By Brian Henning, CAP Director, Operations and Engineering
Last August, I shared a blog post regarding an accidental spill of sediment and metals from a shuttered Colorado gold mine into the Animas River. The Animas is a tributary of the San Juan River in Farmington, N.M., which ultimately feeds into the Colorado River at Lake Powell. I’m pleased to report that we have been monitoring the CAP aqueduct system since the spill and have not detected any elevated contaminant levels.
The spill was caused by an environmental crew, contracted by the U.S. Environmental Protection Agency to pump and treat contaminated water in the mine. The crew entered with a bulldozer and inadvertently breached a “dam” containing contaminated toxic water. This water contained elevated levels of lead, arsenic, cadmium, beryllium, mercury, zinc, iron and copper.
The spill made its way to Lake Powell in approximately seven days, but at no point were elevated levels of heavy metals ever detected. This indicates that the contaminated water was sufficiently diluted prior to entering Lake Powell. Still, as a precautionary measure, CAP continued monitoring until just a few weeks ago.
CAP regularly samples for contaminants on a quarterly basis in the forebay of the Mark Wilmer Pumping Plant near Lake Havasu, as well as various sites along the canal. In response to this spill, we sampled monthly – September through December – and have now resumed our quarterly schedule.
The Arizona Department of Environmental Quality (ADEQ) has sampled Lake Powell extensively and is monitoring data from all other agencies so that they can provide information to the citizens of Arizona. As of August 24, 2015, ADEQ declared Lake Powell to be safe for normal use. Currently, ADEQ does not believe that downstream users of the Colorado River will see impacts from the spill.
CAP takes water quality very seriously and will continue monitoring and communicating those results to our customers.