"If it's yellow let it mellow, if it's brown flush it down," may be a popular mantra on the Sunshine Coast these days – but when can we go back to flushing the yellow?
Sunshine Coast Regional District (SCRD) Area E director Donna McMahon passed on the question from a resident at the Oct. 27 SCRD board meeting: “If it’s raining, can I flush?”
SCRD general manager of Infrastructure Services Remko Rosenboom was quick to answer, “You're always allowed to flush – I will never prevent anybody from flushing.”
But Rosenboom went on to say that the immediate concern isn’t when it’s raining – there’s plenty of water flowing through Chapman Creek and into the water system when it’s raining – it’s when the rain stops that we need to be careful.
The prolonged drought has dried the Chapman watershed and water needs to saturate the soil and infiltrate the aquifer. Flows in Chapman Creek, which feeds the water system, are dropping “extremely fast” after a rain event, said Rosenboom. Normally, the return to lower flow would be gradual as rain absorbed into the watershed is slowly released into the creek. Instead, the soil is so dry that it’s not actually absorbing enough water, rather the water is running off into the creek all at once.
“That's why the water restrictions will need to stay in place, because they are not only for times when it rains, they are also for times when it’s not raining," said Rosenboom.
Rather than big dumps of 50 mm of rain that just get flushed through the system, the watershed requires smaller amounts – 10 mm, 20 mm – of rain over days or weeks to recharge according to Rosenboom.
The SCRD remains under a state of local emergency and users of the Chapman Water System remain on Stage 4 restrictions.