Question

because of the drought, city officials quickly took emergency measuresto protect the supply of water.

which word is the adjective?

Answer 1

Look at the nouns in the sentence, and find the adjective word that helps describe the noun. Adjectives are usually located immediately before the noun they are describing. Does this help?

Answer 2

'emergency' is the adjective here.
Although it is often used as a noun, but here it's usage is as an adjective.

Answer 3

I think there are two:
city describes what officials and emergency describes measures.
What do you think?