Yup. I live on a river. We flooded catastrophically in 2019, which made me suddenly care about the government’s network of river level meters.

Turns out, they abandoned most of them in 2008, as it was the local council who were meant to maintain them, but they couldn’t afford it - a chat with the president revealed they’d been paying €15k a year for each station to maintain it and they’d cost about €100k each.

I went and looked at the battered remains. Sounding tube. Ultrasound transducer. Box of 90’s electronics.

Anyway, long story short I banged out six of them for them for about €80 a piece - the expensive bits were the batteries and the dinky solar panel. ESP32, ultrasonic transducer, GSM and LoRa (as two are outside of the cell network), haven’t had to touch them in five years and we now know when it’s time to evacuate, rather than wading out in the night while trees sail past us at 60kph.

So much stuff like this.

Where are you located? Around 2020 I put together a landslide risk monitoring site that's entirely based on stream gauges:

https://khmpsitka.org

It's an interesting approach that's way simpler than relying on soil moisture sensors placed high up on mountainsides. It's not as widely applicable as measuring soil moisture directly, but it's been running steadily for over 5 years now.

They didn't offer any of the €15k a year to you, did they?

Next you can hook up an abandoned nuke silo, right?