Small amounts of drugs have been found in a well in Continental Ranch, but Tucson Water officials maintain that the levels of the pharmaceuticals are harmless.
Earlier this month, the water utility conducted a test on the Marana area well and where water from the Central Arizona Project enters the Tucson system, said Tucson Water spokesman Mitch Basefsky.
The tests, which measured the chemicals in parts per trillion, detected Carbamazepine, a mood stabilizer; Iopromide, used in X-ray imaging; Sulfamethoxazole, used to treat urinary tract infections; and the antibacterial agent Triclosan.
Carbamazepine tested the highest at 79 parts per trillion. The other three drugs registered between 5 and 11 parts per trillion, Basefsky said.
“These drugs have been found for decades,” Basefsky said. “It’s nothing new that these are being found in wastewater or sewer water.”
The drugs likely made it into the water system by either being flushed or excreted through the urine, Basefsky said.
Treated wastewater is discharged into the Santa Cruz River, not far from the Continental Ranch well, which is drilled to 450 feet, although the water level is near 140 feet.
The water then seeps down, being filtered as it sinks, before it is pumped up again.
New testing methods have made it possible for water quality to be measured in detail, despite a lack of formal health standards for the substances.
However, in order to receive a pharmaceutical dosage of the drugs, you would have to drink 1.3 million gallons of the water.
The well, located in the gravel pit surrounded by the Pines Golf Club at Marana, between Interstate 10 and the Santa Cruz River, also tested positive for three of the drugs in 2002 and was singled out for further testing this year because of its proximity to the river.
The chemicals were not detected in the CAP water.
Tests for these chemicals had been done once every three years, though Tucson Water plans to begin testing annually.
Earlier this year, the town expressed interest in assuming the 8,000 Tucson Water accounts within town boundaries, a switch that the water utility tags at $19 million.
The discovery of such chemicals poses no bearing on the switching of the accounts to Marana, which is currently on hold, said the town’s Utilities Director Brad DeSpain.
Talks over the account switch should resume once the wastewater dispute between Marana and Pima County is resolved in court, DeSpain said.
The town does not test its own wells for the chemicals on the parts per trillion level.
“Part of the reason is the USGS has been conducting these tests on the effluent in the Santa Cruz River,” DeSpain said.
The other reason is the small amounts of the chemicals, DeSpain said. There is little scientific evidence as to what effect the drugs have in such small amounts.
Like other small water districts, a state agency does water quality tests and not the town themselves.
Testing for such chemicals, even at minuscule amounts, is important to determine if they can be filtered out through the recharge process, or if they make it into the water supply, Basefsky said.