Garbage in a river

In Japan, a survey showed that half of the garbage in a river is the plastic shopping bag and some refuse of plastic. The researchers cleaned the river once a month, but the amount of the garbage didn't decrease. So they will tell neighbors the condition of the river, and will clean the river together. The reason why there are a lot of plastic is that there are some convenience stores along the river, and people throw away the plastic bag in the river. Most of these people are young, so researchers says that young people sould have morals. I can't believe the act of these young people who throw away garbage in the river. We have to think about water pollution harder.