A letter signed by nine Sierra conservation groups was delivered to Placer and Nevada County supervisors this morning in an effort to increase pressure on a development project proposed for Donner Summit.

The letter outlines 14 planning principles to serve as a blueprint for supervisors as the owners of Royal Gorge Cross Country Ski Resort prepare to unveil development plans for the region.

In 2007, Sierra Watch and Sierra Club enlisted a team of planners, biologists and hydrologists to access how the development would impact resources in the region. Findings from the survey were used for the recent letter.

Sierra Watch was a key player in the conservation efforts that came out of lawsuits against proposed development in the Martis Valley outside of Truckee. The group was also involved in opposing a ski resort in Lassen County named Dyer Mountain, which recently declared bankruptcy.

Developers Kirk Syme and Todd Foster call their development a conservation community with 950 housing units in four “camps” organized around outdoor recreation, open space and skiing.

The controversial plan will soon be submitted to Placer County.

The joint group letter calls for a protection of the summit’s natural and cultural resources while preserving the values of existing neighborhoods by maintaining a clean abundant water supply and roadways free of traffic congestion.

“The planning principles are designed to ensure a better blueprint for Donner Summit, one that puts responsible development where it belongs and permanently protects the region’s landscape for generations to come,” said Tom Mooers, executive director of Nevada City-based Sierra Watch, in a news release.