Event manager Rachel Jenkinson said the organising group had taken into account feedback about last year's event and aimed to improve on the inaugural mud trudge.
This year the course would be shorter but have more mud and more obstacles.
''We really wanted to up that a lot this year.''
A digger would be digging obstacles later this week in time for the race on Saturday.
The mud used in the event would be natural and not made from powder, Mrs Jenkinson said.
The course was also shortened to 5.5km for both teams and individuals alike.
''It just simplifies things a wee bit too because I think a lot of the people coming along are there for a laugh and what not, so they're not necessarily elite athletes or anything.''
There will be spot prizes recognising things such as best-dressed team.
Entrants were coming from as far away as Te Anau, Queenstown and Christchurch.
A lot of people had provided positive feedback on the Clutha version of the event and rated it ''highly'' in comparison to other similar mud events.
Entries closed last night and Mrs Jenkinson anticipated about 170 people would be taking part, which was down about 100 from last year.
''It's still going to be a good-sized event and bring in a bit of money for St John,'' she said.
Spectators were welcome to stand on the floodbanks or the bridge.
She hoped to run the event again next year but said it might be a good idea to hold it in the summer so participants did not have to worry about the cold as much.
