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California · California (CIWQS)
San Mateo County DPW
D
Frequently reaches water
Reported events
239
Total volume
722K gal
Reached waterways
78 (33%)
Reporting since
2007
What caused the overflows
Other / Unknown
157
Root Intrusion
47
Grease / FOG
22
Equipment Failure
13
Reported overflow events (showing 200 of 239)
| Date | Volume | Cause | Reached water | Receiving water |
|---|---|---|---|---|
| Jun 23, 2026 | 2K gal | Other / Unknown | — | — |
| Jun 23, 2026 | 627 gal | Other / Unknown | — | — |
| Dec 15, 2025 | 131K gal | Root Intrusion | Yes | Redwood Creek |
| Dec 8, 2025 | 13K gal | Grease / FOG | Yes | San Francisco Bay |
| May 14, 2025 | 5K gal | Grease / FOG | Yes | San Francisco Bay |
| Feb 13, 2025 | 2K gal | Other / Unknown | Yes | San Francisco Bay |
| Feb 13, 2025 | 4K gal | Other / Unknown | Yes | San Francisco Bay |
| May 22, 2024 | 1K gal | Grease / FOG | Yes | San Francisco Bay |
| Apr 30, 2024 | 82 gal | Root Intrusion | — | — |
| Dec 30, 2023 | 17K gal | Grease / FOG | Yes | San Francisco Bay |
| Oct 23, 2023 | 487 gal | Root Intrusion | Yes | Redwood Creek |
| Mar 21, 2023 | 36K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Mar 21, 2023 | 23K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Mar 21, 2023 | 2K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Mar 21, 2023 | 32K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Mar 21, 2023 | 42K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Mar 21, 2023 | 23K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Mar 12, 2023 | 4K gal | Other / Unknown | Yes | Separate Storm Drain;Street/Curb and Gutter |
| Jan 31, 2023 | 19 gal | Grease / FOG | — | Paved Surface;Street/Curb and Gutter |
| Jan 14, 2023 | 2K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Jan 9, 2023 | 20K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Jan 9, 2023 | 30K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Jan 9, 2023 | 5K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Jan 9, 2023 | 4K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Jan 9, 2023 | 38K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Dec 31, 2022 | 43K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Dec 31, 2022 | 43K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Aug 22, 2022 | 101 gal | Other / Unknown | — | Other (specify below);Paved Surface;Unpaved surface |
| May 17, 2022 | 3K gal | Root Intrusion | — | Unpaved surface |
| Apr 17, 2022 | 5K gal | Equipment Failure | — | Other (specify below);Paved Surface;Unpaved surface |
| Mar 30, 2022 | 564 gal | Grease / FOG | Yes | Separate Storm Drain;Surface Water;Unpaved surface |
| Mar 5, 2022 | 2K gal | Equipment Failure | — | Paved Surface;Street/Curb and Gutter;Unpaved surface |
| Nov 17, 2021 | 123 gal | Root Intrusion | — | Paved Surface;Unpaved surface |
| Nov 9, 2021 | 870 gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Oct 25, 2021 | 2K gal | Other / Unknown | Yes | Paved Surface;Street/Curb and Gutter;Surface Water;Unpaved surface |
| Aug 31, 2021 | 250 gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| May 21, 2021 | 270 gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter |
| Mar 16, 2021 | 60 gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter |
| Dec 11, 2020 | 229 gal | Other / Unknown | — | Paved Surface |
| Nov 28, 2020 | 54 gal | Other / Unknown | — | Street/Curb and Gutter;Unpaved surface |
