Spillways & Dams

Project Description

In the wake of 2017 failure of the Oroville Dam Spillway, the Division of Safety of Dams (California Department of Water Resources) is requiring owners of high-hazard dams to conduct a comprehensive study of their spillways. PID has two spillways affected by this requirement: one each at Paradise Lake and Magalia Reservoir. Following the detailed analysis, PID will be required to make any required spillway repairs/upgrades that come to light as a result of the study.

Additionally, Magalia Dam, was built in the early 1900s and needs rehabilitation. 

Magalia Dam, built in 1918 is a hydraulic-filled dam, rated poor by the Division of Dam Safety and at full capacity is considered a high downstream hazard should there be a significant earthquake. Because of this rating, the State Division of Dam Safety (DSOD) limits the reservoir elevation to 2200 feet at a loss of approximately 2000 acre-feet of water storage.

The Paradise Irrigation District is actively working on a design to bring Magalia Dam and spillway back into compliance with the DSOD, as well as widen the top of the dam to allow for future widening of Skyway for future fire evacuation needs (limited evacuation routes were an issue during the Camp Fire). While not in compliance, Magalia reservoir’s storage capacity is limited to 796 acre-feet, a small fraction of its designed volume, which reduces water storage that could be used for fire-fighting efforts. The project is designed to also replace and relocate the spillway to the opposite side of the dam reducing damage risk to the water treatment plant.

Current Design Status

The design is fully funded and 60% complete. Design was delayed almost a year by FEMA pending environmental approval for investigative boring. 100% design is expected by Fall 2026. We are also engaged with Bute County to see if there is a desire to reconstruct the road that runs across the dam into Magalia.

Spending Plan

The spending plan will be updated to reflect necessary spending as a result of design work in progress.

Project Details

• Project Manager: Blaine Allen, Engineering
• Funding Source: Operating Fund
  • The District is actively seeking financial assistance for this project.
• Project Status: Planning

Anticipated Project Timeline

• Concept Approval: June 2017
• Planning: May 2017 - September 2017
• Design: Current
• Construction: To Be Determined
• Completion: To Be Determined

Benefits to PID & Its Customers

• Increased spillway safety