The Infiernillo Dam ("Little hell"), also known as Adolfo López Mateos Dam, is an embankment dam on the Balsas River near La Unión, Guerrero, Mexico.

It is on the border between the states of Guerrero and Michoacán.

[1] The dam supports a hydroelectric power station containing six turbine-generators for a total installed capacity of 1,120 MW.

The dam is 149 m (489 ft) high, 344 m (1,129 ft) long and is owned by Comisión Federal de Electricidad.

The diversion tunnels were closed and the reservoir began to fill on June 15, 1964.