Nitrates bad news for well owners

Once a source of water for north Douglas County residents, Well No. 4 in Ridgeview can now only be used for park irrigation.

Nitrates filtering out of septic tanks in the community raised nitrate levels in the well so drastically that its water can no longer be used for human consumption, said Indian Hills General Improvement District General Manager Jim Bentley.

The well was already contaminated when the district took responsibility for the Ridgeview water system several years ago. Once groundwater is contaminated, other local wells could be affected.

Much of Indian Hills is now served by a municipal water system so nitrate problems are not imminent, but no part of the county is immune to these issues and private wells are not checked, Bentley said.

"Nitrates are a problem when they get into the drinking water. They're a real problem when they get into a lot of individual wells," he said. "This isn't the kind of problem we can just get rid of. This is the type of problem that needs to be prevented."

Amy Roukie, administrative services officer for the Nevada Health Division said property owners should be checking their own wells regularly for nitrate contamination, but only public systems are monitored.

"Samples are submitted for testing on any public water system. That's how we know if there's a nitrate problem," she said. "At this time, the Bureau of Health Protection regulates public drinking water and if the nitrates are excessive, we take the septic systems in the area into consideration."

Public systems are required to submit a well sample to the Bureau of Health Protection Services, Roukie said.

"Community systems generally use a facility treatment process, providing a variety of filtration practices to bring water quality into acceptable standards," she said.

Studies by the United States Geologic Survey indicate nitrate levels in the Carson Valley's groundwater have steadily risen with the number of septic tanks, the areas of concentration in Genoa, the Gardnerville Ranchos, Ruhenstroth and Johnson Lane.

During the sampling period for this study, from 1985 to 2001, 56 percent of the wells tested indicate increasing levels of nitrate over time. Thirty-three percent of the wells did not change during the sampling period and 11 percent showed an actual decrease in nitrate levels.

Agricultural and other areas where wastewater is spread onto fields generally don't appear to have elevated nitrate concentrations and the levels do not vary with the seasons, indicating the nitrogen is derived from a relatively constant source, like septic tanks.

Degradation of groundwater quality is possible over a wider area as development continues and once degraded it can take many years to improve, a factor that could limit future growth, according to the study.

Nitrogen contamination can affect the health of residents by binding the hemoglobin molecule in the blood, which is responsible for transporting oxygen throughout the body.

Infants six months of age and younger are the primary victims of this potentially fatal condition, called methemoglobinemia, which is expressed by a bluish skin discoloration.

High nitrate concentrations in drinking water have also been linked to central nervous system birth defects.

In adults and children, these high nitrate concentrations have been linked to diabetes, hypertension, central nervous system birth defects and certain cancers, like non-Hodgkins' lymphoma.

Nitrate levels at or above 10 milligrams per liter are considered toxic for humans, but the environment is impacted long before the concentration reaches that level.

Additional nitrogen can cause algal blooms and change the ecology of the surface water system. The Carson River is susceptible because naturally it has a limited amount of nitrogen available for plant growth, according to the report.

County Manager Dan Holler said overall, nitrate levels in Douglas County are not at a critical level and county officials are making efforts on numerous fronts to get residents on municipal systems that don't disburse nitrates into the environment.

"We want residents to connect to a municipal sewer system because in the long term, it's better for the valley," he said. "But a lot of residents don't want to do that.

"In some areas, people are opposed to more homes because they would require a sewer system." he said.

In Ridgeview, county officials are working to put in a sewer system using Redevelopment money and CDBG grants at no cost to the homeowner, Holler said.

Wells in Douglas County require a sanitary seal for at least the first 100 feet to protect against nitrate contamination, but those seals can go even deeper.

"The water quality is tested at different levels, so the well can be screened off if it doesn't meet the standards," he said.



Susie Vasquez can be reached at svasquez@recordcourier.com or 782-5121, ext. 211.