Understanding hydrogeologic properties that control fluid flow and pressure distribution is important in characterizing earthquake and deformation processes because of the influence pore pressures have on effective stress. Here, we utilize borehole pressure changes in response to Earth tides to determine hydrogeologic properties and time variations for 17 boreholes within NSF Earthscope’s Plate Boundary Observatory (PBO) network along the San Andreas fault and Cascadia subduction zone. Permeability and hydraulic diffusivity determinations range from 6.4_10-16 – 8.4_10-14 m2 and 1_10-4 – 9_10-1 m2s-1, respectively, whereas specific storage values are ~1_10-6 m-1. Values are generally consistent through time, reasonable given lithology, and are comparable to other regional studies and traditional aquifer test determinations available for one borehole. No obvious trends with distance from large faults are observed, in contrast with previously determined variations in the pressure response to seismic waves, and only one borehole exhibits permeability enhancement by earthquakes.