Thermalito Afterbay
Oroville Outdoor Adventurer

Thermalito Afterbay

Thermalito Afterbay, a diversion pool downstream of Lake Oroville, is a fun option for boaters and paddlers. With 17 miles of shoreline and 4,300 surface acres of water, the Thermalito Afterbay is open for boating, swimming, fishing, picnicking, and limited hunting. No-wake speed limits before and after sunset allow for peaceful paddling, swimming and fishing.

Smaller and shallower than Lake Oroville, the Afterbay is located between Highways 70 and 99, easily accessible from Oroville, Chico and Paradise. While similar to the Thermalito Forebay, the Afterbay allows more extensive motorized watercraft use, including motorized boats with two- and four-stroke motors and jet skis, and has a greater focus on preservation and enhancement of wildlife habitat areas.

The surface and shoreline are within the Oroville Wildlife Area, but recreation facilities and boat ramps are managed by the Department of Water Resources. There are also several undeveloped dispersed boat-in day use sites and a water-ski course. Access is good by existing roads, trails, and watercraft.

Monument Hill Day Use Area

At Monument Hill, enjoy 10 picnic tables, nine BBQs, four flush toilets, including an ADA accessible one, a fish cleaning station, and a swimming beach. There are 10 single-vehicle parking spaces (one ADA) and 39 vehicle/trailer combination spaces (three ADA). Additionally, there is a graded and graveled parking area approximately 60 yards square in area that provides room for about 30 to 40 additional vehicles with trailers.

There is also a two-lane boat ramp with a floating dock on the eastern shoreline of the Afterbay.

Trail Access

The Brad Freeman Trail can be accessed from three different trailhead access points:

  • Toland Road: located at the northwest corner of the Afterbay; gated with roadside parking only; no developed facilities at this site
  • Tres Vias: connects about 1.5 miles directly to the east of the Toland Road trail access north of the Afterbay; consists of a dirt lot and dirt road/trail; no developed facilities at this site
  • East Hamilton Road: picnic table and small gravel parking area that fits about five vehicles available at this site

Other Amenities

  • An undetermined number of primitive campsites at an area just north of and adjacent to the Afterbay outlet
  • Paved runway for model aircraft near North Wilbur Road at the Afterbay Canal
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