There is an area west of Salt Lake City in West Valley City, Utah. West Valley is located about 5 miles away from the south end of the Great Salt Lake. The Great Salt Lake is eight times saltier on average than the ocean.
Salt Water freezes at a lower temperature than fresh water. During the winter areas around such bodies of water create an area that may be one half to one zone in temperature higher as based on the USDA Hardiness Zones, the map that shows what plants do best in what climates. It is based on average minimum annual temperatures.
What is interesting is that Joshua Trees grow very well in this area as compared to other areas well outside their range. West Valley City is typically a zone 7, but could the area nearest the Great Salt Lake be closer to a zone 8? Here are some pictures I have taken of several types of yucca that seem to thrive here better than other areas of the Salt Lake Valley.
Bacata also known as a Spanish Dagger beginning to bloom.
A young Joshua Tree planted in a zero scaped curb setting.
Two small yuccas growing on a curb.