New Isla Mayor EDAR: €52,000 Additional Funding for Treatment Plant near Doñana

Key data

The budget for the second agreement for the new treatment plant of Isla Mayor (Seville) grows by €52,000 above what was originally planned. The Guadalquivir River Basin Authority (CHG) publishes this amendment on 6 October 2026, with immediate entry into force, to provide economic and temporal coverage for cost overruns resulting from work delays that are not the contractor's responsibility.

The action is part of Spain's commitment to Directive 91/271/CEE on urban wastewater treatment, whose compliance in the Doñana area remains a European priority. The amendment is processed under Law 40/2015 and RDL 36/2020, which regulates the streamlining of agreements linked to European funds.

What does this regulation establish?

The amendment modifies the second agreement signed between the Guadalquivir River Basin Authority, the Municipality Association of Aljarafe and Aljarafesa (Joint Company of Aljarafe, SA) for the execution of sanitation and treatment actions in the Doñana area.

The specific changes it introduces are as follows:

• Budget increase of €52,000 over the previous agreement amount, raising the total to €3,699,675.47.
• Reprogramming of annual allocations to adjust them to the actual pace of work execution.
• Maintenance of the validity of the original agreement until November 2027, without modifying the completion date.

The reason for the increase is technical and contractual: schedule extensions in the main works contract, agreed due to causes not attributable to the contractor, have required extending work supervision and monitoring services, generating an additional cost that this amendment covers.

Economic and operational impact

The increase of €52,000 represents approximately 1.4% of the total agreement budget (€3,699,675.47). It is not a major budget deviation, but it does require formal reprogramming of annual allocations, which has direct implications for the financial planning of the signing entities.

From an operational perspective, the extension of work supervision and monitoring services means that technical oversight of EDAR construction extends beyond the initial schedule. This is common in large hydraulic infrastructure projects when unforeseen circumstances occur that are not attributable to the contractor (ground conditions, administrative procedures, environmental constraints, etc.).

The reprogramming of annual allocations affects the treasury and spending commitments of the entities involved, which must update their budget forecasts for the period remaining until November 2027.

Who does it affect?

• Municipality Association of Aljarafe: signatory entity of the agreement, responsible for municipal coordination of the action.
• Aljarafesa (Joint Company of Aljarafe, SA): public company managing the sanitation service, co-signatory of the agreement and operational executor.
• Guadalquivir River Basin Authority (CHG): promoting body and main funder of the action.
• Municipalities in the Doñana area (Seville): final beneficiaries of the new treatment infrastructure.
• Contractors and work supervision and monitoring companies linked to the EDAR construction project.

Practical example

The new Isla Mayor EDAR has a total agreement budget of €3,699,675.47. Of that amount, €52,000 corresponds to the increase approved in this amendment to cover the extension of work supervision and monitoring services.

Suppose Aljarafesa had planned to close technical supervision of the work in the third quarter of 2026. When a schedule extension occurs in the works contract due to causes beyond the contractor's control, that supervision must remain active for several additional months. The cost of those extra months of supervision and monitoring amounts to €52,000, which this amendment formally incorporates into the agreement and reprograms in the pending annual allocations until November 2027.

The practical result is that work continues without interruption, with guaranteed economic and legal coverage, and the signing entities adjust their payment commitments to the new execution schedule.

What should entities do now?

1. Update budget forecasts: Municipality Association of Aljarafe and Aljarafesa must incorporate the €52,000 increase and the new annual allocation schedule in their current budgets.
2. Review spending commitments: Verify that the reprogrammed annual allocations fit with each entity's financing capacity until November 2027.
3. Coordinate with CHG: Confirm with the Guadalquivir River Basin Authority the new payment milestones and justification deadlines associated with European funds linked to the action.
4. Update contractual documentation: Work supervision and monitoring contracts must reflect the schedule extension and the new amount covered by the amendment.
5. Verify compliance with Directive 91/271/CEE: Ensure that the updated execution schedule remains compatible with the compliance deadlines of European wastewater treatment regulations.

Official source

Consult complete regulation in official source

Notice: This article is purely informational in nature 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-2026-20811