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This is a rebuild of Drinking Water Watch and not yet the official record. Use the agency’s current Drinking Water Watch for anything you need to rely on.

Chemical and radiological sample results

MS0730010 , Lake Arrowhead

19 of the 57 analytes this system has been tested for have been detected at least once, across 284 samples on record.

The other 38 were tested for and never found. An analyte is counted here if any result on record measured it, so this covers the whole history and not the samples listed below.

Across all 284 samples on record, detections range from November 5, 2003 to April 2, 2025. These figures cover the whole record.

What counts as a non-detect is defined in the help: Less than Indicator. This system’s violations.

What has been detected, ever

Every analyte measured above its reporting level at any point in this system’s record, most often detected first. This is not limited to the samples listed below.

Every analyte ever detected for Lake Arrowhead, with how many results found it and when it was first and last detected. Covers the whole record, not only the samples listed below.
Analyte Kind Detected in First detected Last detected
Copper, Free 1022 Inorganic Chemical 82 of 83 results Sep 27, 2004 Aug 28, 2023
Lead 1030 Inorganic Chemical 41 of 83 results Sep 27, 2004 Sep 9, 2020
Barium 1010 Inorganic Chemical 29 of 29 results Nov 5, 2003 Apr 2, 2025
Fluoride 1025 Inorganic Chemical 24 of 29 results Nov 5, 2003 Apr 2, 2025
Nitrate 1040 Inorganic Chemical 19 of 64 results Jun 16, 2004 Apr 17, 2024
Nitrate-Nitrite 1038 Inorganic Chemical 16 of 64 results Apr 2, 2012 Apr 17, 2024
Nickel 1036 Inorganic Chemical 14 of 29 results May 29, 2013 Apr 2, 2025
Chromium 1020 Inorganic Chemical 12 of 29 results Nov 16, 2004 Dec 13, 2016
Gross Alpha, Incl. Radon & U 4002 Radionuclide 10 of 15 results Mar 12, 2012 Oct 12, 2012
Sodium 1052 Inorganic Chemical 6 of 6 results Sep 16, 2019 Mar 28, 2023
Combined Radium (-226 & -228) 4010 Radionuclide 5 of 15 results Mar 12, 2012 Oct 12, 2012
Radium-228 4030 Radionuclide 5 of 15 results Mar 12, 2012 Oct 12, 2012
Nitrite 1041 Inorganic Chemical 4 of 64 results Dec 6, 2004 Apr 17, 2024
Sulfate 1055 Inorganic Chemical 4 of 4 results Nov 5, 2003 Mar 29, 2004
TTHM 2950 Organic Chemical 2 of 7 results Sep 20, 2007 Jul 15, 2010
Selenium 1045 Inorganic Chemical 2 of 29 results Mar 29, 2004 Nov 16, 2004
Total Haloacetic Acids (Haa5) 2456 Organic Chemical 1 of 7 results Jul 15, 2010 Jul 15, 2010
Toluene 2991 Organic Chemical 1 of 28 results Sep 22, 2004 Sep 22, 2004
Cadmium 1015 Inorganic Chemical 1 of 29 results Nov 5, 2003 Nov 5, 2003

No date range is applied: this list draws on every sample on record. Show the last two years only.

The most recent samples, result by result

The table below lists 71–80 of 284 samples, newest first — collected December 13, 2016 to April 11, 2018. The summary above covers all 284.

33 results from the 10 samples listed here: 20 detected, 13 not detected. Across the whole record it is 278 of 1,425. A sample is analysed for many analytes at once, so one sample appears on as many rows as it had results.

