North Ada County residents concerned a new planned community could leave their wells dry aren't going to leave the future to chance.

Nearly 50 letters of protest have been filed against the water rights application of developer M3 Companies, which wants to tap an aquifer in the Eagle Foothills to serve about 7,100 new residences, schools, businesses and community amenities, including golf courses.

A Boise-based hydrology firm hired by M3 has been studying the area for about 2.5 years and has reported the presence of an aquifer so large that it can serve M3's development without hurting existing water users.

But those protesting M3's application and other area residents want a thorough, independent study of the area's hydrology before the state grants the developer's full water rights request, one of the largest in Idaho history for groundwater for municipal purposes.

"We need the aquifer studies and long-term monitoring in place first, so the Treasure Valley doesn't become the next Atlanta, which over-allocated and is now suffering the economic consequences," said Allison Gilbreath, who lives just north of Eagle.

The Idaho Department of Water Resources has scheduled a pre-hearing conference with M3 officials and those protesting the application at 9 a.m. Sept. 9 at Water Resources' Boise office, 322 Front St. The meeting is open to the public, but the deadline to file a protest has passed.

"What they will do then is identify the issues," John Westra, western regional manager for Water Resources, said of the pre-hearing conference. "They will discuss some settlements and ways to expedite the process."

A hearing date will be set at the Sept. 9 conference. Both sides will present their cases at the hearing, and Water Resources water management division administrator Gary Spackman will write a hearing decision. But Water Resources Director David Tuthill will make the final decision on M3's application.

It doesn't have to be a thumbs-up or thumbs-down decision. It could be something in between.

"The (water rights) approval could be in stages, it could be reduced, it could be pending the state study," Westra said.

Gilbreath favors phasing in M3's water rights.

"For a water right of this magnitude, the only option that makes sense is phasing," she said.

M3's original water rights application was for 42 cubic feet per second, or 27 million gallons per day, but the request has been reduced to 23.18 cubic feet per second (average daily diversion would be 9 cfs, or 5.8 million gallons per day).

Though reduced substantially, the M3 application is still one of the 10 largest applications for groundwater for municipal use in Idaho history, according to Water Resources officials.

A pending application by another developer is larger: Elk Creek Canyon LLC has filed a water rights application for 35 cfs of groundwater near Mountain Home.

M3 Companies has spent nearly $2 million on a hydrologic study of the Foothills north of Eagle over the past 2.5 years, said M3's hydrology consultant Ed Squires of Boise-based Hydro Logic Inc.

A report released in May 2007 by Hydro Logic described a newly identified regional aquifer - the Pierce Gulch Sand Aquifer - that flows westward under Boise, Eagle and Star to the Payette River Basin. It characterized the aquifer as "moderately to highly productive."

Squires said aquifer tests since then have showed it's an even more productive aquifer than they believed a year ago. He said Hydro Logic's findings are supported by a groundwater model done independently by a University of Idaho graduate student.

North Ada County residents pressed for an independent study by the state, and there will be one.

The 2008 Legislature allocated $20 million for studies of Idaho's aquifers, including the North Ada Foothills.

Katy Moeller: 377-6413