Seville Wastewater Treatment Plants and Doñana: +€1.6M in the CHG-EMASESA 2026 Agreement

Key data

The original 2021 agreement between the Guadalquivir River Basin Authority (CHG) and EMASESA to build and finance the necessary infrastructure to enable discharge from Seville's EDAR in a sensitive area near Doñana now exceeds €93.5 million following the second amendment published in the BOE on June 18, 2026 (reference BOE-A-2026-13273).

The amendment is not a minor change: it reflects exceptional price revisions, final certifications and contractual modifications that have increased the total cost, and formalizes the extension of the agreement to cover warranty periods for technical assistance contracts linked to the works.

What does this regulation establish?

The second amendment modifies the agreement signed in 2021 between the CHG and EMASESA. Its purpose is threefold:

• Increase the agreement budget by €1.6 million, as a result of exceptional price revisions, final work certifications and unforeseen contractual modifications.
• Extend the validity of the agreement beyond May 31, 2026, to cover warranty periods for technical assistance contracts associated with the infrastructure.
• Acknowledge the delay in completing two key actions that could not be finished before that deadline.

The two actions that remain pending completion are:

The exceptional price revision for the Tamarguillo EBAP is covered by Royal Decree-Law 3/2022, a regulation that enabled extraordinary price revision mechanisms in public contracts to compensate for the impact of rising material and energy costs.

Economic and operational impact

The increase of €1.6 million represents an adjustment to an agreement that already exceeded €93.5 million, equivalent to an increase of approximately 1.7% of the base budget. However, the exceptional price revision for the Tamarguillo EBAP—estimated at ~€2 million (VAT included)—is the element with the greatest individual economic weight in this amendment.

From an operational perspective, the extension of the agreement means that the CHG and EMASESA maintain their active contractual obligations during the warranty period of technical assistance contracts, which extends technical and administrative supervision of the works beyond the initially planned date.

Who does it affect?

• Guadalquivir River Basin Authority (CHG): organism that co-finances and supervises the infrastructure; must manage the budget increase and agreement extension.
• EMASESA (Metropolitan Water Supply and Sanitation Company of Seville, SA): entity responsible for construction, commissioning and delivery of infrastructure; assumes execution of pending works and price revision.
• Citizens and municipalities in the Seville metropolitan area: end users of the sanitation system whose service quality depends on completion of these infrastructure projects.
• Doñana environment: protected natural area directly benefited by the adaptation of Seville's EDAR discharge treatment to sensitive area standards.
• Contractor and technical assistance companies linked to the Puerto Collector and Tamarguillo EBAP works, whose contracts are extended during the warranty period.

Practical example

The Tamarguillo EBAP is the action with the greatest individual economic impact in this amendment. Since it could not be completed before May 31, 2026, EMASESA must apply the exceptional price revision provided for in RDL 3/2022, estimated at approximately €2 million (VAT included).

This means that, on top of the initial cost of this pumping station, an additional cost is added resulting from the rise in material and energy prices recorded during work execution. This amount is covered by the €1.6 million budget increase formalized by the second amendment, together with final certifications and other contractual modifications of the overall agreement.

In parallel, the Puerto Collector in Palmas Altas also remains incomplete, requiring that technical assistance contracts remain active and the agreement validity be extended so that the CHG and EMASESA can comply with legally required warranty periods.

What should companies do now?

1. If you are a contractor or subcontractor linked to the Tamarguillo EBAP or Puerto Collector: verify that your contract correctly reflects the application of RDL 3/2022 for exceptional price revision and that warranty periods are covered by the agreement extension.
2. If you are a technical assistance provider: confirm with EMASESA or the CHG the extension of contractual periods resulting from the agreement extension, to avoid gaps in warranty coverage.
3. If you are a public manager or CHG or EMASESA technician: update financial and operational planning to reflect the new total budget (over €93.5M) and new completion milestones for the two pending actions.
4. If you are a water or environmental sector company in the Seville metropolitan area: monitor the progress of these infrastructure projects, as their completion may generate new tenders or maintenance contracts associated with the warranty period.

Official source

Consult complete regulation at official source

Notice: This article is for informational purposes only and does not constitute legal advice. For specific decisions, consult a qualified professional. Source: https://www.boe.es/diario_boe/txt.php?id=BOE-A-2026-13273