This winter we’ve seem several flooding events in the River Dodder after very high rainfall.

I posted in November about the river height reaching 1.7 metres at one point – approximately eight times the height of the stepping stones, and high enough to leave silt on the footpath at the side of the river.

One of the impacts of the flooding was that the river bed got moved around a bit. Regular visitors across the stepping stones will probably notice that a bunch of stones have built up on the south side of the river in front of the stepping stones, which now means that the majority of the river water flows on the northern half of the river bed.

The water on the north side of the river is much higher and faster than on the south side. And we have the situation where the stepping stones on one side of the river can be bone dry and the other side flooded.

As such, I’ve decided to adjust the thresholds I use for determining when it’s safe to cross. I want everyone to feel safe crossing the river. So to account for the uneven distribution of water flow I’ve reduced the levels for ‘safe’, ‘passable with care’ and ‘flooded’ to be 2cm lower than previously.

This isn’t an exact science for me, and I’ve adjusted it based on what feels about right – so if anyone has feedback to give from their experience crossing at these stepping stones, do get in contact.

A couple of days ago there was an orange weather warning in place for 3 counties including Dublin for rainfall.

I didn’t manage to capture a screenshot at the time, but I distinctly remember visiting this site at the peak of the rainfall, and seeing the water level at 110cm. For context, the height of the stepping stones is 21cm, so the water was over 5 times the height!

Here’s a graph from the riverwater site that shows it reached around 170cm later in the night:

This morning, despite it being mostly dry yesterday, the water is still at 30cm, so it’s not safe to cross just yet.

The water level data used by this site is currently not available.

It seems that something stopped working on the OPW Realtime waterlevel site on June 10th 2025. That’s the last time that the water level data was updated.

This problem with the water level data not updating happened before, and it was related to an integration between the EPA (Environmental Protection Agency) who operate the water sensor, and the OPW (Office of Public Works) who publish the data, stopping working.

Last time, after I reached out to both the OPW and EPA they got it working again, but they did say at the time that this data exchange between the two government agencies wasn’t something that could be relied upon long term.

So I’m not sure exactly what to do. Do I reach out the OPW and EPA again to see what they can do? I’m not sure if I should be bothering them, for this hobby project that I’m not sure if anyone other than me even visits or cares about.

The EPA’s own page confirms that the water level sensor is working and collecting data – it’s just not been shared with or consumed by the OPW.

I also can’t use the data on the EPA website, as it’s not updated in real time. When I checked today, the newest reading that the EPA publish is from yesterday.

I noticed today that the temperature/humidity and PM air quality numbers are not displaying correctly on the site.

These numbers come from an API call to the sensor.community site, and it seems like the API is currently broken:

See their forum for more details: https://forum.sensor.community/t/is-sensors-api-currently-down/4604

This has broken this site’s integration, and it’s also broken in my Home Assistant.

It looks like they’re working on a fix.

I was finding that any page loads of the Temperature and Air Quality pages were taking a long time, and sometimes timed out without retrieving the data.

To get the sensor data for the pages, I make an API call to the sensor.community site to download a small JSON file, and then parse out the figures I need.

I was using a php file_get_contents call to download the JSON, but then I came across documentation that suggested changing to the wp_remote_get instead. I’ll not attempt to give a tutorial on the differences between the two, because I don’t really understand it. But I changed the code from:

$jsonFile = file_get_contents("https://data.sensor.community/airrohr/v1/sensor/42633/");

to:

$response = wp_remote_get("https://data.sensor.community/airrohr/v1/sensor/42633/");
if ( is_wp_error( $response ) || ( wp_remote_retrieve_response_code( $response ) != 200 ) ) {
	echo 'Something went wrong';
}
$jsonFile = wp_remote_retrieve_body( $response );

and a call that used to take 20-30 seconds to respond now takes 2-3 seconds instead.

Having reached out the the EPA, they established that the water level data feed that went to the OPW waterlevel.ie site had stopped working, and they were able to restore it.

Therefore, the data from the EPA sensor at Waldron’s Bridge is now flowing again to the OPW site, and I’m able to automatically grab the latest water level info, and the dodder.eu site is back in operation.

However, they don’t guarantee that this feed to the OPW site will continue long term, so I might need to look at another option.

I reached out to the OPW to ask about the sensor data, and asked if it could be restored. And they got back to me, saying that the sensor has now been taken over by the EPA, and that I can maybe reach out to them to get access to the data.

This is the EPA page for the Waldron’s Bridge sensor: https://epawebapp.epa.ie/hydronet/#09010

My problem is that they don’t provide an easily readable file of readings for that sensor. On the OPW site, I could download a text file with the latest 24 hours of readings, and pick out the latest reading. But on the EPA site, the smallest data set seems to be 3 months of readings, which is contained within a .zip file, which adds to the complexity of parsing it for the information required.

The waterlevel.ie sensor for Waldron’s Bridge (https://waterlevel.ie/0000009010/) has not updated with any data since 5th July 2024 – 20 days ago at the time of writing.

The data from this water sensor is used by this site to indicate whether the River Dodder stepping stones are flooded or not, and without the data the site won’t work correctly. That’s why it says that the status of the stepping stones is currently ‘Unknown’.

I have reached out the OPW to ask if the data feed can be restored, and will post again if I get an update from them.

Many thanks to Dave for emailing me to let me know about this problem.