All rankings
California · California (CIWQS)
Hillsborough
D
Frequently reaches water
Reported events
316
Total volume
5.5M gal
Reached waterways
125 (40%)
Reporting since
2007
What caused the overflows
Root Intrusion
121
Capacity Issue
81
Equipment Failure
40
Other / Unknown
37
Grease / FOG
28
Rainfall / Flooding
9
Reported overflow events (showing 200 of 316)
| Date | Volume | Cause | Reached water | Receiving water |
|---|---|---|---|---|
| Jun 2, 2026 | 55 gal | Equipment Failure | — | — |
| Mar 19, 2026 | 193 gal | Root Intrusion | — | — |
| Mar 5, 2026 | 134 gal | Grease / FOG | — | — |
| Feb 18, 2026 | 88 gal | Root Intrusion | — | — |
| Feb 10, 2026 | 16 gal | Equipment Failure | Yes | San Mateo Creek |
| Nov 27, 2025 | 100 gal | Root Intrusion | — | — |
| Aug 4, 2025 | 1K gal | Root Intrusion | — | — |
| Jul 18, 2025 | 187 gal | Root Intrusion | — | — |
| Jan 7, 2025 | 228 gal | Equipment Failure | — | — |
| Dec 12, 2024 | 59 gal | Root Intrusion | — | — |
| Dec 2, 2024 | 81 gal | Grease / FOG | — | — |
| Dec 2, 2024 | 164 gal | Equipment Failure | — | — |
| Feb 27, 2024 | 50 gal | Equipment Failure | — | — |
| Jan 30, 2024 | 50 gal | Root Intrusion | — | — |
| Sep 5, 2023 | 111 gal | Root Intrusion | — | — |
| Aug 2, 2023 | 294 gal | Root Intrusion | — | — |
| Jul 25, 2023 | 390 gal | Root Intrusion | — | — |
| Jun 5, 2023 | 3K gal | Equipment Failure | — | — |
| Jan 12, 2023 | 225 gal | Grease / FOG | — | Separate Storm Drain |
| Jan 11, 2023 | 800 gal | Equipment Failure | — | Unpaved surface |
| Dec 31, 2022 | 4K gal | Rainfall / Flooding | Yes | Surface Water |
| Dec 31, 2022 | 8K gal | Rainfall / Flooding | Yes | Surface Water |
| Dec 27, 2022 | 5K gal | Rainfall / Flooding | Yes | Surface Water |
| Nov 5, 2022 | 210 gal | Grease / FOG | — | Separate Storm Drain |
| Nov 5, 2022 | 210 gal | Grease / FOG | — | Separate Storm Drain |
| Oct 4, 2022 | 215 gal | Root Intrusion | — | Street/Curb and Gutter |
| Jan 31, 2022 | 720 gal | Root Intrusion | — | Unpaved surface |
| Dec 23, 2021 | 465 gal | Rainfall / Flooding | Yes | Surface Water |
| Dec 13, 2021 | 8K gal | Rainfall / Flooding | Yes | Surface Water |
| Dec 13, 2021 | 3K gal | Rainfall / Flooding | Yes | Unpaved surface |
| Dec 13, 2021 | 8K gal | Rainfall / Flooding | Yes | Surface Water |
| Jul 18, 2021 | 11 gal | Root Intrusion | — | Paved Surface;Street/Curb and Gutter |
| Mar 26, 2021 | 10 gal | Root Intrusion | — | Unpaved surface |
| Mar 1, 2021 | 45 gal | Root Intrusion | — | Unpaved surface |
| Jan 12, 2021 | 765 gal | Equipment Failure | Yes | Surface Water |
| Oct 13, 2020 | 95 gal | Equipment Failure | — | Unpaved surface |
| Aug 8, 2020 | 759 gal | Root Intrusion | Yes | Surface Water;Unpaved surface |
| Jul 27, 2020 | 20 gal | Equipment Failure | — | Unpaved surface |
| Jul 20, 2020 | 63 gal | Root Intrusion | — | Unpaved surface |
| Jun 23, 2020 | 18 gal | Root Intrusion | — | Separate Storm Drain;Street/Curb and Gutter |
| May 23, 2020 | 2 gal | Root Intrusion | — | Unpaved surface |
| May 22, 2020 | 391 gal | Root Intrusion | — | Unpaved surface |
| May 14, 2020 | 46 gal | Root Intrusion | — | Separate Storm Drain;Street/Curb and Gutter |
