General FAQs

We work closely with dam owners to identify and correct potential problems before they become serious. If we find a potentially unsafe condition, we work with the dam owner to address and remedy the condition in a timely manner. When necessary, we may immediately employ any remedial means necessary to protect life and property, or we may impose a reservoir restriction limiting the water surface to a level that is judged safe. We may also direct the dam owner to implement their emergency action plan (EAP).

DSOD established the Spillway Re-evaluation Program in 2017 to assess dam appurtenant structures, including spillways, to confirm they meet minimum safety standards. This is an on-going screening process and re-evaluation of spillways at dams, starting with these that potentially pose the highest hazard. This evaluation includes the assessment of the spillway’s design and construction and geologic attributes while concurrently reviewing the dam owner’s maintenance and inspection program, the spillway’s historical performance, and any previous spillway repairs. DSOD is working closely with dam owners to expedite the development of the required assessments and restore any known areas of disrepair.

Street Address:

Mr. Erik J. Malvick, Ph.D., P.E., G.E.

Division Manager

Division of Safety of Dams

2720 Gateway Oaks Drive, Suite 300
Sacramento, CA 95833

You should always contact the respective Area or Regional Engineer for a determination as to whether an application will be required for any work to be performed on a dam or its appurtenances. As a general guideline, an application will be required if the work entails more than routine maintenance.

The Division of Safety of Dams (DSOD) has adopted the use of digital signatures in written communication. Questions regarding DSOD's use of digital signatures may be directed to:

Phone: (916) 565-7868
Email: damsafety@water.ca.gov

We don’t recommend any specific individual or firm, but we can provide names of consultants that have worked, or are working on nearby projects. We also recommend that you check out the following organizations and websites:

California Society of Professional Engineers

Phone: 888-285-NSPE (6773)

California Board for Professional Engineers and Land Surveyors

Phone: 866-780-5370

Currently, our files are only available to dam owners and their designated representatives. Members of the public may submit a records request to the Public Records Request Portal.  For further information, email us at damsafety@water.ca.gov. 

Senate Bill 92, a newly enacted law signed by Governor Brown on June 27, 2017, requires DWR to make approved inundation maps available to the public. As dam owner's submit inundation maps to us, they are reviewed and approved before they are made available to the public. Available maps are located on our Inundation Maps page. You may also contact your local emergency management office using the California Office of Emergency Services website for information on dam inundation areas, or you can contact the dam owner.

Yes, our guidelines are summarized below:

• For reservoirs that impound 5,000 acre-feet of water or less, the outlet system should be capable of draining half of the reservoir capacity in 7 or 10 days and full contents within 20 or 30 days, respectively, depending on factors such as downstream and seismic hazard, dam construction methods and age, known deficiencies, and type of dam; as determined by the Division.
  

• For reservoirs that impound over 5,000 acre-feet of water, the outlet system should be capable of lowering the maximum storage depth by 10 percent within 7 or 10 days and draining its full contents within 90 or 120 days, respectively, depending on factors such as downstream and seismic hazard, dam construction methods and age, known deficiencies, and type of dam; as determined by the Division.
  

These guidelines are evaluated on a case-by-case basis, particularly for the very large reservoirs that are in excess of 100,000 acre-feet.

A typical field investigation should:

• Seek to identify geologic hazards that could adversely affect the project.
• Characterize the engineering properties of available earth and rock construction materials.
• Characterize the strength and permeability of the dam, spillway, and outlet foundations.
  

Since each site and project is unique, exploration plans should be submitted to DSOD beforehand for review. DSOD should also be given the opportunity to observe the site conditions firsthand during exploration.

Our policy requires that dam owners regularly exercise (operate) their outlets in order to demonstrate the ability to draw down the reservoir during an emergency. Outlet controls should be fully exercised at least annually and, in our presence, every three years. Experience has proven that regular exercising of gates/valves helps prevent major maintenance problems from developing and is therefore part of a good maintenance program.

We do not operate the outlet controls themselves nor order their operation during routine inspections. It's the responsibility of the dam owner to develop appropriate plans and make the necessary arrangements when dealing with difficult outlet situations. We accommodate reasonable delays in exercising of outlets so owners have time to complete proper planning, coordinate with other agencies, and perform maintenance and repairs, if necessary.

Dam owners should maintain a log detailing all operation and maintenance activities for their outlet system.

Statues pertinent to inundation maps are generally contained in Division 3, Part 1, Chapter 4, Article 6 of the California Water Code.

Regulations pertinent to inundation maps are contained in Title 23, Division 2, Chapter 1, Article 6 of the California Code of Regulations.

If you believe that your dam’s downstream hazard potential classification should be different based on the classifications defined in Title 23, section 335.4 of the California Code of Regulations, please send a letter requesting a re-evaluation of the downstream hazard potential classification, along with supporting documentation to:

Mr. Erik J. Malvick, Ph.D., P.E., G.E.

Division Manager

Division of Safety of Dams

2720 Gateway Oaks Drive, Suite 300

Sacramento, CA 95833

The existing classification will be in effect until any change in classification is made by DSOD. Dam owners are encouraged to plan accordingly to meet deadlines for submitting EAPs. 

