Question - This lake's former Vozrozhdeniya [[vahz-ruzh-DEN-yah]] Island, now joined to the mainland, once housed a Soviet smallpox lab.

This lake's former Vozrozhdeniya [[vahz-ruzh-DEN-yah]] Island, now joined to the mainland, once housed a Soviet smallpox lab. The northern reaches of this lake have been preserved through the construction of Dike Kokaral, while its southern regions, located in Uzbekistan, have been left to degrade. This lake, once fed by the Amu Darya river, suffered after cotton farming diverted much of its water for irrigation. For the point, name this lake in Central Asia that has mostly dried up.

Answer:

Aral Sea