Flood dykes surrounding the upper Bay of Fundy (BoF) are facing increasing risk from rising sea levels and storm surges. As costly mitigation plans including dyke raising are developed, it is relevant to consider approaches that may be used to efficiently screen existing structures for weaknesses. This study examined whether non-invasive geoelectrical surveys could be effective for targeting geotechnical investigations in a megatidal coastal environment like the BoF. The study involved a field trial of two geophysical methods in the Shepody dykelands of southeastern New Brunswick: (i) rapid electromagnetic apparent conductivity mapping (EM) carried out at walking pace, and (ii) Electrical Resistivity Imaging (ERI) which was much slower but offered far superior depth of investigation and depth resolution of anomalies within the dyke and underlying sediments. Both approaches revealed that the dykes, only 2.5 m high, were predominantly resistive features, punctuated by rare electrically conductive zones. Geotechnical (split-spoon) sampling and laboratory analyses of soils revealed that locally elevated conductivities are a consequence of elevated pore water conductivity/salinity. Notably, the most prominent conductive anomaly, extending into the natural foundation sediments, coincided with the location of a drainage channel through the tidal mudflats, a small depression on surface, and audible water flow within a borehole at ~3.5 m depth. We infer that observed conductive anomalies are indicative of increased saltwater intrusion into the dyke foundation and increased seepage into the dyke itself during high tides which could impact dyke stability through its effect on water saturation and internal erosion.