Dams across the country held 40.6 billion cubic meters of water in May, but the level fell to 37.3 bcm in June, down 9%.
Dams were 82% full in May but now are 75% full. In 2018 the storage level was 45%.
Since the beginning of the current water year last September, the volume of water flowing into the dams has reached 84 bcm. The figure was as low as 24 bcm last year. Referring to water flowing out of the dams, IRNA said the volume increased by 191%, reaching 67 bcm, Financial Tribune reported.
Iran registered significant improvement in rainfall in March and April when precipitation in most provinces exceeded the average in 50 years.
According to Iran Water Resources Management Company, Iran recorded 337 millimeters of rainfall since last September, up 180 millimeters compared to average precipitation in the past 11 years.
However, the water levels in dams are gradually plummeting.
The last water year (September 2017-18) was one of the driest in half a century as 45% rainfall deficit was recorded.
Years of drought and unprecedented decline in precipitation last year (which was the driest in half a century) resulted in sharp falls in water levels in dams.
Higher Precipitation
Rainfall registered 101% increase compared to last year. Although all major river basins saw higher precipitation this year, 186 cities are still grappling with water tension.
Iran is divided into six primary river basins: the Caspian Sea basin in the north and Hamoun Wetlands in the east (mainly in Sistan and Baluchestan Province) had the highest and lowest rainfall, with 536 mm and 100 mm respectively.
With 533 mm of rain, the Persian Gulf basin is in second place.
Other basins namely the Persian Gulf and Sea of Oman in the south, Urmia Lake in northwest, Karakum in the northeast and the Central Plateau in Markazi Province each received 533 mm, 491 mm, 310 mm and 212 mm respectively since last September.
Record Consumption
Tehran's all-time daily water consumption record (3.7 million liters) was reported on July 21, Mohammadreza Bakhtiari, managing director of Tehran Province Water and Wastewater Company said.
Bakhtiari noted that consumption in the capital has increased by 250,000 cubic meters per day compared to last year.
"Water use normally experiences a 2.5% hike per annum," he said, adding that in this calendar year -- that started in March -- consumption surged by 4% and at times when the mercury rises to 37°C and above, it jumps by 7%.
Unsustainable consumption patterns plus waste are visibly threatening water supply in the sprawling capital that has expanded in all four directions over the past half century.
According to the official, the rains in March and April led to a false assumption about water abundance.
"The high temperatures notwithstanding, some people think because dams are full they do not need to exercise restraint and use water wisely," Bakhtiari asserted.
Located in one of the world’s most water-stressed regions, Iran’s average precipitation has been lower than the global average for at least 10 years. Iran is among the top 20 countries with unsustainable water consumption.
Experts and environmentalists say if the present trends persist, almost all underground water will dry up within 30 years and the country will face absolute water scarcity.