Public Water System: Harford County D.p.w.

MyTapWater.org's tap water quality report is the compilation of data collected from federal, state, and local government agencies, most prominently the EPA. We strive to populate the report with the latest data concerning water contaminants, lead and copper levels, and water quality violations. We only collect drinking water data from public water systems.

PWS Service Information
PWS ID: MD0120016
Type: Community water system
EPA Region: 03
Primary Service Area: Residential Area
Primary Source: Surface water
Population Served: 104,567
Contact Information
ANDERSON, WILLIAM
ANDERSON, WILLIAM
ABINGDON WATER PLANT
3340 ABINGDON ROAD
ABINGDON, MD 21009

This public water system services 11 zip codes in 1 county.

Summary Results


A summary view of the the times a water contaminant was tested and found to exceed the level set by the EPA (the MCL).

Maximum Contaminant Levels Exceeded (by year):

2013   (1) 2014   (0) 2015   (0)
chlorate

Contaminant Detailed Results


This a view of violations of maximum contaminant levels. In the expanded view you can see each know test date for a given contaminant, the result of the test, the minimum level that can be recognized in a test (MRL), and upper limit that is considered healthy (HRL).

chlorate
Is this in your home's pipes?

Year Test Date MRL HRL Test Result
2013 2013-12-03 20 210 66.266
2013 2013-12-03 20 210 81.802
2013 2013-12-02 20 210 134.291
2013 2013-12-02 20 210 272.818
2013 2013-09-03 20 210 133.115
2013 2013-09-03 20 210 433.514
2013 2013-09-03 20 210 164.956
2013 2013-09-03 20 210 95.651
2013 2013-09-03 20 210 221.415
2013 2013-06-03 20 210 78.267
2013 2013-06-03 20 210 59.591
2013 2013-06-03 20 210 221.992
2013 2013-06-03 20 210 221.214
2013 2013-03-04 20 210 113.527
2013 2013-03-04 20 210 78.293
2013 2013-03-04 20 210 218.845
2013 2013-03-04 20 210 166.139
2013 2013-03-04 20 210 123.11

Other Water Contaminants Tested


The following contaminants were tested and within national EPA guidelines.

The last mile of pipe makes a big difference, learn more about testing your water.

