It appears that there is no boat ramp specifically named State Route 821 Kittitas County in Washington. However, there is a boat launch located at latitude 46.79811859 and longitude -120.46317291 that is accessible from State Route 821 in Kittitas County. This boat launch is called the Yakima River Canyon Boat Launch.

According to the Washington State Parks website, the Yakima River Canyon Boat Launch is a concrete boat ramp that is 24 feet wide. It services the Yakima River, which is a popular destination for fishing and boating in the area. The Washington Department of Fish and Wildlife states that the Yakima River is open to all types of watercraft, including motorized boats, drift boats, kayaks, and canoes.

In terms of the latest information available, it is recommended to check local regulations and conditions before using the Yakima River Canyon Boat Launch. Additionally, it is important to follow proper boating safety guidelines, including wearing life jackets, checking equipment before heading out on the water, and being aware of any potential hazards in the area.