Paso Robles News|Wednesday, May 12, 2021
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Is this city drought-proof? 

By Jim App
City Manager of Paso Robles

Paso Robles Water Supply

City Manager Jim App

Much of California is experiencing the driest year on record, storage in reservoirs declines, and some groundwater levels are reported to be dropping. In response, beginning May 1st, “Level 2” water use restrictions will once again go into effect throughout Paso Robles. This means that limits on landscape irrigation and wash-down of sidewalks and driveways go into effect, along with other water-saving requirements.

Californians have experienced droughts before, most notably the 1987-1992 drought which had a long-lasting impact both on our view of personal water use, and community water planning. So… what has Paso Robles learned as a result of past droughts and just how “drought-proof” is our water supply? Things to consider in answering those questions are:

Current Water Setting

Current citywide demand* 6,700
at 30,500 population
Projected citywide demand 13,400
at 44,000 population

Projected Water Supply

From Lake Nacimiento 5,400
From Salinas River underflow 4,600
From Deep Basin wells 3,400
From Recycled Water 650

* Quantities listed are in acre-feet per year

Multiple Sources

The City’s long-term water supply strategy is to draw from multiple sources of water. Salinas River underflow is taken from shallow wells and deeper wells draw from the large Paso Robles Groundwater Basin. River underflow and deep basin wells provided all the City’s water needs through 2010. At that time, the Nacimiento Water Project went into operation, enabling Paso Robles to supplement its dual-source well system with a third source – lake water.

Nacimiento Water is now being released into the riverbed to benefit City wells, but taking full advantage of the City’s share of Nacimiento Water will require completion of a treatment plant. The construction of that plant begins this Spring. And a fourth source of water – recycled water – is on the horizon.

Can the City Continue to Grow?

Yes. Water supplies and treatment capacity are planned to support a future population of 44,000. One may ask – “Then why do current customers need to conserve water?” It is prudent to conserve during critically dry periods for the simple fact that no one knows how long a drought may last. And, while City water supplies can carry us through repeats of historic droughts, conservation aids in offsetting immediate short-term peak summertime demands.

How Bad Can It Get?

Claiming to be 100% “drought proof” would be bold and perhaps un-informed. What we do know is how bad things have gotten historically. So we chose water supplies and developed our water conservation program around those experiences. The 1987-1992 drought was bad because of its duration, but the current setting is severe because of the low rainfall.

We will continue to keep customers informed about the drought situation and ask the City Council to declare more severe levels of water conservation as needed. For example, peak demand during hot weather gets as high as 10 million gallons per day. If daily supplies fall substantially below that amount, then the City Council may stop development until demand and supply are better balanced. Those combined strategies are intended to ride out Mother Nature’s driest periods.

Could We Do More?

The more immediate step to extend City water supplies is construction of the Nacimiento water treatment plant – construction gets underway this year. Another possible step would be to increase the City’s entitlement in the Nacimiento Water Project. That is being reviewed now. Last, we are updating the City’s recycled water plan to determine what is needed to treat and reuse municipal wastewater. Recycled water will be the City’s fourth source of water.

Each of the steps noted above positions the City to manage through future droughts and grow, remembering that the water supply portfolio provides for up to 44,000 people and businesses.