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MMWD Water Efficiency Program is not Cost-Efficient

On May 1st, the MMWD presented its Water Efficiency Program (see attached pdf at the end of this article).

Good news is that we use less water than we used to

The graph below shows that the MMWD population has remained flat since 2000. Meanwhile, our water consumption has declined radically from over 30,000 acre-feet per year (AFY) in 2000 to around 21,000 AFY during the most recent three years.

Source: MMWD

Our residential per capita water use of 68 gallons per day ranks in the bottom quartile among urban water users in California.

Source: MMWD

While we use 68 gallons per person per day. We use less than half that (around 30 gallons) for indoor use.

Source: MMWD

MMWD Water Efficiency Program (WEP)

The table below discloses the underlying detailed calculations of the core WEP (slide 42) items consisting of:

  1. lawn conversion to drought-tolerant plants (at two different price points);
  2. laundry-to-landscape gray water system (at three different price points);
  3. rainwater catchmen system.

I also benchmark the water cost of the WEP items vs purchasing water from Sonoma (highlighted in yellow). Remember throughout MMWD's history, it has purchased as little water from Sonoma, as it deemed too expensive.

Just to walk you through the calculations on the top row for a 500 square feet lawn to drought-tolerant plants conversion that is estimated at $2 per sqft the itemized cost estimates from left-to-right are calculated as follows:

$ CCF is the unit of water MMWD uses to bill us.

As shown in the table above all the WEP items are a multiple more expensive than the "expensive" Sonoma water.

The table below discloses the multiple of the WEP items' costs vs Sonoma water. As shown, the WEP items range from 2 to 20 times more expensive than Sonoma water.

Keep in mind that the disclosed WEP items reflect the direct cost to the customer!

At such costs, few MMWD customers would voluntarily implement these WEP items.

MMWD is planning to turn these WEP items into mandates on any new or rehabilitated property or landscape.


Given the WEP unattractive economics, it is unlikely to result in much water efficiency implementation. And, it may contribute to curbing building in Marin County.

This will cause increasing tension between the County and Sacramento's unrealistic housing growth targets.

Neither Marin's declining demographic trends nor our inadequate water supply infrastructure justifies or supports Sacramento's housing targets for Marin County.