It sounds like a good idea, but during a rainstorm, trash is quickly swept into drain inlets. Any screen or filtration device placed in front of the drain inlet would cause trash to accumulate and clog the grate, preventing proper drainage and potentially creating a flood hazard. City maintenance crews would be unable to keep up with cleaning these devices potentially creating flooding hazards. However, there are new technologies being developed in the form of filtration or screening devices to be installed and inserted inside catch basins. The Stormwater Program Engineering groups are always evaluating these new technologies for possible future use.