Contaminant MRL HRL Avg Result
4-androstene-3,17-dione 0.0003 0 < 0.0003 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.0003 0 < 0.0003
2013 2013-12-02 0.0003 0 < 0.0003
2013 2013-09-03 0.0003 0 < 0.0003
2013 2013-09-03 0.0003 0 < 0.0003
2013 2013-09-03 0.0003 0 < 0.0003
2013 2013-06-03 0.0003 0 < 0.0003
2013 2013-06-03 0.0003 0 < 0.0003
2013 2013-03-04 0.0003 0 < 0.0003
2013 2013-03-04 0.0003 0 < 0.0003
2013 2013-03-04 0.0003 0 < 0.0003
estriol 0.0008 0.35 < 0.0008 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.0008 0.35 < 0.0008
2013 2013-12-02 0.0008 0.35 < 0.0008
2013 2013-09-03 0.0008 0.35 < 0.0008
2013 2013-09-03 0.0008 0.35 < 0.0008
2013 2013-09-03 0.0008 0.35 < 0.0008
2013 2013-06-03 0.0008 0.35 < 0.0008
2013 2013-06-03 0.0008 0.35 < 0.0008
2013 2013-03-04 0.0008 0.35 < 0.0008
2013 2013-03-04 0.0008 0.35 < 0.0008
2013 2013-03-04 0.0008 0.35 < 0.0008
PFOA 0.02 0.07 0.0021 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.02 0.07 < 0.02
2013 2013-12-02 0.02 0.07 < 0.02
2013 2013-09-03 0.02 0.07 < 0.02
2013 2013-09-03 0.02 0.07 0.02123
2013 2013-09-03 0.02 0.07 < 0.02
2013 2013-06-03 0.02 0.07 < 0.02
2013 2013-06-03 0.02 0.07 < 0.02
2013 2013-03-04 0.02 0.07 < 0.02
2013 2013-03-04 0.02 0.07 < 0.02
2013 2013-03-04 0.02 0.07 < 0.02
PFOS 0.04 0.07 < 0.04 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.04 0.07 < 0.04
2013 2013-12-02 0.04 0.07 < 0.04
2013 2013-09-03 0.04 0.07 < 0.04
2013 2013-09-03 0.04 0.07 < 0.04
2013 2013-09-03 0.04 0.07 < 0.04
2013 2013-06-03 0.04 0.07 < 0.04
2013 2013-06-03 0.04 0.07 < 0.04
2013 2013-03-04 0.04 0.07 < 0.04
2013 2013-03-04 0.04 0.07 < 0.04
2013 2013-03-04 0.04 0.07 < 0.04
chromium 0.2 100 0.2889 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.2 100 0.488
2013 2013-12-03 0.2 100 < 0.2
2013 2013-12-02 0.2 100 < 0.2
2013 2013-12-02 0.2 100 0.235
2013 2013-09-03 0.2 100 0.206
2013 2013-09-03 0.2 100 0.57
2013 2013-09-03 0.2 100 < 0.2
2013 2013-09-03 0.2 100 1.124
2013 2013-09-03 0.2 100 < 0.2
2013 2013-06-03 0.2 100 < 0.2
2013 2013-06-03 0.2 100 0.789
2013 2013-06-03 0.2 100 < 0.2
2013 2013-06-03 0.2 100 < 0.2
2013 2013-03-04 0.2 100 < 0.2
2013 2013-03-04 0.2 100 0.563
2013 2013-03-04 0.2 100 < 0.2
2013 2013-03-04 0.2 100 < 0.2
2013 2013-03-04 0.2 100 1.225
vanadium 0.2 21 0.0294 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.2 21 < 0.2
2013 2013-12-03 0.2 21 < 0.2
2013 2013-12-02 0.2 21 < 0.2
2013 2013-12-02 0.2 21 < 0.2
2013 2013-09-03 0.2 21 0.227
2013 2013-09-03 0.2 21 < 0.2
2013 2013-09-03 0.2 21 < 0.2
2013 2013-09-03 0.2 21 < 0.2
2013 2013-09-03 0.2 21 0.302
2013 2013-06-03 0.2 21 < 0.2
2013 2013-06-03 0.2 21 < 0.2
2013 2013-06-03 0.2 21 < 0.2
2013 2013-06-03 0.2 21 < 0.2
2013 2013-03-04 0.2 21 < 0.2
2013 2013-03-04 0.2 21 < 0.2
2013 2013-03-04 0.2 21 < 0.2
2013 2013-03-04 0.2 21 < 0.2
2013 2013-03-04 0.2 21 < 0.2
chloromethane 0.2 2.69 < 0.2 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.2 2.69 < 0.2
