**8. Conclusions**

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Lake's natural environment have resulted in severe deterioration of the water quality in almost all water bodies, except the elevated stretches of the rivers way beyond the immediate human activities, if medium range aero deposition is regarded as negligible.

Apart from the performed investigations and obtained results, one of the major contributions to the conducted analyses was via the method used to separate the natural background of nutrient emissions from the anthropogenic influences that need interventions. In the case of Prespa Lake, humans started to alter the environmental properties in its catchment more than 1000 years ago by intensive forest clearings that have resulted in accelerated phosphorus leaching. This process has become even more intensified in the past 100-150 years through untreated wastewaters inflow into the system and intensive agriculture. The final observed outcomes have been the full turnover of the dominant algae in the plankton towards cyanobacterial 'water blooms' during summer periods which have also proven to be toxic for microcystins.

In order to prevent further deterioration of the water quality in the watershed, substantial efforts have to be made and many water pollution prevention measures implemented. Even if these activities are fully implemented and operational, the timeframe for full recovery of the ecosystem may be prolonged, since the accumulated quantities of harmful substances are in the range of highly elevated levels. Nevertheless, if no measures are initiated and implemented in the area, the overall environmental quality in Prespa Lake watershed will be much more degraded in the near future. This is especially important for the Prespa Lake itself since it has already started to show clear signs of becoming eutrophic throughout the year with even more frequent and toxic cyanobacterial 'blooms'. If the turnover towards fully eutrophic system is completed, the activities to restore and improve its water quality in that situation will be much more difficult or even impossible, thus rendering Prespa Lake unsafe and unusable for future generations.