| Mar 4, 2020 | 134 gal | Root Intrusion | — | Street/Curb and Gutter |
| Mar 4, 2020 | 37 gal | Root Intrusion | — | Unpaved surface |
| Mar 1, 2020 | 680 gal | Grease / FOG | Yes | Surface Water |
| Jan 27, 2020 | 20 gal | Root Intrusion | — | Separate Storm Drain;Street/Curb and Gutter |
| Dec 24, 2019 | 455 gal | Equipment Failure | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter |
| Nov 7, 2019 | 60 gal | Root Intrusion | — | Unpaved surface |
| Nov 5, 2019 | 5 gal | Root Intrusion | — | Paved Surface |
| Nov 3, 2019 | 120 gal | Root Intrusion | — | Other (specify below);Paved Surface;Street/Curb and Gutter;Unpaved surface |
| Sep 7, 2019 | 102 gal | Grease / FOG | — | Paved Surface;Unpaved surface |
| Jul 15, 2019 | 1K gal | Equipment Failure | Yes | Drainage Channel |
| Jun 4, 2019 | 276 gal | Root Intrusion | — | Unpaved surface |
| May 14, 2019 | 30 gal | Root Intrusion | Yes | Unpaved surface |
| Apr 9, 2019 | 30 gal | Root Intrusion | — | Paved Surface |
| Feb 5, 2019 | 2K gal | Root Intrusion | Yes | Combined Storm Drain (Combined CS only);Street/Curb and Gutter |
| Jan 25, 2019 | 8K gal | Equipment Failure | Yes | Other (specify below);Unpaved surface |
| Jan 14, 2019 | 643 gal | Root Intrusion | — | Paved Surface |
| Nov 30, 2018 | 100 gal | Grease / FOG | — | Unpaved surface |
| Oct 17, 2018 | 825 gal | Root Intrusion | — | Unpaved surface |
| Oct 9, 2018 | 1K gal | Equipment Failure | Yes | Other (specify below) |
| Sep 8, 2018 | 700 gal | Other / Unknown | — | Unpaved surface |
| Sep 7, 2018 | 150 gal | Root Intrusion | — | Paved Surface |
| Sep 5, 2018 | 559 gal | Root Intrusion | — | Unpaved surface |
| May 28, 2018 | 285 gal | Root Intrusion | — | Unpaved surface |
| Feb 25, 2018 | 43 gal | Root Intrusion | — | Paved Surface |
| Feb 22, 2018 | 18 gal | Root Intrusion | — | Paved Surface |
| Feb 12, 2018 | 35K gal | Grease / FOG | Yes | Other (specify below) |
| Jan 30, 2018 | 36 gal | Root Intrusion | — | Separate Storm Drain |
| Nov 20, 2017 | 372 gal | Root Intrusion | Yes | Separate Storm Drain |
| Oct 8, 2017 | 74K gal | Root Intrusion | — | Unpaved surface |
| Aug 3, 2017 | 46 gal | Equipment Failure | — | Separate Storm Drain |
| Jun 5, 2017 | 149 gal | Root Intrusion | — | Unpaved surface |
| Mar 20, 2017 | 24 gal | Root Intrusion | — | Unpaved surface |
| Jan 25, 2017 | 235 gal | Root Intrusion | — | Paved Surface |
| Dec 21, 2016 | 37 gal | Root Intrusion | — | Paved Surface;Street/Curb and Gutter;Unpaved surface |
| Nov 21, 2016 | 53 gal | Root Intrusion | — | Other (specify below) |
| Nov 17, 2016 | 350 gal | Equipment Failure | Yes | Drainage Channel |
| Oct 17, 2016 | 555 gal | Root Intrusion | Yes | Paved Surface;Separate Storm Drain |
| Aug 31, 2016 | 840 gal | Equipment Failure | — | Unpaved surface |
| Aug 26, 2016 | 82 gal | Root Intrusion | — | Paved Surface;Separate Storm Drain;Street/Curb and Gutter |
| May 24, 2016 | 173 gal | Grease / FOG | — | Paved Surface;Separate Storm Drain;Street/Curb and Gutter |
| May 20, 2016 | 26 gal | Other / Unknown | — | Unpaved surface |
