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Did You Know?

If you harvest leaves, twigs and other yard waste into a pile in a corner of your yard in the fall months, by the spring, it will transform into a rich, dark, soil-like material that can nourish plants and improve the soil texture of your garden.

Sanitary Sewer Overflows

Boston Water and Sewer Commission maintains a vast system of sanitary sewers and stormwater drains designed to properly convey sanitary flows to the MWRA's Deer Island Treatment Facility and stormwater to receiving waters. Over the past two decades, the Commission has invested heavily in upgrading the system to increase capacity as well as separate combined sewers, resulting in far reaching environmental benefits. As the Commission's work progresses, BWSC carefully monitors Sanitary Sewer Overflows (SSOs). Some SSOs occur when wet weather events cause inflows to exceed the collection capacity of the system, producing an overflow of sanitary sewerage. SSOs can also occur during dry weather events due to a variety of causes, including blockages and structural failures. The map below displays the location of SSO events throughout the city based on a selected timeframe.


  1. Click on the layer list icon in the upper-right corner to open it. Under Operational Layers, check one box for the desired time frame from the options listed. SSOs that occurred during that period will be indicated by caution symbols on the map.
  2. To view detailed information from a specific event, click on a caution symbol, then the arrow button on the right of the pop-up. To go back to the map, click the down arrow in the upper-right corner. To clear all selections and go back to the map, click the X in the upper-left corner.
  3. To view all SSO events in the current map extent, click the up arrow at the bottom of the map to make the attribute table visible. Table columns can be sorted by clicking on the headings and widened by clicking and dragging on the borders.
  4. Click the plus and minus buttons in the upper-left to zoom in and out.
  5. Click the House button in the upper-left, below the minus button, to return to a full view of the city.
  6. To export SSO event data to an Excel table, select the events you'd like to export in the attribute table, click the Options drop-down button, and click Export to CSV. This button will be grayed out if no data is selected.
sso legend