Even Though The Rain Felt Endless This Winter, It Actually Wasn’t That Wet

It’s official: This week, San Francisco surpassed what’s normal for the water year, and the rainy season isn’t over yet. The city measures 23.65 inches of rain on average in a water year, which runs from October 1 to September 30. After a round of light showers on Monday, the downtown gauge’s water-year total hit 23.69 inches. With more unsettled weather in the forecast, that number is bound to inch up even more in April and May, before holding steady through the summer months. While this season has stood out in many people’s minds as noteworthy and painstakingly rainy, “it’s just a normal year,” said Jan Null, a consulting meteorologist with Golden Gate Weather Services.

San Diego Reservoirs Fill up As More Rain And Snow Moves Into Region

Forecasters said Tuesday that California’s markedly wet winter will continue to deliver significant rain and copious high-elevation snow to the saturated San Diego area this week. From tomorrow afternoon through early Friday, another cold storm is expected to drop a half-inch to three-quarters of an inch of moisture along the coast, three-quarters of an inch to 1.5 inches in the inland valleys, 1.5 to two inches in the mountains, and 0.1 to 0.2 of an inch in the deserts, according to the National Weather Service.

To properly capture water flow from rainfall, you need to assess where it naturally flows first. Photo: Tae Wook, Creative Commons License

Where Does Water Flow in Your Landscaping?

To capture rainwater and any excess irrigation inthe soil or rain barrels, it is first necessary to understand what happens when water comes off the roof of buildings and moves across the property.  

Where is water moving? 

Make a copy of your landscaping site plan, and label it “Water Plan.” It should have the position of the buildings and major landscaping structures. During a rainstorm, watch what happens to water as it comes off the roof of the house and moves through the property. 

  • Are there any low spots where water pools? 
  • Does water run entirely off the property anywhere? 
  • Do any buildings or hard surfaces such as patios appear to be damaged by water? Is the damage caused by rain, by irrigation, or by both?

Note the direction water moves around the property from one area to another, or through multiple areas. 

Turn on irrigation systems for three minutes, and make a note about where there is any pooling or runoff.  

Assess the downspouts for water volume

Use the following process to figure out how much water comes off any hard surface, whether it is a roof, patio, driveway, or sidewalk. 

First, imagine the total roof area of your garage is 20 by 20 feet square, or 400 square feet, and water flows off it in two downspouts.  

If half the water goes into each downspout, the roof size for one downspout is half your total area. In this example, that is 200 square feet. 

Multiply the square footage for your downspout area by 0.62 to get the gallons of water per inch of rain coming from your downspout. Using our example of 200 square feet, the formula is 200 x 0.62 = 124 gallons.  

Once you have this number, you can plan for the resources needed to capture this water runoff for later use using tools such as rain barrels.  


This article was inspired by the 71-page Sustainable Landscapes Program guidebook available at The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at 




Back-To-Back Storms Will Bring Rain, Potential For Debris Flows In Burn Areas

The first of three back-to-back winter storms will arrive in Southern California Thursday morning, bringing the potential for heavy rain along with a chance of debris flows and flooding in areas recently ravaged by wildfires, the National Weather Service said. The first storm, arriving by noon Thursday, will be fairly light — dropping a quarter of an inch to an inch of rain in Los Angeles County. Possible thunderstorms, however, could bring heavier rain to some regions, said Lisa Phillips, a meteorologist intern with the National Weather Service in Oxnard.

Week Will Start Off Warm But Turn Cool, Maybe Rainy

San Diego basked in summer-like weather on Sunday as a high pressure system sent the daytime high to 77 degrees, which is 12 degrees above average. But things are about to change.

Don’t Believe Your Windshield Wipers: Despite Storms, Southern California Water Conservation Is Still Needed

As rain continues to pelt Southern California, signs of an abundance of or even too much water are everywhere: Roads are flooded, reservoirs are filling and the wait time for Radiator Springs Racers at the damp Disneyland Resort has been less than a half hour. But as residents of burn areas evacuate and even heavier rain is forecast for Thursday, those who watch the state and local water supplies note that while the drought is technically over, the need to conserve water is not.

Evacuations Ordered, Roads Closed in California as Flooding Rain Arrives

Heavy rain and mountain snow is spreading across California and will bring the risk of flooding, mudslides and travel delays into Friday. Measurable rain is expected in the state’s largest cities, including in Los Angeles, San Diego, San Francisco and Sacramento. Mandatory evacuations have already been issued for people living near the Holy Fire burn scar due to the potential for flooding and mudslides, while those in Malibu near the Woolsey Fire burn scar have been put on alert for potential evacuation.

Pacific Storm To Bring Rain, Mountain Snow To California

California will see widespread rain and heavy Sierra Nevada snowfall through midweek, potentially bringing travel problems and raising the risk of damaging runoff from wildfire burn scars, forecasters said Tuesday. The wet pattern from a deep atmospheric fetch of Pacific moisture marks a significant change in the weather following conditions that contributed to disastrous and deadly wildfires up and down California, where hundreds of thousands of acres have burned this year.