How to Prepare Your Yard for El Niño: A California Storm Checklist

NOAA's outlook puts the odds of El Niño this winter above 90 percent, and El Niño winters tend to bring heavier storms to Southern California. Most storm damage to a yard comes from two places: water coming off the roof, and the low spot that already floods every year. Fix those two before the rain and you have done most of the work.

This checklist walks through what to do, in the order that matters, with the materials each step needs. None of it takes a contractor, and all of it is easier on a dry October weekend than in the middle of a January storm.

The El Niño yard checklist

1. Clear gutters and downspouts.
2. Move roof water away from the house.
3. Check that the ground slopes away from the foundation.
4. Drain the spot that always floods.
5. Armor slopes and swales against erosion.
6. Stabilize decomposed granite paths.
7. Get sand and bags on hand before the first flood watch.

1. Clear gutters and downspouts

A clogged gutter overflows along its whole length and dumps a roof's worth of water right against the foundation, which is exactly where you do not want it. Scoop out leaves and needles, flush each downspout with a hose, and make sure the water comes out the bottom freely. Do it again after the first storm if trees drop more.

2. Move roof water away from the house

This is the single most useful thing on the list. A downspout that empties at the base of the wall soaks the soil under the foundation, and a 1,000 square foot roof sheds about 600 gallons in one inch of rain. These are the common downspout drainage ideas, from simplest to most permanent:

Option	How it works	Best for
Rock splash pad	A bed of rip rap or 2 to 4 inch river rock where the downspout lands spreads the water out and stops it digging a trench.	Downspouts that already point away from the house
Extension plus rock outlet	Extend the downspout several feet out, then land it on rock.	Most homes; quick and cheap
Buried line to daylight	Solid pipe underground, sloping down to a spot where the ground falls away, finished with a rock outlet.	Yards with somewhere lower to send the water
Dry well	A buried pit filled with drain rock, wrapped in filter fabric, that holds the water and lets it soak in slowly.	Flat yards with no lower spot
Dry creek bed	A shallow channel lined with river rock that carries water across the yard and looks like a design feature when dry.	Long runs and visible front yards

For a dry creek bed, see how to build a dry creek bed.

Rip rap and river rock for splash pads and outlets

3. Check that the ground slopes away from the house

Walk the foundation. Soil next to the wall should fall away from it, and a common rule of thumb is about 6 inches of drop over the first 10 feet. Planting beds and mulch often build up against the house over the years and reverse that slope. Pull the soil back, and if a low spot holds water next to the wall, fill and regrade it before the storms, not after.

4. Drain the spot that always floods

Every yard has one: the corner of the patio, the side yard, the low end of the lawn. A French drain is the usual fix. Dig a trench that falls away from the problem area, line it with filter fabric, lay perforated pipe in a fabric sock, and backfill with clean 3/4 inch drain rock. The fabric keeps soil out of the rock, which is what keeps the drain working for years. Where there is nowhere lower to send the water, end the trench in a dry well.

For the full range of drainage fixes, see landscape rock drainage solutions, and for choosing the stone, river rock vs pea gravel for drainage.

Drain rock and fabric for French drains and dry wells

5. Armor slopes and swales against erosion

Water that runs across bare soil carves channels, and the first big storm of a wet winter is when a slope starts to move. Line the swale or channel that carries runoff with rip rap so the water runs over rock instead of dirt, and set rock at the base of a slope where water collects. Bigger stone stays put in faster water. Landscape rock for drainage and erosion control covers sizing.

6. Stabilize decomposed granite paths

Loose decomposed granite washes out in a heavy storm and ends up on the patio or in the street drain. A stabilizer binds the fines together so a compacted path sheds water instead of eroding. It goes in when the path is built or resurfaced, so if a DG path is on your list this fall, do it with stabilizer before the rain.

For DG paths and patios

7. Get sand and bags on hand early

Sand and sandbags sell out the week a storm is named, so buy them while the weather is dry and keep them near the door they protect. Fill each bag about two-thirds full: that bag weighs roughly 35 to 40 pounds, folds flat and seals against the one below it. Use coarse washed concrete sand or fill sand, which packs firm and drains; garden soil turns to mud. Lay the bags like bricks, overlapping the joints, fold the open end under, and stamp each one down.

For a longer wall or a driveway that floods every year, concrete bunker blocks and K-rail make a barrier that water cannot push over and that comes apart again when the season ends. See the flood control and storm prep collection for sandbag sand and barriers.

Sand and barriers

Frequently asked questions

How do I prepare my yard for El Niño?

Clear gutters and downspouts, move roof water at least several feet from the foundation, drain the low spot that floods every year, line eroding swales and slopes with rip rap, stabilize decomposed granite paths, and get sand and bags on hand before the first flood watch.

How do I divert water away from my house?

Start with the downspouts. Extend each one away from the foundation and let it land on a rock splash pad, or run it underground in a buried pipe to a dry well or to a spot where the ground falls away. Then check the grade: soil next to the house should slope away from it, not toward it.

What is the best rock for downspout drainage?

For a splash pad or the outlet of a buried line, use rip rap or 2 to 4 inch river rock, which is heavy enough not to wash away. For a French drain or dry well, use clean 3/4 inch drain rock wrapped in filter fabric so soil cannot clog it.

How full should a sandbag be?

About two-thirds full. A two-thirds bag weighs roughly 35 to 40 pounds, folds flat and molds into the bag beneath it. Coarse washed concrete sand or fill sand packs firm and drains; garden soil turns to mud.

Does El Niño always mean a wet winter in California?

No. El Niño winters tend to be wetter than normal in Southern California, but it is a tendency, not a guarantee, and Northern California is less predictable. The yard work on this list pays off in any big storm, El Niño or not.

Get the materials

You can get everything on this list from us: rip rap, drain rock, river rock, sand and the full flood control and storm prep collection. Size the job with the coverage calculator, request a quote for delivery, or call (800) 215-7372.