2013 2013-12-02 0.2 2.69 < 0.2
2013 2013-09-03 0.2 2.69 < 0.2
2013 2013-09-03 0.2 2.69 < 0.2
2013 2013-09-03 0.2 2.69 < 0.2
2013 2013-06-03 0.2 2.69 < 0.2
2013 2013-06-03 0.2 2.69 < 0.2
2013 2013-03-04 0.2 2.69 < 0.2
2013 2013-03-04 0.2 2.69 < 0.2
2013 2013-03-04 0.2 2.69 < 0.2
17-beta-estradiol 0.0004 0.0009 < 0.0004 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.0004 0.0009 < 0.0004
2013 2013-12-02 0.0004 0.0009 < 0.0004
2013 2013-09-03 0.0004 0.0009 < 0.0004
2013 2013-09-03 0.0004 0.0009 < 0.0004
2013 2013-09-03 0.0004 0.0009 < 0.0004
2013 2013-06-03 0.0004 0.0009 < 0.0004
2013 2013-06-03 0.0004 0.0009 < 0.0004
2013 2013-03-04 0.0004 0.0009 < 0.0004
2013 2013-03-04 0.0004 0.0009 < 0.0004
2013 2013-03-04 0.0004 0.0009 < 0.0004
17-alpha-ethynylestradiol 0.0009 0.035 < 0.0009 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.0009 0.035 < 0.0009
2013 2013-12-02 0.0009 0.035 < 0.0009
2013 2013-09-03 0.0009 0.035 < 0.0009
2013 2013-09-03 0.0009 0.035 < 0.0009
2013 2013-09-03 0.0009 0.035 < 0.0009
2013 2013-06-03 0.0009 0.035 < 0.0009
2013 2013-06-03 0.0009 0.035 < 0.0009
2013 2013-03-04 0.0009 0.035 < 0.0009
2013 2013-03-04 0.0009 0.035 < 0.0009
2013 2013-03-04 0.0009 0.035 < 0.0009
molybdenum 1 40 < 1 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 1 40 < 1
2013 2013-12-03 1 40 < 1
2013 2013-12-02 1 40 < 1
2013 2013-12-02 1 40 < 1
2013 2013-09-03 1 40 < 1
2013 2013-09-03 1 40 < 1
2013 2013-09-03 1 40 < 1
2013 2013-09-03 1 40 < 1
2013 2013-09-03 1 40 < 1
2013 2013-06-03 1 40 < 1
2013 2013-06-03 1 40 < 1
2013 2013-06-03 1 40 < 1
2013 2013-06-03 1 40 < 1
2013 2013-03-04 1 40 < 1
2013 2013-03-04 1 40 < 1
2013 2013-03-04 1 40 < 1
2013 2013-03-04 1 40 < 1
2013 2013-03-04 1 40 < 1
testosterone 0.0001 0 < 0.0001 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.0001 0 < 0.0001
2013 2013-12-02 0.0001 0 < 0.0001
2013 2013-09-03 0.0001 0 < 0.0001
2013 2013-09-03 0.0001 0 < 0.0001
2013 2013-09-03 0.0001 0 < 0.0001
2013 2013-06-03 0.0001 0 < 0.0001
2013 2013-06-03 0.0001 0 < 0.0001
2013 2013-03-04 0.0001 0 < 0.0001
2013 2013-03-04 0.0001 0 < 0.0001
2013 2013-03-04 0.0001 0 < 0.0001
PFNA 0.02 0 < 0.02 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.02 0 < 0.02
2013 2013-12-02 0.02 0 < 0.02
2013 2013-09-03 0.02 0 < 0.02
2013 2013-09-03 0.02 0 < 0.02
2013 2013-09-03 0.02 0 < 0.02
2013 2013-06-03 0.02 0 < 0.02
2013 2013-06-03 0.02 0 < 0.02
2013 2013-03-04 0.02 0 < 0.02
2013 2013-03-04 0.02 0 < 0.02
2013 2013-03-04 0.02 0 < 0.02
1,1-dichloroethane 0.03 6.14 0.004 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.03 6.14 < 0.03
2013 2013-12-02 0.03 6.14 < 0.03
2013 2013-09-03 0.03 6.14 < 0.03
2013 2013-09-03 0.03 6.14 < 0.03
2013 2013-09-03 0.03 6.14 < 0.03
2013 2013-06-03 0.03 6.14 < 0.03
2013 2013-06-03 0.03 6.14 < 0.03
2013 2013-03-04 0.03 6.14 < 0.03
2013 2013-03-04 0.03 6.14 < 0.03
2013 2013-03-04 0.03 6.14 0.04
chromium-6 0.03 0 0.3326 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.03 0 0.44
