The Manawatu is home to one of the western world's dirtiest rivers ?what's being done to turn this brown awa back to a blue one? Since posting, Horizons Regional Council has been in touch and provided some updated figures: $46 million has been invested into projects to improve the river, over 110,000 native plants have been planted and 474km of waterways are now fenced. The Cawthorn institute’s research was overturned in 2012 due to the fact not all rivers in the western world were tested.