verbs - I threw a coin in a well that [was] or [is] in the forest

Which statement is correct and why?

I threw a coin in a well that was in the forest.

vs

I threw a coin in a well that is in the forest.

Also, is the "is/was" before "in the forest" called a linking verb?

Lastly, is the phrase "that [was/is] in the forest" an adjectival phrase that is describing forest?