Private industry and investment are critical to a nationwide effort to repair and expand a creaky U.S. network of water treatment and delivery systems, according to U.S. EPA's top water official.

Nancy Stoner, U.S. EPA's acting assistant administrator for water, warned in an interview last week that the financial woes of federal, state and local governments combined with a growing list of capital-improvement projects needed to maintain waterworks have rendered the taxpayer-backed system unsustainable.

"I don't think we can continue to provide water and wastewater services as we have in the past," Stoner said. "It's too expensive."

EPA says water and wastewater systems nationwide need $635 billion in capital improvements -- beyond regular operation and maintenance expenses.

The solution, Stoner said, is to attract and leverage private investments -- including privatization of water systems, in some cases -- to secure water supplies and boost the flagging economy.

"I think there's big money to be made in how to address the water resources needs for our country, particularly in the future when we are going to have population growth, development, the decay of existing infrastructure and climate change," Stoner said. "We're going to have serious challenges ahead."

A step in the right direction, Stoner said, is President Obama's proposal to create a $10 billion infrastructure bank. Although Republicans this month blocked the proposal, which was packaged in the $447 billion "American Jobs Act," Democratic leaders vowed last week to try to move the infrastructure bank proposal on its own after the Senate returns from a one-week break on Oct. 31.

Stoner has traveled the country in recent weeks to promote infrastructure investment. She spoke at water conferences in Milwaukee and Los Angeles and toured a water-treatment plant in Minneapolis being upgraded with federal stimulus cash.

"What I'm trying to do is to try to be relevant to the debate that's going on on the economy," Stoner said. "Most people are talking about jobs and talking about the economy, and I think some of them are getting it wrong because they're acting as if environmental protection and ... water protection is antithetical to the long-term economic interests of our country."

The U.S. Geological Survey estimated that leaky pipes lose 1.7 trillion billion gallons of treated water each year. The American Society of Civil Engineers in 2009 graded U.S. water a D-minus. Meanwhile, a growing U.S. population is expected to put more pressure on infrastructure that in many cases was built before World War II.

As one solution, EPA is touting "green infrastructure" -- a catch-all term to describe the use of wetlands and other green spaces as basins to collect and cleanse stormwater before it flows into waterways. Such systems both keep waterways clean and enhance networks of pipelines and treatment plants.

"We're very interested in green infrastructure because it provides not just water-related benefits, both quality and quantity, but it provides a whole host of other benefits," Stoner said. Among those benefits, she said, are expanded green spaces and reduced need to spend on expanding storm sewers and treatment plants.

To be sure, there are many uncertainties about green infrastructure, some of which were highlighted in a report prepared by a nonprofit led by Stoner's predecessor at EPA, Ben Grumbles (Greenwire, Sept. 13).

Stoner acknowledges the complexity of replacing major stormwater plumbing systems.

"We're not yet to the stage -- and I don't know whether we will be in the future ... where it can be completely replaced with green infrastructure," she said.