Planning for Sea Level Rise

Do you like to flush your toilet?  Many of us rely on this small daily action without thinking twice about it. However, due to climate change, even a toilet flush may eventually be a luxury. As greenhouse gas emissions continue to increase due to inaction on climate change, the projections for sea level rise are growing more dire and threatening our basic water and sewage infrastructure.

According to a new study by San Mateo County, some of the most threatened assets in the County are the five wastewater treatment plants located along the edge of the Bay.  A sixth treatment plant is currently in the planning stages; this plant will serve the City of San Mateo, Foster City, and the San Mateo Highlands. When planning started on the treatment plant, the amount of expected rise was 3 feet. Some ten years later, the expected rise will likely include half a foot more of seawater and could potentially be much more.

Until recently, planners took into account a projected sea level rise of 3 feet by 2100. In the past few months, the San Mateo County Vulnerability Assessment and an updated version of the State of California Sea Level Rise Guidance were both released and challenged the current standards.  The new guidelines recommend planning for 3.4 feet of sea level rise for minimum acceptable risk management in a likely scenario, and caution that if emissions go unchecked we could experience over 7 feet of seal level rise, which San Mateo County as a whole is planning for. Such drastic sea level rise would negatively impact every resident in the area – human and non-human alike.  In addition to the rising seas, every year there is a 1% chance of a 3.5 foot flood on the Bay side.

At the least, the advancing seawater places crucial wastewater infrastructure at risk. The planned treatment plant is only designed to withstand a rise of 3 feet, which concerned Helen Wolter, our San Mateo County Legislative Advocate.  With long time local advocate and Planning Commissioner John Ebneter, Committee for Green Foothills advocated for further planning to ensure that the plant would be prepared for the higher level of expected sea level rise. The San Mateo City Council voted 5-0 to approve the plan for the plant but ordered an update of the technical specification documents associated to support the expected sea level rise.

In the future, both new buildings in or near inundation zones and retrofits of existing structures will need to be carefully managed by every municipality in the region.For right now, to safeguard the health and well-being of our communities (and to make sure that everyone’s toilet still flushes), Committee for Green Foothills will be advocating for effective action to mitigate the effects of sea level rise.

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