Question: What are the Juntas de Regantes (WUB) within the Azua Valley?
Schema: create table table_20018310_1 (juntas_de_regantes__wub_ varchar, irrigation_district varchar, PRIMARY KEY (juntas_de_regantes__wub_))
SQL: select juntas_de_regantes__wub_ from table_20018310_1 where irrigation_district = "azua valley"