Reservoir flood plan guidance for engineers

We expect reservoir undertakers to prepare a flood plan which is concise and clear to use in a stressful situation.

Our guidance on how to prepare a reservoir flood plan is written for undertakers of high-risk reservoirs but can be applied proportionately to any reservoir.

We use the availability of flood plans as an indicator of the undertaker’s overall approach to reservoir safety management.

You do not need to approve or certify a flood plan, but you should:

  • review the flood plan using the checklist below
  • review the schedule of testing
  • use your statement or report to provide any recommendations you see fit or confirm that you have no recommendations to make. You should remain silent.

You can read our guidance to undertakers on how to prepare a reservoir flood plan.

We encourage undertakers to write their own flood plan, with the people that will use it, so:

  • they are familiar with it
  • they have confidence when using it
  • their sense of responsibility for it is maintained

Undertakers may ask you to write a flood plan for them. You should include them in the process of developing the flood plan as much as possible. Depending on the hazard posed or the complexity of the reservoir you may consider using another engineer to check your work.

Supervising Engineers

Check the content of a flood plan

A flood plan should be concise, clear and proportionate to the hazard posed by the reservoir.

You should help the undertaker apply the guidance appropriately for the reservoir and provide technical advice when requested, for example, with emergency draw down rates.

The flood plan should reflect the complexity of the management structure and processes. For example, a lower risk non-impounding reservoir owned by an individual should be significantly simpler than a high-risk impounding reservoir with multiple dams, complex valve arrangements and telemetry.


Use the following checklist to assist your review.

Cover page

  • Check the name of the reservoir, its location, construction type and dimension are correct. Note the date of the last revision and test of the flood plan.
  • Planned actions: is it clear who will do what, how and when?
  • Instructions for an emergency drawdown: is it clear how to operate any fixed or mobile draw down facilities available on site?
  • If additional facilities are needed to be brought to site, is it clear what equipment is needed and how it will be acquired?
  • Are calculations or approximations of planned draw down rates included and adequate relative to the hazard posed?
  • Contact details and communications plan. This may be a simple list of contacts for a small reservoir. Verify the phone numbers are correct. Larger organisations may reference a corporate incident communications plan but should only include those parts relative to responding to a reservoir incident.

Health, safety and environment

  • Check that hazards and controls are adequately identified and protected.
  • Check the summary information is provided as set out in the guidance and the location of more detailed information is clear.
  • Check that the flood map is held with the flood plan or a description of the downstream areas at risk of flooding is given.
  • Check the location and access plan. You may need to send to a contractor unfamiliar with the site. Is it clear how to approach and enter the site avoiding known hazards or limitations?
  • Is the site plan clear on how to access the principal structures and areas likely to be needed during an incident? Are site hazards or other limitations marker.
  • Have the principles of our guidance been applied in a proportionate manner?
  • Is there any content in the flood plan which is not directly linked to guiding the actions to be taken during an incident? This may be an unnecessary distraction.
  • Can the flood plan be simplified without losing important content?

Useful associated information which does not itself help an emergency response, may be referenced and stored separately.

High-hazard or complex reservoirs

Check that the additional steps needed at these reservoirs do not impede its functionality to be used in an emergency.

Confirm the availability of the flood plan

In your section 12 statement you should:

  • confirm whether a flood plan has been written, or not
  • confirm whether a schedule of testing exists, and review if one is available
  • check that Part 4 of the prescribed form of record is correct and up to date
  • make any recommendations you see fit

If the undertaker does not have a flood plan, you should recommend them to write one using our guidance on how to prepare a reservoir flood plan. We advise a target timeframe of six months to complete this.

You do not need to provide a certificate of approval, although you may do so if you wish.

Recommend a revision

If your review of a flood plan reveals that there are major changes to the reservoir structures or the undertaker’s operating procedures which have not been accounted for in the flood plan you should recommend a revision of the flood plan. Examples of major changes include:

  • company re-organisation changing levels of authority, responsibility or reporting lines
  • changes to the principal dam infrastructure, for example, a replacement scour valve or installation of a siphon
  • revision of trigger levels or pre-determined response actions

If you recommend a revision you should include:

  • the element of the flood plan to be revised
  • the nature of the revision
  • the timeframe within which the revision should be made

Review the testing of the flood plan

We recommend the undertaker devises a schedule of testing of their flood plan which may include partial testing of individual parts.

Read guidance to undertakers on how to review, test and revise a reservoir flood plan.

A record of each test should be kept along with any comments regarding its outcome or the need to change the flood plan.

You should review the schedule of planned and actual testing.

In your section 12 statement you should confirm:

  • a schedule of testing is available
  • any recommendations for testing as you see fit

If you make a recommendation for testing, you should include:

  • the element of the flood plan to be tested
  • the manner in which it is to be tested
  • the interval between each subsequent test.

Test examples

To test emergency draw drown, the scour valve should be fully opened and the water allowed to run until clear.

Frequency: annually or in accordance with a recommendation by the last inspecting engineer, whichever is sooner

To test the ability to carry out physical repairs, contact the suppliers of materials and labour to confirm availability.

Frequency: annually

To fully test the flood plan, exercise all aspects of the flood plan using all staff identified in the plan

Frequency: within one year of a change of undertaker, or substantial change in staff

Testing may use desk-based scenarios as well as physical activity, but a full incident simulation exercise should be carried out periodically. This should test the undertaker’s response but does not have to include external emergency responders.

You should check this is included in the test schedule.

Undertakers with multiple reservoirs should provide a schedule of testing in accordance with our guidance.

A successful test should demonstrate that the flood plan works, or that lessons from any shortcomings have been recorded, learned from and applied in a revised version. A successful flood plan test does not have to run smoothly.

Construction engineers

If you are appointed as a construction engineer, you should:

  • advise the preparation of a flood plan during the construction phase
  • consider withholding a preliminary certificate until a flood plan is in place

You should check the flood plan before the issue of a final certificate and follow the guidance for supervising engineers above to provide your comments and recommendations.

You can include your recommendations in the annexe to your certificate of efficient execution of works or as a separate document.

Inspecting engineers

You should check and discuss with the undertaker any comments or recommendations made by the supervising engineer.

In your inspection report you should:

  • confirm whether a flood plan has been written, or not
  • confirm any record of flood plan testing which has been carried out
  • make any recommendations you see fit

We consider the availability of a flood plan as an important matter for the overall safety of a reservoir. If there is no flood plan, you should consider including this as a recommendation under section 10(3)(c) as to measures to be taken in the interests of safety.

If you are concerned for the safety of the reservoir or have recommended safety measures, you may also consider providing a recommendation to revise the flood plan.

Read our Guidance for undertakers on how to prepare a reservoir flood plan

Read our Guidance for undertakers of how to review, test and revise a reservoir flood plan

Last updated