| Apr 12, 2016 | 27 gal | Equipment Failure | — | Unpaved surface |
| Mar 13, 2016 | 975 gal | Root Intrusion | — | Street/Curb and Gutter;Unpaved surface |
| Mar 11, 2016 | 207 gal | Equipment Failure | Yes | Surface Water;Unpaved surface |
| Jan 30, 2016 | 2K gal | Root Intrusion | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Jan 25, 2016 | 3K gal | Equipment Failure | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter |
| Jan 19, 2016 | 61K gal | Capacity Issue | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter |
| Jan 19, 2016 | 8K gal | Capacity Issue | Yes | Street/Curb and Gutter;Surface Water;Unpaved surface |
| Jan 19, 2016 | 27K gal | Capacity Issue | Yes | Separate Storm Drain;Street/Curb and Gutter;Surface Water;Unpaved surface |
| Jan 18, 2016 | 6K gal | Equipment Failure | Yes | Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Nov 26, 2015 | 2K gal | Root Intrusion | Yes | Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Oct 30, 2015 | 86 gal | Root Intrusion | — | Paved Surface;Street/Curb and Gutter |
| Oct 23, 2015 | 29 gal | Grease / FOG | — | Paved Surface;Separate Storm Drain;Street/Curb and Gutter |
| Oct 22, 2015 | 72 gal | Equipment Failure | — | Unpaved surface |
| Sep 2, 2015 | 54 gal | Root Intrusion | — | Paved Surface;Separate Storm Drain;Street/Curb and Gutter |
| Jul 26, 2015 | 2 gal | Root Intrusion | — | Paved Surface |
| May 30, 2015 | 15 gal | Equipment Failure | — | Unpaved surface |
| Apr 25, 2015 | 920 gal | Equipment Failure | Yes | Separate Storm Drain;Street/Curb and Gutter |
| Apr 24, 2015 | 6K gal | Equipment Failure | — | Other (specify below) |
| Jan 9, 2015 | 4K gal | Equipment Failure | — | Unpaved surface |
| Dec 11, 2014 | 66K gal | Capacity Issue | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Dec 11, 2014 | 17K gal | Capacity Issue | Yes | Paved Surface;Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Dec 2, 2014 | 798 gal | Rainfall / Flooding | — | Building or Structure;Unpaved surface |
| Nov 3, 2014 | 22 gal | Root Intrusion | — | Paved Surface;Street/Curb and Gutter;Unpaved surface |
| Jul 18, 2014 | 32 gal | Equipment Failure | — | Combined Storm Drain (Combined CS only);Paved Surface |
| Apr 27, 2014 | 185 gal | Root Intrusion | — | Unpaved surface |
| Apr 18, 2014 | 788 gal | Root Intrusion | Yes | Other (specify below);Unpaved surface |
| Apr 15, 2014 | 550 gal | Root Intrusion | — | Unpaved surface |
| Mar 7, 2014 | 800 gal | Other / Unknown | Yes | Separate Storm Drain;Street/Curb and Gutter;Surface Water |
| Mar 4, 2014 | 150 gal | Equipment Failure | — | Unpaved surface |
| Feb 22, 2014 | 20 gal | Equipment Failure | Yes | Separate Storm Drain;Street/Curb and Gutter |
| Feb 17, 2014 | 2 gal | Grease / FOG | — | Paved Surface |
| Feb 16, 2014 | 9 gal | Other / Unknown | — | Paved Surface;Street/Curb and Gutter |
| Jan 22, 2014 | 11 gal | Root Intrusion | — | Unpaved surface |
| Jan 10, 2014 | 159 gal | Equipment Failure | Yes | Other (specify below) |
| Jan 9, 2014 | 42 gal | Equipment Failure | Yes | Paved Surface;Street/Curb and Gutter |
| Dec 24, 2013 | 17 gal | Root Intrusion | — | Paved Surface |
