Water & Climate · Sirena, Corcovado National Park, Osa, Puntarenas

Sirena Station Back to 366 Daily Visitors After Corcovado Repairs

On Sept. 17, 2026, Costa Rica's park agency SINAC raised the daily limit at Sirena Biological Station in Corcovado National Park from 225 back to 366 people, saying the station's broken wastewater plant had been restored and health orders met. Sirena still closes each October, and a court-ordered review of how many visitors Corcovado can safely handle is unresolved.

By Pura-Verde.com Editors · Published October 30, 2026
Original report: The Tico Times: Costa Rica Restores Visitor Capacity at Corcovado's Sirena Station (2026-09-19)

After a summer of sewage reports, protests and shifting rules, Sirena Biological Station in Corcovado National Park is back to its full visitor quota. On Sept. 17, 2026, Costa Rica's National System of Conservation Areas (SINAC) raised the station's daily limit from 225 to 366 people, saying its failed wastewater treatment plant had been put back in working order.

The new limit at Sirena

The change came in resolution SINAC-ACOSA-D-R-0106-2026 from the Osa Conservation Area (ACOSA), as delfino.cr reported on Sept. 18. The 366 daily spaces break down like this:

• 230 day visitors
• 105 overnight guests at the station
• 16 for the Asociación de Desarrollo Integral Carate-Corcovado, the local community association that holds a permit at Sirena
• 15 reserved for the ACOSA administration

The Tico Times followed on Sept. 19. According to Teletica, SINAC said the decision rests on its visitor flow management tool and on operating health permits issued by the Ministry of Health. The plant repairs were done with labor, logistics and money from local organizations and volunteers, under agreements reached at a regional tourism working group.

How Sirena got here

Sirena is Corcovado's main ranger and research station and the destination for most overnight stays in the park. Its treatment plant was built in 2017 for about 100 people a day but had been handling more than 200, and inspections by health and water authorities found poorly treated wastewater reaching a stream inside the park.

Here's how the limit moved during 2026:

1. Late June: ACOSA's interim director cut Sirena to 150 people a day because of the risk of untreated discharges.
2. Early July: After the director was reassigned, his successor raised the cap to 225 through September, relying on a separate restroom block at Los Naranjos for day visitors, Semanario Universidad reported.
3. Aug. 10: The Parlamento Cívico Ambiental, a coalition of environmental groups, put Corcovado on a symbolic "red alert" and demanded an investigation. We covered that in Corcovado's wastewater red alert.
4. Sept. 17: SINAC restored the full 366.

Questions that remain

The new resolution answers the immediate question of whether visitors can return in full numbers. It doesn't close the bigger debate.

In August 2025, Costa Rica's Constitutional Chamber struck down a 2023 resolution that had raised Corcovado's overall daily ceiling, because it didn't show the technical basis for the higher numbers. The Tico Times reported that the Environment Ministry has asked the court for more time to comply with that ruling, which requires scientific justification that visitor levels won't harm the park. Earlier rules had tied any increase in overnight guests to proof that the treatment system could handle the extra load, and The Tico Times noted that questions remain about whether the paperwork supports the higher limit.

When Semanario Universidad reported on the decision on Sept. 24, it relayed MINAE's statement that health orders had been met on time and the plant restored, without independent confirmation. That's worth keeping in mind. Watchdog groups have asked for the inspection reports to be made public, and so far coverage has relied on official statements.

Planning a trip to Corcovado

If you're planning a visit, here's what the September resolution set out:

• October: Sirena, El Tigre and Los Patos close to tourists every October for maintenance and because it's one of the wettest months on the peninsula. San Pedrillo and La Leona stay open.
• Other sectors: Outside October, San Pedrillo allows up to 120 visitors a day, and La Leona, Los Patos and El Tigre up to 80 each.
• Guides: Every visit to Corcovado requires a licensed guide and an advance reservation. Our guide to responsible ecotourism tours in Costa Rica covers how to pick one.

These limits can and do change, sometimes within weeks. Before you book, confirm the current quota and reopening dates for Sirena with SINAC or your guide, rather than relying on any article, including this one. High-season spaces go fast. Browse more national parks on our map.

Frequently asked questions

How many people can visit Sirena Station per day?

Since Sept. 17, 2026, the limit is 366 people a day: 230 day visitors, 105 overnight guests, 16 spaces for the Carate-Corcovado community association and 15 for park administration.

Is Sirena Station open in October?

No. Sirena, El Tigre and Los Patos close to tourists every October for maintenance and heavy rain. San Pedrillo and La Leona remain open that month.

Why was Sirena's capacity reduced in 2026?

Inspections found the station's wastewater treatment plant, designed for about 100 people a day, was releasing poorly treated water into a park stream, so SINAC cut daily visitors in June until repairs were made.

Do I need a guide to visit Sirena Station?

Yes. All visits to Corcovado National Park, including Sirena, require a licensed guide and an advance reservation through the park's system.

Sources and original reporting

1. The Tico Times: Costa Rica Restores Visitor Capacity at Corcovado's Sirena Station (2026-09-19)
2. delfino.cr: Parque Nacional Corcovado restablece aforo de 366 personas diarias en Estación Biológica Sirena (2026-09-18)
3. Teletica: Parque Nacional Corcovado restaura aforo de 366 personas diarias en Sirena (2026-09-18)
4. Semanario Universidad: Sinac vuelve a subir aforo en Corcovado y autoriza entrada de hasta 366 personas al día en Estación Sirena (2026-09-24)
5. Semanario Universidad: Sinac vuelve a aumentar el aforo en Corcovado tras salida de director que alertó por colapso ambiental (2026-07-28)

We wrote this story from the published reports and official sources above. We didn't interview the people named unless the story says so.