| Nov 23, 2020 | 1K gal | Other / Unknown | Yes | Drainage Channel;Paved Surface;Street/Curb and Gutter;Surface Water;Unpaved surface |
| Nov 6, 2020 | 5K gal | Grease / FOG | Yes | Surface Water |
| Oct 28, 2020 | 2K gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter |
| Oct 13, 2020 | 20 gal | Equipment Failure | — | Paved Surface;Unpaved surface |
| Sep 9, 2020 | 30 gal | Other / Unknown | — | Paved Surface;Separate Storm Drain;Street/Curb and Gutter |
| May 23, 2020 | 62 gal | Other / Unknown | — | Paved Surface;Unpaved surface |
| Apr 22, 2020 | 124 gal | Other / Unknown | — | Paved Surface;Separate Storm Drain;Unpaved surface |
| Apr 6, 2020 | 4K gal | Other / Unknown | Yes | Surface Water;Unpaved surface |
| Feb 18, 2020 | 657 gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Feb 9, 2020 | 9 gal | Other / Unknown | — | Unpaved surface |
| Feb 5, 2020 | 839 gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter;Unpaved surface |
| Dec 26, 2019 | 1K gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter;Unpaved surface |
| Oct 30, 2019 | 13 gal | Other / Unknown | — | Paved Surface |
| Oct 23, 2019 | 133 gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter;Unpaved surface |
| Oct 8, 2019 | 331 gal | Other / Unknown | — | Other (specify below) |
| Oct 8, 2019 | 148 gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter |
| Sep 1, 2019 | 380 gal | Grease / FOG | — | Building or Structure;Paved Surface |
| Sep 1, 2019 | 2K gal | Root Intrusion | — | Paved Surface;Unpaved surface |
| Jul 18, 2019 | 6K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Apr 8, 2019 | 100 gal | Root Intrusion | — | Paved Surface;Street/Curb and Gutter;Unpaved surface |
| Apr 2, 2019 | 810 gal | Grease / FOG | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Mar 18, 2019 | 178 gal | Other / Unknown | — | Unpaved surface |
| Feb 17, 2019 | 167 gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Unpaved surface |
| Feb 5, 2019 | 20 gal | Other / Unknown | — | Paved Surface;Unpaved surface |
| Jan 27, 2019 | 1K gal | Other / Unknown | — | Paved Surface;Unpaved surface |
| Jan 21, 2019 | 321 gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Jan 16, 2019 | 83 gal | Other / Unknown | — | Building or Structure |
| Jan 6, 2019 | 1K gal | Other / Unknown | Yes | Other (specify below);Separate Storm Drain;Surface Water;Unpaved surface |
| Dec 27, 2018 | 295 gal | Equipment Failure | Yes | Other (specify below);Paved Surface;Separate Storm Drain;Surface Water;Unpaved surface |
| Dec 18, 2018 | 232 gal | Other / Unknown | — | Paved Surface;Unpaved surface |
| Nov 29, 2018 | 147 gal | Other / Unknown | — | Paved Surface;Unpaved surface |
| Nov 5, 2018 | 2K gal | Root Intrusion | Yes | Other (specify below);Paved Surface;Surface Water;Unpaved surface |
| Oct 26, 2018 | 40 gal | Root Intrusion | — | Street/Curb and Gutter;Unpaved surface |
| Oct 25, 2018 | 26 gal | Other / Unknown | — | Street/Curb and Gutter |
| Sep 25, 2018 | 302 gal | Other / Unknown | — | Other (specify below);Paved Surface |
| Sep 20, 2018 | 125 gal | Other / Unknown | — | Other (specify below);Paved Surface |
| Sep 10, 2018 | 44 gal | Other / Unknown | — | Other (specify below);Paved Surface;Unpaved surface |
| Aug 28, 2018 | 271 gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter |
