Abstract: A filter for a grate of a storm drain, the grate having a plurality of grate slots, includes: (a) a plurality of parallel, spaced-apart chambers dimensioned for being inserted through the grate slots, each the chamber defining an open top and comprising a plurality of apertures in at least one side of the each chamber; and (b) a frame connecting the plurality of chambers to each other, the frame not obstructing the chambers from being inserted through the grate slots such that the filter is removably installable without moving the grate. A lock inserts through one of the grate slots for locking the filter to at least one of the storm drain and the grate. The lock receives a key with a handle for removing the filter from the grate. An indicator indicates when the filter is full. A solar panel powers the indicator.