Stormwater injection wells can be used for flood control and aquifer replenishment. Injection wells are drilled directly into the aquifer, directing surface water downwards and replenishing the basin. Injection wells are particularly effective for minimizing runoff, by creating a path for excess water. This makes injection wells useful for flood control as well. The intake levels of wells can be controlled, making it possible for injection wells to handle overflows and pump water away from the surface. Injection wells have their negatives. Heavily polluted surface wa- ter can result in increased contamination of aquifers, requiring greater water treatment and potentially resulting in significant health hazards. Pollutants can also reduce the efficiency of the well, making it less useful for flood control.