Two common methods for detecting leaks from storage ponds are detection of contaminants in monitoring wells and use of two asphaltic liners with a seep collection system between them. However, significant quantities of the impounded fluid may have leaked by the time contaminants are detected in the wells. Double liners have the advantage that leaks are detected before the fluid escapes into the environment, but they are expensive. An alternative approach is to use electrical resistivity methods to detect leaks. Several studies have mapped conductive zones with electrical methods and have inferred the presence of contaminated groundwater (e.g., Greenhouse and Harris, 1983). A fundamental ambiguity in any such survey is that the subsurface may contain conductive sediments (such as clay or silt) that may be mistaken for contaminated water, however. Parra (1988) proposed an alternative method that detects holes in a liner by mapping the electrical response due to a short circuit across an insulating liner which results from conductive fluid in a hole. An important result is that the electrical response of the leak is detectable only within a few meters with this method.