Multiple River Blockades

By The Red Viper, in 2. AGoT Rules Discussion

if i control multiple river blockades and we are in challenges and my opponent use a locations trigger effect would both river blockades respond to that one trigger and negate it or would only one of the blockades trigger and negate and then if they did another location trigger the second blockade would trigger to negate that?

--The Red Viper

The Red Viper said:

would both river blockades respond to that one trigger

That one