2013 2013-12-03 0.03 0 0.071
2013 2013-12-02 0.03 0 0.195
2013 2013-12-02 0.03 0 0.071
2013 2013-09-03 0.03 0 0.192
2013 2013-09-03 0.03 0 0.579
2013 2013-09-03 0.03 0 < 0.03
2013 2013-09-03 0.03 0 1.205
2013 2013-09-03 0.03 0 0.04
2013 2013-06-03 0.03 0 < 0.03
2013 2013-06-03 0.03 0 0.811
2013 2013-06-03 0.03 0 0.142
2013 2013-06-03 0.03 0 0.039
2013 2013-03-04 0.03 0 < 0.03
2013 2013-03-04 0.03 0 0.704
2013 2013-03-04 0.03 0 0.106
2013 2013-03-04 0.03 0 0.058
2013 2013-03-04 0.03 0 1.333
equilin 0.004 0.35 < 0.004 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.004 0.35 < 0.004
2013 2013-12-02 0.004 0.35 < 0.004
2013 2013-09-03 0.004 0.35 < 0.004
2013 2013-09-03 0.004 0.35 < 0.004
2013 2013-09-03 0.004 0.35 < 0.004
2013 2013-06-03 0.004 0.35 < 0.004
2013 2013-06-03 0.004 0.35 < 0.004
2013 2013-03-04 0.004 0.35 < 0.004
2013 2013-03-04 0.004 0.35 < 0.004
2013 2013-03-04 0.004 0.35 < 0.004
PFBS 0.09 0 < 0.09 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.09 0 < 0.09
2013 2013-12-02 0.09 0 < 0.09
2013 2013-09-03 0.09 0 < 0.09
2013 2013-09-03 0.09 0 < 0.09
2013 2013-09-03 0.09 0 < 0.09
2013 2013-06-03 0.09 0 < 0.09
2013 2013-06-03 0.09 0 < 0.09
2013 2013-03-04 0.09 0 < 0.09
2013 2013-03-04 0.09 0 < 0.09
2013 2013-03-04 0.09 0 < 0.09
1,4-dioxane 0.07 0.35 < 0.07 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.07 0.35 < 0.07
2013 2013-12-02 0.07 0.35 < 0.07
2013 2013-09-03 0.07 0.35 < 0.07
2013 2013-09-03 0.07 0.35 < 0.07
2013 2013-09-03 0.07 0.35 < 0.07
2013 2013-06-03 0.07 0.35 < 0.07
2013 2013-06-03 0.07 0.35 < 0.07
2013 2013-03-04 0.07 0.35 < 0.07
2013 2013-03-04 0.07 0.35 < 0.07
2013 2013-03-04 0.07 0.35 < 0.07
1,2,3-trichloropropane 0.03 0.0004 < 0.03 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.03 0.0004 < 0.03
2013 2013-12-02 0.03 0.0004 < 0.03
2013 2013-09-03 0.03 0.0004 < 0.03
2013 2013-09-03 0.03 0.0004 < 0.03
2013 2013-09-03 0.03 0.0004 < 0.03
2013 2013-06-03 0.03 0.0004 < 0.03
2013 2013-06-03 0.03 0.0004 < 0.03
2013 2013-03-04 0.03 0.0004 < 0.03
2013 2013-03-04 0.03 0.0004 < 0.03
2013 2013-03-04 0.03 0.0004 < 0.03
Halon 1011 0.06 90 < 0.06 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.06 90 < 0.06
2013 2013-12-02 0.06 90 < 0.06
2013 2013-09-03 0.06 90 < 0.06
2013 2013-09-03 0.06 90 < 0.06
2013 2013-09-03 0.06 90 < 0.06
2013 2013-06-03 0.06 90 < 0.06
2013 2013-06-03 0.06 90 < 0.06
2013 2013-03-04 0.06 90 < 0.06
2013 2013-03-04 0.06 90 < 0.06
2013 2013-03-04 0.06 90 < 0.06
cobalt 1 70 < 1 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 1 70 < 1
2013 2013-12-03 1 70 < 1
2013 2013-12-02 1 70 < 1
2013 2013-12-02 1 70 < 1
2013 2013-09-03 1 70 < 1
2013 2013-09-03 1 70 < 1
2013 2013-09-03 1 70 < 1
2013 2013-09-03 1 70 < 1
2013 2013-09-03 1 70 < 1
2013 2013-06-03 1 70 < 1
2013 2013-06-03 1 70 < 1
2013 2013-06-03 1 70 < 1
2013 2013-06-03 1 70 < 1
2013 2013-03-04 1 70 < 1
2013 2013-03-04 1 70 < 1
2013 2013-03-04 1 70 < 1
