A new set of water tests has intensified the dispute over a September 1 discharge at Es Pouet beach in Sant Antoni, after samples commissioned by the environmental group Salvem sa Badia reported bacterial concentrations far above the thresholds used to assess bathing water.

The results contrast sharply with the official analyses cited by Sant Antoni Town Hall, which said its samples from the same episode showed negative results for E. coli and intestinal enterococci and concluded that the bathing water was suitable for public use.

The two sets of results were taken under different sampling circumstances, and the municipality has questioned the location and procedure used for Salvem sa Badia's samples. The conflicting findings mean the new figures should not be presented as proof that the municipality's official results were incorrect.

What Salvem sa Badia's samples found

Salvem sa Badia says it collected samples on September 1 at approximately 18:35, around four hours after the discharge occurred.

One sample was taken from a pool of water that had accumulated on the upper part of the beach. According to the laboratory results presented by the group, that sample contained more than 2,420 colony-forming units of intestinal enterococci per 100 millilitres.

The same sample reportedly contained more than 2,420 colony-forming units of E. coli per 100 millilitres.

The laboratory's measurement reportedly stops at 2,420, meaning the actual concentration could have been higher.

E. coli in the bathing area

A second sample was collected from the sea in the bathing area, according to Salvem sa Badia.

The group reported 990 colony-forming units of E. coli per 100 millilitres.

For coastal bathing water, Spain's regulatory framework lists 500 UFC/100 ml as the value for E. coli corresponding to sufficient quality, while the Balearic Government's operational bathing-water assessment uses up to 500 UFC/100 ml as the threshold for water considered suitable for bathing at a sampling point.

The reported 990 UFC/100 ml would therefore be above that threshold.

The enterococci result was also above the threshold

The reported intestinal enterococci result of more than 2,420 UFC/100 ml in the beach pool is substantially above the Balearic Government's temporary bathing-water thresholds.

The regional monitoring programme considers water suitable for bathing when intestinal enterococci are at or below 200 UFC/100 ml. Between 201 and 1,000 UFC/100 ml, bathing is classified as not recommended temporarily, while values above 1,000 UFC/100 ml correspond to a temporary bathing prohibition under the regional monitoring criteria.

However, these operational thresholds apply to samples taken under the official bathing-water monitoring system and should not automatically be used to classify an independently collected sample as an official bathing-water quality result.

Sant Antoni's official results showed a different picture

Sant Antoni Town Hall reported on September 12 that its official analyses relating to the September 1 episode had found negative results for E. coli and intestinal enterococci.

The municipality said those results showed the bathing water was suitable and that there was no evidence of fecal contamination in the official samples.

The council also said it did not dispute the existence of the results obtained by Salvem sa Badia, but questioned how and where those samples had been collected.

Why the sampling procedure matters

The municipality says official bathing-water samples are taken by authorised personnel at sampling locations designated by the regional health authorities.

It therefore argues that the Salvem sa Badia samples cannot simply be treated as equivalent to the official monitoring samples.

The council has also pointed out that the two sets of samples were not necessarily taken at the same place or under identical conditions.

That distinction is particularly relevant after a short-lived discharge, because bacterial concentrations can change significantly depending on dilution, currents, rainfall and the time elapsed after the incident.

The municipality says the water came from the stormwater network

Sant Antoni has maintained that the September 1 episode was caused by an outlet from the stormwater drainage network rather than a sewage discharge.

According to the municipality, technical checks carried out by municipal services and the company Facsa found no evidence of a leak from the sewage network.

The council also cited a conductivity measurement of 526 microsiemens, which it said was substantially below the typical range it associates with wastewater, around 3,000 to 5,000 microsiemens.

The existence of a stormwater outlet, however, does not by itself establish that the water reaching the beach was microbiologically clean. Surface runoff can carry contaminants, which is one reason the municipality says it conducted precautionary testing.

Salvem sa Badia disputes the explanation

Salvem sa Badia argues that its laboratory results demonstrate that fecal contamination was present in the water during the episode.

The group has questioned the municipality's decision not to close the beach and has argued that the presence of elevated bacterial concentrations warranted precautionary action.

That is the environmental group's interpretation of its own laboratory results and should be distinguished from an official determination about the source of the bacteria.

Other samples from the bay

The dispute has expanded beyond Es Pouet.

Salvem sa Badia says it has also received results from a sample taken on September 4 at the second pontoon of Sant Antoni port after another reported discharge.

That sample reportedly contained 1,119 UFC/100 ml of intestinal enterococci and 137.4 UFC/100 ml of E. coli.

The organisation also reported results from a sample taken at Caló de s'Oli after a separate discharge and temporary closure ordered by Sant Josep on September 8. According to the group, that sample reached the laboratory's maximum measurable value of more than 2,420 UFC/100 ml for both intestinal enterococci and E. coli.

These are separate incidents and should not be presented as evidence that the September 1 Es Pouet event had the same cause.

What the regional monitoring system says

The Balearic Government's bathing-water monitoring programme distinguishes between individual sample results and the final seasonal classification of a bathing area.

For individual samples, the regional system currently uses these thresholds:

• Intestinal enterococci: up to 200 UFC/100 ml, suitable for bathing

• 201-1,000 UFC/100 ml: bathing temporarily not recommended

• Above 1,000 UFC/100 ml: temporary bathing prohibition

• E. coli: up to 500 UFC/100 ml, suitable for bathing

• 501-2,000 UFC/100 ml: bathing temporarily not recommended

• Above 2,000 UFC/100 ml: temporary bathing prohibition

The Government also states that when these values are exceeded, additional sampling is carried out to confirm the result and authorities investigate the cause and corrective measures.

A separate legal classification should not be confused with a single test

Spain's national bathing-water rules use statistical assessment over a series of samples for the formal classification of bathing-water quality.

For coastal waters, the regulatory values include 185 UFC/100 ml for intestinal enterococci and 500 UFC/100 ml for E. coli at the "sufficient" quality level. The legislation also provides for precautionary management measures when short-duration contamination occurs.

Consequently, a single independent sample showing elevated bacteria does not by itself establish the official seasonal quality classification of Es Pouet.

It can, however, provide evidence about conditions at the specific location and time when that sample was collected.

The key disagreement remains unresolved

The evidence currently available shows two different findings.

Sant Antoni's official testing for the September 1 episode was reported as negative for E. coli and intestinal enterococci, and the municipality concluded that the water was suitable for bathing.

Separately, samples collected by Salvem sa Badia approximately four hours after the discharge reported 990 UFC/100 ml of E. coli in the bathing area and more than 2,420 UFC/100 ml of both E. coli and intestinal enterococci in a pool on the beach.

The municipality disputes the comparability of those samples because of differences in sampling location and procedure.

What can be said with confidence

It is accurate to say that new independent tests commissioned by Salvem sa Badia reported bacterial concentrations above the thresholds used by the Balearic Government to assess individual bathing-water samples.

It is also accurate to say that Sant Antoni's official testing produced a different result and that the municipality maintains that the discharge came from the stormwater network rather than the sewage system.

What cannot currently be stated as an established fact is that the September 1 discharge was sewage, that the municipality's official tests were wrong, or that Es Pouet's official bathing-water classification was invalid.

The dispute now centres on the origin of the discharge, the differences between the sampling methods and locations, and what the contrasting laboratory results show about the water at different points during the episode.