A critical appurtenant structure (CAS) is a water barrier or hydraulic control structure that is 25 feet or greater in height, impounds 5,000 acre-ft or more, or DSOD determines poses a significant hazard. Examples of CAS include saddle dams, spillways, gates on dams, gated low-level outlets, and penstocks. The above-mentioned height and volume criteria are not applicable for the low-level outlets. If you are unsure whether you have a critical appurtenant structure at your dam, please contact your Area Engineer or mapregs@water.ca.gov. Critical appurtenant structures are defined in Title 23, section 335.2(a)(3) of the California Code of Regulations. 

The EAP requirements are listed in California Government Code section 8589.5, which includes adherence to FEMA 64. Cal OES has developed an EAP checklist available on their website. For questions on EAP requirements, please contact Cal OES at eap@caloes.ca.gov.

Each pdf map must include the inundation boundary, flood wave arrival time, maximum depth, and maximum velocity. The map must also include the most recent aerial imagery at the specified scale appropriate for emergency response purposes, critical facilities in the inundation area, and must be stamped by a California licensed civil engineer. The complete list of inundation map requirements is in Title 23, section 335.10 of the California Code of Regulations.

You must submit a PDF inundation map for the main dam and separate map(s) for each critical appurtenant structure, if identified. If a dam breach hydraulic model simulation was performed for the map(s), submit a PDF technical study and the geospatial files. Submittal requirements are described in Title 23, section 335.14 of the California Code of Regulations.

You may submit digital files as an email attachment or via download link sent to mapregs@water.ca.gov. Digital files may also be delivered on a USB flash drive or CD. Please send any physical submittals to:

Mr. Erik J. Malvick, Ph.D., P.E., G.E.

Division Manager

Division of Safety of Dams

2720 Gateway Oaks Drive, Suite 300
Sacramento, CA 95833

DSOD reviews the map and supporting technical information to make sure it complies with the regulations. If DSOD has comments, we will email the comments to the owner or consultant, who may revise the map. After comments are addressed and the map meets the regulatory requirements, DSOD will send an approval letter to the owner and again copy Cal OES.

Once submitted, DSOD's review may take several weeks to several months depending on the number of the maps and their complexity.

Upon receipt of your inundation map, DSOD will either respond with an acknowledgement letter containing an assigned engineer’s contact information or the assigned engineer will personally reach out to the phone number or email address listed in the submittal. This engineer should be your primary contact for obtaining a review status update. You may also email mapregs@water.ca.gov or call the general DSOD number (916) 565-7800.

California Water Code section 6161(d) specifies the following deadlines for EAPs that must contain approved inundation maps. These deadlines were based on the downstream hazard potential classification of dams.

• Extremely high hazard: January 1, 2018
• High hazard: January 1, 2019
• Significant hazard: January 1, 2021

Title 23, section 335.16(a) of the California Code of Regulations requires owners to update their map(s) at least every 10 years from the map preparation date of the dam.

Section 6161(c) of the California Water Code requires the approved maps to be made publicly available. DSOD publishes approved inundation maps on a GIS-based web viewer at the following link: https://fmds.water.ca.gov/maps/damim/

Section 6161(a) of the California Water Code requires owners to submit an electronic copy of their latest EAP to Cal OES and DSOD. Submittal details for Cal OES are at their website. You may submit your EAP to DSOD as a pdf by emailing it as an attachment or via download link to mapregs@water.ca.gov. Digital files may also be delivered in a USB flash drive or CD. DSOD does not require a printed hard copy of the EAP.

Once Cal OES approves your EAP, submit a pdf file with a cover letter to DSOD.

We do not recommend any specific individual or firm, but your Area Engineer can provide names of consultants that have worked on similar projects.

Yes, section 6161(e) of the California Water Code and Title 23, section 335.16(a) of the California Code of Regulations requires inundation maps to be updated a minimum of every 10 years, and more frequently when there are significant changes to the dam or downstream hazard potential. When an inundation map is being updated for its 10-year cycle, a new model simulation may not be required in cases where there are no changes to the dam, downstream conditions, model assumptions, and state-of-practice; see Title 23, section 335.16 of the Regulations for more information.

The 10-year update is based on the map preparation date listed on the existing inundation map for the main dam [23 C.C.R. § 335.16(a)]. The updated maps for the main dam and all the critical appurtenant structures should be submitted at the same time.

You may call your Area Engineer or send your question to mapregs@water.ca.gov. We will usually respond within one business day, but due to high email volume it may take longer. We appreciate your patience.

Submit the map(s), geospatial files, and technical memorandum per California Code of Regulations Title 23, section 335.14. An updated technical memorandum that includes the modeling assumptions as described in Title 23, section 335.8(a) of the Regulations must also be submitted.

Submit updated map(s) with updated aerial imagery, critical facilities, map preparation date, the California-licensed professional civil engineer's seal, along with all map requirements in Title 23, section 335.10 of the California Code of Regulations. Also submit a written explanation of why a new model simulation is not required and note all changes made to update the map(s) (see Title 23, section 335.16 of the Regulations). An updated technical memorandum and geospatial files are not needed if the model simulation was not updated.