Fundação Renova

Understand the differences between the water quality monitoring of the Doce River, estuary and marine waters and the bathing water quality

Published in: 06/14/2017

Water Monitoring

The Renova Foundation analyzes the impacts caused by the collapse of the Fundão dam on the quality of water and sediments along the Doce River

There are different methods and objectives for each type of water quality analysis of oceans, rivers and beaches. The work involving the water quality monitoring in different points of the Doce River, estuary and marine waters, carried out by the Renova Foundation, was defined based on the guidelines of environmental agencies that make up the Technical Boards, created to guide, monitor and supervise the execution of the actions managed by the institution, according to the Transaction and Conduct Adjustment Term (TTAC).

The collection and analysis of the water quality currently performed by the institution includes parameters related to ions, nutrients, total and dissolved metals as well as sediment analysis, which include conventional physicochemical parameters and total metals. The main objective is to identify the impacts caused by the collapse of the Fundão dam on the water quality in the coastal zone and to verify if the actions carried out along the Doce River are resulting in improvements in the quality of water and sediments. In this process, technical reports are produced and submitted to the competent environmental agencies for evaluation of the results, which are also being published through the website:

All Renova’s monitoring work is within the scope of the Quali-Quantitative Systematic Monitoring Program of Water and Sediments (PMQQS), which provides for the monthly analysis of the coastal zone of Espirito Santo, at a depth of 10 meters. The program does not include the monitoring and issuance of reports referring to the beach water quality for bathing, since this is an exclusive action of public authorities.

Up to the end of February 2016, the Foundation also conducted analyses of biological parameters, such as thermotolerant coliforms and Escherichia coli, but at points in the coastal area away from the beach, which do not reflect the monitoring method for bathing water quality, as determined in Resolution 274 of the National Council of the Environment (Conama). The results indicated an elevation of thermotolerant coliforms and Escherichia coli with the arrival of the tailings, possibly because they were carried by the high river flow. However, these waters quickly returned to pre-collapse conditions. The presence of coliforms is not associated with the tailings, since they are characteristic of domestic sewage.


Bathing water quality monitoring assesses whether water is suitable for recreation of direct and prolonged contact. According to Resolution 274 of 2000 of Conama, the basic indicator for the classification of beaches in terms of bathing is the density of microbiological parameters such as fecal coliforms (thermotolerant), Escherichia coli or enterococci.

To do this, samples should be collected at the beach in points with the highest concentration of bathers, at a depth of 1 meter, with weekly frequency, for subsequent evaluation of the microbiological parameters.

Different factors can alter the parameters of the bathing water quality, such as domestic dumps in the vicinity, existence of streams that flow into the sea, physiography of the beach, occurrence of rainfall and tidal conditions.


With the collapse of the Fundão dam, in November 2015, there was a greater water flow of the Doce River and consequent increase of the microbiological parameters in the sea, which can alter the bathing water quality. However, these parameters have decreased over time, returning to pre-event conditions.

Despite this, there are still tailings deposited at the bottom of the river bed and the mouth of the Doce River, that interact with the sea near the river mouth. This situation, together with several factors – such as tides, winds, waves, currents, rains, droughts and climate change – affect the dispersion of the tailings. However, the analysis of chemical composition, conducted by Renova, showed that the tailings in the water are classified inert, that is, they do not contain toxic components and are not hazardous, according to the Brazilian Standard of Solid Waste Classification (NBR).


The Renova Foundation values ​​transparency and dialogue with the impacted communities and with society in general. We have been contacted by some Internet users on social networks about the dissemination of data related to the bathing water quality monitoring along the coast of Espirito Santo, and for this reason we have prepared this explanatory text on the differences between monitoring activities and detailing the actions carried out by the institution. Don’t hesitate to contact us if you have any question or concern regarding this matter.

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