2013 2013-03-04 1 70 < 1
2013 2013-03-04 1 70 < 1
strontium 0.3 1500 87.8573 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.3 1500 73.401
2013 2013-12-03 0.3 1500 133.852
2013 2013-12-02 0.3 1500 82.286
2013 2013-12-02 0.3 1500 94.094
2013 2013-09-03 0.3 1500 101.157
2013 2013-09-03 0.3 1500 76.916
2013 2013-09-03 0.3 1500 79.971
2013 2013-09-03 0.3 1500 51.611
2013 2013-09-03 0.3 1500 116.33
2013 2013-06-03 0.3 1500 77.14
2013 2013-06-03 0.3 1500 71.978
2013 2013-06-03 0.3 1500 93.918
2013 2013-06-03 0.3 1500 131.552
2013 2013-03-04 0.3 1500 66.6706
2013 2013-03-04 0.3 1500 67.4486
2013 2013-03-04 0.3 1500 75.8091
2013 2013-03-04 0.3 1500 134.557
2013 2013-03-04 0.3 1500 52.7407
HCFC-22 0.08 0 < 0.08 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.08 0 < 0.08
2013 2013-12-02 0.08 0 < 0.08
2013 2013-09-03 0.08 0 < 0.08
2013 2013-09-03 0.08 0 < 0.08
2013 2013-09-03 0.08 0 < 0.08
2013 2013-06-03 0.08 0 < 0.08
2013 2013-06-03 0.08 0 < 0.08
2013 2013-03-04 0.08 0 < 0.08
2013 2013-03-04 0.08 0 < 0.08
2013 2013-03-04 0.08 0 < 0.08
estrone 0.002 0.35 < 0.002 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.002 0.35 < 0.002
2013 2013-12-02 0.002 0.35 < 0.002
2013 2013-09-03 0.002 0.35 < 0.002
2013 2013-09-03 0.002 0.35 < 0.002
2013 2013-09-03 0.002 0.35 < 0.002
2013 2013-06-03 0.002 0.35 < 0.002
2013 2013-06-03 0.002 0.35 < 0.002
2013 2013-03-04 0.002 0.35 < 0.002
2013 2013-03-04 0.002 0.35 < 0.002
2013 2013-03-04 0.002 0.35 < 0.002
bromomethane 0.2 140 < 0.2 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.2 140 < 0.2
2013 2013-12-02 0.2 140 < 0.2
2013 2013-09-03 0.2 140 < 0.2
2013 2013-09-03 0.2 140 < 0.2
2013 2013-09-03 0.2 140 < 0.2
2013 2013-06-03 0.2 140 < 0.2
2013 2013-06-03 0.2 140 < 0.2
2013 2013-03-04 0.2 140 < 0.2
2013 2013-03-04 0.2 140 < 0.2
2013 2013-03-04 0.2 140 < 0.2
PFHpA 0.01 0 < 0.01 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.01 0 < 0.01
2013 2013-12-02 0.01 0 < 0.01
2013 2013-09-03 0.01 0 < 0.01
2013 2013-09-03 0.01 0 < 0.01
2013 2013-09-03 0.01 0 < 0.01
2013 2013-06-03 0.01 0 < 0.01
2013 2013-06-03 0.01 0 < 0.01
2013 2013-03-04 0.01 0 < 0.01
2013 2013-03-04 0.01 0 < 0.01
2013 2013-03-04 0.01 0 < 0.01
PFHxS 0.03 0 < 0.03 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.03 0 < 0.03
2013 2013-12-02 0.03 0 < 0.03
2013 2013-09-03 0.03 0 < 0.03
2013 2013-09-03 0.03 0 < 0.03
2013 2013-09-03 0.03 0 < 0.03
2013 2013-06-03 0.03 0 < 0.03
2013 2013-06-03 0.03 0 < 0.03
2013 2013-03-04 0.03 0 < 0.03
2013 2013-03-04 0.03 0 < 0.03
2013 2013-03-04 0.03 0 < 0.03
1,3-butadiene 0.1 0.0103 < 0.1 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-03 0.1 0.0103 < 0.1
2013 2013-12-02 0.1 0.0103 < 0.1
2013 2013-09-03 0.1 0.0103 < 0.1
2013 2013-09-03 0.1 0.0103 < 0.1
2013 2013-09-03 0.1 0.0103 < 0.1
2013 2013-06-03 0.1 0.0103 < 0.1
2013 2013-06-03 0.1 0.0103 < 0.1
2013 2013-03-04 0.1 0.0103 < 0.1
2013 2013-03-04 0.1 0.0103 < 0.1
2013 2013-03-04 0.1 0.0103 < 0.1

