Update: March 18, 2025 AT 2:00 P.M.
Following the March 18, 2025 storm event, flows in the Cosumnes River dropped below the 7 foot Action/Monitor Stage by 2:00 pm on March 18, 2025. Diversions, which started on March 17, 2025, were then stopped. Water may be present in the impacted canal and agricultural field areas for up to 48 hours after the diversions have stopped.
Update: March 17, 2025 AT 12:00 P.M.
Flows in the Cosumnes River are projected to rise above the 7 foot Action/Monitor Stage by noon on March 17, 2025. Diversions will begin at this time and stop when the observed data collected at Michigan Bar reaches 7 foot (via the California Nevada River Forecast Center).
Background
On February 4, 2025, the Sacramento County Board of Supervisors ratified a Proclamation of Local Emergency related to Winter Storms of February 2025. This Proclamation authorizes the Director and Deputy Director of Emergency Services to utilize powers, functions, and duties prescribed by relevant law and policy. Furthermore, California Governor’s Executive Order N-16-25 temporarily authorizes local agencies to trigger provisions in California Water Code section 1242.1 without an adopted floodflows diversion plan. In consultation with Sacramento County Department of Water Resources (DWR), this February 13, 2015 announcement from Sacramento County Office of Emergency Services serves as the formal Notice of Floodflow Diversions for Groundwater Recharge required by California Water Code section 1242.1.
To lessen impacts of the imminent risk of flood and inundation of low-lying land, roads, and structures in the Cosumnes River Watershed (downstream of Dillard Road), the Rancho Murieta Community Service District will begin diverting an estimated 250 acre-feet of floodflows from the Cosumnes River through existing diversion infrastructure to the east of the Rancho Murieta community. These floodflows will then continue flowing through the Cosumnes Irrigation Association’s ditch system to the agricultural fields west of the community of Rancho Murieta, where it will be applied for the purpose of groundwater recharge. Those interested in diverting flood flows should contact the County to ensure appropriate notices are in place. Please contact County staff at CosumnesRiver@SacCounty.gov or 916-874-8546.
Any changes to this schedule, including communication of cessation of the imminent threat conditions, will be shared as amendments to this notice.
The flow threshold and timing of when these floodflows will be diverted were determined by using the water levels in the Cosumnes River at Michigan Bar as projected by the California Nevada River Forecast Center. It is projected that at 4:00 pm on February 13th, the water levels will rise above the 7 feet Action/Monitor Stage. Diversions will then be suspended once flows in the Cosumnes River drop below the Action/Monitor Stage at Michigan Bar, which is anticipated to be on February 15th.
Reclamation District 800 has also issued a Local Emergency Proclamation and identified specific areas of erosion concerns brought on by storms that devasted the area in 2023. Additionally, current Sacramento-San Joaquin Delta conditions/restrictions do not apply to the Cosumnes River Watershed, and this action complies with all provisions of Water Code Section 1242.1.
Location of Noticing
Sacramento County Office of Emergency Services Website
Sacramento County Department of Water Resources Website
