Dubhe Mystery Cache

This cache is part of the PCFT Geo/Astro art series, which is inspired by the Big and Little Dippers, and the stars that make up their patterns. Each virtual point in the pattern is named for the star that holds that respective position in the sky.
Final coords will be provided when you answer the question through the Certitude link.
Some of the caches will contain a FTF prize!

This cache is located along the Green Loop of Palm City Farms Trail

Dubhe - The upper right star in the "bowl" of the Big Dipper - together with Merak, the lower right star in the bowl, form the famous "pointers". A line extended from Merak to Dubhe and extended to 5 times that length will end up very near Polaris, the North Star. Very handy for getting one's bearings when the GPSr goes dead!

Another puzzle in this series touches on the Equatorial Coordinate system, essentially defining lat/lon for stars & other celestial objects.

The latitude of an Earth-bound observer will dictate which celestial objects will pass directly overhead; that is to say, celestial objects having the same "celestial latitude" as the latitude of the observer on Earth, will pass directly over the head of the observer once every 24 hrs as the Earth rotates on its axis.

The Equatorial Coordinate System does not use the term "celestial latitude". Determin what the actual term is, and find the associated value for Dubhe. . . Then (here's the tricky part), find the large(est) North American lake from which one could observe Dubhe passing directly overhead.

Name that lake! (nospaces)

You can validate your puzzle solution with certitude.

Congrats to GeoSleuth & VMOMOO6 on FTF!