OPPD, USACE coordinate ahead of 2020 flood season

Ahead of the new year, OPPD is working to understand what might happen with the Missouri River in 2020 and its potential flooding impacts on district operations and property.

By maintaining close communications with the U.S. Army Corps of Engineers, a cross-functional OPPD team is working to analyze river trends and proactively line up resources to mitigate forecasted impacts.

Projections

The Corps projects above-average releases from upstream reservoirs over the winter in an effort to deplete stored waters. Snowpack in the mountains and plains is a variable, one they’ll monitor closely. When that accumulation melts in the spring, it will likely be on top of saturated soil which would increase runoff.

At a public meeting in late October, the Corps of Engineers shared this presentation which included the following:

  • The Corps expects to have the Mainstem Reservoir System water storage at 56.1 million acre feet (MAF) prior to the spring runoff season.
  • 1 MAF is at the top of the system, which leaves all designated storage zones available to start the 2020 runoff season.
  • These storage zones consist of 23% of the total capacity of the reservoir system.

USACE 3

 

  • The Corps has released water from the Gavins Point Dam at 80,000 cubic feet per second (CFS), and has begun lowering to 22,000 CFS for the winter release rate.
  • They may continue releasing at higher rates if weather is mild.
    In normal years, the winter release rate is around 17,000 CFS.
  • They explained that the ground is highly saturated throughout the basin. Forecasts show this will remain the case through winter.
  • This may result in a spring runoff where precipitation won’t soak into the ground and will run off into the river and streams.
  • Contributing factors (e.g., wind, low precipitation) have aided reducing soil saturation throughout the basin.

 

Business Continuity

OPPD’s Business Continuity Plan (BCP) is applying the lessons learned from flooding in 2019. They can then use those lessons to address potential 2020 floods.

The group has actively gathered information from 2019 and is analyzing the data for possible inclusion in the BCP ahead of the upcoming flood season. They are also working closely with operations teams to evaluate protective measures left in place from 2019 that may provide future protection.