| Nov 25, 2013 | 478 gal | Equipment Failure | — | Unpaved surface |
| Nov 13, 2013 | 218 gal | Root Intrusion | Yes | Paved Surface;Separate Storm Drain |
| Oct 1, 2013 | 450 gal | Equipment Failure | — | Drainage Channel |
| Aug 27, 2013 | 3 gal | Grease / FOG | — | Paved Surface |
| Aug 7, 2013 | 321 gal | Other / Unknown | — | Unpaved surface |
| Jun 16, 2013 | 420 gal | Root Intrusion | — | Unpaved surface |
| May 30, 2013 | 324 gal | Other / Unknown | — | Unpaved surface |
| Apr 30, 2013 | 75 gal | Other / Unknown | — | Other paved surface |
| Apr 6, 2013 | 2K gal | Root Intrusion | — | Separate storm drain;Street/curb and gutter;Unpaved surface |
| Mar 17, 2013 | 150 gal | Other / Unknown | — | Separate storm drain |
| Mar 2, 2013 | 840 gal | Root Intrusion | — | Unpaved surface |
| Dec 31, 2012 | 2K gal | Root Intrusion | Yes | Combined storm drain (combined CS only) |
| Dec 23, 2012 | 41K gal | Capacity Issue | Yes | Street/curb and gutter;Surface water;Unpaved surface |
| Dec 23, 2012 | 6K gal | Capacity Issue | Yes | Separate storm drain;Street/curb and gutter |
| Dec 23, 2012 | 6K gal | Capacity Issue | Yes | Separate storm drain;Street/curb and gutter |
| Dec 22, 2012 | 12K gal | Capacity Issue | Yes | Separate storm drain;Street/curb and gutter;Surface water |
| Dec 6, 2012 | 330 gal | Equipment Failure | — | Unpaved surface |
| Dec 2, 2012 | 450 gal | Capacity Issue | Yes | Separate storm drain |
| Dec 2, 2012 | 58K gal | Capacity Issue | Yes | Surface water;Unpaved surface |
| Dec 2, 2012 | 99K gal | Capacity Issue | Yes | Street/curb and gutter;Surface water |
| Nov 30, 2012 | 24K gal | Capacity Issue | Yes | Surface water;Unpaved surface |
| Nov 30, 2012 | 68K gal | Capacity Issue | Yes | Separate storm drain;Street/curb and gutter;Surface water;Unpaved surface |
| Oct 7, 2012 | 360 gal | Root Intrusion | — | Separate storm drain;Street/curb and gutter;Unpaved surface |
| Sep 8, 2012 | 275 gal | Root Intrusion | — | Unpaved surface |
| Aug 28, 2012 | 40 gal | Other / Unknown | — | Unpaved surface |
| Jun 29, 2012 | 1K gal | Other / Unknown | Yes | Separate storm drain;Street/curb and gutter;Surface water;Unpaved surface |
| Jun 29, 2012 | 27 gal | Root Intrusion | — | Combined storm drain (combined CS only) |
| Jun 20, 2012 | 150 gal | Grease / FOG | — | Unpaved surface |
| Apr 13, 2012 | 27K gal | Capacity Issue | Yes | Other paved surface |
| Apr 13, 2012 | 180K gal | Capacity Issue | Yes | Combined storm drain (combined CS only);Street/curb and gutter;Surface water |
| Apr 13, 2012 | 60K gal | Capacity Issue | Yes | Beach;Building or structure;Combined storm drain (combined CS only) |
| Mar 24, 2012 | 114K gal | Capacity Issue | — | Other (specify below) |
| Mar 16, 2012 | 135K gal | Capacity Issue | Yes | Street/curb and gutter;Surface water;Unpaved surface |
| Mar 14, 2012 | 162K gal | Capacity Issue | — | Street/curb and gutter;Other (specify below) |
| Mar 14, 2012 | 810 gal | Capacity Issue | Yes | Other paved surface;Surface water |
| Feb 21, 2012 | 65 gal | Root Intrusion | — | Separate storm drain;Street/curb and gutter |
| Feb 5, 2012 | 275 gal | Root Intrusion | — | Unpaved surface |
