Community Water System · PWSID CA0600008

Colusa Co. Wwd #1 - Grimes

Serves 512 peopleGroundwaterOwner: Local GovernmentGrimes, California
Nothing open right now.

On record since 2009: 68 violations. 61 over the limit · 7 missed or late tests. Most recent began 2024-10-01.

For this year's test results, ask the utility for its annual Consumer Confidence Report. Every community system must publish one.

61Over the limit
0Treatment lapse
7Missed or late test
0Notice or report

More violations on record than 98% of active water systems in California. Small systems with no staff chemist often rack up missed-test violations; big utilities rarely do.

The record, year by year

20052009 · Over the limit: 32009 · Over the limit: 32009 · Over the limit: 32010 · Over the limit: 42010 · Over the limit: 42010 · Over the limit: 42010 · Over the limit: 420102011 · Over the limit: 42011 · Over the limit: 42011 · Over the limit: 42011 · Over the limit: 42012 · Over the limit: 42012 · Over the limit: 42012 · Over the limit: 42012 · Over the limit: 42013 · Over the limit: 42013 · Over the limit: 42013 · Over the limit: 42013 · Over the limit: 42014 · Over the limit: 32014 · Over the limit: 32014 · Over the limit: 32015 · Over the limit: 32015 · Over the limit: 32015 · Over the limit: 32015 · Missed or late test: 120152016 · Over the limit: 42016 · Over the limit: 42016 · Over the limit: 42016 · Over the limit: 42017 · Over the limit: 42017 · Over the limit: 42017 · Over the limit: 42017 · Over the limit: 42017 · Missed or late test: 22017 · Missed or late test: 22018 · Over the limit: 42018 · Over the limit: 42018 · Over the limit: 42018 · Over the limit: 42019 · Over the limit: 42019 · Over the limit: 42019 · Over the limit: 42019 · Over the limit: 42020 · Over the limit: 42020 · Over the limit: 42020 · Over the limit: 42020 · Over the limit: 42020 · Missed or late test: 120202021 · Over the limit: 42021 · Over the limit: 42021 · Over the limit: 42021 · Over the limit: 42021 · Missed or late test: 12022 · Over the limit: 42022 · Over the limit: 42022 · Over the limit: 42022 · Over the limit: 42022 · Missed or late test: 12023 · Over the limit: 42023 · Over the limit: 42023 · Over the limit: 42023 · Over the limit: 42023 · Missed or late test: 12024 · Over the limit: 42024 · Over the limit: 42024 · Over the limit: 42024 · Over the limit: 42025
One square = one violation, by the year it began. Empty columns are years with nothing on EPA's record.
90% over the limit · 6110% missed or late test · 7

Across California, 52% of violations are missed or late tests and 29% are water over a limit.

