Leiria, Portugal, Aug. 14, 2025 (Lusa) - Three weirs on the River Lis will be opened on Thursday to increase the flow and mitigate the effects of the discharge of untreated effluent, following the breakdown of a station in the municipality of Leiria, it was announced.
A statement sent to the Lusa news agency said that the company Águas do Centro Litoral (AdCL), the Portuguese Environment Agency (APA) and the Association of Irrigators and Beneficiaries of the Lis Valley will carry out a coordinated action aimed at mitigating the effects of the discharge of wastewater into the River Lis on Tuesday.
"The intervention consists of temporarily increasing the flow of the River Lis by opening three weirs - Parque, Arrabalde and Salgadas - from Leiria to the mouth," in Praia da Vieira, in the municipality of Marinha Grande.
According to the statement issued by AdCL, "this action will increase the water flow, helping to clean the riverbed and transport accumulated sediment and waste".
"During the operation, 1,000 litres of water will be released per second, while ensuring the ecological flow necessary to preserve aquatic ecosystems," it explained.
The operation began at 4 p.m. and the final effects are expected to be felt at the mouth of the river at around 9 p.m.
"This decision is the result of a meeting between the Secretary of State for the Environment, the Leiria and Marinha Grande town councils, the Intermunicipal Community of the Leiria Region, the APA and AdCL, following the failure of the pumps at the Monte Real pumping station, which caused the emergency discharge of raw waste water into the watercourse," he explained.
On Wednesday, AdCL announced that the Monte Real (Leiria) station, which lifts effluent to the Coimbrão wastewater treatment plant, was "temporarily inoperable due to a breakdown in the lifting system pumps".
According to the company, "the station's emergency discharge system was activated, as well as the upstream pumping station (Serra de Porto do Urso)", and the discharges occurred "respectively into the River Lis and an adjacent irrigation ditch".
This situation led to a ban on bathing in Praia da Vieira and the Leiria Municipality advised against activities in the stretch of the River Lis downstream of Monte Real, such as irrigation, bathing and fishing.
The fault was resolved today, and the discharge of effluent ended.
Also today, at the municipal government meeting, the mayor of Leiria, Gonçalo Lopes, explained that the stretch from the pumping station, where the fault occurred, to the mouth is 14 kilometres long, and the estimate is that between 900 and 1,000 cubic metres of effluent were discharged every hour. The fault lasted for around 38 hours.
Describing the state of the river, "polluted, with waste, some dead fish and others in distress", Gonçalo Lopes said that, despite the opening of weirs, the water "won't take everything", as there is effluent left on the bottom and banks of the river.
Pointing to environmental damage to the watercourse, economic damage above all to tourism in Praia da Vieira and to agriculture, the mayor also recognised that the incident had caused "reputational damage".
According to Gonçalo Lopes, the repair and cleaning of the banks could cost around €3 million, but if an operation to dredge the river goes ahead, the cost will be higher.
The mayor considered that this incident "creates an obligation to speed up investments that have been planned for a long time", in addition to the improvement of existing infrastructures by AdCL.
Álvaro Madureira, an independent councillor elected by the PSD, predicted that the "blame will die alone" in this "environmental crime", and argued that AdCL's management should "get out on its own feet" because it "has some vices of inoperativeness".
Meanwhile, the PS Parliamentary Group has questioned the government about the breakdown at the station and what measures it intends to adopt to contain the environmental damage and said it would be repaired.
SR/ADB // ADB.
Lusa
