it's a problem when the rivers are at record lows with no rain in sight. the river get's closed because salmon are not able to go up with any semblance of normalcy. The rest is people's imaginations and assumptions. Notice how as soon as we had one decent rain and were close enough to a forecast of rain that will bring flows back to normal, the river opened up? Snagging is one of the things that happens in low water, but not why the department closes rivers.