Chemical and radiological sample results for Lake Arrowhead, every result from 71 to 80 of 284 samples shown, newest first. Not detected means the amount was below the level the laboratory can reliably report, which is given beside it.
Result Analyte Monitoring period
Collected
Apr 11, 2018 10:30
Sampling point
TF103 Treatment Plant T103
Sample type
Routine
Lab sample
180412-009NI
Laboratory
MSDH Lab
Not detected below 0.1 mg/l Minimum Reporting Level , sample collected Apr 11, 2018 10:30, sampling point TF103 Nitrate-Nitrite 1038 EPA method QC10107041C Jan 1, 2018 – Dec 31, 2018
Not detected below 0.08 mg/l Minimum Reporting Level , sample collected Apr 11, 2018 10:30, sampling point TF103 Nitrate 1040 EPA method QC10107041C Jan 1, 2018 – Dec 31, 2018
Not detected below 0.02 mg/l Minimum Reporting Level , sample collected Apr 11, 2018 10:30, sampling point TF103 Nitrite 1041 EPA method QC10107041C Jan 1, 2018 – Dec 31, 2018
Collected
Sep 27, 2017 07:20
Sampling point
DS000 Distribution
Sample type
Routine
Lab sample
170929-085PB
Laboratory
MSDH Lab
0.006 mg/l , sample collected Sep 27, 2017 07:20, sampling point DS000 Copper, Free 1022 EPA method 200.8 Jan 1, 2017 – Dec 31, 2019
0.0006 mg/l , sample collected Sep 27, 2017 07:20, sampling point DS000 Lead 1030 EPA method 200.8 Jan 1, 2017 – Dec 31, 2019
Collected
Sep 27, 2017 06:30
Sampling point
DS000 Distribution
Sample type
Routine
Lab sample
170929-084PB
Laboratory
MSDH Lab
0.0698 mg/l , sample collected Sep 27, 2017 06:30, sampling point DS000 Copper, Free 1022 EPA method 200.8 Jan 1, 2017 – Dec 31, 2019
0.0008 mg/l , sample collected Sep 27, 2017 06:30, sampling point DS000 Lead 1030 EPA method 200.8 Jan 1, 2017 – Dec 31, 2019
Collected
Sep 27, 2017 06:00
Sampling point
DS000 Distribution
Sample type
Routine
Lab sample
170929-083PB
Laboratory
MSDH Lab
0.1339 mg/l , sample collected Sep 27, 2017 06:00, sampling point DS000 Copper, Free 1022 EPA method 200.8 Jan 1, 2017 – Dec 31, 2019
0.004 mg/l , sample collected Sep 27, 2017 06:00, sampling point DS000 Lead 1030 EPA method 200.8 Jan 1, 2017 – Dec 31, 2019
Collected
Sep 27, 2017 03:00
Sampling point
DS000 Distribution
Sample type
Routine
Lab sample
170929-082PB
Laboratory
MSDH Lab
0.0161 mg/l , sample collected Sep 27, 2017 03:00, sampling point DS000 Copper, Free 1022 EPA method 200.8 Jan 1, 2017 – Dec 31, 2019
0.0006 mg/l , sample collected Sep 27, 2017 03:00, sampling point DS000 Lead 1030 EPA method 200.8 Jan 1, 2017 – Dec 31, 2019
Collected
Sep 27, 2017 06:30
Sampling point
DS000 Distribution
Sample type
Routine
Lab sample
170929-081PB
Laboratory
MSDH Lab
0.0124 mg/l , sample collected Sep 27, 2017 06:30, sampling point DS000 Copper, Free 1022 EPA method 200.8 Jan 1, 2017 – Dec 31, 2019
0.0021 mg/l , sample collected Sep 27, 2017 06:30, sampling point DS000 Lead 1030 EPA method 200.8 Jan 1, 2017 – Dec 31, 2019
Collected
Apr 11, 2017 01:49
Sampling point
TF102 Treatment Plant T102
Sample type
Routine
Lab sample
170412-028NI
Laboratory
MSDH Lab
3.37 mg/l , sample collected Apr 11, 2017 01:49, sampling point TF102 Nitrate-Nitrite 1038 EPA method QC10107041C Jan 1, 2017 – Dec 31, 2017
3.37 mg/l , sample collected Apr 11, 2017 01:49, sampling point TF102 Nitrate 1040 EPA method QC10107041C Jan 1, 2017 – Dec 31, 2017