How far over the limit

at the limit2×5×10×100×+Arsenic2024-10-01 · Arsenic: measured 23.50 UG/L vs limit 10.00 UG/L (2.4×)2024-07-01 · Arsenic: measured 23.60 UG/L vs limit 10.00 UG/L (2.4×)2024-04-01 · Arsenic: measured 22.40 UG/L vs limit 10.00 UG/L (2.2×)2024-01-01 · Arsenic: measured 22.90 UG/L vs limit 10.00 UG/L (2.3×)2023-10-01 · Arsenic: measured 22.90 UG/L vs limit 10.00 UG/L (2.3×)2023-07-01 · Arsenic: measured 25.30 UG/L vs limit 10.00 UG/L (2.5×)2023-04-01 · Arsenic: measured 25.90 UG/L vs limit 10.00 UG/L (2.6×)2023-01-01 · Arsenic: measured 26.50 UG/L vs limit 10.00 UG/L (2.6×)2022-10-01 · Arsenic: measured 26.20 UG/L vs limit 10.00 UG/L (2.6×)2022-07-01 · Arsenic: measured 25.40 UG/L vs limit 10.00 UG/L (2.5×)2022-04-01 · Arsenic: measured 25.00 UG/L vs limit 10.00 UG/L (2.5×)2022-01-01 · Arsenic: measured 22.70 UG/L vs limit 10.00 UG/L (2.3×)2021-10-01 · Arsenic: measured 23.80 UG/L vs limit 10.00 UG/L (2.4×)2021-07-01 · Arsenic: measured 24.90 UG/L vs limit 10.00 UG/L (2.5×)2021-04-01 · Arsenic: measured 23.60 UG/L vs limit 10.00 UG/L (2.4×)2021-01-01 · Arsenic: measured 24.60 UG/L vs limit 10.00 UG/L (2.5×)2020-10-01 · Arsenic: measured 22.80 UG/L vs limit 10.00 UG/L (2.3×)2020-07-01 · Arsenic: measured 23.50 UG/L vs limit 10.00 UG/L (2.4×)2020-04-01 · Arsenic: measured 24.10 UG/L vs limit 10.00 UG/L (2.4×)2020-01-01 · Arsenic: measured 22.20 UG/L vs limit 10.00 UG/L (2.2×)2019-10-01 · Arsenic: measured 22.70 UG/L vs limit 10.00 UG/L (2.3×)2019-07-01 · Arsenic: measured 23.50 UG/L vs limit 10.00 UG/L (2.4×)2019-04-01 · Arsenic: measured 23.00 UG/L vs limit 10.00 UG/L (2.3×)2019-01-01 · Arsenic: measured 20.80 UG/L vs limit 10.00 UG/L (2.1×)2018-10-01 · Arsenic: measured 20.40 UG/L vs limit 10.00 UG/L (2.0×)2018-07-01 · Arsenic: measured 23.90 UG/L vs limit 10.00 UG/L (2.4×)2018-04-01 · Arsenic: measured 25.10 UG/L vs limit 10.00 UG/L (2.5×)2018-01-01 · Arsenic: measured 23.00 UG/L vs limit 10.00 UG/L (2.3×)2017-10-01 · Arsenic: measured 24.00 UG/L vs limit 10.00 UG/L (2.4×)2017-07-01 · Arsenic: measured 26.00 UG/L vs limit 10.00 UG/L (2.6×)2017-04-01 · Arsenic: measured 24.00 UG/L vs limit 10.00 UG/L (2.4×)2017-01-01 · Arsenic: measured 25.00 UG/L vs limit 10.00 UG/L (2.5×)2016-10-01 · Arsenic: measured 24.00 UG/L vs limit 10.00 UG/L (2.4×)2016-07-01 · Arsenic: measured 24.00 UG/L vs limit 10.00 UG/L (2.4×)2016-04-01 · Arsenic: measured 24.00 UG/L vs limit 10.00 UG/L (2.4×)2016-01-01 · Arsenic: measured 24.00 UG/L vs limit 10.00 UG/L (2.4×)2015-04-01 · Arsenic: measured 24.00 UG/L vs limit 10.00 UG/L (2.4×)2015-01-01 · Arsenic: measured 23.80 UG/L vs limit 10.00 UG/L (2.4×)2014-10-01 · Arsenic: measured 23.60 UG/L vs limit 10.00 UG/L (2.4×)2014-07-01 · Arsenic: measured 24.10 UG/L vs limit 10.00 UG/L (2.4×)2014-01-01 · Arsenic: measured 24.30 UG/L vs limit 10.00 UG/L (2.4×)2013-10-01 · Arsenic: measured 24.60 UG/L vs limit 10.00 UG/L (2.5×)2013-07-01 · Arsenic: measured 25.20 UG/L vs limit 10.00 UG/L (2.5×)2013-04-01 · Arsenic: measured 24.60 UG/L vs limit 10.00 UG/L (2.5×)2013-01-01 · Arsenic: measured 24.70 UG/L vs limit 10.00 UG/L (2.5×)2012-10-01 · Arsenic: measured 25.60 UG/L vs limit 10.00 UG/L (2.6×)2012-07-01 · Arsenic: measured 0.0258 MG/L vs limit 0.0100 MG/L (2.6×)2012-04-01 · Arsenic: measured 25.80 UG/L vs limit 10.00 UG/L (2.6×)2012-01-01 · Arsenic: measured 26.10 UG/L vs limit 10.00 UG/L (2.6×)2011-10-01 · Arsenic: measured 25.30 UG/L vs limit 10.00 UG/L (2.5×)2011-07-01 · Arsenic: measured 0.0260 MG/L vs limit 0.0100 MG/L (2.6×)2011-04-01 · Arsenic: measured 26.10 UG/L vs limit 10.00 UG/L (2.6×)2011-01-01 · Arsenic: measured 26.80 UG/L vs limit 10.00 UG/L (2.7×)2010-10-01 · Arsenic: measured 25.60 UG/L vs limit 10.00 UG/L (2.6×)2010-07-01 · Arsenic: measured 0.0270 MG/L vs limit 0.0100 MG/L (2.7×)2010-04-01 · Arsenic: measured 0.0269 MG/L vs limit 0.0100 MG/L (2.7×)2010-01-01 · Arsenic: measured 0.0270 MG/L vs limit 0.0100 MG/L (2.7×)2009-10-01 · Arsenic: measured 0.0259 MG/L vs limit 0.0100 MG/L (2.6×)2009-07-01 · Arsenic: measured 0.0259 MG/L vs limit 0.0100 MG/L (2.6×)2009-04-01 · Arsenic: measured 0.0255 MG/L vs limit 0.0100 MG/L (2.5×)
Each dot is one over-the-limit violation: the measured value divided by the limit it broke, on a log scale. Most legal limits for chemicals are running averages set for a lifetime of drinking, so “just over” and “ten times over” are very different news. Hover a dot for the numbers.

