Martis Valley is a geographic area of 70 square miles (180 km2) in the United States, extending northward from the North Shore of Lake Tahoe, California, to the west of the California-Nevada border. It is located in Placer and Nevada Counties. Located in the Sierra Nevada mountains north of Lake Tahoe, Martis Valley is largely rural and forested. Elevation ranges from approximately 5,800 to 8,600 feet above mean sea level.
The area is roughly coextensive with the Martis Creek Basin, which drains into the Truckee River. It includes Martis Creek, Donner Creek, and Prosser Creek, major tributaries to the Truckee River. There are several natural lakes, Dry Lake, and Gooseneck Lake, Donner Lake. The Prosser Creek Reservoir, a small manmade lake, was created in 1962. A larger lake, Martis Creek Lake, was built in 1972 by the United States Army Corps of Engineers as flood risk reduction for Reno, Nevada. The area also includes Martis Creek Lake Recreation Area, operated by the US Army Corps of Engineers, the northern portion of the Northstar at Tahoe ski resort, the Lahontan Golf Club, and the Truckee-Tahoe Airport. California State Route 267, one of two main roads connecting Truckee and Lake Tahoe, runs through the valley.
In the 2000s Martis Valley faced development pressure due to its proximity to Truckee, California and Northstar at Tahoe, a popular ski resort. Developers initially obtained approval to build 6,000 homes on 25,000 square miles (65,000 km2) of subdivisions, which would have more than doubled the population of Truckee, California. In response environmentalists, preservationists and other activists created an organization in 2000, Sierra Watch, that filed lawsuits to prevent the development. After a judge issued an injunction against development, the litigation was eventually settled via a series of agreements that resulted in scaled-back housing projects, as well as preserving and providing more than $100 million for various wildlife and historic preservation initiatives.