Hundreds of Picture Rocks residents can expect to see significantly higher water bills in the coming months, while thousands more will see more modest increases.

Avra Water Co-op and Rancho del Conejo Community Water Co-op, which both exclusively serve customers in Picture Rocks, are preparing to raise customers' bills to offset rising infrastructure costs.

Picture Rocks is an unincorporated community near Saguaro National Park West and North Sandario Road.

Avra, which formed in 1976, has more than 2,500 connections. The co-op last applied for a rate increase in 2007. It's based at 11821 W. Picture Rocks Road.

Rancho del Conejo, which was established in the late 1960s and has 315 connections, is applying for its third rate increase in 20 years. It's at 13130 W. Rudasill Road.

The U.S. Environmental Protection Agency lowered the levels of acceptable naturally occurring arsenic in drinking water in 2006. Avra responded by shutting down wells that did not comply with the new standard and drilling new ones. Ranch del Conejo seeks a rate increase to cope with costs of treatments to reduce its levels of naturally occurring arsenic and bring the utility's water into compliance.

Recharging the treatment system costs between $70,000 and $80,000, typically every two years.

Avra's rate increase was approved by the Arizona Corporation Commission in January and went into effect Feb. 1. Customers should see the rate increase on their March bills, which will arrive at the beginning of April.

Avra general manager Chris Ward said the median user's bill of $40.39 will increase $1.65 to $42.04.

Ward doesn't expect much backlash from the rate change.

"There will be people who don't read any of the newsletters who call and ask questions about it when the bill comes," Ward said, "but generally they're pretty understanding."

Rancho del Conejo vice president Albert Lannon said his co-op's rate increase, which would raise the median user's bill from $25.90 to $40.40, could be approved by the commission in early May.

Ward said Rancho del Conejo customers might experience "rate shock" due to the drastic increase, but Lannon said customers he's spoken to are looking at it philosophically.

"Nobody has complained to the commission," Lannon said. "What several people have told me is they've gotten it real cheap for years. Now we're catching up with everybody else. It's a necessity. We're working with a base of 315 customers. The math is pretty (obvious). That's why there's a big increase."

Lannon said the co-op is struggling with decaying infrastructure.

"We have two part-time employees. The board and myself are all volunteers. Our backhoe doesn't work, and the trailer we've worked out of for 40 years is old and crumbling," he said. "We don't spend a lot of money."

Ward said his co-op puts off rate increases when it can.

"We try to hold up as long as possible," he said. "The increased prices of fuel and insurance add up over time. This is kind of as low (a rate increase) as possible."

Contact reporter Phil Villarreal at 573-4130 or