an earth dam on the rio uchusuma was built in 1982-1986 and forms a reservoir also called paucarani on the southeastern foot of the volcano just southwest from the natural lake paucarani. this reservoir has a capacity of of water and is a key part of the water supply of tacna; water is transferred from the paucarani reservoir through the canal uchusuma to tacna, covering 90% of tacna's water consumption for both irrigation and human use.