Castaic Creek is a significant waterway in northern Los Angeles County, California, best known for its man-made reservoirs rather than as a free-flowing river. The creek originates in the Sierra Pelona Mountains and flows south, eventually joining the Santa Clara River. However, its natural course is interrupted by two major impoundments: Castaic Lake and the smaller Castaic Lagoon. Castaic Lake, formed by Castaic Dam, is the terminal reservoir for the west branch of California's State Water Project. This large reservoir, with 29 miles of shoreline, offers diverse paddling opportunities.

The Upper Lake is expansive and can experience strong winds, making it suitable for more experienced paddlers and powerboats. It's a popular destination for kayak fishing, particularly for largemouth bass. The Lower Lake, also known as Castaic Lagoon or Castaic Afterbay, provides a more sheltered environment ideal for beginners and families. This 197-acre body of water has approximately 3 miles of shoreline and is restricted to non-motorized watercraft, creating a peaceful setting for kayakers, canoeists, and stand-up paddleboarders. Paddling difficulty ranges from easy on the calm lagoon to moderate on the upper lake, depending on wind conditions. No whitewater opportunities exist on the impounded sections.

The best times for paddling are typically spring through fall, with summer being the busiest season. Swimming is allowed in designated areas of the lagoon from Memorial Day to Labor Day when lifeguards are on duty. The area around Castaic Lake supports a variety of wildlife, including bald eagles, osprey, and various waterfowl. The lake is surrounded by chaparral and oak woodland habitats typical of the region.

Key access points include the main boat ramp at Castaic Lake for the upper reservoir and a two-lane launch ramp at the lagoon. The nearest town is Castaic, with Santa Clarita and the greater Los Angeles area within easy driving distance. Castaic Lake State Recreation Area encompasses both lakes and over 11,200 acres of parkland. It serves multiple purposes, including water supply, flood control, and recreation. The area is of particular importance to the Los Angeles metropolitan region as a drinking water reservoir and emergency water storage facility.

Safety considerations include checking wind conditions before paddling the upper lake and being aware of powerboat traffic. All watercraft must be inspected for invasive species before launching. Note that Castaic Lake State Recreation Area does not accept the Annual State Parks Pass, and separate fees apply for vehicle entry and watercraft use. While primarily a day-use destination, the recreation area does offer camping facilities, allowing for multi-day paddling experiences exploring both the upper and lower lakes.