Land subsidence due to overexploitation of aquifers is often attributed to incoherent public policies. Taking the case of the Mahyar valley in Iran as an example, and based on a mixed-method research design, this study analyses the effects of policy incoherence on well use for agricultural irrigation and the resulting groundwater levels. Results show how an accumulation of policy incoherence over time results in an increased construction of wells, ultimately leading to a groundwater table drawdown, with a significant decrease of 7.61 m in the last 16 years.