The Environmental Administration has issued the environmental report for the restoration of the Lamiakoko dartsena

The Director of the Environmental Administration of the Basque Government has issued the environmental impact report in favor of the project to restore the Lamiako estuary in Leioa (Bizkaia), promoted by Lamiako Real Estate Holding, S.L. and other promoters. The resolution is dated August 13, 2026, and was published in the BOPV official gazette, issue number 178, on September 17, 2026, with official reference 2026/3918. According to the report, the project will not require an ordinary environmental assessment, provided that the established protection and correction measures are met.

Processing and legal framework

The Leioa City Council completed the initial request for the simplified environmental impact assessment of the project before the Directorate of the Environmental Administration of the Basque Government on December 12, 2025. On January 30, 2026, the directorate initiated the consultation process for public administrations and interested parties, in accordance with Article 79 of Law 10/2021, and the file was available on the department’s website for citizens to make observations.

The project falls under the simplified assessment according to Article 7.2 of Law 21/2013, as it is comparable to paragraph c) of group 8 of Annex II: works for the adaptation of ports, projects for the defense of shores, and river dredging, when the alteration of the physical characteristics of the water body may damage its ecological status. The competent body is the Directorate of Environmental Administration, according to the structure established by Decree 410/2024. The report will not be an obstacle to the strategic environmental statement establishing the modification of the General Plan of Leioa (areas 17A, 17B, 18A, and 18B).

Project content and key figures

The objective of the project is the partial desilting of the estuary, restoring a wide section as a marshland area. The works include the diversion of the final section of the Gobela river, the excavation of anthropogenic fills occupying the estuary, and the opening of new connections with the Nervion-Ibaizabal estuary, beneath the old BI-711 road. The initiative is located within the framework of the Landscape Action Plan for the Lamiako estuary approved by the Leioa City Council in November 2018.

• Low marsh: area submerged on 75% of days.
• High marsh: submerged on a maximum of 30% of days.
• Permanent coastal lagoon, renewed only during spring tides.
• Ponds to facilitate self-purification before the water reaches the marshes.
• 153,000 m3 of fill excavated to create the new course of the Gobela and restore three habitats.
• 145,000 m3 of fill to compose an urban park; 7,000 m3 of surplus will be managed externally.
• Drainage works: OF-1, OF-2, OF-3, and OF-4, including intersections linked to Felipe del Río street and the BI-711 road.
• Execution period: 18 months, of which 9 correspond to material works.

Three alternatives were analyzed: alternative 0, that is, not carrying out the project, was discarded because it offered no ecological, landscape, or social benefit; and alternative 2 was selected, as it is the most similar to the natural mouth, with a meandering layout and wider marsh areas.

Environmental measures and conditions

The report establishes a set of protection and correction measures so that the project does not have to be subjected to an ordinary environmental assessment.

• Maintaining in situ the specimens of protected flora Juncus acutus or, if necessary, relocating them with the permission of the Provincial Council of Bizkaia.
• Manual removal of invasive exotic species; the use of pesticides, fungicides, and phytocides is prohibited.
• Systematic surveys to detect fauna areas of interest, and the halting of works in the case of protected species.
• Sediment retention systems, which must be reviewed during periods of heavy rainfall.
• Machinery park on an impermeable floor and with a system for collecting effluents.
• Works during daytime hours only; if they last more than 6 months, an acoustic impact study must be carried out.
• Waste management according to the hierarchy of Law 7/2022, and the valorization of soil surpluses in nearby works.

Heritage risks and validity

Regarding heritage, the report establishes measures to protect the Udondo bridge —also called the Isabel II bridge, the only cast-iron bridge in the Basque Autonomous Community and a property of cultural interest— to ensure that changes in the river’s course and new tidal dynamics do not affect its stability. It also foresees the conservation of the volumetry and external appearance of the old office building of the company Dow Chemical Ibérica, S.L.

Regarding contaminated soils, the project does not coincide with the marsh area inventory, but there are soils inventoried with codes 48054-00035, 48054-00036, and 48054-00127 between the railway and Felipe del Río street. The area borders the Bilbao-Erandio zone of significant potential flood risk (code ES017-BIZ-IBA-01).

According to article 79.5 of Law 10/2021, the report will lose its validity if the project is not executed within four years of its publication; in that case, the promoter must restart the simplified assessment procedure.

The Lamiako dartsen area is one of the few zones capable of recreating marsh and estuarine ecosystems in the Nervión estuary, historically occupied by industrial and residential developments. The report clears the way for the project, but imposes strict conditions on the construction phase, and fulfilling these measures will be essential to avoid an ordinary environmental assessment.

Fuente: Boletín Oficial del País Vasco, n.º 178, 17 de septiembre de 2026, Otras Disposiciones, pp. 1-14 (official reference: 2026/3918).