Lead & copper at the tap

Utilities sample taps in homes most likely to have lead pipes, and report the 90th-percentile result: 9 in 10 homes sampled came in at or below this number. Above the red line (the action level) the utility must act. The action level is not a safe level; EPA's health goal for lead is zero. EPA's file does not date these results, so they are shown highest first.

Lead, 90th percentile 5 results on file · action level 15 ppb

9.8 ppb
3.3 ppb
0 ppb
0 ppb
0 ppb

Every violation on record

  1. 2024-10-01ArsenicMCL, Averagemeasured 23.50 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  2. 2024-07-01ArsenicMCL, Averagemeasured 23.60 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  3. 2024-04-01ArsenicMCL, Averagemeasured 22.40 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  4. 2024-01-01ArsenicMCL, Averagemeasured 22.90 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  5. 2023-10-01ArsenicMCL, Averagemeasured 22.90 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  6. 2023-10-01Lead and Copper RuleFollow-up Or Routine LCR Tap M/RBack in compliance
  7. 2023-07-01ArsenicMCL, Averagemeasured 25.30 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  8. 2023-04-01ArsenicMCL, Averagemeasured 25.90 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  9. 2023-01-01ArsenicMCL, Averagemeasured 26.50 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  10. 2022-11-01Revised Total Coliform RuleMONPeriod ended · no return to compliance on file
  11. 2022-10-01ArsenicMCL, Averagemeasured 26.20 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  12. 2022-07-01ArsenicMCL, Averagemeasured 25.40 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  13. 2022-04-01ArsenicMCL, Averagemeasured 25.00 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  14. 2022-01-01ArsenicMCL, Averagemeasured 22.70 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  15. 2021-10-01ArsenicMCL, Averagemeasured 23.80 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  16. 2021-10-01Revised Total Coliform RuleMONBack in compliance
  17. 2021-07-01ArsenicMCL, Averagemeasured 24.90 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  18. 2021-04-01ArsenicMCL, Averagemeasured 23.60 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  19. 2021-01-01ArsenicMCL, Averagemeasured 24.60 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  20. 2020-12-01Revised Total Coliform RuleMONBack in compliance
  21. 2020-10-01ArsenicMCL, Averagemeasured 22.80 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  22. 2020-07-01ArsenicMCL, Averagemeasured 23.50 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  23. 2020-04-01ArsenicMCL, Averagemeasured 24.10 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  24. 2020-01-01ArsenicMCL, Averagemeasured 22.20 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  25. 2019-10-01ArsenicMCL, Averagemeasured 22.70 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
Show the other 43 entries
  1. 2019-07-01ArsenicMCL, Averagemeasured 23.50 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  2. 2019-04-01ArsenicMCL, Averagemeasured 23.00 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  3. 2019-01-01ArsenicMCL, Averagemeasured 20.80 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  4. 2018-10-01ArsenicMCL, Averagemeasured 20.40 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  5. 2018-07-01ArsenicMCL, Averagemeasured 23.90 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  6. 2018-04-01ArsenicMCL, Averagemeasured 25.10 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  7. 2018-01-01ArsenicMCL, Averagemeasured 23.00 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  8. 2017-10-01ArsenicMCL, Averagemeasured 24.00 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  9. 2017-10-01Lead and Copper RuleFollow-up Or Routine LCR Tap M/RBack in compliance
  10. 2017-07-01ArsenicMCL, Averagemeasured 26.00 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  11. 2017-04-01ArsenicMCL, Averagemeasured 24.00 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  12. 2017-01-01ArsenicMCL, Averagemeasured 25.00 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  13. 2017-01-01NitrateMonitoring, RegularBack in compliance
