Salmon lice (Lepeophtherius salmonis) infestations cause major disruptions in marine Atlantic salmon (Salmo salar) farming operations. Effective mitigation of these pests is reliant on monitoring for epizootics and pre-emptive treatment of lice populations before they become self-propagating. Farms typically consist of multiple salmon-rearing cages (net pen s) arranged in a grid. Initially, planktonic lice infest individual net pens, but as the population grows, all the net pen s in a farm become affected. Subsequently, monitoring and treatment requirements are often gauged at the farm level. Studies that focus on elucidating the infection dynamics of salmon lice often concentrate on a regional scale, incorporating multiple farms for analysis, but have rarely examined the dynamics that occur within a farm. In this study, the interactive effects that occur between net pens and the environment at a farm scale were investigated . Specifically, this study examined whether increased environmental exposure differentially affected lice abundance and aggregation in the net pen s of a farm. Through weekly sampling of lice burdens , we compared exposed net pen s, which inhabit the corners of the grid arrangement, and those that are buffered from exposure by adjacent net pen s. We followed the establishment and eventual epizootic infestation of salmon lice on a farm over a summer growing season until the infestation required treatment. We found that exposed net pen s had consistently higher overall abundances and indicators of aggregation. We also found that egg-bearing female lice numbers fluctuate between these net pen groups before exponential growth in the overall lice population of the farm. These results have important implications for the adoption of better monitoring strategies, more informed experimental designs, and further understanding of self-propagating infestations in salmon lice.