admin's picture

By Katie Worth

HAGATNA, Guam (Pacific Daily News, Feb. 16) - Anybody who has ever been to Saipan knows that you can't drink its tap water because it is, as Chamorros say, hanom kalakas -- gross water. Saipan has over-tapped its underground freshwater source, causing salt water to mix in with fresh water, leaving the drinking water essentially undrinkable.

But what many people may not know is that Guam's tap water could be on its way to the same fate. Guam Environmental Protection Agency officials have said they have noticed a rise in salinity, or saltiness -- a sure sign that sea water is getting into the freshwater supply --in some of Guam's northern wells.

No one really knows how long it would take for the aquifer to return to normal if it was contaminated with seawater.

Fortunately, Guam's problem may be solved before it gets worse.

This week, Guam EPA is starting a two-year, $400,000 project to create a modern, three-dimensional model of Guam's northern aquifer. The project will help officials determine when and where they can tap the underground freshwater source without causing the aquifer to get any saltier.

Victor Wuerch, a Guam EPA hydrogeologist, said his agency is funding the project and will work on it in cooperation with the U.S. Geological Services and the University of Guam's Water and Environmental Research Institute. This week, they will begin training to create the long-overdue map.

Tamuning resident Angie Carlos, who visits family on Saipan regularly, said it would be disastrous if Guam's water deteriorated to the point that Saipan's has.

"In Saipan, their water is salt water. You can hardly brush your teeth because the water is so salty it makes you gag," she said.

She added that if Guam's water were to get as bad as Saipan's is, she would consider moving off island.

"For me, water is very important. At least here, you can use the water for cooking, but not in Saipan. If it got that bad here, I'd move -- I would not want to live with it," she said.

The northern part of Guam is a limestone shelf sitting on top of what Wuerch called a "volcanic basement." The limestone is permeated with water, and has a layer of fresh water. The fresh water is from rain and is floating on top of a layer of salt water -- from the ocean.

Guam Waterworks Authority has wells all over the northern part of the island, tapping down into the fresh water.

But when those wells pump too much of the fresh water out of a particular area, the saltwater layer rises in that area and begins to mix with the fresh water.

"In Saipan, what they've done is put in too many wells and they pumped the fresh water too fast and tried to produce too much water to meet demand in a limited area, and they pulled out most of the fresh water; therefore, the density balance was upset and the salt water moved up into the freshwater section," he said.

Wuerch said for the last 10 years or so, this also has been happening in isolated areas on Guam, and GEPA has had to shut down some GWA wells and shift water pumping to other areas of the aquifer.

The good news is that the problem can be solved with a good model of the aquifer, which takes into account factors such as rainfall, limestone permeability and groundwater flow patterns, Wuerch said.

There does exist a model of the island's aquifer, Wuerch said, but it is 20 years old and only two-dimensional, meaning it only takes into account horizontal water flow, and not vertical water flow.

"We're using numbers generated by the 20-year-old, two-dimensional model to regulate Guam Waterworks in terms of where they place wells and how much they can extract," he said.

"But it's obviously not working since we're seeing saltwater intrusion in some wells where the old model predicted we could pump water out of the aquifer without a problem," he said. "So we're basically just trying to get our modeling efforts up to modern-day standards," he said

For about 15 years, Wuerch said, the agency has been considering the need to create a new model of the map, but no one was able to find or commit funds to the project until recently.

The new model will be far superior to the old one, he said, because it will give scientists and managers far better tools to predict where the fresh water is abundant and how to tap into the water table without disturbing the integrity of the aquifer.

Carlos said she thinks the project is well worth investing in, if it means saving Guam's water source.

"Water is a main priority to me -- you can't live without it," she said.

February 16, 2004

Pacific Daily News: www.guampdn.com


Rate this article: 
No votes yet

Add new comment