What are nitrates?

What are nitrates?

A form of nitrogen and oxygen used by plants. Nitrates travel freely through water and can stay in soil for decades.

Where do nitrates come from?

A variety of sources. Since at least the 1940s, farmers have applied commercial fertilizer containing nitrogen to crops.

Human waste can be a source, too, the result of failing septic systems, which was a problem in the Lower Valley's Parker area until a public water system was constructed.

Poorly constructed or old, shallow wells -- there are many in the Lower Valley -- are also conduits for nitrate pollution.

In the Lower Valley, manure is also a major source of nitrates. A single dairy cow produces nearly 150 pounds of wet manure a day.

Wildlife manure and municipal and industrial wastewater can be sources. Geologic formations and the direction that water flows underground can also influence nitrate concentration.

How do nitrates reach underground drinking water?

Nitrate-rich manure overapplied as liquid waste on crops can leach into aquifers. Nitrates move readily with water through subsurface soils.

Lagoons used to store liquid manure may overflow or develop holes on the sides or bottoms, creating an opportunity for nitrates to enter the soil or run into ditches that drain into rivers and streams.

Commercial fertilizer applied to crops for decades can also leach into aquifers.

Why are nitrates considered a problem?

Drinking water high in nitrates and other contaminants poses risks to infants, pregnant women, the elderly and people with compromised immune systems. In infants, high nitrates can cause methemoglobinemia, or blue baby syndrome. Research isn't conclusive, but pregnant women are believed to be at greater risk for having babies with birth defects as a result of drinking water high in nitrates.

The conditions of people with heart or lung diseases, certain inherited enzyme defects, or cancer may be worsened by ingesting too many nitrates.

In addition, some experts believe that long-term ingestion of water high in nitrates may increase the risk of certain types of cancer.

No agency systematically keeps track of the rate of such medical problems.

Many scientists consider nitrates a warning of overall water problems. If nitrates are high, well water may also contain bacteria like E.coli, which can cause infections, and other contaminants, including pesticides, viruses and pathogens.

For more information on health effects, check the state Department of Health's Web page on nitrates at www.doh.wa.gov/ehp/dw/Programs/nitrate.htm.

What is considered a safe level?

The U.S. Environmental Protection Agency uses 10 milligrams per liter (the equivalent of 10 parts per million) as the maximum level for safety. Nitrate levels in well water tested six years ago around Granger, Sunnyside, Outlook, Mabton and Grandview ranged from a high of 55 milligrams per liter to a low of 0.07. Forty of the 195 wells tested, or 21 percent, exceeded the federal limit. EPA considers 5 milligrams a "red flag," indicating the need for more frequent testing.

Is nitrate pollution a new problem?

No. Because nitrates are stable, they can stay in the water and soil for decades. The nitrates found in many Lower Valley wells could be very old, referred to as a "legacy problem" by regulators. This is part of the reason that it's so difficult to pinpoint the source of nitrate pollution.

How can I get my well tested?

There are several certified laboratories around the Yakima Valley listed under "laboratories-analytical" in the Yellow Pages that will test your water for about $42. But you need to know how to collect a sample properly; the companies will provide the instructions and a sanitized bottle.

What should I do if my water exceeds the limit?

Do not boil the water. This only increases the concentration of nitrates.

Have the well's casing examined for holes. Make sure your septic system is working properly.

Unfortunately, solutions can be expensive, such as drilling a deeper well or buying a reverse-osmosis water system that filters out nitrates, but not bacteria.

These systems range in cost from $300 to $3,000, not including replacement parts and filters. A disadvantage: They use a lot of water because they only recover up to 15 percent of the water entering the system. The rest is discharged as waste.

• Jobs
  www.yakjobs.com
• Homes
  www.yakhomes.com
• 
• 
  
• Autos
  www.yakwheels.com

• All Special Pubs Yakima Magazine Channels YakJobs.com YakWheels.com YakHomes.com Playdate Yakima Bride Yakima Wheels (Print) Home Buyer's Guide Baby Brag Book Graduates 2009 Summer in the Valley Prep Football 2009 Women in Business Holiday Gift Guide
• Advertisement