| Aug 20, 2018 | 121 gal | Other / Unknown | Yes | Other (specify below);Paved Surface;Separate Storm Drain;Surface Water;Unpaved surface |
| Aug 9, 2018 | 91 gal | Other / Unknown | — | Other (specify below);Paved Surface;Unpaved surface |
| Jun 22, 2018 | 53 gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter;Unpaved surface |
| Jun 19, 2018 | 9K gal | Other / Unknown | Yes | Paved Surface;Street/Curb and Gutter;Surface Water |
| Jun 6, 2018 | 119 gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter |
| May 16, 2018 | 2K gal | Other / Unknown | — | Unpaved surface |
| Jan 24, 2018 | 3K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Dec 18, 2017 | 59 gal | Root Intrusion | — | Unpaved surface |
| Dec 10, 2017 | 64 gal | Root Intrusion | — | Unpaved surface |
| Oct 18, 2017 | 2K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Oct 17, 2017 | 6K gal | Root Intrusion | — | Paved Surface;Unpaved surface |
| Oct 11, 2017 | 1K gal | Other / Unknown | Yes | Paved Surface;Surface Water;Unpaved surface |
| Oct 10, 2017 | 1K gal | Other / Unknown | Yes | Paved Surface;Surface Water;Unpaved surface |
| Sep 22, 2017 | 10 gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter |
| Jul 22, 2017 | 142 gal | Other / Unknown | — | Unpaved surface |
| Jul 19, 2017 | 20 gal | Other / Unknown | — | Paved Surface |
| Jul 9, 2017 | 12 gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter |
| Jun 17, 2017 | 6K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| May 27, 2017 | 73 gal | Other / Unknown | — | Paved Surface;Unpaved surface |
| Feb 7, 2017 | 3K gal | Other / Unknown | — | Paved Surface;Unpaved surface |
| Feb 7, 2017 | 5K gal | Other / Unknown | Yes | Other (specify below);Paved Surface;Separate Storm Drain;Surface Water |
| Jan 9, 2017 | 10K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Dec 12, 2016 | 74 gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter |
| Oct 14, 2016 | 5K gal | Equipment Failure | Yes | Separate Storm Drain;Surface Water |
| Sep 22, 2016 | 138 gal | Other / Unknown | — | Paved Surface;Separate Storm Drain;Street/Curb and Gutter |
| Aug 1, 2016 | 700 gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Jul 12, 2016 | 2K gal | Other / Unknown | Yes | Surface Water;Unpaved surface |
| Jul 9, 2016 | 618 gal | Other / Unknown | Yes | Drainage Channel;Other (specify below);Paved Surface;Surface Water;Unpaved surface |
| Jul 7, 2016 | 1K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Jul 5, 2016 | 9K gal | Other / Unknown | Yes | Building or Structure;Paved Surface;Separate Storm Drain;Surface Water;Unpaved surface |
| Apr 29, 2016 | 175 gal | Root Intrusion | — | Other (specify below);Paved Surface;Separate Storm Drain;Unpaved surface |
| Apr 1, 2016 | 383 gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter;Unpaved surface |
| Mar 6, 2016 | 1K gal | Other / Unknown | Yes | Other (specify below);Paved Surface;Separate Storm Drain;Surface Water;Unpaved surface |
| Dec 13, 2015 | 105 gal | Other / Unknown | — | Street/Curb and Gutter |
| Nov 26, 2015 | 422 gal | Other / Unknown | — | Street/Curb and Gutter;Unpaved surface |
| Nov 18, 2015 | 564 gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter;Unpaved surface |
| Oct 25, 2015 | 38 gal | Root Intrusion | — | Paved Surface;Unpaved surface |
| Oct 18, 2015 | 144 gal | Equipment Failure | — | Paved Surface;Street/Curb and Gutter;Unpaved surface |
| Aug 20, 2015 | 11K gal | Root Intrusion | Yes | Surface Water;Unpaved surface |
