The Environmental Prosecutor's Office in Santa Cruz de Tenerife is investigating contaminating discharges in the city because of the poor condition of the Buenos Aires wastewater treatment plant (EDAR), the city's main plant. The facility is municipally owned and treats wastewater from Santa Cruz's urban core and parts of San Cristóbal de La Laguna and El Rosario.
The criminal proceedings were disclosed in the 2025 annual report of the Canarias Prosecutor's Office. According to the document, the investigation began after a complaint by an association of environmental professionals over the alleged defective state of the plant and the Cabo Llanos wastewater pumping station (EBAR), located in the same area. The report links that situation directly to discharges of wastewater into the sea without proper treatment and control. The Prosecutor's Office declined to give further details, saying the proceedings are confidential.
The two installations form part of a single interconnected hydraulic system. Cabo Llanos collects wastewater from the lower and central areas of Santa Cruz and pumps it to Buenos Aires, where biological treatment uses microorganisms to break down organic matter and pollutants. The treated effluent is mainly sent to the island irrigation network managed by the public company BALTEN.
Both plants are overwhelmed. A 2017 report from the then Ministry of Agriculture, Fisheries, Food and Environment said the Cabo Llanos pumping station could not treat all the flow it received, so the surplus was discharged through an outfall in the Muelle de la Hondura area after only basic treatment. An official 2011 estimate put the station's daily flow at 20,900 cubic metres.
The Buenos Aires plant is also operating at its limit, but because of the high pollutant load of the water it receives rather than the incoming volume. Another public document from 2017 says the plant, with capacity to treat 30,000 cubic metres a day, was designed for a pollutant load of 200 to 250 milligrams per litre of BOD5. Although flow is around 26,000 cubic metres a day, BOD5 averages around 791 milligrams per litre, almost four times the maximum envisaged. The report warned of poor performance in biological treatment, with results that often failed to meet required standards for treated water, as well as secondary settling problems caused by construction issues and low effluent quality for growing demand for reused water in agriculture and for irrigation of parks and gardens.
This limits the plant's ability to take the additional wastewater arriving from Cabo Llanos. The reform and expansion of both installations was tendered in 2018 by the General Directorate of Water, under the Ministry for Ecological Transition and the Demographic Challenge (MITECO). The contract was awarded for 20.17 million euros, below the 32.4 million euro base tender budget, to a joint venture of Joca Ingeniería y Construcciones and ALPI Construcciones. The project includes a new pipeline to lift all wastewater reaching Cabo Llanos directly to Buenos Aires and would double the treatment capacity of the EDAR to 55,000 cubic metres a day.
MITECO expected the work to finish in 2022, but the ministry has postponed completion several times and the latest date given is summer 2028. In a written parliamentary reply in November 2025, the State justified the delays by citing an urban setting where many services were uncharted or in different locations from those previously reported; delays in processing licences and environmental authorisations that added new conditions to the project; problems with equipment supply and a lack of qualified labour; and the need to technically redesign some parts of the work. At that time, work on Phase 1 of the Buenos Aires plant was underway and only Phase 2 remained, while at Cabo Llanos only urbanisation work was left, according to the ministry.
MITECO did not answer questions from Canarias Ahora. Santa Cruz de Tenerife city council, the owner of both facilities, has called for the Insular Water Council of Tenerife (CIATF), which depends on the Cabildo, to take over management of the complex. It has also criticised the central government's delays. Council sources said all sea discharges in Santa Cruz have authorisation from the Canary Islands government; they described the plant as a state-dependent project more than four years behind its original schedule and said its completion would end discharge in the area. The same sources said the city has invested 14 million euros to provide treatment plants and pumping stations at various points along the coast and argued that the State had not done its part.
The municipal response came on 20 October. Three days later, public services councillor Carlos Tarife of the PP announced that the council would take the Spanish government to court over the delay in the treatment plant works, according to El Día.
The Canarias Prosecutor's Office report records ten crimes against natural resources and the environment in Santa Cruz de Tenerife province in 2025. Most were related to complaints about discharges into the maritime-terrestrial public domain and the poor maintenance and conservation of wastewater treatment plants, pumping stations and outfalls. The report cites the Playa Jardín case in Puerto de la Cruz, where six public officials have been reported, and the industrial discharges in the Güímar industrial estate, where the Prosecutor's Office is seeking prison sentences for four mayors and former mayors of Tenerife. It does not mention the investigation into mass fish deaths in Telde, in which it has also found numerous irregularities at the Silva EDAR.
In total, the environment sections of the Prosecutor's Office opened 157 pre-procedural proceedings in Canarias in 2025: 84 in Las Palmas province and 73 in Santa Cruz de Tenerife, a 67% increase on 2024. By category, land-use and urban-planning investigations were the most numerous, with 91 cases, followed by animal mistreatment (38), environment (20), forest fires (9), historical heritage (4) and flora and fauna protection (3). The Prosecutor's Office explicitly attributed the rise in Santa Cruz de Tenerife to growing pressure on rural land, the resurgence of self-build cases and others involving developers, whether national or not and generally from Eastern Europe, linked to vacation rentals. It also said it observed a trend toward centralising complaints at the prosecutor's office to seek precautionary suspension of works at the same time.
Sources: elDiario.es.