The Lago Piccolo di Monticchio changes colour. In the cold season the surface water cools below the water underneath it, the lower layers rise, they oxidise, and the basin turns rust yellow, while the Lago Grande next to it stays pale blue. Then the iron oxide, heavier than water, settles back to the bottom and the earlier colour takes the lake over again. The two sheets of water fill what is left of the crater of Monte Vulture, an extinct volcano whose last eruption dates to the Late Pleistocene, 130,000 years ago, and which went on showing secondary activity until 1820. The regional reserve was established in 1984, covers 187 hectares across Atella and Rionero in Vulture, and is administered by the Province of Potenza.
What to see
A low-altitude beech wood comes down to the bank: the beeches reach the water at 650 metres above sea level, an unusual height for the species, and they manage it because of the microclimate inside the crater. It was in that wood, in 1963, that the South Tyrolean researcher Federico Hartig found Brahmaea europaea, a moth with a seven-centimetre wingspan and the only species of the Brahmaeidae family living in Europe. Most of the other wildlife is what populated Lucania before the settlement push of the twentieth century: almost the same species as the Pollino, on a far smaller patch of ground.
The lake passes 30 metres deep in places, and from the bank you can make out very dense algal growth below the surface. According to the Arpa Basilicata surveys of 2017 the native species are eel, tench and freshwater crab; perch arrived from the Po-Veneto district, while largemouth bass, mosquitofish and carp are all foreign to the basin. Above the shore stands the abbey of San Michele Arcangelo, cut into the tuff.
Visiting
The reserve lies within the territory of Atella, and the lakefront is where everyone coming up to Monticchio ends up: market stalls, and a small jetty renting out pedalos. Look first at the colour of the water and at the point where the beeches touch the bank; the abbey cut into the tuff, higher up, is worth keeping for last.
Our editors' tip
If you can choose, come in winter and stand where both lakes are in view at once: it is the only moment when the comparison works, the Grande pale blue and the Piccolo rust yellow. From the pedalo, look down instead: the algal growth is visible to the naked eye under the surface of the water.