Ralston Afterbay Reservoir, also known as Oxbox Reservoir, lies at the base of a canyon and where the Rubicon River and the Middle Fork of the American River converge. The reservoir is surrounded by narrow steep sided canyon walls blanketed in a thick forest of conifers. There are day use/picnic areas located at the boat launch area as well as on the island by the dam. The day use area by the boat launch will have restroom facilities and grills in addition to picnic tables. When the water level drops, currents develop making it more challenging to navigate, however, swimming areas emerge. This generally occurs during mid summer months. Also, it is not uncommon for the reservoir to be completely drained by late summer.