How much rainwater have you kept in your yard so far this season? It's not too late to start harvesting it.

Indeed, this is the best time to do some simple earthworks to take advantage of free irrigation.

Catlow Shipek suggests a two-step method to get started.

First, take a look at how the rainwater runs off your roof and through your property. "Observe it during a rainstorm," advises Shipek, co-founder of the Watershed Management Group.

Then spend time digging the softened dirt and building some features that direct that water to plants. "The next day carve it out," he says.

The contours, used in what's called passive water harvesting, guide and slow water so it seeps into the soil at the plant's roots and not run off into the street.

"You are in control of where the water goes on your land," explains Dan Dorsey, office manager and teacher at the Sonoran Permaculture Guild.

Depending on the slope of the land, contours don't need to be deep to collect some water. That means you can create a feature in just a couple of hours.

"Start with a small feature and you can expand it," says Shipek.

A contour can be as simple as a water-collecting basin around a plant, Dorsey says.

"I like a series of basins, says Dorsey. Connecting them with spillways allows water that fills one basin to flow into an adjoining one.

Don't dig below-ground basins for established plants to avoid damaging roots, he says. Instead, build up a basin with a berm, an above-ground barrier, around the plant or in an arc on the downstream side.

For plants on mounds, build a berm around the entire mound or downstream, he says.

Basins should be at least as wide as the spread or canopy of the plant.

Shipek uses a swale, a shallow ditch, to divert water from his home's foundation to other parts of the yard. The dirt he dug up for the swale was used to build up basin berms around existing trees.

Some other tips from the experts:

• Whenever you put in a new plant, put it in a below-ground basin.

• Use the dirt you dig up to create walking paths between contours.

• If you don't want to see drastic contours in your yard, loosely cover them with organic mulch. It helps even out the landscape, improve the soil and slow soil erosion.

• Beautify swales with plants inside them. They eventually disappear from sight under canopies.

• Line features with rock to slow soil erosion. It also adds a finished look.

More help

These organizations offer workshops and resources on planning and creating passive rainwater harvesting systems:

• Pima County Cooperative Extension's WaterSmart program,

• Sonoran Permaculture Guild,

• Tucson Water's Rainwater Harvesting Incentives/Rebate Program,

• Watershed Management Group,

Contact local freelance writer Elena Acoba at