Lower or Upper box?
The lower box you will have the Red river coming in, so its runable but low. The upper, 300-400 is the bottom end of where some people start running it.
The deal is farmers in the San Louis (Colorado) valley consume most of the water for agriculture. On good years we might get 1/4 the flow that the Rio Grande has in Del Norte Co cross the border in NM. On bad years and in the summer, I believe they are only required to let 100 cfs cross the border.
Hopefully it at least gets up to 500 cfs crossing the border this season.