During winter storage, the risk of groundwater contamination increases because frozen or saturated soil cannot provide a reliable barrier. If a lagoon, pit, or storage pile leaks during cold weather, the escaping liquid can quickly move downward through cracks created by freeze–thaw cycles and reach areas that normally remain sealed.
Since plants and microbes are largely inactive in winter, they can't absorb or break down escaping nutrients. Warm spells can also create brief periods when meltwater carries contaminants even deeper into the soil before the ground fully refreezes. Unlined or aging structures are particularly vulnerable, as small weaknesses can expand in cold conditions. Once nutrients reach groundwater, they can persist for long periods and affect wells or nearby springs.
