We report on our observations of the 79 and 119 \mu m doublet transitions of OH for 24 local ( z < 0.262 ) ULIRGs observed with Herschel-PACS as part of the Herschel ULIRG Survey ( HERUS ) . Some OH119 profiles display a clear P-Cygni shape and therefore imply outflowing OH gas , other profiles are predominantly in absorption or are completely in emission . We find that the relative strength of the OH emission component decreases as the silicate absorption increases . This locates the OH outflows inside the obscured nuclei . The maximum outflow velocities for our sources range from less than 100 to \sim 2000 km s ^ { -1 } , with 15/24 ( 10/24 ) sources showing OH absorption at velocities exceeding 700 km s ^ { -1 } ( 1000 km s ^ { -1 } ) . Three sources show maximum OH outflow velocities exceeding that of Mrk231 . Since outflow velocities above 500–700 km s ^ { -1 } are thought to require an active galactic nucleus ( AGN ) to drive them , about 2/3 of our ULIRG sample may host AGN-driven molecular outflows . This finding is supported by the correlation we find between the maximum OH outflow velocity and the IR-derived bolometric AGN luminosity . No such correlation is found with the IR-derived star formation rate . The highest outflow velocities are found among sources which are still deeply embedded . We speculate that the molecular outflows in these sources may be in an early phase of disrupting the nuclear dust veil before these sources evolve into less obscured AGN . Four of our sources show high-velocity wings in their [ C II ] fine-structure line profiles implying neutral gas outflow masses of at least 2–4.5 \times 10 ^ { 8 } M _ { \odot } .