  14. 2016-10-01ArsenicMCL, Averagemeasured 24.00 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  15. 2016-07-01ArsenicMCL, Averagemeasured 24.00 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  16. 2016-04-01ArsenicMCL, Averagemeasured 24.00 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  17. 2016-01-01ArsenicMCL, Averagemeasured 24.00 UG/L · limit 10.00 UG/LPeriod ended · no return to compliance on file
  18. 2015-10-01Lead and Copper RuleFollow-up Or Routine LCR Tap M/RBack in compliance
  19. 2015-10-01ArsenicMCL, Averagemeasured 24.00 UG/LBack in compliance
  20. 2015-04-01ArsenicMCL, Averagemeasured 24.00 UG/L · limit 10.00 UG/LBack in compliance
  21. 2015-01-01ArsenicMCL, Averagemeasured 23.80 UG/L · limit 10.00 UG/LBack in compliance
  22. 2014-10-01ArsenicMCL, Averagemeasured 23.60 UG/L · limit 10.00 UG/LBack in compliance
  23. 2014-07-01ArsenicMCL, Averagemeasured 24.10 UG/L · limit 10.00 UG/LBack in compliance
  24. 2014-01-01ArsenicMCL, Averagemeasured 24.30 UG/L · limit 10.00 UG/LBack in compliance
  25. 2013-10-01ArsenicMCL, Averagemeasured 24.60 UG/L · limit 10.00 UG/LBack in compliance
  26. 2013-07-01ArsenicMCL, Averagemeasured 25.20 UG/L · limit 10.00 UG/LBack in compliance
  27. 2013-04-01ArsenicMCL, Averagemeasured 24.60 UG/L · limit 10.00 UG/LBack in compliance
  28. 2013-01-01ArsenicMCL, Averagemeasured 24.70 UG/L · limit 10.00 UG/LBack in compliance
  29. 2012-10-01ArsenicMCL, Averagemeasured 25.60 UG/L · limit 10.00 UG/LBack in compliance
  30. 2012-07-01ArsenicMCL, Averagemeasured 0.0258 MG/L · limit 0.0100 MG/LBack in compliance
  31. 2012-04-01ArsenicMCL, Averagemeasured 25.80 UG/L · limit 10.00 UG/LBack in compliance
  32. 2012-01-01ArsenicMCL, Averagemeasured 26.10 UG/L · limit 10.00 UG/LBack in compliance
  33. 2011-10-01ArsenicMCL, Averagemeasured 25.30 UG/L · limit 10.00 UG/LBack in compliance
  34. 2011-07-01ArsenicMCL, Averagemeasured 0.0260 MG/L · limit 0.0100 MG/LBack in compliance
  35. 2011-04-01ArsenicMCL, Averagemeasured 26.10 UG/L · limit 10.00 UG/LBack in compliance
  36. 2011-01-01ArsenicMCL, Averagemeasured 26.80 UG/L · limit 10.00 UG/LBack in compliance
  37. 2010-10-01ArsenicMCL, Averagemeasured 25.60 UG/L · limit 10.00 UG/LBack in compliance
  38. 2010-07-01ArsenicMCL, Averagemeasured 0.0270 MG/L · limit 0.0100 MG/LBack in compliance
  39. 2010-04-01ArsenicMCL, Averagemeasured 0.0269 MG/L · limit 0.0100 MG/LBack in compliance
  40. 2010-01-01ArsenicMCL, Averagemeasured 0.0270 MG/L · limit 0.0100 MG/LBack in compliance
  41. 2009-10-01ArsenicMCL, Averagemeasured 0.0259 MG/L · limit 0.0100 MG/LBack in compliance
  42. 2009-07-01ArsenicMCL, Averagemeasured 0.0259 MG/L · limit 0.0100 MG/LBack in compliance
  43. 2009-04-01ArsenicMCL, Averagemeasured 0.0255 MG/L · limit 0.0100 MG/LBack in compliance

System details

Population served512
Service connections114
Water sourceGroundwater
System typeCommunity Water System
OwnerLocal Government
StatusActive
CityGrimes
EPA ZIP on file95950

Areas served

  • Colusa County

Reading this record

Colusa Co. Wwd #1 - Grimes is a community water system that draws from groundwater and serves about 512 people in Grimes, California. Everything above comes from the EPA's Safe Drinking Water Information System (SDWIS), where states report every violation by every public water system.

Four kinds of violation. Only one is a measurement of the water: over the limit means a test came back above a legal maximum (an MCL). A treatment lapse means a required protective step was not done, such as disinfection, filtration, fixing a defect an inspector found, or filing a lead-pipe inventory. A missed or late test means a required test was skipped or never reported. That is the most common kind, and the most misread: it does not mean the water was bad, and it does not mean the water was fine. Notices and reports covers public notices and the annual Consumer Confidence Report.

Status. “Back in compliance” means the state recorded a return to compliance. “Period ended” means the violation's compliance period is over but no return to compliance was ever filed, which is common in older records. EPA's federal copy lags state records by months, so call the utility for anything current.