The following circulation from the Environment Agency is being posted widely on canal websites. It is reasonable to assume that other river and canal levels are also well below average:
“Water levels in the upper River Thames, particularly upstream of Abingdon lock, will be shallower than you are used to in some places, due to below average rainfall this year.
With this in mind we are asking boaters to take extra care, especially immediately downstream of locks where the natural gradient of the river means levels are always slightly lower than elsewhere in the reach.
For your safety, we have marked all known shallow areas in the main navigation channel (the middle third of the river, also known as the ‘fairway’) with red and green buoys. Please ensure you are familiar with the rules of navigation around obstructions marked in this way – they are there to protect you and your boat from harm. You may find the diagram on page 13 of the River Thames cruising guide helpful.
Remember, boats coming towards you may have to manoeuvre around an obstruction even if you don’t. Also, other boats may be harder to handle than yours, and their skippers less experienced, so please be considerate.
Where we can, we will also mark obstructions that we are aware of, or are reported to us, outside of the main navigation channel. We cannot mark every one however, so do please be vigilant. You can report an obstruction to us on 03708 506 506. Please also remember that a mooring may be shallower than the last time you used it.
We are doing all that we can to maintain the depths of navigation as published on www.gov.uk.
Actions we are taking include closing all our weirs and placing ‘summer boards’ on those that can accommodate them to raise their height. This means we can hold more water back, so raising levels. We are also carrying out additional checks for any leaks in our weir gates and ensuring they are staunched.
In addition, we have instructed our lock staff in the Oxford area to try to avoid emptying locks unless they contain at least one boat, wherever possible. This ensures we are making the most of the considerable volume of water that is released downstream each time a lock is used.
If water levels continue to drop, it will be increasingly difficult for us to maintain depths, even if we implement additional measures such as restricted lock use. We hope to avoid the need for additional measures but may not be able to unless there is significant rainfall over the coming weeks.
Where possible we will also ask our lock staff to advise you of any known shallow areas ahead of you. To help you assess whether or not to continue your journey, you may want to check your boat’s draft if you don’t already know it. Above Iffley Lock we cannot guarantee the navigation channel will always be sufficiently deep for craft with a draft of 0.9m or more.
We are of course monitoring the situation very closely and will let you know immediately if there are any further developments you need to be aware of.
We hope you have found this communication helpful in planning your cruising this summer, and hope it is not unduly affected by weather conditions.
Thank you for your understanding and co-operation.”
River Thames Waterway Operations