Sandbags, with or without plastic tarps, offer a simple, effective way to greatly reduce floodwater damage to your home. When they are properly filled and placed, they create a barrier that will divert moving water around, rather through, your home. Even the most carefully placed sandbags will not guarantee a water-tight seal, but they definitely can prevent a lot of heartache. Note that local water agencies use sandbags atop levees to prevent overtopping of streams.
Our friends at SLV Post have put together a comprehensive list of locations, from Watsonville to the San Lorenzo Valley, that make sandbags available to residents. Note that some will require proof of residency.
Read 'Where to Get Sandbags in Santa Cruz County' at the San Lorenzo Valley Post.