Boaters on any river must be fully aware of the strength of current or flow. When we cruise the River Thames in particular, we ensure we are up to date with the weather conditions and forecast, which is a good indicator of river conditions.
The rate of flow can change very quickly even following the odd thunderstorm. During late winter and early spring and especially after a wet period, boaters can see the Yellow “Stream Increasing” boards or even the “Red” boards appear at the locks to warn boaters of the speed of the flow on the river. In fact, the red boards generally mean “Stop”. These boards are displayed by Environment Agency staff, particularly the Lock Keepers, who continually monitor the strength of flow and depth of the river at locks.
The catchment area for the River Thames is almost 5000 square miles (13000 km²), extending from Luton to Basingstoke at the Thames Estuary, to Newbury, Swindon and the eastern slopes of the Cotswolds in the west. For instance, after a spell of rain in the Cotswolds, that can mean “Watch Out” a day or so later in the lower reaches of the river!
We have noticed for most of this winter the red boards have been in place at many locks, so not only do boaters who are on the move need to take care, it is necessary for owners of moored boats to ensure that their lines are secure and that they allow for the possibility of any change in the level of the river.
Readers may think that this is stating the obvious, but it is surprising how often we see reports of boats that have broken free from their mooring or have become a danger to others and in extreme cases have been flooded or occasionally sunk.
Guests often ask us about the state of the river and we talk about being stuck at Abingdon in November 2012 and again in June 2016 where we spent 3 days moored on the lock landing at Marlow. Here the level of the water had risen at least 3 feet in a very short time.
As a contrast, we have also encountered the River Thames in the summertime when the lock keepers have struggled to keep the levels sufficiently high enough to stop boats from grounding. This is mainly on the upper reaches above Oxford but it can also apply to the lower sections of the river.
All things considered we must all remember that the water can be a very enjoyable experience but we must always treat it with great respect.