| Jan 23, 2012 | 18K gal | Capacity Issue | Yes | Surface water |
| Jan 22, 2012 | 360 gal | Grease / FOG | — | Unpaved surface |
| Jan 20, 2012 | 36K gal | Capacity Issue | Yes | Surface water |
| Dec 11, 2011 | 1K gal | Root Intrusion | — | Unpaved surface |
| Nov 28, 2011 | 50 gal | Grease / FOG | — | Separate storm drain |
| Nov 2, 2011 | 40 gal | Other / Unknown | — | Separate storm drain |
| Oct 29, 2011 | 3K gal | Other / Unknown | — | Separate storm drain |
| Oct 16, 2011 | 25 gal | Root Intrusion | Yes | Surface water |
| Oct 6, 2011 | 20 gal | Root Intrusion | — | Separate storm drain |
| Oct 2, 2011 | 5K gal | Root Intrusion | Yes | Surface water |
| Sep 24, 2011 | 25 gal | Other / Unknown | — | Other paved surface;Unpaved surface |
| Jul 20, 2011 | 60 gal | Root Intrusion | — | Separate storm drain;Unpaved surface |
| Jul 17, 2011 | 25 gal | Grease / FOG | — | Street/curb and gutter |
| Jul 15, 2011 | 30 gal | Root Intrusion | — | Other paved surface;Street/curb and gutter |
| Jun 21, 2011 | 100 gal | Root Intrusion | — | Unpaved surface |
| May 11, 2011 | 450 gal | Other / Unknown | — | Unpaved surface |
| Apr 27, 2011 | 200 gal | Root Intrusion | — | Unpaved surface |
| Apr 9, 2011 | 5 gal | Other / Unknown | — | Street/curb and gutter |
| Mar 26, 2011 | 14K gal | Capacity Issue | Yes | Surface water |
| Mar 26, 2011 | 1K gal | Capacity Issue | Yes | Surface water |
| Mar 26, 2011 | 3K gal | Capacity Issue | Yes | Surface water |
| Mar 24, 2011 | 180K gal | Capacity Issue | Yes | Surface water |
| Mar 24, 2011 | 18K gal | Capacity Issue | Yes | Unpaved surface |
| Mar 24, 2011 | 27K gal | Capacity Issue | — | Separate storm drain;Street/curb and gutter |
| Mar 24, 2011 | 18K gal | Capacity Issue | — | Separate storm drain;Street/curb and gutter |
| Mar 24, 2011 | 41K gal | Capacity Issue | Yes | Surface water |
| Mar 24, 2011 | 50K gal | Capacity Issue | Yes | Surface water |
| Mar 24, 2011 | 900 gal | Capacity Issue | — | Separate storm drain |
| Mar 23, 2011 | 5K gal | Capacity Issue | Yes | Surface water |
| Mar 23, 2011 | 18K gal | Capacity Issue | Yes | Surface water |
| Mar 20, 2011 | 15K gal | Capacity Issue | Yes | Surface water |
| Mar 20, 2011 | 20K gal | Capacity Issue | Yes | Surface water |
| Mar 20, 2011 | 26K gal | Capacity Issue | Yes | Surface water |
| Mar 18, 2011 | 279K gal | Capacity Issue | Yes | Surface water |
| Mar 3, 2011 | 30 gal | Root Intrusion | — | Other paved surface |
| Feb 25, 2011 | 17K gal | Capacity Issue | Yes | Surface water |
| Feb 25, 2011 | 18K gal | Capacity Issue | Yes | Surface water |
| Feb 17, 2011 | 3K gal | Capacity Issue | Yes | Surface water |
| Feb 16, 2011 | 75 gal | Equipment Failure | — | Other paved surface |
| Jan 26, 2011 | 50 gal | Root Intrusion | — | Unpaved surface |
| Jan 16, 2011 | 3K gal | Other / Unknown | Yes | Surface water |
| Dec 28, 2010 | 38K gal | Capacity Issue | Yes | Surface water |
| Dec 28, 2010 | 6K gal | Capacity Issue | Yes | Surface water |
Source: California (CIWQS). Volumes are utility-reported estimates. Some events lack precise coordinates or volumes.