A seepage path the width of a doorway can drain a reservoir or compromise a dam. And a borehole ten meters away will never see it.
Mapping the induced-current response
Willowstick's MM-ECD method establishes a low-power alternating-current circuit through the area of interest and measures the resulting magnetic field on a surface grid. Water-bearing zones can be relatively conductive, but the response also depends on dissolved ions, saturation, clay and mineral content, geology, temperature, and survey geometry.
The measured response is normalized against a homogeneous-earth reference and processed into an electrical-current distribution model. Hydrogeology, instrumentation, geology, and site history are then used to interpret preferential conductive connections that may represent seepage pathways.
The result is spatially continuous geophysical coverage and an interpreted 2D or 3D model—not a direct measurement of water velocity, discharge, chemistry, or pressure. Those quantities require appropriate instrumentation, sampling, or hydraulic testing.
Why integration matters
MM-ECD magnetic measurements are surface based and can be repeated. A reviewable deliverable documents the acquisition, processing, assumptions, interpreted targets, and limitations. Where appropriate, Microseismic Resonance (MSR) adds a separate constraint on subsurface discontinuities and fluid-conducive zones; boreholes, piezometers, seepage measurements, and geology remain essential sources of direct evidence.