#EN1215-19 El Niño

El Niño is a naturally occurring event in the equatorial region which causes temporary changes in the world climate. El Niño events occur approximately every four to twelve years, ranging in strength from weak, moderate, and strong. Depending on the strength of an El Niño event, it can last from winter to spring.

The effects in the United States can be seen with warmer temperatures in the western Pacific and fewer hurricanes in the East. As a result, more moisture and cooler temperatures are observed in the southern portion of the United States whereas the northern portion of the United States will see below average rainfall and drier than average conditions. As a result, more rainfall will occur in the west and tropical storm conditions can be expected.

During an El Niño year, more erosion can occur due to intense rain events. El Niño years can also bring dangerous floods, mudslides, and extreme weather conditions. In addition, construction hours are often limited due to severe weather, and material deliveries may not be able to come in when needed. Working conditions after or during a rain event can be dangerous to the workers’ safety. Cautionary procedures should be in place to prepare for a storm, as well as during and after a storm to reduce risk as much as possible.

To prepare for an El Niño, general contractors and QSPs should perform the following:

  • Monitor daily weather reports for any incoming precipitation from NOAA
  • Implement BMPs and ensure their effectiveness
  • Inspect adjacent drain inlets to sites for blockage and draining capacity
  • Locate extra stock of BMPs onsite to deploy when needed
  • All employees should participate in a SWPPPs refresher training session to review all protocols during a rain event