Electric power networks mustbecontinuouslymonitored. Such monitoring can beefficiently accomplished by placing phase measurement units (PMUs) at selected network lo-caions.DuetothehighcostofthePMUs,their number must be mini-mized. The problem of monitoringan electric power system by placing as few phase measurement units (PMUs) in the system as possible is closely relatedtothe well-known domination problem in graphs. In this work, we solve the power domination problem for WK-recursive networks.