Lead and Copper Data


Lead and copper are recorded separately from other contaminants because of the Lead and Copper Rule. As with all other results, these are the findings at the water supply. Lead and copper can be — and often are — added to drinking water in between the water facility and a tap.

Sample ID Contaminant Sampling Start Date Sampling End Date Result
MD25861 lead 2014-01-01 2014-12-31 0mg/L
MD26334 lead 2013-01-01 2013-12-31 0mg/L
MD27919 lead 2009-01-01 2011-12-31 0mg/L
MD30688 lead 2006-01-01 2008-12-31 0mg/L

Violations


Known violations of the Safe Drinking Water Act as recorded by the EPA.

Compliance Dates Rule Violation Type Contaminant Name Status
2009-07-01 - 2009-09-30 Nitrates Monitoring, Regular Nitrate Returned to Compliance
1999-01-01 - 1999-12-31 Inorganic Chemicals Monitoring, Regular Fluoride Returned to Compliance
1992-07-01 - 1993-01-13 Lead and Copper Rule Initial Tap Sampling for Pb and Cu Lead and Copper Rule Returned to Compliance
1992-12-01 - 1992-12-31 Total Coliform Rule Monitoring, Routine Minor (TCR) Coliform (TCR) Returned to Compliance
1992-01-01 - 1992-09-17 Lead and Copper Rule Initial Tap Sampling for Pb and Cu Lead and Copper Rule Returned to Compliance
1992-01-01 - 1992-06-30 Lead and Copper Rule Water Quality Parameter M/R Lead and Copper Rule Returned to Compliance
2011-10-01 - N/A Lead and Copper Rule Follow-up Or Routine LCR Tap M/R Lead and Copper Rule Returned to Compliance

What My Water Data Means


Water data isn't always easy to interpret, but by following the links on this page you should be able to have most of your questions answered. By clicking the name of a water contaminant or secondary substance you can learn about that specific substance. Ultimately this page should give you some insight towards learning if your water is safe, what water filter you should buy (if any), and how well your local water compares against other sources.

Sources


The origin of MyTapWater.org's water data is explained on our Data Sources page.

Why Is My Water Data Not More Recent?


The recency of the data for your ZIP code depends on the last your water source was tested, by a federal, state, or local agency. More information about the timing can be determined by learning about the dataset in question and seeing how often the EPA (other another governing body) mandated testing.