Los Altos Weather – 32% Mandatory Water Reduction

In my home town of Los Altos, California, April was drier and warmer than average, continuing the trend, but only slightly. We continue pumping much more groundwater from the aquifer beneath our valley than we replace. The overdraft rate in 2015 is higher than in 2014, when we drew down the groundwater reserve by a quarter. California imposed a 25% mandatory water reduction for urban users, with higher users making larger reductions. Los Altos residents use more water than most, so we will have a 32% water use reduction. Shown above, concerned residents attended a meeting at Covington School to learn about water restrictions, conservation, and surcharges.

Los Altos Weather

Our April rainfall was near-normal — we received .88″, a bit lower than the .98″ average.

Near-normal rain in April
Near-normal rain in April

Reflecting our drought, our cumulative rainfall since January 2013 is 52% of average.

52% of normal rainfall since January 2013
52% of normal rainfall since January 2013

The warm trend continues, with overnight temperatures 4 degrees warmer than normal, and the high only one degree above normal.

Overnight temperatures continue above normal
Overnight temperatures continue above normal

Groundwater Overdraft Grows

In 2014 the usable groundwater in the aquifer under the Santa Clara Valley was drawn down 22%, from 301,700 acre-feet (AF) to 235,400 AF.  We can continue overdrafts at this rate for more than three years before we risk the valley floor sinking permanently.

2014 Groundwater Storage
2014 Groundwater Storage

How are we doing in 2015? The Water District only report this at year-end, but we can get a rough estimate by looking at the inflow and outflow done by man. So far this year, we’re pumping more than we put back, faster than we did in 2014. So it’s getting worse.

The change in our usable groundwater is the outflow minus the inflow. The outflow is dominated by what we pump from the ground. The inflow is the managed recharge, natural recharge, and other natural flows. The change in inflow is dominated by the managed recharge, the water that sinks into the ground at man-made basins. The Water District tracks these flows done by man: the pumping (outflow) and the managed recharge (inflow). Managed recharge minus pumping is the net flow by man.

The graph below looks at what we take out (pump) versus what we put back (managed recharge) for 2014, 2015, and 2009-2013. The 2009-2013 average (dashed green line) shows a net outflow in our dry summer. Our groundwater was relatively stable during this period, because natural recharge is significant and not counted here. In 2014 (light blue line), we pumped much more groundwater than we recharged, causing the 66,300 AF reduction in our usable groundwater. For each of the first four months of 2015, we are pumping water faster than we recharged it in 2014. This looks bad for our aquifer, but new mandatory water use reduction measures will curb customer demand and pumping.

2015 net groundwater flow exceeds 2014
2015 overdraft worse than in 2014

Mandatory Water User Reduction

Most of the groundwater pumped in the valley goes to local urban customers — residences and businesses (Apple, Intel, Google, etc.). Our governor ordered a mandatory 25% reduction in water use for urban customers. To promote water conservation, California now prohibits some practices that waste water.

For further conservation, communities using more water per person are expected to conserve more, since the extra water presumably is for landscaping. Customer are grouped by their water retailer. During the summer of 2013, customers of our local water retailer, California Water, used more water (173 gallons per person) than most, so our water reduction rate is 32%. We conserved 16% in 2014, so we’ll have to double our conservation in 2015.

California Water held a meeting at Covington Elementary School on May 11 to explain the rules. The crowd is shown above. Cal Water explained water restrictions, conservation, and surcharges. If Cal Water customers don’t meet the 32% reduction, Cal Water can be fined $10,000 per day, so they now have a strong incentive to reduce water use.

In 2013, Cal Water customers used 29 CCF (hundred cubic feet) of water per household, where one CCF is 748 gallons. We used 26 CCF per household in 2014, and our 2015 budget is 20 CCF (68% of 29 CCF). Plants need more water in our hot, dry summer. To allow for this, each household will get a water budget equal to 68% of the household’s usage for that month in 2013. For every CCF used over budget, there will be a surcharge of $8.16. We can bank usage under budget to offset future overages. The budget and surcharge will start with our July water bill. Surcharges will be held to compensate water retailers for lost revenue from reduced sales.

There will be restrictions on when we can watering landscaping — how many days a week we can water (two or three) and which days of week — but the City of Los Altos hasn’t decided this yet.

There will be an appeals process for health and safety, business or economic needs, and significant long-term savings already achieved. Repeated violations can result in fines, flow restriction,  and potentially discontinuing water service. These rules run through February 2016, and they can be extended or modified if our 4-year-old drought continues.



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I enjoy travel, art, food, photography, nature, California native plants, history, and yoga. I am a retired software engineer. The gravatar is a Nuttall's woodpecker that visited our backyard.

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