Ground Water Quality — Nitrate

What is Nitrate?

Nitrate is an oxidized form of nitrogen that typically comes from inorganic fertilizers, decaying organic matter, wastewater from commercial operations, animal manure and human sewage. Only rarely cases nitrate originates from geologic formations. It is an odorless, colorless, and tasteless compound. It is highly mobile in water and can cause health problems if it enters drinking water.



The Environmental Protection Agency has set a maximum contaminant level (MCL) for nitrate in public drinking water of 10mg/L. Idaho Department of Water Resources considers ground water nitrate levels above 2mg/L to be impacted.


Reporting Range Concentration
Low End < 0.5 to 1.99mg/L
Impacted 2 to 10 mg/L
Exceeds Drinking Water Standard > 10 mg/L

What are the Health Risks?

  • Blue Baby Syndrome: An oxygen deficiency that can induce illness and death in infants.
  • Who is at risk:
    • Babies less than 6 months old
    • Pregnant women
    • Elderly
  • Healthofficials recommend that water with greater than 10mg/L nitrate not be used for drinking, cooking or formula preparation for infants under six months and for pregnant women.

Treatments

Boiling, filtering, and softening are not treatments for removing nitrate. Contact a licensed professional for treatment options.


Effective Treatments Include:


  • Reverse Osmosis: Nitrate is removed by forcing water through a membrane.
  • Distillation: Water is purified by capturing the steam of boiled water and condensing it. Nitrate is left behind when the water turns to vapor.
  • Ion Exchange: Nitrate ions are exchanged for another ion.

Trends in Idaho

In 1995, 100 sites were selected to be sampled annually (sample collection at one site was discontinued in 2000). Of the annual sites, 27 sites showed evidence of nitrate increases and 16 sites had nitrate decreases. The following graph is an example of trends in nitrate concentrations at Annual Sites.




Nitrate in Idaho (1990-2004)

A report by Neely in 2005 indicated that nitrate has impacted ground water quality in many places in Idaho: