Although Mount Baldo enjoys a relatively high intake of water from rain and snow (precipitation varies from about 1000 mm a year in the foothill area up to over 1,500 mm a year on the summits) it is poor in surface runoff, especially in the Veronese area, due to the great development of karst processes in the limestone.
The Trento side of Mount Baldo, however, has a greater abundance of springs at all altitudes because of its substantial impermeable marl layers and large basaltic outcrops. Thanks to its shell shape, many alluvial fans, accumulation of clay debris and because of the impermeability of the marly Red Ammonitic limestone (at a certain depth), spring water is quite abundant also in the syncline area of Ferrara di Monte Baldo – namely Novezza, Ferrara, Spiazzi and in the Salve Regina Valley up to Pazzon, Caprino and Pesina.
The Western slope of Mount Baldo is the driest. There are however some small sources of hidden condensation in the summit zone, such as those close to Cima Valdritta, or of water retention in correspondence to the calcareous marl levels of the Lower Lias in the area of the Buse Cirque and Telegrafo Cirque. A second alignment of springs is located in the mid-mountain zone, generally where the valley incisions reach certain impermeable levels of the Upper Lias, like in the spring of Val Trovai, at Malga Piombi, Albi di Brione and Breola Valley. The lacustrine springs belong to the third alignment, which is the most abundant.
Mount Baldo displays some interesting wetland biotopes that can be related to the category of the so-called “small waters” (small bodies of water). They can be natural or artificially created by man. These habitats have common characteristics: shallow depth, standing water, extreme variations in temperature, lack of thermal stratification, and turbidity. “Small waters” can dry up, because they evaporate or because the bottom is not waterproof enough. Such basins are called “astatic”. Fairly large biotopes with variations in water level that never dry up are called “perennial basins”.
“Small waters” can be divided into three categories:
PONDS – Basins where water gathers that look like small lakes, characterized by having a depth of at least one meter (up to a maximum of 3-5 meters)
SWAMPS – Bodies of water with a variable depth that never exceeds a meter, but more often with a depth of barely half a meter. They may dry up in certain periods of the year. If the depression has vegetation emerging from the whole body of water then it’s called MARSH.
PUDDLES The maximum depth of puddles is 50 cm and their size is very small. They are often temporary since they fill up between fall and spring and dry up during the summer.
Pasture puddles are small basins of water created by farmers for watering cattle and sheep and situated close to an alpine hut.
These basins were built using natural depressions and dolines and made waterproof by coating the bottom with pressed clay. Puddles are distinctive also for their shallowness (which is normally no deeper than 50 cm), round shape, limited size, standing water (since there is no current to move it), considerable changes in water temperature throughout the day (caused by the shallowness of the basin), lack of thermal stratification (from surface to the bottom there are no great differences of temperature), turbidity.
Normally, during the time they are used, these puddles are characterized by a complete or almost complete absence of aquatic plants that cannot survive trampling by livestock, nor thrive in water contaminated by animal droppings. In vast areas of Mount Baldo, puddles are the only aquatic ecosystems found at high altitudes (as a consequence of the karstic substrata) where life is possible for amphibians (frogs and newts) and for insects that are specialized to live in such environments (water beetles, dragonflies, etc).
Many puddles have been abandoned, so that grass has gradually grown into them; others have become increasingly restricted because of the lack of maintenance. Even the waterproofing of the bottom is maintained only thanks to the continuous trampling of livestock: an unused puddle slowly disappears and grasses over.