The Collaborative International Dictionary of English v.0.48:

Acequia \A*ce"qui*a\ ([aum]*s[=a]"k[-e]*[.a]; Sp.
   [aum]*th[=a]"k[-e]*[aum]), n. [Sp.]
   A canal or trench for irrigating land. [Sp. Amer.]
   [Webster 1913 Suppl.]