Three feet.

Thirty-six inches.

It doesn’t sound like a lot.

But when it comes to water spread over dozens of square miles it’s a lot.

And when those three inches represent water consumed over the course of the past year that’s not being replaced, you might want to give serious thought to what could be coming down the tracks.

The underground water source that dropped three feet in the past year is Ripon’s exclusive source of drinking water.

Don’t get too smug if you live in Manteca or Lathrop.

Both cities rely on well water along with surface treatment water procured from the Stanislaus River via the South San Joaquin Irrigation District.

Water levels in underground aquifers that Manteca pumps out of are dropping just like water levels at New Melones Reservoir.

And while water levels in Lathrop aren’t dropping as much due to salt water moving in to fill the void in aquifers, the growing presence of salt water creates even more issues given it impacts drinkability and enough of it can kill vegetation.

Of course, neither seems to worry many of us. Underground and surface water sources both are out of sight and out of mind. The aquifer is hundreds of feet below us and New Melones is 50 miles away.

What you don’t see — or in this case can’t see — can and will hurt you, your family, your neighbors, and the community.

Make no mistake about it. We are in the third year of a drought.

And at the same time the evidence is mounting we’ve been in a megadrought for a lot longer.

Hydrologists have already conceded the core of the Southwest — Arizona, New Mexico, southern Nevada, and parts of Colorado — are 20 years into a megadrought.

Lake Powell behind Hoover Dam is at a historic low. The dam that tamed the lower Colorado River  is expected to become a diminishing source of hydroelectric power to further exacerbate the growing energy crisis.

This matters for a number of reasons if you reside in Manteca, Ripon, Lathrop and everywhere else in California.

First, in terms of climate and hydrology we are part of the greater Southwest.

Second, it has been well-established by dendrology — the science of reading past hydrology via tree rings with the help of carbon dating — that megadroughts typically spanning 50 to 100 plus years punctured by periods of normal or above average precipitation and have been the standard for thousands of years in what we call the American West that includes California.

Third, and arguably most important because it will trigger at some point draconian action in Sacramento, a lot of the Colorado River water normally ends up flowing through faucets in Southern California.

People and industry in the Los Angeles Basin, the coast south to San Diego, and the Inland Empire rely on imported water from both the Colorado River, the Cascade snowmelt and the Sierra snowmelt. The snowmelt on the western slopes of the Sierra is captured by the State Water Project. On the eastern slope it is captured and diverted by the Los Angeles Department of Water and Power.

Manteca, Ripon, and Lathrop are part of the Central Sierra watershed. People, farmers, and businesses depend on only the snowmelt to the east of us. We don’t tap into snowmelt from the eastern slope, from the Colorado River or from north of the Delta.

And — regardless of how crude this may sound — there are much more of “them” in Southern California than “us” in the Northern San Joaquin Valley.

Rest assured there will be pressure to keep SoCal closer to whole when it comes to a sustained drought than this region.

It gets complicated for us due to horse trading between the State Water Project (Oroville reservoirs) and the Central Valley Project (New Melones, Shasta, and Folsom) that will likely happen in a bid to protect the Delta ecosystem and endangered salmon as drought persists.

Rest assured there are those already looking at New Melones and the water it stores to replace flow commitments to the Delta from Shasta, Oroville, and Folsom to shore up water commitments to urban users in Southern California and the Bay Area.

That is one of many reasons why it is foolish that many of us are still wasting water whether it is flooding gutters, being too lazy to shut off the automatic sprinklers after days when we do get a reasonable amount of rain, and hose down driveways and patios instead of pushing a broom.

In the coming years we are likely to become more and more reliant on ground water as political, bureaucratic, and legal wars break out over what surface water is available.

The cold hold truth about underground water is that its supply ebbs with the hydrology of nature above ground with one inconvenient caveat.

The aquifers we have been dipping into for the past 170 years in the American West were built up over thousands of years.

The depletion rate of higher underground sources of water are tied into what happens on the surface. Less water on the surface means less water seeping into the ground — if any — to replenish underground water sources. But aquifers that are much deeper don’t bounce back in a year or so of above average precipitation.

That means the more we keep drinking water that hasn’t seen the sunlight for centuries the closer we come to a feast or famine status when it comes to annual rainfall and snowmelt.

Once we get to that point, it won’t end well.

Prolonged drought destroyed the Anasazi civilianization that flourished for centuries in the Southwest. It was one of many regional civilizations that collapsed throughout what is now the United States during a  drought that lasted 300 years.

Today the American West civilization has become massive. Back when no one in what we call the Central Valley was tapping underground water sources before the 1840s, estimates place the native population of the 450-mile long region at less than the 88,000 people that call Manteca home today.

We have overbuilt water basins — the Los Angeles basin is a prime example — way beyond the ability of local hydrology to support it with water.

It has been done by unprecedented transfers of water from other basins to deep drilling. And that deep drilling for water to sustain Los Angeles has occurred on farmland and desert hundreds of miles away as extracted water is piped in a futile effort to quench LA’s insatiable thirst created by a growth machine that literally can’t be supported by local water resources.

The sooner we realize water is precious and not something to be used absentmindedly on non-native grass that consumes an inordinate amount of liquid gold just to look pretty or to allow to run down the drain for no good reason, the sooner we can reset water consumption to weather the reality we live in.

Simply put, we ignore drought at our own peril.

This column is the opinion of editor, Dennis Wyatt, and does not necessarily represent the opinions of The Bulletin or 209 Multimedia. He can be reached at dwyatt@mantecabulletin.com