Providing sewer service to the Tuolumne Band of Me-Wuk Indians could prove to be an ongoing challenge if the tribe's rapid growth continues.

That was the assessment of Danny Tuel, manager of the Tuolumne City Sanitary District's sewer plant, who spoke at the district's Wednesday meeting.

His comment came following district engineer Harold Welborn's announcement that, due to an increase in wastewater use at the tribe's Black Oak casino, the gaming facility is responsible for two-thirds of the load within the district.

To accommodate the ever-increasing sewer load, a $6 million sewer expansion project is under way. The project will also allow current casino expansion plans, including the construction of a hotel, to proceed. The sewer project will be done in phases over several years.

Welborn has stressed throughout discussion of the project that the tribe "is paying their fair share" thanks to a formula the sewer district uses in calculating the number of single-family homes the casino is equivalent to in terms of its wastewater usage.

The majority of the funding for the first phase of the project, which includes construction of the sewer plant, is coming by way of roughly $4.5 million the tribe has paid to the district for current and future sewer connection fees.

Welborn said that figure is set to increase by $2.9 million due to recent calculations that show the tribal casino's wastewater use is equivalent to 1,258 homes, not the 853 for which they paid the connection fees.

Additionally, Welborn said, with the tribe looking into upgrading its casino expansion plans, the tribe's contribution could increase in the future.

"They're planning for bigger and better," he said. "If they make a significant change, we'll be back," he told the board.

In addition to the casino hotel, the tribe is also planning to develop an 18-hole golf course and 69-home subdivision on the West Side property near Tuolumne.

Those projects will be equivalent to 305 dwelling units, according to Welborn.