Learn to Manage your Water

By Steve Savage

U.C. Cooperative Extension, El Dorado Co. Master Gardeners

Publication Date: July 23, 2004

In the sixth year of an extended drought, reservoirs are at 25% of capacity. Deliveries to agricultural interests in the Central Valley have been slashed, and home owners have been ordered to cease all landscape irrigation. Has it happened yet? No. Could it happen? You bet! With water storage essentially capped and an ever increasing population, eventually something must give. However, there is something the public can do to help forestall the above scenario. Through sensible water management and conservation techniques, water use in the home landscape can be drastically reduced.

One of the most effective ways to manage water use is to purchase, install, and use an irrigation controller that will allow you to establish different watering zones. Through proper controller programming, different areas of the landscape can be irrigated on separate schedules according to the water needs of the landscape. For instance, lawn areas require several lengthy water applications per week in the summer, while a bed of drought tolerant perennials or an area of drought tolerant ground cover might require only a single irrigation every two or three weeks. A good controller will allow you to water on the proper schedule instead of watering everything at the rate of the highest use area of the landscape, in this case the lawn.

If you live on sloping terrain, as many of us do in El Dorado County, you can reduce water use by using proper water application techniques to avoid runoff. On slopes, use of short “on and off” cycles are best so that the application rate matches the soil's ability to absorb water. To do this, turn on your sprinklers and allow them to run until the first signs of runoff appear. Turn the sprinklers off to allow this water to soak into the soil. After a half hour or so, turn the sprinklers on again until runoff begins. Once again, turn the water off to allow absorption. Repeat the cycle until enough water is applied to thoroughly soak the soil to the necessary depth. With the sprinkler run times and number of cycles necessary now known, program your controller accordingly for the slope area sprinklers.

How often should I water? As a general rule, infrequent, deep watering is preferable to frequent, shallow watering. Watering too often and too shallowly encourages excessive evaporation, shallow rooting and hence less drought tolerance, salt buildup, and may provide optimal conditions for certain diseases. Infrequent, deep watering, on the other hand, encourages deep rooting which helps the plants to be more drought tolerant, decreases evaporation loss, reduces the chance for disease, and lessens weed growth by lessening the amount of time the surface soil, where weed seeds lie, remains moist.

So how deep is deep enough? Lawns and flower beds need to be wetted to a depth of 12 inches, shrubs to one to two feet, and trees to two to three feet. The best time to water for water conservation is in the early morning, when less water will be lost to evaporation. Late afternoon, when air temperature is high and humidity is low, is the worst time, as evaporation loss will be at its highest.