A Conversation with Scientific Director, Dr. Vanessa Bézy: How Water Quality Testing and Biogardens Are Connected in Nosara
- WCA Nosara
- Mar 20
- 3 min read
Learn how water quality testing in Nosara revealed fecal contamination and led WCA to promote biogardens as a practical, regenerative wastewater treatment solution in Costa Rica.
At WCA, community questions about brown foam in the ocean led to water quality testing, which revealed fecal contamination and highlighted the need for better wastewater treatment. Biogardens are one practical, nature-based solution.
Water quality testing and biogardens might seem like two entirely separate things, but in Nosara they are deeply connected. One is science and data collection, the other is a wastewater treatment system -- Together, these initiatives show how conservation works best when we listen to our community’s questions and work together to come up with practical actions.
Our work at the Wildlife Conservation Association always begins with the community, we listen to what people are noticing, asking, and worrying about regarding the environment around them. These initiatives were both born from the community asking “What’s that brown foam in the ocean? Is it safe? What's causing it? How do we fix it?”
These questions gave rise to volunteer-run water quality testing in Nosara. We started collecting water samples from different points in the ocean to test for pollution. We detected fecal contamination in coastal waters, especially in the rainy season when rainfall carries this pollution to the ocean. Then we started testing up streams and rivers, and we found out that most of the pollution is coming from Nosara. Then we also asked the question - is this agricultural, domestic animal, or human waste? And we found out the biggest contributors were dog and human waste. Human sewage is especially concerning because it can carry pathogens that make people sick, while excess nutrients can also fuel harmful algal blooms that disrupt marine ecosystems.
So, what do we do about it? And more importantly, why isn’t wastewater being treated in the first place? In Costa Rica, only 15% of sewage receives some type of treatment, the rest goes untreated into rivers and streams.
If we can learn from our neighbors in Tamarindo -- where they started having serious water quality issues in early 2000s and might get wastewater treatment by 2030-- waiting for government action may be too little too late, and the community is the one that will suffer. We started visiting homes in the area and saw very quickly most homes had poorly built and sized septic tanks, if that.
We saw many septic tank failures, in areas where the high water table and minimal space available are a real challenge. The cost of an advanced system, even a conventional one, is prohibitive to community members who need it most - those living in flood zones. Add to that the lack of regulations and enforcement, and its clear this issue - like many others in Costa Rica - falls in the hands of each property owner and community.
What solutions are available? Which ones are realistic in places like Nosara? How do we make solutions practical, economical, and regenerative?
This is where biogardens come in. Biogardens are a nature-based wastewater treatment system that converts your sewage into a beautiful green space and pollinator garden. These systems are lower-cost, low-maintenance, and more resistant to flooding, making them especially well-suited to coastal communities like ours. They filter and clean wastewater, removing pollutants at the source before they reach groundwater, rivers, and the ocean.
Water quality testing identified the problem. Biogardens are addressing one of the root causes. The two are connected because science should lead to action. Testing without solutions is incomplete; solutions without evidence are not enough. Together, they create a cycle for positive change: where community concerns lead to understanding, and understanding leads to practical action -- so the community is empowered to implement solutions to our environmental challenges, building a future in balance with nature.
Learn more
Costa Rica’s wastewater treatment gap
Septic systems & groundwater contamination
Nature-based wastewater treatment
Tamarindo Wastewater Issues
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