Helicopters To Drop In Boulders To Try And Stabilize Oroville Dam's Emergency Spillway

OROVILLE (CBS13) - Repair crews are hoping boulders will help be the stopgap against erosion at the Oroville Dam emergency spillway.

The California Department of Water Resources says the plan is to drop large rocks and boulders, called rip-rap, into the erosion causing concern at the emergency spillway.

DWR's hope is that they'll be able to drop enough rock to protect the impacted area from further erosion.

Helicopters will be used to drop in the boulders.

Severe erosion on the emergency spillway led officials to issue evacuation orders to nearly 200,000 residents in the areas downstream of the Oroville Dam. The emergency spillway came into use for the first time in the dam's history over the weekend.

The issue with the emergency spillway is separate from the continued problems at the dam's primary spillway, which saw a huge hole develop in the concrete after officials increased water flows after recent storms.

Officials stress that the Oroville Dam has not been compromised. Both spillways are separate structures from the dam.

The emergency spillway is unregulated and will only come into use when water levels at the lake overflow the top.

Water has since stopped flowing over the emergency spillway as Lake Oroville's levels have receded. However, officials remain cautious and evacuation orders have not been lifted.