Residential sewage discharged into the river is not caused by the property. How to write a letter to the industry Committee?

Let's talk about who did it first, and then talk about the harm of sewage entering the river. The discharge of residential sewage into the river is not caused by the property. When writing a letter to the industry Committee, you can first say who is responsible for the sewage discharged into the river, and then talk about the harm of sewage discharged into the river. For example, the owners of this community discharge sewage into the river, which not only pollutes the water resources in the river, but also brings air pollution to the surrounding environment and residents' lives. I hope you can come forward to solve this problem.