I have been at the track several times in the last week, it's in good shape (apart from the leaves) and has not been affected at all by the rain.
The Fraser River did rise 3 metres in 36 hours, a staggering amount! It reached 5.5 metres at the Mission Bridge Gauge (it would have to reach 6.3 to affect the track) and then it receded. It's currently below 2.5 metres.
Interestingly enough the track will have all kinds of flooding issues with 12 hours of heavy rain because if can't drain fast enough.