Harvesting rainfall

According to various reliable websites, Mariposa’s average rainfall over the last 30 years has been 31-to-33 inches, depending on the source.

That’s a lot of water you could be capturing (current lingo prefers “harvesting”). Why should you do it? The answer is obvious. We all want save as much water as possible, and in this drought, every drop counts.

Mariposa County Master Gardeners will present a free rainwater harvesting workshop, 10 a.m. to noon, Sept. 26, at the Board of Supervisors chambers, 5100 Bullion St.

Regina Hirsch of Mountain Sage Nursery in Groveland is the presenter and will focus on systems for the home gardener. She will cover not only roof-to-gutter-to-container systems, but using basins and barriers made of earth to keep the rain from running off.

Container systems can be as easy as an old-fashioned rain barrel sitting beneath your downspout or as intricate as systems of pipes, filters, pressure gauges, overflow valves and enormous water tanks. Hirsch will help you figure out what’s best for your yard.

Here is a formula for you to figure out how much water you could collect from your roof: (1) Take the average rainfall. (2) Take the square footage of your roof. (3) Multiply those two numbers together. (4) Multiply the result by 0.623 (the number of gallons one inch of rain will produce on one square foot of surface). You’ll be surprised at how much water you could leave in your well.

You must register by phone for this workshop, 209-966-2417 or on the website,

Mariposa Master Gardeners