Map shows San Luis Obispo County is in ‘extreme drought’

pgeweather@pge.comAugust 24, 2013 

On Thursday, the National Drought Mitigation Center (NDMC) released its latest drought monitor map for the United States. The NDMC classifies drought in five categories of increasing severity:

• D0: abnormally dry.

• D1: moderate drought.

• D2: severe drought.

• D3: extreme drought. 

• D4: exceptional drought. 

This month, the drought classification for San Luis Obispo County changed from D2, severe drought, to D3, extreme drought. 

The past two rain seasons (July 1-June 30) have seen well-below-average precipitation. In fact, this year’s January-June period for the city of San Luis Obispo will go down as the third-driest such period on record at Cal Poly (home of climatology for the city) since 1870, when weather observations started. 

Since January, Cal Poly has recorded only 3.5 inches of rain. Normally, it should have received about 15 inches. 

The county’s extreme drought condition will continue to increase competition for water among agricultural, environmental, residential and industrial interests, and as the price of water increases, conservation will become progressively important.

Back in the late 1800s, Mark Twain supposedly said, “Whiskey is for drinking; water is for fighting over.” 

There is no tangible evidence that the humorist and writer actually said this. Regardless, the phrase illustrates the importance of water in all our lives.

About the same time this quote was supposedly uttered, the Point San Luis Lighthouse was under construction. A well was too expensive to drill, so the builders installed a 15,000-square-foot rain collector behind the lighthouse that drains into two 25,000-gallon cisterns — tanks for storing rainwater. Each inch of rain that falls on this collector produces about 9,400 gallons of water. 

It takes a little more than 5 inches of rain to fill both cisterns. The Port San Luis Harbor District and Point San Luis Lighthouse Keepers use this water for irrigation and firefighting.

Local architect and Cal Poly graduate Rick Rengel has done a lot of volunteer work at the light station. 

He told me, “The Point San Luis Lighthouse cisterns are a throwback to the days of old that are now becoming popular again.” 

You see, LEED, or Leadership in Energy & Environmental Design, certification for buildings now awards points for cisterns. Today, water from cisterns is considered nonpotable — in other words, not fit for human consumption. But it certainly can be used for other needs. 

In the future, water from cisterns will be increasingly used for purple (lavender) pipe applications. Reclaimed water is distributed in purple pipes to distinguish it from potable water. Reclaimed water or recycled water can be utilized in irrigation or to recharge groundwater aquifers. 

Rengel went on to say, “Earth is our best filter system, and it’s free.” 

Remember, even in the driest years, we always get a few weather systems that produce rain. 

Did you know that PG&E delivers some of the nation’s cleanest power? More than 50 percent of the electricity the company provides to customers comes from sources that are renewable and/or emit no greenhouse gases.

John Lindsey’s column is special to The Tribune. He is a media relations representative for PG&E and a longtime local meteorologist. He is president of the Point San Luis Lighthouse Keepers. If you have a question, send him an email at

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