Elevated sea levels are already rolling into Southern California waters, leading to coastal erosion and other damage. An El Niño-driven Kelvin wave is further exacerbating conditions along the coast. And Tropical Storm Rachel could bring rain across the region this weekend.

But all of this is probably just the beginning of a very wet Southern California rainy season.

Authorities have been sounding the alarm.

“ Residents need to hear this information, and they need to hear it repeatedly, enough times so that they too can act,” L.A. County Supervisor Hilda Solis said during a recent presentation about El Niño preparations.

Heavy rain, flooding and debris flows can pose serious threats to homes and infrastructure. Officials and climate scientists say the best way to protect yourself and your property is to make preparations now, well before peak El Niño conditions arrive.

Here’s what you can do to prepare your home.

Preparing your property

One of the first steps to getting your home ready for El Niño is to understand how vulnerable it is to flooding when heavy rain or surging surf hits your neighborhood.

“It really is incumbent upon people to pause, evaluate where they live, where they travel and to really think about what would happen if those areas were flooded out,” said Kerjon Lee, spokesperson for the L.A. County Department of Public Works. “ Knowing your community, your neighborhood, where mud and debris flow might occur — is really critical.”

You can review your risks using California’s MyHazard tool, which allows you to input your address and cycle through potential risks.

Floodwaters and the landscape

Knowing if your property or neighborhood has flooded in the past can be helpful, and you can learn a lot from simply looking at the landscape in and around your home.

If your house is at the bottom of a hillside, for example, it’s probably more susceptible to debris flows, especially if the slope burned in a wildfire in the last several years. Burn scars are especially vulnerable to landslides and flooding because they lack the established vegetation that helps hold soil in place and absorbs water during heavy rain.

Other landmarks to look out for near your property are creeks, canals, drainage channels, debris basins and even low-lying roadways.

It’s also a good idea to understand how rainwater flows onto your property, where it collects and how it leaves. The goal should be for water to flow through your property safely and efficiently, without causing damage to neighbors.

That means clearing debris and overgrowth from gutters and drains now, before extreme weather hits.

Officials are also urging residents to report clogged or blocked storm drains to their local public works department.

If you live in L.A. County and are concerned about potential mud or debris flows, you can contact the county’s Department of Public Works for free advice.

Sandbags

If your property is at high risk of flooding, consider stockpiling sandbags. Many fire departments and public works departments offer sandbags to their local communities.

You can check sandbag distribution locations and availability here:

• L.A. County
• Orange County 
• Ventura County
• Santa Barbara County
• Riverside County
• San Bernardino County

Be prepared to fill the sandbags yourself, as most places only offer empty ones. Never fill sandbags with beach sand or empty used ones onto the beach.

Once you have sandbags, make sure you know how to use them properly.

Here are a few tips:

• Only fill sandbags half-full, not all the way full.
• Do not place sandbags directly against the outer wall of a building as wet bags can create added pressure on the foundation. 
• Sandbags should be placed parallel to the direction of water flow.
• The open ends of sandbags should be folded underneath and face upstream so they aren’t forced open as water flows around them.
• Sandbags should be used to redirect floodwater rather than create a dam or block its path. 
• Sandbags can be used to protect doorways, but to do so, they should have a waterproof layer like heavy plastic or waterproof canvas placed behind them. 

This diagram shows the proper way to place sandbags so that they are parallel to the flow of water or debris and redirect it away from structures.

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Los Angeles County Department of Public Works

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Local agencies offer thorough instructions on how to use sandbags online. L.A. County Public Works offers a breakdown in its Homeowners Guide.

Sandbags and other materials for protecting your home, including plywood, lumber or plastic sheeting, should be stored in a dry location away from potential flooding.

Other flood considerations

If valuables could be damaged or destroyed by floodwaters, consider moving them away from the ground or, if possible, to upper floors. Keep important documents in waterproof containers or sealed bags, and make sure to create digital copies.

Another recommendation is to check trees on your property for dead branches, cracks or other issues that might make them unstable, especially those that hang over structures. If you’re unsure or concerned about your trees, you can hire an arborist to inspect them. To trim or remove them, you will likely have to hire a professional. Cities and counties generally do not handle tree maintenance on private property.

Finally, consider purchasing flood insurance if your home is at risk — and do so as early as possible.

Standard homeowners insurance policies typically do not cover flood damage, and new flood insurance plans can take at least 30 days to kick in. If you want to consider signing up for a plan, the National Flood Insurance Program is a good place to start.

If floodwaters do enter your home, public health officials recommend drying wet areas as quickly as possible, as saturation can lead to mold. If mold does take hold, clean the area using a disinfectant. Also, wear gloves and a mask to protect your skin and lungs and throw away moldy items that can’t be cleaned.