What exactly does “swimmable” mean?
I have given Nick Smith some stick over the last couple of weeks for not letting sleeping dogs lie. Part of the problem is that the new standards for what constitutes a ‘swimmable’ waterway are, on the face of it, worse than what we had before.
Ministers Dr Nick Smith and Nathan Guy recently announced the goal that 90 percent of our rivers and lakes would be “swimmable” by 2040. Critics accused them of doubling the allowable levels of faecal bacteria and coming up with a definition of swimmable that means it’s OK for one in 20 people to get sick. Dr Smith responded by calling that “junk science”. What’s going on here?
Previous water quality guidelines had separate criteria for swimming and other activities. A river or lake was graded an A for swimming if tests for the E. coli bacterium came back with less than 260 bacteria per 100 ml of water 95 percent of the time.
The criteria for an A for other activities was less strict; the median (middle) value of all the tests taken over a year needed to be less than 260 bacteria per 100 ml. A river or lake got a B if the values were 260-540 E. coli, a C if they were 540-1000 and a D if they were over 1000. So, under the old guidelines, some of our lakes or rivers could easily have an A for water sports but a B (or no rating at all) for swimming.
In the government’s new policy document (‘Clean Water’ – PDF, 3.68MB), the threshold number of E. coli has been set at 540 bacteria per 100 ml of water. Now to get a blue (“excellent”) rating, the water must have less than 540 E. coli for 95 percent of the time.

As much at home writing editorials as being the subject of them, Cam has won awards, including the Canon Media Award for his work on the Len Brown/Bevan Chuang story. When he’s not creating the news, he tends to be in it, with protagonists using the courts, media and social media to deliver financial as well as death threats.
They say that news is something that someone, somewhere, wants kept quiet. Cam Slater doesn’t do quiet and, as a result, he is a polarising, controversial but highly effective journalist who takes no prisoners.
He is fearless in his pursuit of a story.
Love him or loathe him, you can’t ignore him.
To read Cam’s previous articles click on his name in blue.