Mountain pine beetles have killed a large percentage of mature lodgepole pine trees over an area of more than 14 million hectares in the B.C. Interior. Research has shown that this can increase the magnitude of spring runoff. Forest licensees are also permitted to log beetle-attacked pine stands at an accelerated rate. The net effect is that most of B.C.’s mature pine stands will be changing rapidly over the next decades due to deterioration of the overstory, natural regeneration, clearcut harvesting, and managed reforestation. This project documents differences in structure between pine stands at different stages of growth and deterioration, changes within stands over time, and the effects of those differences on snow hydrology at the stand level. This will help watershed modellers predict possible changes in stream flow due to pine beetles and forest management. The map shows the locations of five study areas where this work is being done.