Murky plumes of wastewater flow into the Santa Clara River each day, carrying a stew of contaminants such as disease-causing bacteria, grease, nitrates and human waste.

The sources are antiquated wastewater treatment facilities in Santa Paula, Fillmore and Piru — three of the county's poorest communities now facing state sanctions and multimillion-dollar construction costs to build new sewage plants.

It's a scenario playing out across the nation. Aging, inadequate systems are pumping billions of gallons of untreated and undertreated sewage into the nation's water supply, costing millions of dollars in related healthcare costs, according to the Environmental Protection Agency.

In a typical year, 74,000 Southern Californians go to the doctor with eye, ear and skin infections, stomach ailments and respiratory diseases caused by exposure to sewage-polluted waters, a recent UC Irvine study found.

The solution — building new sewage plants that meet current standards — is quickly becoming the No. 1 expense in cities large and small. The impact can be catastrophic for small towns that must raid already-lean budgets for new pipes and plants. Sewage rates once as low as $25 a month are being raised by as much as 500 percent to help defray the cost.

"It's a huge problem nationwide, and it will all fall back on ratepayers," said Reddy Pakala, director of Ventura County's Water and Sanitation Department, which oversees Piru's 33-year-old plant. "There are many, many water systems that are 70 to 100 years old. We are going to see more and more sewage rates doubling and tripling."

A new, $10 million plant must be built by 2009 in Piru, a town of 2,200 where more than half the families earn less than $50,000 a year and a third are on fixed incomes. Sewage rates will have to jump from $40 to $120 a month.

Nationally, the cost to upgrade and repair sewage infrastructure is in the billions, according to the American Water Works Association. The EPA estimates $390 billion will be needed over the next 20 years to replace existing systems and build new ones.

Delays increase construction costs

In California, $7 billion was spent to repair and build new sewage systems in 2004, but the need was at least $11.5 billion, according to the state Water Resources Control Board.

California's 34 million residents and thousands of businesses flush more than 4 billion gallons of wastewater into public sewage systems every day. Roughly 100,000 miles of sewer pipes and 200 wastewater treatment plants process the waste and then discharge most of it into streams, rivers, bays, estuaries and ocean waters.

Santa Paula and Fillmore city officials have known for years they must upgrade their plants, but they have delayed the project. Now, the towns, which have the county's lowest per-capita incomes and highest minority populations, face even higher bills because construction costs have risen dramatically.

Santa Paula has violated state discharge standards since 1997, with its treated sewage listed as a major threat to water quality. From 2000 to 2004, the plant was cited for 353 violations involving total solids, 527 involving coliform and 1,444 for turbidity, or murky water. The state ordered the city in 2001 to upgrade its sewage plant, which was built in 1939 and was last upgraded in the 1980s. Millions in fines have accumulated, and the city is seeking a settlement.

Fillmore, which was assessed a $264,000 civil penalty by the state in 2005 for violating discharge standards, faces a bill of $82 million for construction of a new sewage plant. Bert Rapp, the city's public works director, said the new plant will be state-of-the-art and able to meet the strictest of water quality regulations, present and future.

Expansion will be possible

Using a membrane technology that filters the smallest of microbes, the facility will be initially designed to handle 1.8 million gallons of sewage a day, with the capability for future expansion as the city of nearly 15,000 people grows.

The plant will be designed, built and operated for the next 20 years by American Water, a private operator.

The city won $3 million in state grants and sold bonds to pay the rest of the bill, instead of borrowing from a state revolving fund.

On July 1, the first of several rate hikes was implemented. Fillmore residents used to paying $25 a month are now paying $66. The rate will double again next year. New homes and businesses will have to pay $3,000 to hook up to the new system, in addition to the higher rates.

Not surprisingly, some residents are unhappy with the final cost.

"We think we're paying too much — a notice was sent out in 2003 that said a new plant would cost $24 million and the sewer bill would be $45 a month," said Gayle Washburn. "What happened to that?"

Settling for a Chevrolet

Santa Paula expects to spend about half of what Fillmore is paying. The city of 29,000 has a $63 million operating budget.

"If we have to settle for a Chevrolet versus a Cadillac, that's OK as long as it does the job and meets the state's requirements" for discharge, said Wally Bobkiewicz, city manager. "Many of our residents are poor or on fixed incomes and can't afford $70, $80, $100 sewer bills."

Thousand Oaks also received notice from the state a decade ago to upgrade its plant. The city immediately began improving the facility and avoided the escalating construction costs confronting Santa Paula and Fillmore.

Thousand Oaks' facility is one of the best in the county, with treated wastewater that's almost drinkable and low rates — $25.50 — for residents. It sells its reclaimed water for about $1 million each year, and uses a field of solar panels to generate much of the energy needed to run the plant.

It's only a matter of time before ratepayers in other cities will be paying more as well, experts say.

Usually a city's most expensive facility

"Typically the most expensive facility in a city is a wastewater treatment plant," sometimes more costly than putting police on the street or funding retirement for employees, said Chuck Rogers, superintendent of Thousand Oaks' Hill Canyon Wastewater Treatment Plant.

"With infrastructure, it's OK maybe not to take the highest degree of care of it all the time, but when you don't do that for an extended time, you find yourself in big trouble, where it's so badly deteriorated you're facing the big bucks."

Thousand Oaks has spent $60 million on upgrades to its facility over the past 10 years, and $100 million in total since it was built 40 years ago. The city's plant, along with Moorpark's and Simi Valley's, is new when compared to some of those in older cities, such as Oxnard, which spent $125 million last year to upgrade aging pipes.

Stricter water quality regulations are driving the cost as well. "We all live in a large community that requires us to have restored and protected water quality," said Francine Diamond, chair of the Los Angeles Regional Water Quality Control Board. "We have to all participate in making sure our water is safe and public is safe. Health and safety must be protected — it's up to the cities to do that."