| Aug 15, 2015 | 178 gal | Other / Unknown | — | Paved Surface;Unpaved surface |
| Jul 16, 2015 | 120 gal | Grease / FOG | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water;Unpaved surface |
| May 13, 2015 | 74 gal | Other / Unknown | — | Paved Surface;Unpaved surface |
| Jan 5, 2015 | 91 gal | Root Intrusion | — | Unpaved surface |
| Dec 7, 2014 | 56 gal | Equipment Failure | — | Paved Surface;Street/Curb and Gutter |
| Dec 4, 2014 | 250 gal | Other / Unknown | — | Unpaved surface |
| Dec 3, 2014 | 780 gal | Other / Unknown | Yes | Other (specify below);Paved Surface;Separate Storm Drain;Surface Water;Unpaved surface |
| Nov 20, 2014 | 651 gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter;Unpaved surface |
| Nov 6, 2014 | 18 gal | Other / Unknown | — | Paved Surface;Unpaved surface |
| Oct 6, 2014 | 61 gal | Equipment Failure | — | Unpaved surface |
| Jun 6, 2014 | 645 gal | Other / Unknown | — | Paved Surface;Unpaved surface |
| May 22, 2014 | 12 gal | Other / Unknown | — | Paved Surface |
| May 8, 2014 | 175 gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Surface Water |
| Mar 18, 2014 | 2K gal | Root Intrusion | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water;Unpaved surface |
| Jan 6, 2014 | 8 gal | Other / Unknown | — | Unpaved surface |
| Jan 3, 2014 | 132 gal | Other / Unknown | — | Unpaved surface |
| Jan 1, 2014 | 3K gal | Grease / FOG | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water;Unpaved surface |
| Dec 29, 2013 | 373 gal | Root Intrusion | — | Paved Surface;Street/Curb and Gutter;Unpaved surface |
| Dec 24, 2013 | 306 gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Dec 12, 2013 | 2K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Surface Water;Unpaved surface |
| Dec 8, 2013 | 935 gal | Root Intrusion | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Unpaved surface |
| Jul 30, 2013 | 96 gal | Other / Unknown | — | Other paved surface;Street/curb and gutter |
| Jun 22, 2013 | 16 gal | Other / Unknown | — | Other paved surface;Street/curb and gutter |
| Jun 17, 2013 | 9 gal | Other / Unknown | — | Unpaved surface |
| Apr 15, 2013 | 79 gal | Other / Unknown | — | Other paved surface;Other (specify below) |
| Apr 12, 2013 | 104 gal | Other / Unknown | — | Unpaved surface |
| Mar 21, 2013 | 10K gal | Other / Unknown | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Feb 17, 2013 | 899 gal | Other / Unknown | — | Other paved surface;Unpaved surface |
| Jan 29, 2013 | 2K gal | Root Intrusion | — | Other paved surface;Unpaved surface |
| Jan 19, 2013 | 750 gal | Root Intrusion | — | Street/curb and gutter |
| Dec 27, 2012 | 9K gal | Other / Unknown | Yes | Separate storm drain;Surface water;Unpaved surface |
| Dec 27, 2012 | 2K gal | Other / Unknown | — | Separate storm drain;Street/curb and gutter;Surface water |
| Dec 9, 2012 | 889 gal | Grease / FOG | — | Separate storm drain;Street/curb and gutter;Surface water |
| Nov 30, 2012 | 2K gal | Other / Unknown | — | Separate storm drain;Street/curb and gutter |
| Nov 29, 2012 | 791 gal | Other / Unknown | — | Surface water |
| Nov 17, 2012 | 2K gal | Other / Unknown | — | Separate storm drain;Street/curb and gutter;Surface water |
| Aug 31, 2012 | 134 gal | Other / Unknown | — | Other paved surface;Street/curb and gutter;Unpaved surface |
| Aug 30, 2012 | 10 gal | Other / Unknown | — | Unpaved surface |
