HUB IN THE SPOTLIGHT: ZÖLD XVII || Bioblitz for Drinkable Rivers: A Neighborhood’s Struggle To Renaturalize Urban Waterways

Flowing with Community to Reclaim River Health.

“The stream running through our district is called the Rákos, which means crayfish in Hungarian,” explains Balázs Kozác, founder of the neighborhood environmental organization ZÖLD XVII – or Green 17, referencing Budapest’s 17th district. “They used to be abundant here, but unfortunately, we don’t have our native crayfish anymore—only invasive species like the ones from Louisiana.”

For Balázs, this is emblematic of the Rákos’s story. The largest tributary to the Danube in the area, it holds a rich history and plays a key role in shaping the surrounding terrain. And yet it has been neglected by modernity: channeled, drained, diluted, and polluted. But now, local residents want to change that. We at Drinkable Rivers sat down with Balázs to hear how a neighborhood community is using citizen science and cross-organizational collaboration to bring their home river into the spotlight—and hopefully back to health.

We’re chatting now in the lead-up to a big 24-hour Bioblitz event you’re organizing on the banks of the Rákos. But take us back: where did your journey with citizen science start?

Balázs Kozác: Funnily enough, I started participating in water quality competitions all the way back in primary school. So I guess I was involved in citizen science before I even knew the term! Fast forward some years, and after studying environmental engineering and working on urban planning projects abroad, I decided to start an NGO back home in my neighborhood—Budapest’s 17th district, on the eastern outskirts of the city.

I founded ZÖLD XVII because there was nothing else like it around. Most NGOs in Hungary focus on social issues like poverty and education, so it’s not easy to find and motivate volunteer groups around environmental topics. We needed a common point of interest, and that was our Rákos: everyone here likes to walk and cycle along the greenway by the creek, but the water itself is totally degraded. There’s rarely enough water in the channel to swim due to overuse, and even if there were, it would be too polluted. So it’s a site where we can really raise awareness of—and connection to—ecological issues through hands-on activities.

Indeed, you organize various participatory activities through ZÖLD XVII. Where does the Drinkable Rivers kit come into play?

BK: Well, we first got involved in citizen science through a Horizon Europe project. With a small group of volunteers, we started measuring water quality, observing species in and around the creek, and organizing guided “wet walks” to reconnect people with the water. Then I learned about Drinkable Rivers through colleagues at a DANUBE4All conference in Romania.

I’m particularly interested in how the DR kit’s E. coli test could be used to highlight the high level of contamination in the water, advocate for the multipronged benefits of renaturalization, and lobby for government action. We’re excited to test it out for the first time at our upcoming 24-hour Bioblitz event!

Let’s get into the event. For those unfamiliar with the idea of a bioblitz, what exactly are you planning?

BK: In a Bioblitz, we gather as many people as possible to collect as much ecological information as possible about a localized area in a short time. Scientists, naturalists, and community volunteers count as many plants, animals, and fungi as they can, take water and air quality measurements, and create an ecological snapshot of the habitat. It’s a great way to get people up close with nature in an otherwise urbanized area, bring together like-minded organizations, and gain public visibility.

For this year’s Bioblitz, we’re expecting 200–300 participants. We’ll start the day with bird spotting, followed by fishing and crabbing. Visitors can join different plant research activities, hunt for specific species in a quadrat, go on guided walks with rangers and foresters, and attend lectures throughout the day. We’ve invited many other regional and national citizen science organizations to set up tents focused on, for example, ivy or pollination. At night, we’ll count moths and butterflies. And of course, we’re planning a big kickoff of the Drinkable Rivers kit with a water quality test in the Rákos!

We hope it goes well! Do you see any challenges moving forward? What do you need to succeed?

BK: We’re very curious to see how the Drinkable Rivers kit performs and what it can add to the other water quality measurement tools we’ve used. The plan is also to compare the data we collect with lab and government data to evaluate our methods.

Citizen science data is too often seen as inaccurate or unreliable—we see that as a challenge for our advocacy efforts, but also as an area where we can help shift institutional perception. We’d also love to have more background information on water quality parameters to help our participants better interpret the data they collect.

In the end, everything we do as ZÖLD XVII aims to bring attention to the Rákos and the need for environmental restoration. The more we can show, the more we can change.