Grover Hot Springs State Park

Grover Hot Springs State Park is located on the east side of the Sierra at the edge of the Great Basin Province, characterized by open pine forest, and sagebrush and meadows. The park has a pool complex with a hot pool and a swimming pool hot springs, a campground, picnic area and hiking trails.
A full range of seasons and weather offer the visitor the opportunity to experience a variety of conditions, from major blizzards to dry scorchers, from warm clear nights to intense, blasting thunderstorms. Winds of great speeds are capable of whipping through the park causing damage during any month of the year. Pristine clear, warm days can be followed by cold stormy nights.
Proper preparation for the full range of potential conditions can make a visit to the park not only safe and warm but also dry and comfortable.
 

Why are the Hot Springs Green?
The main reason for the color is the mineral deposits on the bottom of the pool. These mineral deposits are laid down on the surface of the paint by an oxidation reaction between the mineral salts in the water and the sanitizing agent (Bromine) used. 
When the pool is viewed from some distance, rather than from directly overhead, the light that is reflected from the bottom loses certain wavelengths that are absorbed by the various color patterns on the bottom. The remaining light waves then pass back up through the water and are reflected at the surface. This reflected light is in the yellow-green wavelengths of the spectrum.
A natural mineral pool ranging between 102 and 104 degrees
 
From California State Park Website