Urgent Alert

Hydropower and water safety

Stay safe near dams, reservoirs and other waterways

Our hydroelectric system is one of the largest in the country. The system provides clean, renewable energy and offers many recreational opportunities. Reservoirs, dams, rivers and streams are available for swimming, fishing and boating. Campgrounds, picnic areas, boat launches and trails are ready for you to enjoy. Before you visit our recreational areas, take a moment to learn about hydropower and water safety.

How water generates electricity

The movement of water rushing from a higher elevation to a lower one produces hydropower. This movement turns a turbine and creates electricity. Dams hold the water, creating reservoirs. Water moves from the reservoirs to powerhouses through waterways, such as rivers and streams. After reaching a powerhouse, the water generates electricity that is transported to the power grid.


hydropower safety


More facts about the PG&E hydroelectric system


Our hydroelectric system:

  • Is built along 16 river basins. The basins stretch nearly 500 miles in our service area.
  • Uses water from more than 98 reservoirs. Most of the reservoirs are located in the higher elevation of California's Sierra Nevada mountain range.
  • Has 67 powerhouses.
  • Produces roughly 3,900 megawatts (MW) of power.
  • Can provide power for nearly four million homes.


A hydroelectric system can have large amounts of rushing water present at any time, sometimes without warning. It is important to be cautious around facilities and recognize warning signs. 

What to do during emergencies

Although our dams and reservoirs are very safe, an emergency is always possible. When you’re around water that is part of a hydropower system, you must understand emergency warning signs. Know what to do during emergencies.

Follow these tips when visiting waterways:

  • Dams and reservoirs
  • Rivers, streams and other waterways
  • Canals, flumes and penstocks

When you visit a reservoir, river or other body of water, use the following guidelines:


  • Obey all warning signs and restrictive buoys when you swim or boat.
  • Use the buddy system; that is, never fish, swim, boat or raft alone.
  • Don’t dive or jump into unfamiliar or shallow water. Submerged trees or rocks can cause serious injury.
  • Wear a Coast Guard-approved life jacket in and around water at all times, even when water levels are low.
  • Avoid sudden immersion in cold water. This action can stimulate the gasp reflex and cause an involuntary inhalation of air or water. The gasp reflex can trigger cardiac arrest, temporary paralysis, hypothermia and drowning.
  • Teach children that swimming in open water is different from swimming in a pool. They must be aware of uneven surfaces, currents and undertow. They must also watch for signs of changing weather.
  • Actively supervise children around water. Give them your undivided attention.
  • Comply with all warning signs in campgrounds, fishing areas and picnic areas below dams.
  • Make a plan with your family so that everyone knows to get out of the water at a moment's notice.

Designed for hydropower production, reservoirs also offer recreational areas for camping, picnicking, boating, fishing and hiking. Be sure to take the following precautions around dams and reservoirs:


  • Stay out of spillways and water intake areas. Water can rush in, making these areas dangerous for play.
  • Don’t swim or play near a dam or powerhouse. These areas can have strong underwater currents, sudden water discharges, slippery surfaces and submerged hazards.
  • Obey all warning signs and restrictive buoys. These warnings are intended to keep people away from areas where water activity can change suddenly, posing a risk of injury or death.

Comply with all laws and requirements when boating on a reservoir. Use the following safety guidelines:


  • Plan ahead and be prepared for changes in the weather.
  • Before you go boating, file a float plan, that is, a written statement with the details of your trip. Leave the float plan with a reliable person whom you can trust to notify the Coast Guard if you don’t return on schedule.
  • Never operate a boat while intoxicated.
  • Know your skill level.

Learn more about boating on a reservoir. Visit California State Parks – Division of Boating and Waterways.

Many Northern California waterways are part of a vast hydropower system, with dams located upstream and downstream of the most popular recreational areas. During certain times of the year, sudden changes can occur in water levels and river flows. Heavy rains, melting snow or electric generator use can change a waterway from a slow stream to a raging river in minutes.


Use the following tips to protect yourself and your family in these areas:


  • Always be alert and aware of your surroundings. Dams hidden from view can still affect the water in unexpected ways.
  • Look for water level changes, including those affected by rain and melting snow.
  • Be aware of your location when powerhouses are nearby or across a stream.
  • Remember that some roads and trails might not be accessible after a water release. The extra water can flood these areas temporarily.
  • Learn the meanings of powerhouse warning signs, strobe lights and sirens. Move to a safe area when warned.

Canals, flumes and penstocks move water from one part of the hydropower system to another. Canals and flumes might look inviting, but they can be very dangerous because the amount of water in them can increase quickly. Use the following tips to stay safe near these areas:


  • Never get into a flume or canal. The water might appear calm, but it is extremely powerful.
  • Stay off flumes. Flumes have steep, slippery sides and contain icy cold water. Getting out of a canal or flume can be very difficult.
  • Obey all warning signs, and never play on or near a canal or flume.
  • If you drop a personal article in a canal or flume, leave it. Retrieving it is not worth the risk of injury or death.

Be aware of the following emergency warning signs when you’re in or around water:


  • Intensified sound of rushing water
  • Increased water speed or depth
  • Increased amounts of debris in the water
  • Changed appearance of water from clear to muddy
  • Unusually colder water temperatures

When you’re in the water during an emergency, take the following actions:


  • Drop any items that might weigh you down.
  • Stay calm and lie on your back.
  • Keep your feet up and pointed downstream to avoid hitting rocks and getting tangled.
  • Go with the current and move diagonally across it until you reach shore.
  • Roll onto dry land to drain your boots or waders.

When you’re near the water during an emergency, take the following actions:


  • Move to higher ground.
  • Access the National Weather Service Emergency Alert System on a weather radio.
  • Do not walk through moving water.
  • Avoid driving through flooded areas.
  • Make an evacuation plan for your family in advance and follow it.

Staying safe around water

 Learn more about water safety in and around our facilities.