The reservoir submerged the former village of El Atazar, though its population was relocated prior to flooding.
Its construction required the relocation of several kilometers of regional roads.
The dam's double-arch design was chosen specifically to withstand the geological pressures of the Lozoya Valley canyon.
The water capacity is approximately 425 million cubic meters.
The facility is managed by Canal de Isabel II, the public entity responsible for Madrid's water cycle.
Embalse de El Atazar is the largest reservoir in the Community of Madrid, supplying nearly half of the region's total water consumption. Located in the Sierra Norte, it occupies a significant portion of the Lozoya River valley. The dam, a double-curvature arch structure completed in 1972, stands 134 meters high and spans 484 meters at its crest. The surrounding terrain is characterized by Mediterranean scrubland and holm oak forests. The reservoir is a primary hub for regulated water sports, including sailing and canoeing, under the management of the Madrid Water Canal (Canal de Isabel II). Its catchment area covers 700 square kilometers, collecting snowmelt from the Somosierra and Ayllón massifs. The facility serves as a critical strategic reserve for the capital's water supply system.
The viewpoint near the town of El Berrueco provides an elevated panoramic vantage point looking across the main body of the reservoir.
Bring polarized sunglasses to reduce glare from the water surface, which is helpful for photography and spotting local wildlife.
Check water level status on the Canal de Isabel II portal before planning water-based activities, as levels fluctuate based on annual rainfall.
Carry windproof layers, as the high-altitude valley can become significantly cooler than the city center even in summer.
Do not attempt to access the dam structure itself, as it is a high-security restricted area; stick to marked peripheral trails and observation points.
Access to water sports activity zones is generally limited to warmer months; check local municipal seasonal permits.
Strictly no swimming allowed in the main reservoir area; observe all posted boundaries regarding protected water zones.
