California’s Model Water Efficient Landscape Ordinance (M-WELO)

What is M-WELO?

In 1990, during the second driest period in California’s recorded climate history up to that time, California’s legislature passed the Water Conservation in Landscaping Act requiring the Department of Water Resources to adopt a Model Water Efficient Landscape Ordinance (M-WELO).

In 1993, the Department of Water Resources adopted the M-WELO, updating it in 2009, and, again this past July ( July of 2015) in response to the California governor’s drought executive order. Cities are required to implement and enforce the M-WELO, or an equally efficient Water Efficient Landscape Ordinance (WELO). Walnut Creek implemented its WELO in 2012 ( depts/cd/planning/landscaping.asp).

Our own Golden Rain Foundation board of directors effectively used this WELO to coordinate GRF and Mutual landscaping in GRF policies ENV-3.1 and ENV-3.2 (seek to reduce landscape water demand) and GRF/Mutual policies HMU-2.1 through HMU-2.6. Now Walnut Creek must update its WELO by Dec. 31, 2015 to comply with the updated M-WELO, or the M-WELO shall take precedence, according to Julie Saare-Edmonds of the Department of Water Resources.

Updated M-WELO

The updated M-WELO aims to enhance environmental and aesthetic values provided by landscape, but curbs landscape water demand. It minimizes the amount of area planted with lawn, requires more area for low water using plants (including California natives), maximizes irrigation efficiency by requiring highly efficient drip technology where appropriate and prohibits wasteful runoff.

The bulk of the M-WELO applies to new construction and landscape renovation projects tied to permits. New construction in Walnut Creek with landscape areas of 500 square feet or greater must comply with the M-WELO. The M-WELO does not require any alteration of the configuration of existing landscape.

The M-WELO also requires cities to prevent water waste in all existing landscapes: “No property owner or tenant shall permit runoff from an irrigated landscape area due to excessive irrigation run times, low head drainage, overspray, or other similar conditions where water flows onto an adjacent property, walkways, roadways, parking lots, structures, or other non-permeable surface….” No one is exempt, according to Andy Smith of the Walnut Creek Planning and Zoning Department. Smith also acknowledges that, although waste prevention is mandatory, funding limitations make it unenforceable in practical terms. Therefore, compliance with the M-WELO’s rules for existing landscape largely depends upon the motivation of managing agencies. Where willingness and capability are present we can expect water efficient landscape initiatives.

How M-WELO Impacts Rossmoor

We see some of this very positively in Rossmoor through MOD’s turf removal activities and the installation of smart irrigation control technology. We also see this initiative in the Mutual 8 drought tolerant landscape project that introduced drip irrigation, the most efficient irrigation technology commercially available. These and additional actions are examples of very positive ways for any community to achieve the goal of water efficient landscape.

The M-WELO mandates rethinking of landscape and irrigation system design and conformance with new water efficient criteria by prohibiting the placement of sprinklers within two feet of hardscape. If planted, the two-foot setback must use drip irrigation; otherwise it can be covered with mulch, gravel, stone, etc. The M-WELO also requires areas less than10 feet wide to be “irrigated with subsurface (drip) or other means that produces no runoff.” These solutions will eliminate runoff and overspray waste.

Hydrozoning: Zone Planting

Another design solution involves hydrozoning. This means that plants with similar water need and microclimate placement get zoned together according to irrigation requirement, and separately from others with different water need and microclimate placement. Hydrozoning makes it possible to irrigate plant groupings much more efficiently.

For example, median space between parallel roadways frequently includes high water-using lawn with very low water -using tree species. The M-WELO prohibits planting high and low water users in the same hydrozone, an ineffective grouping for water conservation. In addition, the M-WELO prohibits placing high water-using plants, including lawns, in medians. Replacing the median lawn with native shrubs and groundcovers that have water needs more closely matched to that of the trees is just one of several preferable solutions.

It’s all very well and good to do the right thing, but what about costs? The city of Santa Monica and Metropolitan Water District answer this question with their “side by side” demonstration project that employs M-WELO guidelines. Their nine-year study (2004-2013) documented resource consumption of two next-door gardens, a native garden and a traditional garden. The native garden used 83 percent less water, produced 56 percent less green waste and required 68 percent less maintenance than the traditional garden.

This example illustrates the long-term cost saving potential through a greater use of the M-WELO guidelines. The results also created a more water efficient and sustainable future for Community landscapes. (Internet search:

This post first appeared in the Rossmoor News, October 7, 2015, author Tom Stewart.

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