San Juan reservoir

Madrid · Comunidad de Madrid

Tajo basin Reservoirs in Comunidad de Madrid

Province: Madrid
Basin: Tajo
River: Alberche
Dam: Gravity · 1955

50.7%

Current level

70 hm³

Stored water

138 hm³

Total capacity

0.0 hm³

Weekly change

-10.0 hm³

Vs. 2025

+10.7 hm³

Vs. 10-year mean

Historical trend

Stored water volume · hm³

hm³

Weekly summary

The San Juan reservoir (embalse de San Juan), in the Tajo basin and linked to San Martín de Valdeiglesias, Madrid and Comunidad de Madrid, is at 50.7% of its capacity, holding 70 hm³ against a maximum capacity of 138 hm³. It is currently steady in the latest update.

Compared with 2025: below (-7.2 points). Compared with the recent historical mean: above (+7.8 points).

Its main uses include water supply, irrigation and hydroelectric power.

References
Reference	Level	Difference
Previous week	50.7%	0.0 pts
Same week 2025	58.0%	-7.2 pts
10-year mean	43.0%	+7.8 pts

Technical data

Characteristics of the dam and its recorded uses.

Characteristics

Municipality: San Martín de Valdeiglesias
River: Alberche
Dam type: Gravity
Year built: 1955
Surface area: 650 ha
Upstream: El Burguillo
Downstream: Picadas

Recorded uses

Water supply
Irrigation
Electricity
Industrial
Fishing
Boating
Swimming
Restaurants

Not recorded: picnic.

Source: MITECO Inventory of Dams and Reservoirs.

Data: MITECO · AEMET