Emergency incidents: what owners should do

Washington has many active fault zones. Small earthquakes occur frequently, but are usually too small to be felt. Less common are larger earthquakes, but these can cause significant damage to dams.

Owners should inspection their dams after an earthquake and report any damage to the Dam Safety Office.

For more information on earthquakes in Washington:

• The Pacific Northwest Seismograph Network
• Washington State Department of Natural Resources – Earthquakes and Faults

Tsunami

In Washington, the Pacific coast, Strait of Juan de Fuca, Puget Sound, and large lakes are at risk for tsunamis. Dam owners who live and/or operate in these areas should evaluate if they are at risk.

For more information about tsunami’s in Washington:

• Tsunami tips, preparedness information, and tsunami evacuation maps by county
• Washington State Department of Natural Resources – Tsunami Info

Washington is among the most flood-prone states west of the Mississippi River. In Washington, the costs of flood damages exceed the cost of all other natural hazards. 

Our Washington Conservation Corps (WCC) program is available to help with flood problems that are related to dams.

WCC crews can deploy to perform flood-fighting and prevention actions such as sandbagging, operating pumps, clearing roads, and more. They are stationed across the state and can often respond quickly.

Requests for assistance must be routed through the city or county emergency management office where the dam is located. You can look up the local emergency management office at this link: Local Emergency Management Offices.

Sometimes the WCC services are free or at reduced costs depending on available funds and the cause of the problem. You can contact either of the following WCC managers to discuss process, availability, and funding options: Joshiah Downey at 360-480-2603 or Bridget Talebi 360-480-2293.

General information about the WCC assistance program can be found at WCC Response and Recovery Information.

Here are resources for dam owners:

• Floods and floodplain management planning and project resources for communities
• Magnitude, frequency, and trends of floods at gaged and ungaged sites in Washington, based on data through water year 2014 — USGS

It's important that dam owners understand the potential impacts of wildfire on dams, especially if wildfires are followed by heavy rains. Wildfires can damage:

• The surface of a dam or spillway, especially grass cover on embankment slopes or grass lining in a spillway channel.
• Associated facilities, especially wood structures or plastic pipes.

Wildfires also change the water conditions of a watershed, such as how fast water can move and how vulnerable land is to erosion. Heavy rains in a burned area can create:

• More and faster runoff from rainfall, especially high-intensity storms.
• Large amounts of sediment, which may reduce storage capacity in a reservoir.
• Debris flows (mudslides) or downed timber, which may obstruct spillways or access to a dam.
• More floating debris (dead trees, branches, sticks, etc.) in a reservoir, which may obstruct spillways.

What to do after a fire

If a wildfire occurs at or near a dam or within the watershed, dam owners should consult a qualified engineer or engineering hydrologist to assess the increased hydrologic risk; this is especially true if the dam is classified as "significant hazard" or "high hazard." The following resources are intended as a potential starting point for qualified consultants to assess dam safety after a fire:

• Recommended dam safety protocols for burned watershed hydrology calculations — guidance for calculating post-fire watershed parameters
• Spreadsheet for calculating post-fire watershed parameters — read the above guidance document before using this spreadsheet

In addition to this guidance from the dam safety office, the Natural Resources Conservation Service compiled their own more comprehensive guidance for performing post-wildfire hydrologic analyses:

• Hydrology Technical Note 4 – Hydrologic Analyses of Post-Wildfire Conditions — August 2016

If rain is forecast after a fire

Dam owners must closely monitor runoff and spillway performance especially after heavy rain or flash flooding. Dam owners need to be ready to implement their emergency action plans in case the spillway capacity is exceeded.

• Wildfire impacts on dams
• Focus on dams and wildfires