Interventions to improve the quality of high altitude aquatic environments

The Gran Paradiso National Park includes well-preserved environments where the impact of human activities is minimal. It should be noted, however, that the climatic conditions of high mountain zones may weaken the effectiveness of the techniques normally adopted to mitigate the impact of the human presence, as in the case of effluent management.  The natural equilibrium of lakes and streams may be severely impaired by the inflow of wastewater.

The LIFE+ BIOAQUAE project aims to flank traditional water treatment systems with phytodepuration techniques, to assess their efficacy and feasibility in alpine zones. Phytodepuration consists of using selected plant species to create a suitable habitat for the growth of bacterial flora having a natural water cleansing effect. The plants taken from areas adjacent to the installation are suited to the local conditions. The final goal is to create an ecological filter supplementing traditional treatment systems to obtain water that is clear and poor in organic constituents.

One of the sites selected for the action is the Pontese Mountain Hut, situated at an altitude of ca 2200 m. The area surrounding the shelter, consisting of siliceous screes, is listed in Annex I to EU Habitats Directive and therefore should be actively preserved and protected.

Although the shelter uses all the treatment systems required by the law, wastewater continues to reach the Telessio Lake and increase the load of organic substances in the water, with more or less evident effects on the lake and its banks.

The envisaged phytodepuration action will use local plant species to foster the formation of a shrub-filled area between the mountain hut and the lake. This ecological filter will help to reduce the quantity of organic compounds transported by the water coming from the mountain hut’s Imhof tank, and at the same time will provide a wet shrub-filled area important for local wildlife.

The other site is the Nivolet inferiore Lake (2500 m), whose calcareous grasslands are listed in Annex I to EU Habitats Directive. The data collected since 2009 have shown that this lake has higher organic substance contents than other alpine lakes, and that the water is not as clear as it should be. These are symptoms of alterations to the physical-chemical composition of the lake water, with potential effects on wildlife. The main cause seems to be the proximity of pasturelands actively used in summer: though it is treated in accordance with the applicable regulations, in fact, the manure produced by the cows still manages to reach the lake. The plan for this site is to create an impermeable basin where to grow aquatic plants of the types already present in adjacent wetland areas, so as to filter the water and create ideal water cleansing conditions.

This wetland area, particularly interesting for wildlife, will be created between the pastureland and the lake.