Water in Sri Lanka’s major reservoirs stood at 34.3% of effective capacity on September 6, unchanged from the previous day, according to data from the Irrigation Department’s Water Management Branch, reported by Daily Mirror.
The dataset covers 74 major reservoirs with a combined gross capacity of 3,114,407 acre-feet. Present effective storage was 1,020,713 acre-feet.
The numbers reconcile this time
Those two figures are worth pausing on. Measured against gross capacity, 1,020,713 acre-feet is 32.8% — not 34.3%. The gap is explained by dead storage: the 34.3% is calculated against effective capacity of roughly 2.98 million acre-feet, some 138,000 acre-feet below the gross figure.
That is a change from the release this site examined on 22 August, whose published aggregates — 1,067,914 acre-feet against 1,210,531 acre-feet of stated effective capacity — worked out to about 88% and could not be reconciled with the 35.9% headline. The September release is internally consistent.
Sixteen days on, one district has gained
The August 22 release listed the same five leading districts, which allows a direct comparison:
| District | Aug 22 | Sept 6 | Change |
|---|---|---|---|
| Kurunegala | 74.9% | 73.3% | −1.6 |
| Puttalam | 66.2% | 62.6% | −3.6 |
| Kandy | 62.3% | 60.2% | −2.1 |
| Monaragala | 58.4% | 54.4% | −4.0 |
| Galle | 56.6% | 62.9% | +6.3 |
Galle is the outlier. It is the only one of the five to rise, and it has moved from last on the list to second — above Puttalam, though Daily Mirror’s own report lists it last, after Monaragala, in what it presents as descending order. The ordering in the published summary is not consistent with the figures it gives.
The national decline over the same sixteen days was 1.6 percentage points, from 35.9% to 34.3% — a slower slide than the 37% recorded on 14 August would have projected.
Two spilling, several near empty
Ambewela in Badulla and Vakaneri in Batticaloa were both spilling at 100% of effective storage.
Vakaneri is the more notable of the two. It stood at 96.2% on August 22 and has since filled. It also sits in a district whose four major reservoirs were reported at just 25.3% of capacity on the same day — so one Batticaloa tank is overflowing while the district aggregate remains among the lowest in the country.
At the other end:
- Nagadeepa and Morana, both in Badulla — 1.1% each
- Ethimale, Monaragala — 4.3% (5.4% on August 22)
- Viyathikulam, Mannar — 6.5%
- Rottikulama, Ampara — 6.7% (8.1% on August 22)
- Mora Wewa, Trincomalee — 9.4% (9.5% on August 22)
Badulla therefore contains both a reservoir that is spilling and the two emptiest tanks in the dataset. The district figure conceals a spread of roughly 99 percentage points.
What the flat reading does not mean
A national figure holding steady day-on-day is not evidence the dry spell has broken. The three tanks that can be tracked back to August 22 — Ethimale, Rottikulama and Mora Wewa — all fell further, and four of the five leading districts declined. What has changed is where the water is: the gains are in the southwest and one eastern tank, while the dry-zone deficit is intact.
Releases for the Yala season have already been terminated across Polonnaruwa, and the Meteorology Department has described the current El Niño as the strongest in 75 years heading into the Maha season.
Not reported
Daily Mirror does not give a rainfall summary alongside the storage figures, as earlier releases have done, and does not say what caused the Galle and Vakaneri gains. It does not list the storage position of Senanayaka Samudra, the country’s largest reservoir, whose depletion alone pulls the national average down substantially. No other verified newsroom had published the September 6 dataset at the time of writing.
