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FAQ

Frequently Asked Questions

 

Water situation

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What is the problem?

The Alto Río Laja Watershed stretches across seven municipalities in northern Guanajuato State in Central Mexico. Ninety-nine percent of the water consumed in this region comes from a large underground reservoir known as the Alto Río Laja Aquifer, which serves several thousand distinct communities – including San Miguel de Allende.

The aquifer supplies water to over 680,000 residents. Our aquifer is declining at an alarming rate, from 2-4 meters per year. The underground water that remains is contaminated with arsenic and fluoride – up to 14 times World Health Organization recommendations – known to cause developmental disabilities in children, crippling skeletal fluorosis, organ failure, and cancer. Typical treatment systems cannot remove arsenic and fluoride, which affects upwards of 300 million people worldwide, and systems that can are expensive, require constant maintenance, and are often developed in laboratories instead of on the ground in poor communities. Roughly 3.6 billion people – nearly half the global population – currently live in water scarcity conditions, and waterborne pathogens are responsible for the death of approximately 2,000 children daily.

The Alto Río Laja Aquifer in Central Mexico is in a permanent state of decline. The aquifer supplies water to over 680,000 residents, many in poor rural communities. Eighty-five percent (85%) of the water is used for agriculture, forcing wells ever deeper into geological substrates. Wells are starting to go dry, and the water that remains may contain 14 times or more the World Health Organization recommended limits for arsenic and fluoride – a toxic cocktail. Experts estimate that 30% more groundwater is extracted from the aquifer than gets refilled naturally by rainfall, leading to a 2-4 meter loss per year. As the water table declines, more wells will go dry and arsenic and fluoride concentrations will continue to rise, imperiling the health of tens of thousands.

This is a public health crisis for our region and much of Mexico. Entire generations are being plagued with the negative impacts of arsenic and fluoride in their drinking water, and worst of all, these issues impact poor children and pregnant women so much more acutely. A recent study with the National Public Health Institute found that 82% of children in some local communities presented mild-to-severe dental fluorosis. Signs of crippling skeletal fluorosis, developmental disorders, learning disabilities, skin conditions, renal failure, and a host of cancers are associated with arsenic and/or fluoride have been documented.

The aquifer is declining at an alarming rate. Wells are going dry, and the water that remains may contain eight times or more the World Health Organization recommended limits for arsenic and fluoride—a toxic cocktail known to cause unsightly dental fluorosis in children, painful skeletal fluorosis, developmental and mental disabilities, organ failure, and cancer among longer-term water consumers.

Children are at greatest risk as their growing bodies absorb these minerals at a much higher rate, and exposure to high fluoride in utero has shown severe impacts on children’s mental development later in life.

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Why is this happening?

The cause of this crisis is unsustainable over-extraction of groundwater for agriculture, forcing wells ever deeper into mineral-rich “fossil water,” which is contaminated with naturally occurring arsenic and fluoride.

Ours was once a region of traditional dry-land farming, but with the introduction of export-oriented agricultural policies, the rush to pump has driven down the water table from five meters in the 1950s to more than 200 meters in recent years. Today, wells regularly exceed 500 meters in depth or more.  

Roughly 85% of water pumped from the aquifer goes to agriculture. Crops like broccoli and lettuce bound for markets in North America and Europe are frequently lavished with several times the amount of water as used in other regions. We are exporting our finite water supply, and lax enforcement of water policies, compounded by expansion of agriculture, is the culprit.

Experts estimate that 30% more groundwater is extracted from the aquifer than gets refilled naturally by rainfall. As the water table declines, more wells will go dry and arsenic and fluoride concentrations continue to rise, imperiling the health of hundreds of thousands.

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Why is there arsenic and fluoride in the water?

Firstly, it should be noted that deep groundwater obtained with properly constructed production wells are generally very safe all over the world. Groundwater has sustained vast populations around the world and has helped feed the planet with crops irrigated with groundwater.

Groundwater comes from small pores in rocks and sediments that are very similar to what you see on the surface of the soil. Water flows very slowly through these small spaces and can take thousands of years to travel from the surface of the ground as a raindrop the wells that we drink from. During this time, minerals that contain many elements, including arsenic and fluoride, dissolve into the water.

In general, the older the groundwater, the longer the time that the water has spent in contact with the minerals, and so the higher the concentrations of dissolved elements in the water. We often refer to this water as having a "high mineral content". So, the arsenic and fluoride in the groundwater occurs naturally, and this is the reason that scientists sometimes refer to this as "geogenic" pollutants. They originate within the natural rocks of the aquifer.

Unfortunately, the concentrations of arsenic and fluoride are difficult to predict and therefore must be measured. This was recommended for all countries by the Millennium Development Goals of the United Nations. Even after sampling many wells in a region, we can not predict what we will find in a new well. Therefore, long-term water monitoring is very important.