The most likely causes for the dead zone in the Great Lakes are the amount of phosphorus nitrogen and fertilizer running off into the lake. When the lake becomes rich in these nutrients and you add warmer temperatures into the equation you can expect an algal bloom. Once the bloom dies the decomposition depletes much of the oxygen in the water which is severe because of the size of the algal bloom. This coupled with things such as low water inflow and temperature of water are the most popularly believed reasons for dead zones in Lake Erie. The simple tests would include monitoring the sources of inflow into the lake such as tributaries, sewage and run off. With these results you can track the levels of incoming nutrients and make better predications
