From all the information gathered it could clearly be seen that the debris avalanche, mudflows, tephra deposits and storm flows all had large impacts on the drainage system on and around Mount St Helens. However there is definitely an interaction between all of these factors. Hot pyroclastic material in the debris avalanche along with the tephra deposits melted snow and glacial ice. This freed water then mixed with the sediments to give mudflows. Again the melting of the snow and ice along with rainfall caused the storm flows. Therefore it is hard to separate out the consequences and say which was more important, as one process seems to act as a pre-cursor for another process. However the initial debris avalanche stands out as the most important as it was the trigger of the eruption and it produced greater volumes of sediment than any of the other processes, it also acted as a trigger for mudflows and storm flows.
Since May 1980,there has been a substantial natural recovery of the drainage system around Mount St Helens. Yet during this period of recovery, floods and mudflows damaged many roads, and many homes were lost due to stream-bank erosion.