In fall 2024, the Marin County Flood Control and Water Conservation District completed the infrastructure for a portable pump station at Drake Avenue and Donahue Street in Marin City, near the Highway 101 ramps. These pumps are used during high tide events that occur at the same time as rainstorms to help reduce flooding at the intersection.
The portable pumps were first used in December 2024 for a major storm that occurred during a king tide event. The pump station worked as planned, allowing stormwater runoff to bypass the Marin City Pond, which was at capacity due to the storm and king tides, and discharged it into Richardson Bay. The result was that traffic flowed normally through the Donahue and Drake intersection despite the weather, maintaining access into and out of Marin City. Without the portable pump station, the intersection would have been flooded for an extended period of time.
How the system works:
Marin City Pond is the main drainage area for stormwater in the Marin City community. Normally, water flows through a pipe into the pond and then drains out to Richardson Bay. However, during high tides, water cannot flow through the pipe. To prevent tidal flooding back into Marin City, a gate on the pipe is closed during high tides. When the gate is closed and it is raining, the stormwater has nowhere to go. That’s when portable pumps are used – they help move the water away from the intersection, bypassing the pond, and sending the water directly into Richardson Bay. This minimizes the flooding and helps keep the roadway clear.
The portable pump station does have some limits. It can only pump water that reaches it, and water may pond in some areas before it can flow to the station. Other parts of the stormwater system, like storm inlets, catch basins and pipes, can sometimes get clogged with leaves or trash, causing water to pool in certain spots.
Additionally, the pump station is only used when necessary. If the tide is low enough, the stormwater can still drain through the pond’s pipe naturally, even during heavy rains. The water capacity of the pond’s drainage pipe far surpasses the capacity of the pump station. The topography of the area and related gravity pathway facilitates a natural path for the stormwater to flow into the pond and out through the pipe, dispensing it into Richarson Bay.
To learn more:
More information on the completed pump station project can be found on the project webpage and in the news release. For information on other efforts in the works to help with flooding in Marin City, visit the Marin City Stormwater Plan project webpage.