Most of us have seen polluted streams and lakes. But one of the biggest threats to our drinking water is invisible, because the water itself is underground. We asked Dr. Katta J. Reddy, a senior research scientist at the Wyoming Water Resources Center, to explain what groundwater is and why it needs to be protected.
What is groundwater?
Usually groundwater is defined as the water trapped in the pores beneath the soil, in the pores in the rocks. It supplies our nation’s wells and springs. Groundwater moves like a river–fast at one place, and slowly at other places.
Why is it important?
Fifty percent of our population depends on groundwater. But in rural areas, 90 percent of the population may depend on groundwater.
Groundwater supplies are threatened mainly by human activities, but some natural events also can cause contamination. There are basically two types of contaminants: biological and chemical.
What kinds of health problems would result from these contaminants?
It depends on the contaminant. For example, some bacteria biological) can cause dysentery or irritated, watery eyes. Some organic or inorganic (chemical) contaminants, such as nitrate, could be serious. Groundwater that has a high concentration of nitrate is very dangerous to infants who drink the water. It can produce blue baby syndrome, which is a lack of oxygen that may cause the babies to suffocate.
Where do contaminants come from?
One source of contamination is agricultural fertilizers. And nitrate occurs naturally in soils. Other contaminants come from industrial waste disposal, city disposal sites, industrial activities, and the heavy fertilization and irrigation of lawns. Mining activities also have an impact on groundwater.
If you have shallow groundwater and the soils are highly leaching, such as sandy soils, those groundwaters will contaminate faster than with a less leaching soil such as clay. And with a deeper groundwater system, it will take a longer time for the contaminants to reach the groundwater.
Can pollutants that enter at once point end up someplace else?
Yes. When we dump something on the ground, we assume the soil’s going to take up everything, clean everything. But that’s not the case. The contaminants can go into the groundwater, the groundwater will flow, and slowly the contaminants can appear somewhere very far away. So people who are using groundwater may be affected far from the point of entry.
What kinds of warning signs can people look for?
One good warning sign is the odor. If there is a sudden change in the odor, something definitely is wrong. Sometimes you can even see some suspended particles. The difficult thing is, you cannot detect or see some of these contaminants, such as nitrates, because they don’t have any color. The only way to know is to get a chemical analysis of the groundwater.
If there are contaminants in my water, will I get sick right away?
It depends on the contaminant. Some biological contaminants can cause diarrhea, which comes on rather quickly. But certain contaminants will take a longer time because they have to accumulate. Our body naturally removes excess contaminants. But if you overload it with contaminants, health problems may result after several years.
Can pollution in groundwater be cleaned up?
Once you contaminate groundwater, there are no easy cures. We’re talking about a huge amount of water, not just one or two gallons. That makes it very expensive to clean up. So, of course, it’s better to cut out the source of contamination–to conserve, not to contaminate anything. Groundwater is one of our vital natural resources, and whenever we get a chance, we need to protect it.
The biggest problem is that we never relate what happens here to what can affect us there. This is a cycle; it’s a continuum. What you do here will come back to haunt you sooner or later. So you dig up something, or you dump something, and assume it’s OK. Nothing is immediately apparent. But that’s not the case. Your activity will affect the groundwater, and you’ll discover this when you drink water from your kitchen sink.