What about LoRaWAN?
But wouldn’t it work for this use case he had?
I believe that in the long term and as the number of devices per unit of area increases, licensed technologies will be the only viable option.
However I've seen that there is proprietary protocol symphonylink from LinkLabs, that uses LoRa. They claim that it allows for having every frame ACKed, even bulk data uplink (OTA firmware upgrades). If so, I would tend to pick such technology for pond water telemetry.