California freshwater shrimp reproduce once a year. Mating likely occurs sometime between September and November. The male transfers and fixes a sperm sac to the female after her last molt. Females keep the eggs, ranging in number from 50 to 120, attached to her legs through the winter. Young are released in May or early June and are approximately 0.24 inch (6 millimeters) in length.

California freshwater shrimp reach sexual maturity by the end of their second summer of growth and may live longer than 3 years.

The California freshwater shrimp reaches a maximum length of 1.96 inches (50 millimeters), and females are generally larger than males. Juveniles and males appear translucent to nearly transparent while mature females are often brown with a tan stripe down its back. The California freshwater shrimp is readily distinguished from other shrimp species that are found in California by the tiny tufts of hair-like structures on the claws of the first and second pairs of legs. Females range in size between 1.38 to 1.96 inches (35 to 50 millimeters) in length. Males range in size from 1.18 to 1.38 inches (30 to 35 millimeters) in length.

The California freshwater shrimp is found in low elevation, low gradient, freshwater streams in Marin, Napa and Sonoma counties, California. The shrimp typically shelters near the edges of stream pools and under stream banks, exposed root material, or submerged leafy branches.