A Virginia river is being listed among the most endangered waterways in America.Preview: Edison High in Alexandria is testing out a new weapons detection system. The school is among the first in the district to see the new screeners in action, which are similar to the ones being used at sporting events and concerts. The OpenGate screeners will be making their rounds to all 25 FCPS high schools at least once a week during morning arrival through the end of the school year. The pilot program is part of the district's push to keep schools safe.