Water conservation with irrigation


Figure 05: Planting area irrigated with MP Rotators at the Japanese Friendship Garden San Diego. photo by Keiji Uesugi

As the water shortage issue worsens in California amid multi-year drought conditions driven by climate change, the state is exploring more ways to encourage water conservation. Gov. Gavin Newsom and the state legislature have invested $5.2 billion over three years “to support the immediate drought response and built water resilience,” his Website states. He signed an executive order in March calling on local water suppliers to take local actions to conserve water and for the State Water Resources Control Board to consider a ban on watering decorative grass at businesses and institutions.

As large-scale solutions are vital to tackling the water crisis, there are many steps homeowners can take to reduce water use and help conserve water.

Figure 01: Hunter MP Rotator is a sprinkler nozzle that delivers water through rotating streams
images from hunterindustries.com

Lawns can require a significant amount of water. If replacing your lawn is not an alternative, there still are ways to reduce water use while maintaining the health of your turf. Recent advances in sprinkler technology have made it possible to reduce water waste from use of traditional sprays. A product I have been using on various landscape projects is the MP Rotator by Hunter Irrigation. (Disclaimer: Hunter Irrigation has been a longtime supporter of the Cal Poly Pomona Landscape Architecture Department where I teach and has made donations to the university, but I do not get anything from them for referencing their products. I just think their products are dependable and good quality).

MP means “matched precipitation,” which refers to how the nozzle can match your landscape’s precipitation rate to how quickly your soil can absorb it. It features a nozzle that delivers water through rotating streams as shown in Figure 01.

There are many benefits to water being delivered with rotating streams:
• The slower application rate allows water to absorb into the soil more slowly and thus more efficiently.
• The slower application rate also removes water runoff that ends up going down the storm drain.
• Less water is lost to evaporation.
• Effective for watering turf and planting areas with shrubs and other ground cover.
• Each nozzle has a wide range of distance and angles the water can be sprayed, which reduces the number of sprinklers required in your yard. This saves on installation cost.

If you have pop-up sprinklers in your yard, you can easily replace them with MP Rotators because they are designed to attach to the pop-up sprinkler spray bodies commonly sold at landscape supply stores such as the Rainbird 1800 series and Hunter’s own Pro-Spray bodies. Rainbird also has their own rotating streams sprinkler nozzle.

I used the MP Rotators at my home several years ago and saw immediate reduction in my water bill, and the planting area still looked healthy. The Japanese Friendship Garden San Diego also installed them with their Phase 2 expansion in 2015. It has been seven years, and the planting continues to do well with these sprinklers.

Figure 05: Planting area irrigated with MP Rotators at the Japanese Friendship Garden San Diego. photo by Keiji Uesugi

In conclusion, this irrigation tip is meant to help shed light on a fairly simple way you can support water conservation and reduce your water bill while still maintaining the overall quality of your landscape. Every little bit helps, so I hope you will strongly consider updating your home irrigation system.

If you have any other questions or are interested in learning about other landscape watering strategies such as drip irrigation, feel free to e-mail me at keijiu@gmail.com, and I will consider a future column on that subject.


Keiji Uesugi, PLA is the principal of the landscape architecture firm, TUA Inc. in West Covina, Calif., and a faculty member of the landscape architecture department at Cal Poly Pomona University. A licensed landscape architect with more than 20 years of professional experience, he is an expert in cultural landscapes and Japanese gardens of North America. He can be reached at keijiu@gmail.com. The views expressed in the preceding column are not necessarily those of the Nichi Bei Weekly.

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