The Whitewater River run from Big Bear Dam to Private Land in Sec 19, T1N, R1W in California is a popular whitewater rafting destination. The ideal streamflow range for this run is between 400-800 cfs. The segment mileage of this run is approximately 12 miles and it has been rated as a Class III-IV rapids. This means that the whitewater segment has moderate to difficult rapids, requiring moderate to high skill level and experience to navigate.

Some of the specific rapids/obstacles include "Upper Hot Springs," "Lower Hot Springs," and "Staircase." These rapids feature steep drops, tight turns, and technical maneuvers that can challenge even experienced paddlers.

There are specific regulations to the area that rafters must adhere to. For instance, all rafters must wear a properly fitting lifejacket and helmet while on the river. Alcoholic beverages are also prohibited during the trip. Additionally, all rafting companies must hold a valid permit to operate on the river.

In conclusion, the Whitewater River run from Big Bear Dam to Private Land in Sec 19, T1N, R1W in California is a thrilling adventure for experienced whitewater rafters. With ideal streamflow, a segment mileage of 12 miles, and Class III-IV rapids featuring specific challenges, rafters must adhere to specific regulations to ensure a safe and enjoyable experience.