The Iowa DNR is responsible for the state's dam safety program. The program involves the review and approval for the construction of new dams, maintaining an inventory of existing dams that meet minimum size criteria and the periodic inspection of certain dams. Currently there are approximately 3800 dams on the state's dam inventory.
Dams that have the potential to create extensive damage to downstream houses or buildings, or to cause loss of life should they fail and release their impounded water are required to be regularly inspected. There are currently 321 dams that require regular inspections either on a 2 or 5 year inspection frequency.
Permits may be required to construct a dam, modify an existing dam, drawdown the water level, or remove a dam. In these cases, please review the Permit Application Process
For more information, please contact:
Jon Garton (515-725-8360; Jonathan.Garton@dnr.iowa.gov
When Approval is Required
Bulletin No. 16, Design Criteria and Guidelines for Iowa Dams
Application for Permit to Store Water for Beneficial Use
Climatology of Iowa Series 2, Revised
In Iowa, dams are classified according to the downstream damages that would occur if that dam were to fail. The more risk, the higher the standards that have to be met when that dam is constructed or modified. There are 3 dam classifications: High Hazard, Moderate Hazard and Low Hazard. These classifications do not describe the current condition of the dam. High Hazard class dams have to meet the state's highest level of criteria and are inspected on a 2 year cycle.
Dams are classified as High Hazard when it is located in an area where dam failure may create a serious threat of loss of human life.
A Moderate Hazard Dam is where failure may damage isolated homes or cabins, industrial or commercial buildings, moderately traveled roads, interrupt major utility services, but are without substantial risk of loss of human life. Dams are also classified as Moderate Hazard where the dam and its impoundment are themselves of public importance, such as dams associated with public water supply systems, industrial water supply or public recreation or which are an integral feature of a private development complex.
Low Hazard dams are classified as such where damages from a failure would be limited to loss of the dam, livestock, farm outbuildings, agricultural lands and lesser used roads and where loss of human life is considered unlikely.
The purposes of dam inspections are as follows:
- Evaluate the construction, operation and maintenance of dams
- Identify observable deficiencies in dams or appurtenant structures
- Identify other flood plain structures or uses which may affect the hazard class of a dam or use of an associated impoundment
Dam Inspection Guidance
Dam Inspection Checklist
Operation & Maintenance
Dams need to be used efficiently and managed to protect environmental quality, enhance public safety and flood protection, and to support and balance a variety of economic, social and ecological needs.
Routine maintenance and inspection of dams and related facilities must be an ongoing process to prevent dam failures. Negligence can threaten overall safety of a dam and have a catastrophic impact on communities, private property and public works downstream. Dam failures causing extensive damage or loss of life are not frequent, but failures do occur and are a legitimate public concern.
Technical Manual for Dam Owners: Impacts of Animals on Earthen Dams (FEMA 473)
Technical Manual for Dam Owners: Impacts of Plants on Earthen Dams (FEMA 534)
Dam Owner's Guide to Plant Impact on Earthen Dams (FEMA L-263)
Dam Owner's Guide to Animal Impacts on Earthen Dams (FEMA L-264)
Conduits Through Embankment Dams (FEMA L-266)
Maintenance Manual for Dam Owners
Emergency Action Plans
Being prepared in the event of an emergency is one of the most important responsibilities of a dam owner. The Federal Dam Safety Guidelines and the National Dam Safety Program Act, passed by Congress in 1996, and reauthorized in 2006, both consider a well planned and coordinated EAP to be an essential responsibility of the owner.
It has long been established that having an EAP reduces the potential for loss of life downstream of dams. The dam owner can be held responsible and liable for loss of life caused by failure of the dam. Compliance with government or professional standards does not necessarily absolve an owner from liability, but it does establish a standard of care to be used by owners.
The EAP accomplishes three important objectives:
- Identifies the area below the dam that would be flooded from a failure,
- Establishes lines of communication for the dam owner and emergency response personnel, and
- Provides for warnings and evacuations to be conducted by police, fire, and rescue teams.
As the dam owner, you are responsible for developing and maintaining the EAP and for updating it on annual basis. The importance of meeting with your local emergency management agencies at least once a year cannot be overstated. This meeting ensures that everyone understands the EAP, including pre-planned emergency procedures and inundation maps. Once completed, the EAP should be submitted to this office for review and approval.
Emergency Action Planning Resources from the Association of State Dam Safety Officials
Lake Delhi Failure Investigation by the Independent Panel of Engineers
After the failure of the Lake Delhi Dam in July of 2010. An Independent Panel of Engineers was formed to investigate the failure. The final report from the panel is available at the links below:
Lake Delhi Dam Reconstruction Design Alternatives Report
In September 2011, the State of Iowa provided funding assistance to the Lake Delhi Combined Recreational Facility and Water Quality District to complete a study determining the feasibility of repairing the dam, restoring Lake Delhi, and bringing the facility in compliance with current dam safety and design standards.
This report was submitted to the State on December 21, 2011. It can be reviewed via the links below.
Appendix A Field Investigations and Data Collection
Appendix B Hydrologic and Hydraulic Studies Report
Appendix C Geotechnical Analysis and Design_Part1
Appendix C Geotechnical Analysis and Design_Part2
Appendix D Structural Analysis and Design
Appendix E Archaeological Reconnaissance Report_Part1
Appendix E Archaeological Reconnaissance Report_Part2
Appendix F Reconstruction Exhibits
Appendix G Cost Estimate and Construction Schedule
Appendix H Project Scope