Little Grass Valley is a census-designated place in Plumas County, California, USA. As of the 2020 census, it had a total population of 25.
According to the United States Census Bureau, the CDP has a total area of , all land. It is on the east side of the Little Grass Valley Reservoir, which covers about .
Little Grass Valley first appeared as a census designated place in the 2000 U.S. census.
The 2020 United States census reported that Little Grass Valley had a population of 25. The population density was . Of the population, 19 people (76%) were White, 1 (4%) was Asian, and 5 (20%) were Hispanic or Latino.
There were 11 households, of which 4 were families and 6 were one person living alone. The median age was 57.5years.
There were 147 housing units at an average density of , of which 11 (7.5%) were occupied year round, and 136 (92.5%) were used seasonally.
Little Grass Valley was initially occupied by the Maidu Native American tribe during the summers. During the California Gold Rush, it became a mining camp. The camp disappeared before 1900, but there are still gold mines in the area. The land in the valley was used to graze cattle and there was a Boy Scout Camp located on the banks of the South Fork of the Feather River. In 1963 the whole area was flooded and a lake filled the valley. Today there are campgrounds all around the lake, cabins on the south side, and it is the center of a snowmobiling area. It is about from La Porte (population 43).
In the state legislature, Little Grass Valley is in , and .
Federally, Little Grass Valley is in .
About north of Little Grass Valley Lake lies a small, natural lily pond called Fowler Lake. Its coordinates are , and its altitude is .
The school district is Plumas Unified School District.