The Orange Water and Sewer Authority will hold a public hearing tonight on plans to raise water and sewer rates an average of 24 percent. The meeting begins at 7 p.m. in the OWASA building, 400 Jones Ferry Road in Carrboro.

OWASA leaders say two factors are driving the increase:

-- a projected 13 percent reduction in demand compared to last year's estimate, mostly due to customers' heightened awareness of the need to save water.

-- a projected 39 percent ($1.3 million) drop in connection fees from development in southern Orange County, due to the slow construction economy.

"The combination of conditions that led to the proposed rate and fee increases is extremely unfortunate," said Randy Kabrick, OWASA board chairman.

"We recognize that our customers are experiencing cost increases for fuel and other essential items," he said in a statement. "We also recognize that the need to increase rates is directly related to our requests that customers conserve as much water as possible in response to the 2007-08 drought."

The 24 percent increase for typical customers is one of three scenarios OWASA is considering, planning director Ed Holland said Monday. The others call for 17 and 12 percent increases.

For a typical residential customer using 5,000 gallons per month, the proposed 24 percent rate hike would increase the monthly bill from $58.18 to $72.69. That's $14.51 more a month, or $174.12 more a year.

In addition, an odor-elimination project at OWASA's Mason Farm Wastewater Treatment Plant -- which Holland said the agency is paying for with cash instead of a bond because it is "just about maxed out on credit" -- will run an estimated $4.2 million over three years.

The proposed budget -- 2 percent higher than the current budget -- includes $18.4 million for operations, $9.5 million for bond debt payments and $13.9 million for capital projects.