Mark and Focus analysis
Cantareira’s Storage Recovery Changes October’s Withdrawal Ceiling
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Cantareira’s storage rose enough in September to move the São Paulo supply system into its Attention band for October. The monthly decision sets a withdrawal ceiling while retaining demand measures and rules for water transferred from another basin.
Cantareira has crossed a monthly operating threshold, not reached an unconditional all-clear. ANA and SP Águas announced that the supply system would enter Band 2, Attention, on October 1. Useful storage stood at 41.10% on September 30, compared with 32.99% on August 31. The higher reading falls inside the 40–60% interval that determines October’s band.
Storage becomes a withdrawal rule
Under the joint resolution governing operation, SABESP can withdraw up to 31 cubic meters per second from Cantareira in the Attention band. The ceiling under normal conditions is 33. These are operating allowances, not reported actual withdrawals or a forecast of how quickly the reservoirs will recover further.
The monthly threshold makes the consequence of the storage reading legible to the operator and other water users. A recovery in volume changes what the utility may take, while the rule continues to distinguish the Attention band from normal conditions. Daily monitoring of levels, flows and storage remains part of the agencies’ shared management.
The allowance does not remove the other limits
October’s operation can also use water transferred from the Jaguari hydropower reservoir in the Paraíba do Sul basin, subject to the authorized limit. That supplementary route should remain visible as a separate source and permission. It is not an unlimited addition to Cantareira’s own withdrawal ceiling.
ANA and SP Águas continue to recommend operational demand management, including lower consumption, reduced losses and rational use by other users. During the dry period, requests for releases to the Piracicaba, Capivari and Jundiaí basins are communicated by their basin committees to SP Águas. The supply decision therefore remains connected to users beyond metropolitan São Paulo.
September’s gain has a concrete consequence: a different October allowance under an established rule. For readers assessing supply security, the most useful comparison is between that permitted withdrawal, actual demand and the water retained in storage. The band communicates a management condition; it cannot by itself demonstrate that dry-season pressure has ended.
Take-Out
A storage-band transition converts recovery into a defined operating allowance. The withdrawal ceiling should be read alongside demand controls and transfer limits, rather than as permission to use every available source without restraint.
Questions and answers
What readers should know
- What changed on October 1?
- Cantareira moved into Band 2, Attention under its joint operating rules.
- What measurement determined the change?
- Useful storage was 41.10% on September 30, within the 40–60% band used for October operation.
- How much can SABESP withdraw?
- The announced Cantareira ceiling is 31 cubic meters per second; normal conditions allow up to 33.
- Can transferred water also be used?
- Water transferred from the Jaguari hydropower reservoir may be used within the authorized transfer limit.
- Does the change end demand management?
- No. ANA and SP Águas continue to call for consumption and loss reduction and rational use of stored water.
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