they have not been dug to death as xloox said dig down to the wash to find the sapphires
do your homework ,if you are there for a week or two look for the shallow wash areas (ie 1 to 2 feet deep )
there are plenty of areas with shallow wash
there is not much sense in chasing the river wash if it is 4 or more feet deep when you have only have up to a couple of weeks at the most to chase the sapphires you will spend 90% of your time removing overburden instead of river wash which holds the sapphires
as xloox said pick a hole someone else has started (as long as there is no bucket in the hole) a bucket upside down with rocks on it or a bucket upright with rocks in it, that indicates that someone is still working that hole so you wiil have to choose another hole ,don't worry there is plenty to choose from
i go to the willows area when i get a chance to go
as the wash in the area i go to is about 2 feet deep max ,gives me plenty time to chase the wash
example above ,the billy boulders (overburden) removed from a hole approximately 2 feet deep by about 6 meters long at the willows area
dug to death no way ,still plenty out there to find