Lago di Gerosa: how to get there and trails

Where Lago di Gerosa is

Lago di Gerosa is in the southern part of the Marche, in the Sibillini Mountains area. It is about 6 km from Montemonaco and close to the town of Comunanza. Its shores mark the border between the municipalities of Comunanza and Montemonaco, in the province of Ascoli Piceno, and Montefortino, in the province of Fermo. The lake begins at San Giorgio all'Isola, a hamlet of Montemonaco, and ends at the dam, which is in the municipality of Comunanza.

The lake is fed mainly by the Aso river, which runs down from the slopes of Monte Vettore toward the Adriatic and is both the inflow and the outflow of the reservoir. The dam was built between 1977 and 1983 by the Consorzio di Bonifica dell'Aso and now belongs to the Consorzio di Bonifica delle Marche. It is a masonry gravity dam with a maximum height of 77 meters. When full, the lake covers about 64 hectares.

The dam serves mainly to irrigate the Aso valley: the reservoir holds 15,400,000 cubic meters of water and can irrigate more than 3,483 hectares. The water also feeds two hydroelectric plants in the municipality of Comunanza, one at Gerosa and one at Villa Pera. A third plant near the lake depends instead on the Arato reservoir, in Montefortino. Lago di Gerosa also has a seaplane base and is used by helicopters and Canadair aircraft to take on water when fighting fires.

How to get to Lago di Gerosa

Lago di Gerosa is reached by car from Montemonaco, Comunanza or Ascoli Piceno. The access roads pass through San Giorgio all'Isola or the hamlet of Gerosa.

From Montemonaco. Leave the village by crossing the bridge after the small panoramic square. After about 1 km you reach a wide junction with signs: follow the signs for Comunanza, go through the village of Ropaga and descend to San Giorgio all'Isola. There, turn left, still toward Comunanza, and after about 1 km you are at the lake.

From Comunanza. From the center, take the SP 237 toward Montemonaco. After about 9 km the lake appears on the left. Coming from the coast, drive up from Pedaso, on the A14, along the Val d'Aso road to Comunanza.

From Ascoli Piceno. Take the SS 4 Salaria to Mozzano and right after the village turn right toward Comunanza, on the SP 237. Pass Roccafluvione and Croce di Casale, then turn left onto the SP 67 to the turnoff on the right for the lake.

By bus. The line to Montemonaco stops at the Gerosa junction, on provincial road 86, about a kilometer from the lake: about a quarter of an hour on foot.

For parking at Lago di Gerosa, San Giorgio all'Isola is a good option, and some trails also start there. Coming from Comunanza, right after the church take a small road on the left that leads to a parking area. On the Comunanza shore there is also a playground, a handy meeting point.

Trails and hikes at Lago di Gerosa

The simplest walk at Lago di Gerosa is the gravel path that circles the reservoir. It is level and can be walked or cycled. Along the way there are rest areas, and the flat dirt sections along the shores are also suitable for Nordic walking. On one side of the lake runs the paved road, on the other a dirt road that follows the whole shore. The right bank, almost entirely wooded, is the least accessible.

Sentiero del Guerin Meschino, from San Giorgio all'Isola to Montemonaco. This is a hiking loop graded E, about 12.5 km long, with about 450 meters of elevation gain. It starts from San Giorgio all'Isola and climbs the Aso valley on a gravel road. After about 3 km it reaches the junction for Rascio and after another kilometer San Lorenzo in Vallegrascia. It then heads back toward the Rava mill and fords the Aso stream: watch out for wet pebbles, and trekking poles help. The trail continues through Vallefiume and Pignotti to the church of Santa Maria in Casalicchio. From there a ridge climbs to Montemonaco, and a trail finally descends back to San Giorgio all'Isola.

By mountain bike. A loop of about 35 km, with about 800 meters of total elevation gain, starts and ends at the lake. From San Giorgio all'Isola it climbs to Altino di Montemonaco and follows a stretch of the Grande Anello dei Sibillini, through the woods of Altino and the meadows of Monte Oialona. It is a moderate route for riders with off-road experience. Gravel riders will also find the route from Roccafluvione, long and graded difficult. It climbs to Croce di Casale, descends to Gerosa for the lake loop and then climbs back.

For the longer loops it is best to start early, bring enough water and hiking shoes, and check the weather before setting out.

When to visit Lago di Gerosa

Summer is the busiest time at Lago di Gerosa. The small beaches and green areas on the banks attract families looking for a day outdoors, and the shade of the pine woods along the shore is pleasant even in the hottest hours. In summer activity also moves onto the water: the length of the reservoir makes it suitable for canoeing, sailing and rowing, and canoe, sailing and fishing competitions are often held on the lake.

Spring and fall suit those interested in birdwatching. The lake is a stopover for migratory ducks, which pass through twice a year: between March and May and between October and November. Great crested grebes hunting fish, roe deer, porcupines and badgers can also be seen on the lake and along the shores.

Fishing is possible in every season. The species present are mainly European perch, largemouth bass, pumpkinseed, common barbel, eel, triotto (Italian roach), rudd, chub, crucian carp, bleak, carp, tench, brown trout and rainbow trout.

What to see near Lago di Gerosa

Near Lago di Gerosa the main stop is the church of San Giorgio all'Isola. It is in the hamlet of the same name in Montemonaco, on a wide meadow near the start of the lake. It is a church of Romanesque origin, probably dating from the 10th-11th century, and for centuries it belonged to the abbey of Farfa: a deed of 996 entrusts it to three priests. It was enlarged in the 15th century and decorated in the 16th century. Its tower facade makes it recognizable from afar. Inside, the apse preserves Byzantine-style frescoes from the 12th century, and there are 16th-century paintings including a Saint George slaying the dragon.

The church was damaged by the 2016 earthquake. In July 2025 the start of repair, conservation and seismic upgrading work by September had been announced. Before planning a visit to the interior, check the status of the work.

Along the Sentiero del Guerin Meschino are other places in the Aso valley. The village of San Lorenzo in Vallegrascia has its own church. Among the vegetation stand the ruins of the Rava mill, and farther on is the church of Santa Maria in Casalicchio. The route then reaches Montemonaco, the closest village to the lake, a few kilometers from San Giorgio all'Isola.

To discover other bodies of water in the area, the page on the lakes of the Sibillini Mountains also covers Lago di Pilato and Lago di Fiastra. In the Montemonaco area there are also Il Laghetto and the Laghetto di Palazzo Borghese.