If it goes ahead, it would cover an area the size of three football pitches and it would be big enough to hold over two million gallons.
However, it is the contents of this farm-based lagoon that really is causing a stink amongst the residents of Longtown.
An application from two adjoined farms containing a thousand dairy cows has been submitted to build a lagoon to contain animal waste, also known as slurry.
***Andy Burn reports.*
More top news
The first of seven races will begin at 5:45pm, and 76 horses are competing. The UK's top female jockey is amongst the competitors.
Thousands of people are expected to flock to Brampton to catch a glimpse of the colourful breed, which is more common in warmer climates.
More than 120 young athletes are taking part in this year's Borders Sport and Leisure Sports Academy.