Not detected below 0.02 mg/l Minimum Reporting Level , sample collected Apr 11, 2017 01:49, sampling point TF102 Nitrite 1041 EPA method QC10107041C Jan 1, 2017 – Dec 31, 2017
Collected
Apr 11, 2017 01:40
Sampling point
TF101 Treatment Plant T101
Sample type
Routine
Lab sample
170412-020NI
Laboratory
MSDH Lab
2.93 mg/l , sample collected Apr 11, 2017 01:40, sampling point TF101 Nitrate-Nitrite 1038 EPA method QC10107041C Jan 1, 2017 – Dec 31, 2017
2.93 mg/l , sample collected Apr 11, 2017 01:40, sampling point TF101 Nitrate 1040 EPA method QC10107041C Jan 1, 2017 – Dec 31, 2017
Not detected below 0.02 mg/l Minimum Reporting Level , sample collected Apr 11, 2017 01:40, sampling point TF101 Nitrite 1041 EPA method QC10107041C Jan 1, 2017 – Dec 31, 2017
Collected
Apr 11, 2017 02:07
Sampling point
TF103 Treatment Plant T103
Sample type
Routine
Lab sample
170412-010NI
Laboratory
MSDH Lab
2.45 mg/l , sample collected Apr 11, 2017 02:07, sampling point TF103 Nitrate-Nitrite 1038 EPA method QC10107041C Jan 1, 2017 – Dec 31, 2017
2.45 mg/l , sample collected Apr 11, 2017 02:07, sampling point TF103 Nitrate 1040 EPA method QC10107041C Jan 1, 2017 – Dec 31, 2017
Not detected below 0.02 mg/l Minimum Reporting Level , sample collected Apr 11, 2017 02:07, sampling point TF103 Nitrite 1041 EPA method QC10107041C Jan 1, 2017 – Dec 31, 2017
Collected
Dec 13, 2016 02:45
Sampling point
TF103 Treatment Plant T103
Sample type
Routine
Lab sample
161214-073IN
Laboratory
MSDH Lab
Not detected below 0.0005 mg/l Minimum Reporting Level , sample collected Dec 13, 2016 02:45, sampling point TF103 Arsenic 1005 EPA method 200.8 Jan 1, 2014 – Dec 31, 2016
0.0343 mg/l , sample collected Dec 13, 2016 02:45, sampling point TF103 Barium 1010 EPA method 200.8 Jan 1, 2014 – Dec 31, 2016
Not detected below 0.0005 mg/l Minimum Reporting Level , sample collected Dec 13, 2016 02:45, sampling point TF103 Cadmium 1015 EPA method 200.8 Jan 1, 2014 – Dec 31, 2016
0.0005 mg/l , sample collected Dec 13, 2016 02:45, sampling point TF103 Chromium 1020 EPA method 200.8 Jan 1, 2014 – Dec 31, 2016
0.395 mg/l , sample collected Dec 13, 2016 02:45, sampling point TF103 Fluoride 1025 EPA method 300.0 Jan 1, 2014 – Dec 31, 2016
Not detected below 0.0005 mg/l Minimum Reporting Level , sample collected Dec 13, 2016 02:45, sampling point TF103 Mercury 1035 EPA method 200.8 Jan 1, 2014 – Dec 31, 2016
0.0006 mg/l , sample collected Dec 13, 2016 02:45, sampling point TF103 Nickel 1036 EPA method 200.8 Not recorded
Not detected below 0.0025 mg/l Minimum Reporting Level , sample collected Dec 13, 2016 02:45, sampling point TF103 Selenium 1045 EPA method 200.8 Jan 1, 2014 – Dec 31, 2016
Not detected below 0.0005 mg/l Minimum Reporting Level , sample collected Dec 13, 2016 02:45, sampling point TF103 Antimony, Total 1074 EPA method 200.8 Jan 1, 2014 – Dec 31, 2016
Not detected below 0.0005 mg/l Minimum Reporting Level , sample collected Dec 13, 2016 02:45, sampling point TF103 Beryllium, Total 1075 EPA method 200.8 Jan 1, 2014 – Dec 31, 2016
Not detected below 0.0005 mg/l Minimum Reporting Level , sample collected Dec 13, 2016 02:45, sampling point TF103 Thallium, Total 1085 EPA method 200.8 Jan 1, 2014 – Dec 31, 2016

Routine (10).