has reached that height only occasionally. After World War II, the lake's shores retreated a kilometre in the west (the eastern shore is deeper and more steeply sloped). In 1958 the water of the lake reached the lowest recorded level, at -2.63m vs reference level. Since 1958 the level increased again to reach reference level in June 1989. After the water level started again to fall, and in 2003 the shore retreated over and the level fell in October 2003 to -1.85m vs reference. From 2004 to the summer of 2006, there was plenty of rain. of rain fell during the last 20 days of August 2005 and over during the remaining part of the year. During the following five years rain was insufficient (especially in 2006 and 2007 winters were very dry and summers hot) so by October 2012 the water level was -1.51 m vs the reference. Fortunately, since 2012 winters have been very rainy so the level of the lake has progressively increased to reach in February 2014 the reference level. In April 2014 the water level increased further to reach 0.30 m above the reference. A channel from the reservoir at Montedoglio in Tuscany to supply agriculture and lakeside towns (and thereby eliminate the need to draw water from the lake) was opened in 2012. Conservation The inhabitants of the communes around Trasimeno and the Umbrian people have successfully protected their lake, whose waters are fit for swimming and whose valleys and islands are intact environments. In 1995 a natural park was established over the entire surface and the shores. A bicycle path was opened in 2003 around the lake that allows tourists to explore it. There are also cross-country paths, especially over the hills on the eastern side. During the last twenty years several alien species (Louisiana crawfish, black bullhead, stone moroko and goldfish) have been introduced in the lake, putting under threat the autochthonous water life. The goldfish was the first alien species to be introduced in the lake and today accounts for about 50% of the total fish presence. Surroundings Half of Trasimeno is surrounded by hills, rich in olives that are an important agricultural resource. On the western shore, near Tuscany, there are vineyards, and fruit and vegetables are grown. The hills are much lower and the climate is warmer. Monte Subasio near Assisi, about to the east, and Monte Amiata, about