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EF/ ICR Logo Treated Water Levels of Total Trihalomethanes (TTHM) for
CITY OF LOS ANGELES


Water System Total Trihalomethanes Report
REMINDER: Data Purpose: The ICR data were collected as part of a national research project to support development of national drinking water standards. They should NOT be used to determine local water systems compliance with drinking water standards, nor should they be used to make personal judgements about individual health risks.

Units: Sample measurements are taken in micrograms per Liter (ug/L) and are regulated in milligrams per Liter (mg/L). A microgram per Liter is equivalent to one contaminant part per billion (ppb). A ppb can be thought of as one grain of salt in a swimming pool. Data for Total Trihalomethanes, haloacetic acids 5, and bromate are presented in ppb. 1 mg/L = 1000 ug/L, or 0.080 mg/L = 80 ug/L = 80 ppb, which happens to be the TTHM standard in the Stage 1 DBP Rule.

Calculation in Regulations is Different: Comparisons with compliance calculations based on the existing Total Trihalomethanes standard in CFR Part 141.30 may not be warranted since the standard is based on an annual average of public water system quarterly averages and not on treatment plant results as shown here. Also the results here are based on different types of samples.

Results of Zero: A result of zero may indicate that a sample was analyzed, but that the result was less than the lowest value that the analytical method can reliably report.


Treated Water Levels of TTHM for Los Angele s Aqueduct Filtration Plant

Water Type Quarter Avg(tthm) (ppb) Min(tthm) (ppb) Max(tthm) (ppb)
Surface Water JUL 1997 - SEP 1997 26.6 15.1 35.7
Surface Water OCT 1997 - DEC 1997 34.5 27.8 48.5
Surface Water JAN 1998 - MAR 1998 26.1 18 33.8
Surface Water APR 1998 - JUN 1998 41.2 31.8 53
Surface Water JUL 1998 - SEP 1998 27 22 31.4
Surface Water OCT 1998 - DEC 1998 23.9 19.1 29.1


Treated Water Levels of TTHM for Eagle Rock Reservoir(LA-17)

Water Type Quarter Avg(tthm) (ppb) Min(tthm) (ppb) Max(tthm) (ppb)
Purchased Water JUL 1997 - SEP 1997 118.6 115.9 124
Purchased Water OCT 1997 - DEC 1997 100.3 95.3 108.8
Purchased Water JAN 1998 - MAR 1998 65.4 62.4 69.3
Not Reported APR 1998 - JUN 1998 51.7 48.4 56.2
Not Reported JUL 1998 - SEP 1998 75.1 58.9 84.5
Not Reported OCT 1998 - DEC 1998 42.7 21.6 72.2


Treated Water Levels of TTHM for Lower Stone Canyon Reservoir

Water Type Quarter Avg(tthm) (ppb) Min(tthm) (ppb) Max(tthm) (ppb)
Surface Water JUL 1997 - SEP 1997 29.7 28.6 31
Surface Water OCT 1997 - DEC 1997 28.6 27 30.6
Surface Water JAN 1998 - MAR 1998 24.9 23.8 25.7
Surface Water APR 1998 - JUN 1998 61.5 58.5 63.2
Surface Water JUL 1998 - SEP 1998 64.2 61.7 66.7
Surface Water OCT 1998 - DEC 1998 32.1 28.2 37.8


Treated Water Levels of TTHM for River Supply Conduit

Water Type Quarter Avg(tthm) (ppb) Min(tthm) (ppb) Max( tthm) (ppb)
Surface Water JUL 1997 - SEP 1997 12.8 10.5 17
Surface Water OCT 1997 - DEC 1997 17.9 11.8 28.1
Surface Water JAN 1998 - MAR 1998 15.3 13.2 17.5
Surface Water APR 1998 - JUN 1998 57.1 55 59.1
Surface Water JUL 1998 - SEP 1998 33.3 27.6 44
Surface Water OCT 1998 - DEC 1998 31.3 26.6 40.1


Treated Water Levels of TTHM for Upper Hollywood Reservoir

Water Type Quarter Avg(tthm) (ppb) Min(tthm) (ppb) Max(tthm) (ppb)
Surface Water JUL 1997 - SEP 1997 75.2 60.3 98.9
Surface Water OCT 1997 - DEC 1997 49.2 42.5 60.8
Surface Water JAN 1998 - MAR 1998 28.8 25.9 33
Surface Water APR 1998 - JUN 1998 54.8 48.3 66
Surface Water JUL 1998 - SEP 1998 62.4 53.2 79.7
Surface Water OCT 1998 - DEC 1998 34.3 26.2 49.4


How does this utility's treated water compare to treated waters nationally for TTHM? Click on "view report" to see the state and national levels of TTH M.

Quarter State Report National Report
JUL - SEP 1997 view report view report
OCT - DEC 1997 view report view report
JAN - MAR 1998 view report view report
APR - JUN 1998 view report view report
JUL - SEP 1998 view report view report
OCT - DEC 1998 view report view report


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