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:

Ms. Sharon K. Tapia, P.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. For further information or to set up an appointment to review our files, contact our file administrator at (916) 565-7869. Our office is located at 2720 Gateway Oaks Drive, Suite 300, Sacramento, CA 95833.

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.

If you believe that your dam’s hazard classification should be different based on the hazard classifications defined in Section 335.4 of the regulations, please send a letter requesting a re-evaluation of the hazard classification, along with supporting documentation to:

Ms. Sharon K. Tapia, P.E.

Division Manager

Division of Safety of Dams

2720 Gateway Oaks Drive, Suite 300

Sacramento, CA 95833

Please be aware that it could take DSOD up to 60 days to make a determination after receiving all necessary information, and that 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 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 Section 335.2(a)(3) of the regulations. 

The EAP requirements are listed in Government Code 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 map must include the inundation boundary, flood wave arrival time, maximum depth, and maximum velocity. The map must also include aerial imagery (ex: google earth picture) at a scale that is appropriate for emergency response purposes, critical facilities in the inundation area, and must be stamped by a California licensed civil engineer. The entire list of inundation map requirements is in Section 335.10 of the regulations.

You must submit the inundation map for the main dam and separate map(s) for each critical appurtenant structure, if identified, and a supporting technical study. Submit the map(s) as pdf(s), and also submit the appropriate geospatial files. In addition, submit a pdf and one hard copy of the technical study. Submittal requirements are described in Section 335.14 of the regulations.

You may submit the electronic files on a flash drive, CD, email attachment or download link to mapregs@water.ca.gov. Please send the hard copy of the technical study to:

Ms. Sharon K. Tapia, P.E.

Division Manager

Division of Safety of Dams

2720 Gateway Oaks Drive, Suite 300

Sacramento, CA 95833

When DSOD receives an inundation map and technical study, we send the owner an acknowledgement letter and copy Cal OES. DSOD reviews the map 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 requirements contained in the regulations, DSOD will send an approval letter to the owner and again copy Cal OES.

DSOD is prioritizing review of the maps for the highest hazard dams first. Once we begin reviewing your map, our review time may take several weeks to several months, depending on the number of the maps and their complexity.

You may email mapregs@water.ca.gov or call the general DSOD number (916) 565-7868.

The cost of a map can vary significantly based on the available information and the complexity of the work involved. DSOD estimates that on average each inundation map costs about $25,000. Owners have reported that consultants are quoting about $10,000 to develop EAPs. Some owners are developing EAPs themselves. 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.

Unfortunately, the legislature did not allocate any funds to help dam owners pay for inundation maps. Cal OES is administering several grants that may be applicable; for more information please contact Steven Larson with Cal OES at PDFM@caloes.ca.gov or HMGP@caloes.ca.gov.

DSOD staff continues to research grants and will contact dam owners if a grant may be applicable to inundation maps.

 Water Code section 6161 specifies the following deadlines for EAPs that must contain approved inundation maps. These deadlines are based on the hazard classification of dams.

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

The deadlines are for EAPs, but the EAPs are required to contain approved inundation maps. Therefore, you should submit your inundation map to DSOD with enough time to allow for review and approval. We recommend submitting your inundation map at least 6 months before your deadline.

DSOD and Cal OES do not have the authority to extend deadlines; however, DSOD is committed to working with owners toward better emergency preparedness.

Communication is important; if you are concerned that you may not meet the EAP submittal deadline, DSOD encourages you to send letters to DSOD and Cal OES explaining why you can’t meet the deadline, your progress so far, and when you plan to submit the inundation map and EAP.

If an owner does not develop a map and EAP upon order by the Department, then the Department is authorized to prepare a map and EAP and recover costs from the dam owner.

The Department is also authorized to impose penalties and will address enforcement on a case-by-case basis.

Senate Bill 92 requires the approved maps to be made publicly available. DSOD has approved maps posted at the Division's Inundation webpage.

Senate Bill 92 requires that owners submit their EAP electronically to Cal OES and DSOD. Submittal details for Cal OES are at their website. You may submit your EAP to DSOD via flash drive or CD.  DSOD does not require a hard copy.

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

DSOD developed permanent regulations that went into effect on November 29, 2018. Changes from the emergency regulations include:

• Submittal of inundation maps with enlargement and construction applications
• How to request a re-evaluation of a dam’s hazard classification
• How to request acceptance of a sediment release modeling approach
• Technical studies must be stamped by a licensed engineer (similar to inundation maps)

Explanation of each provision of the regulations is documented in the Initial and Final Statements of Reasons.

Yes - We don’t recommend any specific individual or firm, but your Area Engineer can provide names of consultants that have worked on similar projects.

Yes, we have drawings for many dams, but not all. Currently, our files are only available to dam owners and their designated representatives. For further information or to set up an appointment to review our files, contact our file administrator at (916) 565-7869. Our office is located at 2720 Gateway Oaks Drive, Suite 300, Sacramento, CA 95833.

Yes - Senate Bill 92 requires maps to be updated a minimum of every 10 years, and more frequently when there are significant changes to the dam or downstream hazard. 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 Section 335.16 of the regulations for more information.

The 10-year cycle is based on the map date of the main dam. 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.