HomeMy WebLinkAbout10-1, Attachment Public Health Goals Report 2013Attachment 1
TRUCKEE DONNER PUBLIC UTILITY DISTRICT
REPORT ON DISTRICT'S WATER QUALITY RELATIVE TO PUBLIC HEALTH GOALS
Background:
Provisions of the California Health and Safety Code specify that larger (>10,000 service
connections) water utilities prepare a special report by July 1, 2013 if their water quality
measurements have exceeded any Public Health Goals (PHGs). PHGs are non -enforceable
goals established by the Cal-EPA's Office of Environmental Health Hazard Assessment
(OEHHA). The law also requires that where OEHHA has not adopted a PHG for a constituent,
the water suppliers are to use the MCLGs adopted by the USEPA. Only constituents which have
a California primary drinking water standard and for which either a PHG or MCLG has been set
are to be addressed.
There are a few constituents that are routinely detected in water systems at levels
usually well below the drinking water standards for which no PHG nor MCLG has yet been
adopted by OEHHA or USEPA including Total Trihalomethanes. These will be addressed in a
future required report after a PHG has been adopted.
The law specifies what information is to be provided in the report.
If a constituent was detected in the District's water supply between 2010 and 2012 at a
level exceeding an applicable PHG or MCLG, this report provides the information required by
the law. Included is the numerical public health risk associated with the MCL and the PHG or
MCLG, the category or type of risk to health that could be associated with each constituent, the
best treatment technology available that could be used to reduce the constituent level, and an
estimate of the cost to install that treatment if it is appropriate and feasible.
What Are PHGs?
PHGs are set by the California Office of Environmental Health Hazard Assessment (OEHHA)
which is part of Cal -EPA and are based solely on public health risk considerations. None of the
practical risk -management factors that are considered by the USEPA or the California
Department of Health Services (CDHS) in setting drinking water standards (MCLs) are
considered in setting the PHGs. These factors include analytical detection capability, treatment
technology available, benefits and costs. The PHGs are not enforceable and are not required to
be met by any public water system. MCLGs are the federal equivalent to PHGs.
Water Quality Data Considered:
All of the water quality data collected by our water system between 2010, and 2012 for
purposes of determining compliance with drinking water standards was considered. This data
was all summarized in our 2010, 2011, and 2012 Annual Water Quality Reports which were
mailed or made available through electronic means to all of our customers in June of the
following year.
Guidelines Followed:
The Association of California Water Agencies (ACWA) formed a workgroup which
prepared guidelines for water utilities to use in preparing these newly required reports. The
ACWA and California Department of Public Health guidelines were used in the preparation of
our report.
2013 Public Health Goal Report
Truckee Donner Public Utility District
Best Available Treatment Technology and Cost Estimates:
Both the USEPA and CDHS adopt what are known as BATs or Best Available
Technologies which are the best known methods of reducing contaminant levels to the MCL.
Costs can be estimated for such technologies. However, since many PHGs and all MCLGs are
set much lower than the MCL, it is not always possible, nor feasible, to determine what
treatment is needed to further reduce a constituent downward to or near the PHG or MCLG,
many of which are set at zero. Estimating the costs to reduce a constituent to zero is difficult, if
not impossible because it is not possible to verify by analytical means that the level has been
lowered to zero. In some cases, installing treatment to try and further reduce very low levels of
one constituent may have adverse effects on other aspects of water quality.
Constituents Detected That Exceed a PHG or a MCLG:
The following is a discussion of constituents that were detected in one or more of our
drinking water sources at levels above the PHG, or if no PHG, above the MCLG.
Arsenic: The MCL for arsenic is 10 ppb; the PHG and MCLG for arsenic is 0.0004ppb. We
have detected arsenic in 6 of our 12 wells: Glenshire Drive Well at 9.3ppb, Martis Valley Well at
8.2ppb, Airport Well at 9.4ppb, Old Greenwood Well at 2.4ppb, Sanders Well at 8.9ppb, and
Northside Well at 30ppb. The category of health risk associated with arsenic, and the reason
that a drinking water standard was adopted for it, is that people who drink water containing
arsenic above the MCL throughout their lifetime could experience an increased risk of getting
cancer. The Office of Environmental Health Assessment (part of California Environmental
Protection Agency) has set the PHG at 4ppt (0.0004ppb). The PHG is based on a level that will
result in not more than 1 excess cancer in 1 million people who drink 2 liters daily of this water
for 70 years. The actual cancer risk may be lower or zero. The BAT that we are using for this
report to lower the level below the MCL to 4ppt is fixed bed adsorption system. The estimated
cost to install and operate such a treatment system on all 6 wells that would reliably reduce the
arsenic level to 4ppt would be approximately $7,203,000 initial construction cost with additional
O&M cost of $6,481,900 per year. This would result in an assumed increased cost for each
customer of $557 per year.
RECOMMENDATIONS FOR FURTHER ACTION:
The drinking water quality of the Truckee Donner Public Utility District at this time meets
all State of California, Department of Public Health and USEPA drinking water standards set to
protect public health. To further reduce the levels of the constituents identified in this report that
are already below the health -based Maximum Contaminant Levels established to provide "safe
drinking water", additional costly treatment processes would be required. The effectiveness of
the treatment processes to provide any significant reductions in constituent levels at these
already low values is uncertain. The health protection benefits of these further hypothetical
reductions are not at all clear and may not be quantifiable. Therefore, no action is proposed.
The money that would be required for these additional treatment processes might provide
greater public health protection benefits if spent on other water system operation, surveillance,
and monitoring programs.
2013 Public Health Goal Report
Truckee Donner Public Utility District 2