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January 24, 2021
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Laguna Wastewater Treatment Plant impacted by flooding

March 8, 2019

The City of Santa Rosa has proclaimed the existence of a local state of emergency as of Feb. 28, 2019 following the recent atmospheric river weather event. 

The Laguna Wastewater Treatment plant was impacted during the storm by localized flooding, and sewer flow rates coming into the plant were higher than ever recorded, placing strain on the system. 

The Laguna Treatment plant closed to non-essential staff due to severe localized flooding Feb.26 and most of Feb. 27. Only plant operators managing the increased flows remained to ensure that treatment operations continued throughout the storm event and took extraordinary steps to maintain the system. 

Sewer flowrates were over five times the winter daily average and remained above the system capacity for a sustained period. Treatment plant operators diverted raw sewage into equalization basins located at the treatment plant and at the West College Facility until they reached maximum capacity. Once the system was no longer able to hold back additional water, operators were forced to send the water through the treatment plant at higher rates than the treatment process is designed to handle. These historically high flow rates led the city to begin to discharge treated effluent from Meadow Lane Ponds into Colgan Creek and the Laguna de Santa Rosa and from Delta Pond into Santa Rosa Creek.  Due to the flooding, high flows, and dangerous storm conditions, City Water Reclamation staff were escorted by the Fire Department’s Swift Water Rescue Team to Delta Pond to open the valves necessary to begin the emergency discharge. 

The Laguna Treatment plant has a discharge permit that allows discharge into these waterways, however, the discharges into the local waterways was done on an urgent basis without the same level of data gathering required in the treatment plant’s permit due to the emergency nature of the operation. Access to this pond for monitoring the discharge conditions continues to be limited due to high floodwaters.

Additionally, current forecasts suggest another atmospheric river is scheduled to bring more precipitation to the area beginning March 5, which could further strain the treatment plant’s ability to treat water and to store recycled water. Staff continue to evaluate the situation and available options to manage treatment, discharge and storage, as necessary to continue essential operations at the treatment plant.  Once floodwaters recede, the staff will be better able to assess conditions and identify any necessary resources.