HILO, Hawai'i — A proposed marina, hotel, time-share and retail development in Kona will need new wells, water lines and storage tanks to supply about 2.6 million gallons of fresh water each day for the huge project, which is planned for a dry leeward area of the Big Island.

A new environmental report notes that the Kona Kai Ola project planned on state-owned land just south and east of the existing Honokohau harbor will also alter or eliminate nearby anchialine ponds, cutting off the source of brackish water that now flows into the ponds.

Some of the ponds will also be excavated to create the new marina, but the draft environmental impact statement for the project contends that "these ponds are already degraded by nutrient enrichment, trash from visitors and the introduction of minnows."

The developer proposes to convert some of the ponds into saltwater "marine systems," and to offset the loss of the ponds by restoring other anchialine ponds in places such as the adjoining Kaloko-Honokohau National Historic Park, the environmental report said.

The debate over the Hono-kohau project proposed by Jacoby Development Inc. of Atlanta is expected to be contentious.

The Kona community is already furious at traffic congestion, and many residents blame county government for allowing developments to go up without proper planning to be sure roads and other infrastructure is in place to accommodate the extra visitors and residents.

The Jacoby project would add 52 acres of commercial development, 700 new hotel rooms and up to 1,800 time-share units to that mix. The developer is also proposing to build 500 to 1,000 "workforce housing" affordable rental units near the project.

The project would also involve excavating at least 12 feet down over 45 acres of lava fields to build a completely new 800-slip marina.

The project is planned for 200 acres of land the developer leases from the state Department of Hawaiian Home Lands, and another 330 acres of state lands Jacoby plans to lease from the state Department of Land and Natural Resources.

The developer contends in the environmental report that the project will supply badly needed slips for the growing boating community in Kona, and will help the two state departments to earn money from lands that are now vacant.

The impact statement stresses that 224 acres of the project will be set aside as green space, open space or public spaces, with lagoons, water features and ponds dotting the development.

The developer is also promising to extend Kealakehe Parkway through neighboring Queen Lili'uokalani Trust property to link it up with Kuakini Highway to ease traffic congestion in the area, and to create a new shuttle service to move visitors to and from the development.

The project needs a variety of government approvals, including a rezoning and a special management area permit from the county, and approval from the state Commission on Water Resource Management to drill new wells.

In an unusual tactic for a Hawai'i environmental report, the impact statement does not consider the usual array of alternatives to the project, such as the alternative of building a more modest development.

The authors of the report argue that since Jacoby is obligated under its agreement with the state to build an 800-slip marina, the project must be dense enough "to provide an acceptable level of economic return" to the developer.

"The market study found that the currently proposed density and mix is the optimum to meet the anticipated financing and development cost obligations for the public features associated with the development," according to the impact statement summary.

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.