Lac du Drennec Live Cam

Located on the Elorn River between Commana and Sizun, the lake, filled in September 1981, is the water reservoir of northern Finistère. Water quality is a constant concern. Its surface area is one square kilometer and its maximum depth is 20 meters.

It is a particularly suitable site for beginners in water sports: no risk of drifting offshore, little chop and no swell, clear banks, etc. The wind regime also makes it an attractive lake for high-level competitors and is often used by Finistère/Breton teams. Water sports are regulated by prefectural decree.

Reservoir of History and Highland Landscapes

Nestled at 200 meters above sea level in the Armorican Massif, Lac du Drennec is more than a functional reservoir—it is a living chronicle of Breton ingenuity, rural traditions, and ecological renewal. Surrounded by rolling heather moorland, oak woodlands, and the granite ridges of Monts d’Arrée, the lake offers visitors an intricate tapestry of “Commana tourism,” “Brittany hiking trails,” and “historic French reservoirs.” From its origins in early 20th‑century hydro‑engineering to its present status as a hotspot for water sports and birdwatching, Lac du Drennec embodies the dynamic interplay between human intervention and wild landscape.

Engineering Ambition: Constructing the Drennec Dam

Conceived in 1929 and completed in 1932, the Drennec dam was built to secure potable water for the city of Brest and its growing industrial belt. Engineers selected a narrow granite gorge on the Aulne River, where schist bedrock provided a stable foundation. The initial plans called for a gravity dam of cyclopean masonry—blocks of local granite carefully dressed and laid in hydraulic lime mortar. At 22 meters high and 180 meters long, the impoundment created a 60‑hectare reservoir with a storage capacity exceeding 5 million cubic meters—an engineering marvel of its era.

Hydrological Design and Spillway Innovations

Lac du Drennec’s catchment area spans over 200 square kilometers of upland moors and woodland streams. To manage seasonal high flows, engineers installed an ogee‑shaped spillway and an auxiliary overflow channel lined with stepped granite blocks, dissipating energy and preventing downstream erosion. Beneath the dam, a controlled-outlet conduit—lined with cast-iron valves—regulates discharge for both water supply and ecological flow requirements. This dual‑purpose infrastructure laid the groundwork for modern “Brittany water resource management.”

Socio‑economic Impacts on Commana and Beyond

The creation of Lac du Drennec reshaped local livelihoods. Farmers in the valley—once reliant on fluctuating riverine meadows—gained more consistent irrigation for flax and barley fields. Seasonal workers were employed in dam maintenance, forestry, and fish stocking programs. The reservoir also catalyzed the emergence of “Commana hydro-tourism,” as anglers sought trout and pike introduced by the local pisciculture association. Cafés and inns in Commana adapted to welcome weekend visitors, merging rural Breton hospitality with water‑based recreation.

Relocation of Farmland and Cultural Memory

Flooding the upper valley necessitated the expropriation of a handful of farms. Barns were dismantled, and stone walls carefully cataloged for reuse in nearby structures. Elders still recount how ancestral fields, marked by megalithic menhirs and Celtic standing stones, vanished beneath the reservoir’s surface. Annual “commémoration des noyés” ceremonies honor the submerged heritage, blending Catholic blessing rites with the older Celtic reverence for water’s power.

Surrounding Topography and Monts d’Arrée Dynamics

Encircling Lac du Drennec, the Monts d’Arrée present a heathery, undulating summit landscape unique in Brittany. These uplands, reaching over 380 meters, are composed of Precambrian schist and quartzite—the oldest rocks in the Armorican Massif. Weathering and periglacial activity during the Pleistocene sculpted tors, blockfields, and patterned ground. Trails crisscross the ridgelines, inviting “Monts d’Arrée hiking” enthusiasts to traverse from the Peuc’h Ber, with its panoramic ocean vistas, to Roc’h Trevezel, dotted with gothic oratories.

Moors, Heather, and Upland Ecology

The moorlands above Lac du Drennec bloom with purple heather (Calluna vulgaris) in late summer, interspersed with bilberry and crowberry. Peaty soils support Sphagnum moss carpets, creating a mosaic of bog pools that sustain dragonflies, damselflies, and the rare large heath butterfly. In winter, the uplands turn silvery with hoarfrost, as golden plovers and skylarks wheel overhead—draws for “Brittany birdwatching” tours focusing on upland species seldom found elsewhere in the region.

Oak Woods and Riparian Habitats

Closer to the reservoir shore, veteran sessile oaks and ash trees shade trails. The understory of hazel and holly harbors songbirds—European robin, Eurasian wren—and small mammals like the wood mouse. Riparian corridors teem with otter signs—spraints on rocks—evidence of successful reintroduction programs. Conservation initiatives, under “Commana ecological restoration,” have fenced sensitive bank areas to allow native willow and alder to regenerate, safeguarding spawning grounds for brown trout.

Recreational Pursuits: From Sailing to Trail Running

Today, Lac du Drennec is a magnet for outdoor adventurers. Its sheltered waters enable dinghy sailing, windsurfing, and stand-up paddleboarding under steady westerly breezes. A yacht club offers “Brittany sailing lessons,” with Optimist dinghies for juniors and Laser rigs for seasoned sailors. Around the shoreline, a 10-kilometer loop trail invites “trail running Brittany” aficionados to time themselves on mixed-terrain segments, including grassy levees, stony beach stretches, and woodland paths.

