On 19 March, Dwr Cymru Welsh Water (DCWW) conducted one of their routine valve tests at Ystradfellte reservoir, releasing up to 4-5 cumecs of water into the river system for around 3 hours. Usually, SWOAPG is notified in advance of these tests – and sends out an alert to notify users – but on this occasion, due to an administrative oversight, we were not notified. The BBNPA staff at Cwm Porth car park had been notified, but didn’t pass the message on to cavers. As a consequence, groups entered the cave unaware that the river would rise suddenly and a number of school groups were caught on the ‘wrong side’ of the river – which rose around midday to cover the entrance slabs – and required assistance to exit the cave. More seriously, a military group had planned to enter through ‘spider cave’ (adjacent to the resurgence) after lunch and, had they entered before the river rose would have found themselves in what became a sumped area of cave with the potential for multiple casualties. Luckily no-one was hurt, but this was clearly a very serious ‘near miss’.
Both DCWW and BBNPA have taken this incident very seriously and are working with us to ensure that this can’t happen again. Measures being considered include:
- a more robust notification system, to ensure that messages from DCWW are received by (not just sent to) those who need to know – SWOAPG will continue to send these messages in our daily alerts – both in advance and again on the day of release – but if you’d like to be added as a direct recipient of DCWW’s notifications, please let us know;
- signage and messaging from staff in Cwm Porth car park on scheduled release days;
- timing the tests towards the beginning or end of the day, so they impact fewer cave users;
- providing information for users about reservoir levels; and
- increasing our mutual understanding of the cave system and its hydrology; our understanding of the processes used at the reservoir; and how we can best work together to prevent similar incidents in future – to which end, we will be meeting with DCWW and BBNPA staff, visiting both the cave and the reservoir, on Tue 9 June; please let us know if you believe you could add value to this meeting (particularly if you have a good understanding of the cave’s hydrology!).
PS the next scheduled valve test is not until October 2026.