| Aug 4, 2012 | 344 gal | Grease / FOG | — | Separate storm drain;Street/curb and gutter |
| Aug 1, 2012 | 161 gal | Other / Unknown | — | Street/curb and gutter |
| Jul 19, 2012 | 445 gal | Root Intrusion | — | Building or structure;Other (specify below) |
| Jul 15, 2012 | 4K gal | Grease / FOG | — | Separate storm drain;Street/curb and gutter |
| Jul 6, 2012 | 947 gal | Other / Unknown | — | Other paved surface;Street/curb and gutter |
| Jun 28, 2012 | 57 gal | Other / Unknown | — | Unpaved surface |
| Feb 7, 2012 | 145 gal | Equipment Failure | Yes | Surface water |
| Dec 31, 2011 | 5 gal | Root Intrusion | — | Unpaved surface |
| Aug 22, 2011 | 249 gal | Other / Unknown | — | Street/curb and gutter |
| Jul 25, 2011 | 25 gal | Other / Unknown | — | Street/curb and gutter |
| Jul 12, 2011 | 30 gal | Other / Unknown | — | Street/curb and gutter |
| May 13, 2011 | 57 gal | Grease / FOG | — | Separate storm drain |
| Apr 8, 2011 | 29 gal | Root Intrusion | — | Unpaved surface |
| Apr 6, 2011 | 80 gal | Other / Unknown | — | Separate storm drain |
| Mar 18, 2011 | 1K gal | Other / Unknown | Yes | Surface water |
| Mar 14, 2011 | 5 gal | Other / Unknown | — | Street/curb and gutter |
| Feb 13, 2011 | 3K gal | Other / Unknown | — | Unpaved surface |
| Jan 2, 2011 | 2K gal | Equipment Failure | — | Separate storm drain |
| Nov 8, 2010 | 60 gal | Other / Unknown | — | Street/curb and gutter;Unpaved surface |
| Oct 30, 2010 | 250 gal | Other / Unknown | — | Street/curb and gutter |
| Oct 25, 2010 | 420 gal | Other / Unknown | — | Unpaved surface |
| Oct 21, 2010 | 70 gal | Other / Unknown | — | Separate storm drain |
| Jun 22, 2010 | 1 gal | Other / Unknown | — | Street/curb and gutter |
| Jun 21, 2010 | 190 gal | Other / Unknown | — | Storm drain;Street/curb and gutter |
| May 1, 2010 | 188 gal | Root Intrusion | — | Unpaved surface |
| Apr 14, 2010 | 30 gal | Other / Unknown | — | Unpaved surface |
| Mar 8, 2010 | 3K gal | Other / Unknown | Yes | Surface water;Unpaved surface |
| Mar 3, 2010 | 10 gal | Other / Unknown | — | Unpaved surface |
| Jan 8, 2010 | 151 gal | Other / Unknown | — | Other paved surface;Other (specify below) |
| Dec 29, 2009 | 5 gal | Other / Unknown | — | Other paved surface;Street/curb and gutter |
| Dec 8, 2009 | 255 gal | Equipment Failure | — | Storm drain |
| Nov 8, 2009 | 190 gal | Grease / FOG | — | Unpaved surface |
| Nov 7, 2009 | 570 gal | Grease / FOG | — | Storm drain;Street/curb and gutter |
| Oct 27, 2009 | 10 gal | Root Intrusion | — | Other paved surface;Unpaved surface |
| Oct 20, 2009 | 10 gal | Other / Unknown | — | Street/curb and gutter |
| Aug 19, 2009 | 40 gal | Other / Unknown | — | Unpaved surface |
| Jul 22, 2009 | 15 gal | Root Intrusion | — | Street/curb and gutter |
| Jul 10, 2009 | 123 gal | Other / Unknown | — | Street/curb and gutter;Unpaved surface |
| Jun 2, 2009 | 5 gal | Root Intrusion | — | Unpaved surface |
| Apr 14, 2009 | 72 gal | Grease / FOG | — | Storm drain |
| Mar 28, 2009 | 5 gal | Root Intrusion | — | Unpaved surface |
| Mar 10, 2009 | 104 gal | Other / Unknown | — | Street/curb and gutter |
| Mar 9, 2009 | 15 gal | Grease / FOG | — | Street/curb and gutter |
| Feb 25, 2009 | 4 gal | Root Intrusion | — | Street/curb and gutter;Unpaved surface |
| Feb 18, 2009 | 825 gal | Root Intrusion | Yes | Surface water |
Source: California (CIWQS). Volumes are utility-reported estimates. Some events lack precise coordinates or volumes.