Angling and Fish Stocking Programs

Anglers prize Lac du Drennec for its wild brown trout and introduced pike-perch, offering both fly-fishing and spin-casting opportunities. The local fishing federation coordinates annual stockings of rainbow and Brook trout, ensuring population diversity. Stocking schedules, accessible via “Commana fishing permits” portals, balance recreational demand with ecological health. Catch-and-release regulations on select shoreline sectors protect trophy-sized specimens.

Educational Nature Trails and Interpretive Panels

Along the western shore, thematic trails with interpretive panels explain the reservoir’s geology, dam mechanics, and biodiversity. Children follow “water cycle” scavenger hunts, tracing turns in shaded groves to sites demonstrating sediment traps and reed bed filtration units. QR codes link to multimedia content, presenting historical photographs of dam construction and oral histories from former engineers.

Heritage Sites and Spiritual Retreats

Commana, a stone’s throw from Lac du Drennec, is famed for its parish close—an ensemble of 17th-century granite church, calvary, and ossuary adorned with polychrome sculptures. Pilgrims traditionally walked from the parish close to the reservoir’s shore to perform water blessing rituals on Saint-Yves Day, seeking protection and abundance. This pilgrimage, revived as part of “Brittany religious heritage” festivals, culminates in communal picnics featuring local galettes and cider.

Chapel of Saint-Michel and High-Point Vistas

Perched on a hill overlooking the lake, the 12th-century Chapel of Saint-Michel offers sweeping views of Lac du Drennec and the Monts d’Arrée massif. Its Romanesque nave, restored in the 1980s, contains fresco fragments depicting agricultural scenes—plowing, shearing—and water-themed motifs, hinting at the community’s longstanding bond with local hydrological features.

Stone Crosses and Wayside Calvaries

Rural tracks around the lake are punctuated by granite crosses and miniature calvaries, marking sites of prayer and remembrance. One such cross near the dam’s crest is inscribed with the date 1741, predating the reservoir by two centuries—an evocative juxtaposition of ancient spirituality and modern infrastructure. Guided “Commana spiritual walks” explore these markers, weaving tales of local saints and water miracles.

Flora and Fauna Conservation: A Living Laboratory

Since its creation, Lac du Drennec has become a focal point for biodiversity monitoring. Ornithologists count over 80 bird species annually, from migratory mallard flocks to wintering great crested grebes. Herpetologists document populations of common frogs and the rare natterjack toad in emergent reed pools. Ongoing “Brittany citizen science” initiatives involve volunteers in ringing wildfowl and recording amphibian chorus intensity, providing long-term data on climate impacts.

Invasive Species Control and Water Quality

Non-native American mink, introduced in nearby valleys, posed a threat to waterfowl and small mammals. Coordinated trapping programs—conducted under ethical guidelines—in tandem with habitat enhancement have curtailed mink numbers. Water quality is monitored monthly for nutrients, turbidity, and microplastics, ensuring “Commana reservoir stewardship” aligns with EU Water Framework Directive standards.

Wildflower Meadows and Pollinator Pathways

Shoreline meadows, once plowed for hay, now flourish with wildflowers—oxeye daisy, common knapweed, and bird’s‑foot trefoil—that support bees, butterflies, and hoverflies. Conservationists have sown pollinator-friendly seed mixes in buffer strips around access points, linking the reservoir to wider ecological corridors across the Monts d’Arrée.

Culinary Delights and Local Produce

Proximity to Brittany’s famous creperies and cider farms enriches the dining options around Lac du Drennec. Lakeside cafés serve savory buckwheat galettes filled with seafood caught in the reservoir—smoked trout stuffed with chèvre frais and chives. Nearby farms produce artisanal goat cheeses flavored with lake reeds (juncus)—an emerging “Brittany terroir innovation.”

Farm‑to‑Table Events and Seasonal Festivals

Each September, the Fête du Lac celebrates the reservoir’s bicentenary—an occasion for crepe‑making competitions, cider tastings, and night‑time illuminated paddle races. Chefs showcase “Commana gastronomic tours,” creating dishes that feature wild berries, forest mushrooms, and freshwater smoked fish, reflecting the region’s symbiosis of lake and land.

Fish Smoking and Preservation Workshops

Local artisans offer “Brittany fish smoking” workshops in traditional smokehouses near the dam wall. Participants learn wood selection—oak for a robust flavor, beech for a delicate aroma—and smoking techniques that impart a golden hue and subtle sweetness. Finished products are served with Breton buttered bread and local floral honeys.

New Tip: For serene early‑morning reflections, paddle a kayak to the dam’s downstream channel at dawn—the still waters often mirror the Monts d’Arrée ridge, creating perfect photographic symmetry.

Interesting Fact: During droughts in the 1950s, the lake’s drawdown revealed the foundations of a long‑lost stone bridge from the 14th century, once part of the ancient route connecting Commana with the pilgrimage site at Sainte‑Marie du Menez‑Hom.