The worst UK drought since 1929 has forced the closure to boats of the Leeds-Liverpool canal through Hyndburn from next month.
Canal boats will not be allowed to use locks on a 60-mile stretch between Wigan and Gargrave from August 2.
British Waterways forecast reservoirs feeding the canal - including Rishton - will then be just 10 per cent full.
Water is lost every time a lock is opened and waterways bosses say the canal could be closed for "many weeks" to manage the impact on navigation and wildlife, until reservoirs reach at least 20 per cent holdings.
It will be the first time a stretch of the canal has been closed since a similar drought in 1995.
Vince Moran, British Waterways operations director, explained: "Canals depend upon a complex system of reservoirs and rivers to remain topped up with water. The lowest rainfall in almost a century combined with high temperatures has left the regions' water supplies at record low levels.
"We have been doing all we can over the last three months to conserve water levels within what is a popular and 200-year old working canal, and we would only close it as a last resort.
"Unless we have significant rainfall within the next fortnight therefore we will be forced to put in stop planks along the canal, and shut off the water supply to the canal from all seven reservoirs."
British Waterways first put out notices warning of shortages at the beginning of May and the canal has been closed between 4pm and 10am since mid-June. The towpath will remain open to the public, but walkers are warned to take extra care at the towpath edge as water levels fall.
Gemma Tomlinson, of Hyndburn's PROSPECTS Foundation, sits on the borough's canal working group. She said: "If we have drought conditions it is understandable that measures like this are taken.
"Our main concern is with wildlife in and along the canal, and the additional stress it may be put under from the lower water levels. The canal is an important resource for feeding, breeding and nesting as well as exhibiting a diverse range of flora. We hope that British Waterways will be sensitive to this and keep a close eye on the canal, in particular protected sites such as the biological heritage site in Hyndburn."
Altogether there are 2,000 boats moored on the canal and 15 trade businesses, including marinas, hire boat operators, and trip boats. Hapton Valley Boats, which offers boats for hire for a day/weekend or holidays of one week and longer, confirmed they would be moving their three-boat fleet from Hapton to Bradley in Yorkshire, between Skipton and Bingley Five Rise Locks.
A spokesman said: "The closure of our length of canal will not stop the company providing a professional service to its customers. All current customers will be contacted by the company by phone over the next few days."