By Mark Kinver
Science and environment reporter, BBC News
Habitat loss caused the UK's water vole population to crash in recent years
A survey of the UK's waterways called 2009 a "bumper year" for water voles, which had been considered to be one of the nation's fastest declining mammals.
The study, organised by British Waterways, recorded 89 sightings of the rare rodent - twice as many as in 2008.
The number of water voles had crashed by 90% in recent years as a result of habitat loss and being preyed upon.
Of the 42,500 entries sent to the survey's website, mallards were the most frequently sighted species.
Water voles (Arvicola amphibius) are the UK's largest species of vole and are often mistaken for rats.
Adult males can measure in excess of 20cm (8ins), and weigh more than 300g (10.5oz). The rodents have an average lifespan of two years.
Although once a common sight along waterways, their numbers have plummeted in recent years.
Canals provide ideal conditions for a wide range of plant and animal species
Minks that escaped from fur farms were very efficient predators of water voles. Also, changes to farming practices and flood management schemes affected the rodents' habitats.
However, the resurgence in inland waterways has also been beneficial for wildlife.
Most of the sightings were recorded on the Kennet and Avon Canal, which runs between Reading and Bristol.
"The canals are like linear habitat corridors," Mark Robinson, British Waterways' national ecology manager, told BBC News.
"As well as water, we also have towpaths with grasslands and boundary hedges.
"These corridors are also excellent for species like bumblebees, butterflies, lots of flowering plants."
This year's survey is the sixth annual assessment conducted by British Waterways, but it has been the first year that people have been able to submit their findings online.
"This is the first year that we have made the survey completely internet-based," Dr Robinson explained.
"As a result, we have had a lot more entries than in the previous years.
"In the past, we would have between 6,000 and 7,000 individual records of species sent to us. This year, we have had in excess of 42,000 records.
"But with such a massive increase, we do have to bear in mind that we have received more sightings of species, including water voles.
"However, the benefit is that it tells us where we have got the voles. One of the key points to the survey is that we find out where we have got rare or endangered species."