Water vole surveys typically involve two visits. During each visit, a thorough visual search of the watercourse and its surrounding 10-meter buffer (where access permits) is conducted. Evidence of water vole presence, including live or dead individuals, burrows, tracks, droppings, and feeding remains, is recorded where observed.

Water vole surveys must be conducted within a specific timeframe, typically between April and September. Two visits are required: one between April and June, and another between July and September.

Surveys should be avoided during and immediately following periods of heavy rain or high water levels, as these conditions can wash away evidence of water vole presence.