes or floods. For further information please refer to the manual entitled "An Owners Guidance Manual for the Operation and Maintenance of Dams in New York State".
Photo courtesy of Arkansas Soil & Water Commission
It is helpful to plan an inspection in advance to assure that you will observe every part of the dam. The following is a recommended sequence for a visual inspection. A more detailed inspection should also be planned on a periodic basis as described in the Owner's Guidance.
Walk across the crest from abutment to abutment.
- Upstream/Downstream Slope:
Walk across the slope in an up and down or zigzag pattern from abutment to abutment.
- Embankment-Abutment Contacts:
Walk the entire length of the embankment-abutment contacts (groin).
- Outlet Conduit:
Observe all accessible features of the outlet conduit.
Visually observe the entire length of the spillway or spillways, and all other visible features.
- Downstream Channel:
Travel the route of the stream below the dam to maintain familiarity with locations of residences and property that can be affected by dam failure. Dam Owners should be aware of new downstream development(s) and how these development(s) may impact the hazard class of their dam. Go far enough downstream to cover the area that could be affected by a dam failure.
- Downstream Toe:
Walk the entire length of the downstream toe. Reservoir Slopes: Scout the reservoir perimeter in an effort to develop an overall familiarity with its conditions.
What to Look For:
The following is a list of some of the conditions a dam owner may discover and should look for during the inspection. This list should not be construed as an all-encompassing, last word on the problems that may be encountered.
Potential problem indicators for a dam, photo courtesy of
British Columbia Dam Safety Guidelines
- turbid discharge
- structural cracking
- foundation movement
- animal burrows
- debris in gates and spillways
- wave erosion
- excessive vegetation
- soil displacement on slopes (sloughing)
It is important for the dam owner/operator to keep records throughout the life of the dam. Accurate records can help in the evaluation of the performance and condition of the structure over time. Regulations require that dam owners establish a permanent file to retain inspection records, including records of actions taken to correct conditions found in such inspections throughout the life of the dam. The following items will aid the dam owner/operator in keeping good records.
- Inspection Checklist
A convenient way of compiling inspection observations into a record is by recording them directly onto an inspection checklist. The checklist should be carried by the dam inspector as he/she traverses the entire structure. Samples of checklists can be found in the Owner's Guidance.
- Field Sketch
A good practice in addition to filling out the inspection checklist is to draw a field sketch of observed conditions. The field sketch is intended to supplement the information recorded on the inspection checklists; however, it should never be used as a substitute for clear and concise inspection checklists. A copy of the plan view of the dam, usually included as part of the construction drawings for the dam, can be a good base for drawing a field sketch.
Inspection photographs can be vitally important. Over time, photographs provide a pictorial history of the evolving characteristics of a dam. The dam owner/operator often finds them to be great money savers because they can illustrate that some observed conditions (seepage, foundation movement, etc.) have existed for many years and may have reached a state of equilibrium. With this knowledge, quick and economical remedial actions can be developed and implemented, or avoided altogether. Photographs should be dated on the back and labeled with brief descriptions of the locations shown in the pictures. Photographs should focus on specific features of the dam as well as general views of the dam.
- Monitoring Data
As previously indicated, it may become necessary to make measurements of various items during the course of a dam inspection. This may include measurements of seepage rates, spillway discharge rates, settlement, and for some dam owners, readings from instruments such as piezometers, crack gauges, and survey monuments. The reservoir level, referenced in a consistent manner, should be recorded at each inspection. It is important that this data also be compiled in a systematic manner and placed in the permanent file.
- Accompany Your Engineer During Periodic Inspections
Many engineers encourage dam owners or operators to accompany them or even assist them on dam inspections. Also, many owners accompany DEC engineers during their periodic inspections. Owners can learn many things from experienced inspectors, such as:
- What to look for
- How to photograph
- Certain features of a dam
- What records to keep
- How to read different types of instrumentation
For Questions or Comments Contact:
New York State Department of Environmental Conservation
Bureau of Flood Protection and Dam Safety, Dam Safety Section
625 Broadway, 4th Floor
Albany, NY 12233-3504
Telephone: (518) 402-8185