This article was contributed by Shawn Novack, water conservation program manager with the Water Resources Association San Benito County.
During this time when we are sheltered in our houses due to COVID-19, residential water use has been going up. This is expected due to all the hand washing, people cooking more at home and people using their toilets more often at home rather than at their place of work. These are all necessary activities and constitute our new reality.
But we need to think about our water supply and not lose our focus on using this precious resource as efficiently as possible. Our wet season just ended and with pretty meager results. Overall, California received about half of its normal rain and snowpack this year. Locally, we are in pretty good shape since our groundwater basin is close to full and we are still measuring decent soil moisture. However, if next year is dry, we could be right back in drought.
The biggest water user in the residential sector for this time of year is landscape irrigation. As temperatures get hotter, more water is used.
Landscape irrigation represents well over half the water use in the average household. There are many proven ways to reduce high summer landscape water usage to keep our water supply in decent shape. Especially our groundwater supply.
At the time of this writing, the Water Resources Association San Benito County (WRASBC) is not going out to meet with customers at their homes for irrigation checks. This service is provided under normal conditions, but to keep customers and staff safe, we have refrained from offering this service for the time being. The WRASBC hopes they will be able to offer this service in June or July.
In the meantime, the following irrigation tips are being offered to assist our community in using water efficiently.
In early to mid-spring, when the air temperature is in the 70s in our county, lawns need about one-half to three-quarters of an inch of water per week. In the heat of the summer, water needs increase to about 1 inch to 1.5 inches per week. Knowing how much water to apply is half the battle. The other half is figuring out how much water is delivered by your irrigation system.
To calculate your home sprinklers’ output, the WRASBC recommends conducting a catch can test. Place small cans with straight sides, like pet food or tuna cans, on the lawn in several places and run the sprinklers for 20 minutes. Use a ruler to measure the water in each can and determine the average. Multiply by three to get an hourly irrigation rate.
The number one rule is to overlap the spray from sprinkler head to sprinkler head, known as “head to head coverage.” This applies to fixed spray sprinklers and rotors. The actual distance between sprinkler heads is determined by the gallon per minute sprinkler head and the water pressure in the system. If standalone spacing is used, your lawn will likely develop brown areas where insufficient water is being applied. This can be partially overcome by increasing watering time, but this approach will increase cost of watering and waste considerably more water.
Walking around town, one sees a lot of runoff. Much of the water that is applied to lawns runs directly into the gutters. Not only is this wasted water, but the runoff carries pollutants—including pesticides and fertilizers—into the gutters and, eventually, into waterways. The problem is that typical sprinkler systems apply water faster than the soil can absorb it, which leads to runoff. This is especially true for our local clay soils that don’t absorb water very well and for landscapes that are installed on a sloping hill.
To prevent runoff, use “cycle and soak,” a setting available on many irrigation controllers. If your controller doesn’t have this setting you can program your timer to irrigate for a small amount of time, then let the soil absorb the water for about an hour, then apply more water for a short interval.
Sprinklers that spray a mist over lawns are another cause of water waste. Much of the water evaporates before it reaches the ground. Sometimes this is due to high pressure.
You can save water by converting to rotary nozzles. The nozzles shoot out streams of water that provide very uniform watering and at a low volume to allow the soil to absorb the water. They have been shown to improve efficiency by 10 to 20%. The WRASBC is offering rebates on this hardware.
In landscape borders, homeowners can save water by using a drip irrigation system. Drip irrigation will target water directly where the plants are growing, so no water is wasted wetting ground in areas where plant roots cannot reach. For optimal efficiency, the system must be carefully monitored throughout the growing season.
Drip can be a great water saver, but it can also waste water if the system is poorly designed, if it’s allowed to run too long, or if lines are accidentally cut with a shovel or other tool.
Another water-saving strategy is preventing evaporation at the soil surface. The WRASBC suggests topping the soil with bark, wood chip, straw or other mulch.
Bark and wood chips provide a long-lasting barrier to water evaporation from the soil. Straw mulch works well in vegetable gardens. It saves water, keeps down weeds, and helps cool plant roots in the heat of the summer.
Whatever irrigation system is used, it is essential to check soil periodically throughout the year to determine how wet or dry it is and adjust the irrigation schedule as needed. The easiest way to check soil moisture is using a screwdriver.
Just push a screwdriver down into the soil. When the soil is moist, it will go all the way down. If the soil is moist only a few inches, the screwdriver will only go down that far.
The WRASBC hopes to be back in the field soon to assist our community in using water efficiently.
For more water saving ideas visit: www.wrasbc.org