Arsenic at Kane County school is naturally occurring

BIG ROCK -- The Kane County Health Department says high concentrations of arsenic found in a middle school's water supply are naturally occurring.

Health department executive director Paul Kuehnert says the geology of northern Illinois is behind the high levels of arsenic found at Hinckley-Big Rock Middle School in September.

The school is taking steps to filter its water supply to reduce arsenic levels to below government standards.

Three separate tests conducted at the school had found arsenic levels of 11 parts per billion, 15 parts per billion and 39 parts per billion. The government standard is 10 parts per billion.

The Illinois Water Survey is offering free water testing for residents concerned about their well water.