The Weimar Project
The statute of our association provides for the protection of the lake in collaboration with European research institutes. In May 2017, a group of scientists from the Bauhaus-University of Weimar (Germany), specialists and international experts in urban water management, stayed for a week on Lake Bolsena. The group included Professors Jörg Londong and Ralf Englert, Associate Professor Stephanie Schneider and five students, for whom the ‘Lake Bolsena project’ marked the end of their master’s degree program.
What was the goal of the study?
To identify causes of degradation of the waters of Lake Bolsena and to propose measures to arrest this degradation. The study was entitled “Phosphorus entry routes in Lake Bolsena, Italy, and identification of measures for its reduction”; the full version is only available in German.
A summary is attached at the end of this article.
How was the study carried out?
Through field investigations to identify the sources of phosphorus intake; through inspection of the lake sewage system; through taking water samples and measuring physical/chemical parameters; through meetings with experts from the University of Tuscia; through meetings with managers from ARPA, COBALB and the engineering firm responsible for the renewal of the plant; through meetings with with environmental associations.
What were the most important results?
An objective opinion, from scientists with international experience, on the current status of the sewage system and on urgently needed measures. At the time of the survey, a level of degradation was detected which had previously been hidden, even to insiders.
What measures did they propose?
A combination of technical, institutional and informative measures, in order to promote lasting improvements to the state of the lake:
– repair of the existing sewage infrastructure or creating one where necessary;
– measures to reduce bringing in of phosphorus from agriculture;
– institutional and informative changes to facilitate effective water management.
Thank you to…
The Lake Bolsena Association; the Mazziotti family for their generous hospitality; institutional speakers. Also, specifically, the Director of the Research and Development division of ARPA Lazio, A. Martinelli; Professor B. Ahlert, the initiator of the project; and the whole Weimar group, who we hope to see again soon!
Synthesis
The problem of phosphorus in Lake Bolsena
Where does it come from? What can be done to reduce it?
Lake Bolsena is a lake of volcanic origin in central Italy. Its position in a collapsed caldera and its long water renewal time lend a particular character to the body of water. It has great importance for the territory, especially for tourism, fishing and various agricultural activities in the lake’s catchment area.
Several environmental indicators show a deterioration in the quality of the lake water. In particular, a significant increase in the concentration of phosphorus has been observed. This heightens the risk of eutrophication of the lake. The agency responsible for evaluating the water quality has downgraded its ecological status from “good” to “sufficient“. This fact is also reflected in the assessment of the trophic level according to the German LAWA guidelines, which assess a current “mesotrophic” state different from the “oligotrophic” state of reference.
During field inspections, serious shortcomings and defects were found in the waste water treatment infrastructure. Furthermore, there is an urgent need to improve the organisational structure with respect to water management in the lake basin.
In order to analyse the nutrient input in the body of water, the hydrological balance and the phosphorus balance were checked. The most important sources of phosphorus input, those with the greatest potential for improvement, are wastewater emissions caused by the malfunctioning of the collection system, soil erosion in agricultural areas and leaks in pipelines after heavy rainfall.
For the reduction of phosphorus intake in the future, we suggest various potentially improving measures. Of technical measures, priority should be given to the repair of the existing sewer infrastructure. We also see potential for improvement in the field of agriculture, including the creation of buffer areas to reduce soil erosion.
Institutional changes are also needed to make non-deficit water management possible. In terms of awareness raising and the agreement of people to changes and additional burdens, we suggest information measures. These should facilitate dialogue between local politicians, associations and the population, in order to find shared and feasible solutions to current problems. In summary, we believe that only a combination of technical, institutional and information measures can achieve lasting improvement.
The objective should be to bring Lake Bolsena back to a “good ecological state“, in accordance with European legislation (Water Framework Directive). The current state is alarming, but not irreversible; however if the contribution of phosphorus persists, it could become irreversible. Therefore, to avoid further deterioration, it is urgent to act immediately.