Current through September 17, 2024
004.01 Source Water
Monitoring
Systems must conduct the following monitoring on the schedule
in 179 NAC 25-004.02 unless they meet the monitoring exemption criteria in 179
NAC 25-004.03 or the Department has approved a different sampling
schedule.
25-004.01A Filtered systems
serving at least 10,000 people must sample their source water for
Cryptosporidium, E. coli, and turbidity at
least monthly for 24 months.
25-004.01B Unfiltered systems serving at
least 10,000 people must sample their source water for Cryptosporidium
at least monthly for 24 months.
25-004.01C
Filtered Systems and
E. coli monitoring
1. Filtered systems serving fewer than 10,000
people must sample their source water for E. coli at least
once every two weeks for 12 months.
2. A filtered system serving fewer than
10,000 people may avoid E. coli monitoring if the system
notifies the Department that it will monitor for Cryptosporidium
as described in 179 NAC
25-004.01D. The
system must notify the Department no later than 3 months prior to the date the
system is otherwise required to start E. coli
monitoring.
25-004.01D Filtered systems serving fewer
than 10,000 people must sample their source water for
Cryptosporidium
at least twice per month for 12 months or at least monthly for 24
months if they meet one of the following, based on monitoring conducted under
179 NAC
25-004.01C or 40
CFR 141 Subpart W:
1. The annual mean
E. coli concentration is greater than 100 E.
coli/100 mL.
2. The system
does not conduct E. coli monitoring as described in 179 NAC
25-004.01C.
25-004.01E For filtered systems
serving fewer than 10,000 people, the Department may approve monitoring for an
indicator other than E. coli under 179 NAC
25-004.01C. The
Department also may approve an alternative to the E. coli
concentration in 179 NAC
25-004.01D item 1
to trigger Cryptosporidium monitoring. This approval by the
Department must be provided to the system in writing and must include the basis
for the Department's determination that the alternative indicator and/or
trigger level will provide a more accurate identification of whether a system
will exceed the Bin 1 Cryptosporidium level in 179 NAC
25-012.
25-004.01F Unfiltered systems serving fewer
than 10,000 people must sample their source water for Cryptosporidium
at least twice per month for 12 months or at least monthly for 24
months.
25-004.01G Systems may
sample more frequently than required under 179 NAC 25-004 if the sampling
frequency is evenly spaced throughout the monitoring period.
004.02 Monitoring Schedule
Systems are required to begin source water monitoring no
later than the month beginning with the date listed in this table or on a
schedule approved by the Department:
SOURCE WATER MONITORING STARTING DATES
TABLE
Systems that serve . . . |
Must begin source water monitoring no later than the
month beginning . . . |
(1) At least 100,000 people |
April 1, 2015 |
(2) From 50,000 to 99,999 people |
October 1, 2015 |
(3) From 10,000 to 49,999 people |
October 1, 2016 |
(4) Fewer than 10,000 and monitor for E. coli
a |
October 1, 2017 |
(5) Fewer than 10,000 and monitor for
Cryptosporidiumb |
April 1, 2019 |
a Applies only to filtered
systems.
b Applies to filtered systems that
meet the conditions of 179 NAC
25-004.01D and
unfiltered systems.
004.03
Monitoring Avoidance
25-004.03A Filtered
systems are not required to conduct source water monitoring under this chapter
if the system will provide a total of at least 5.5-log of treatment for
Cryptosporidium, equivalent to meeting the treatment
requirements of Bin 4 in 179 NAC
25-013.
25-004.03B Unfiltered systems are not
required to conduct source water monitoring under this chapter if the system
will provide a total of a least 3-log Cryptosporidium
inactivation, equivalent to meeting the treatment requirements for
unfiltered systems with a mean Cryptosporidium concentration
of greater than 0.01 oocysts/L in 179 NAC
25-014.
25-004.03C If a system chooses to provide the
level of treatment in 179 NAC
25-004.03A or
25-004.03B, as
applicable, rather than start source water monitoring, the system must notify
the Department in writing no later than the date the system is otherwise
required to submit a sampling schedule for monitoring under 179 NAC
25-005. Alternatively, a system may
choose to stop sampling at any point after it has initiated monitoring if it
notifies the Department in writing that it will provide this level of
treatment. Systems must install and operate technologies to provide this level
of treatment by the applicable treatment compliance date in 179 NAC
25-015.
004.04 Plants Operating Only Part of the Year
Systems with surface water or ground water under the direct
influence of surface water plants that operate for only part of the year must
conduct source water monitoring in accordance with this chapter, but with the
following modifications:
1. Systems
must sample their source water only during the months that the plant operates
unless the Department specifies another monitoring period based on plant
operating practices.
2. Systems
with plants that operate less than six months per year and that monitor for
Cryptosporidium must collect at least six
Cryptosporidium samples per year during each of two years of
monitoring. Samples must be evenly spaced throughout the period the plant
operates.
004.05 New
Sources
25-004.05A A system that begins using
a new source of surface water or GWUDI after the system is required to begin
monitoring must monitor the new source on a schedule the Department approves.
Source water monitoring must meet the requirements of this chapter. The system
must also meet the bin classification and Cryptosporidium
treatment requirements of 179 NAC
25-012,
25-013, or
25-014, as applicable, for the new
source on a schedule the Department approves.
25-004.05B The requirements of 179 NAC
25-004.05 apply to surface water and GWUDI systems that begin operation after
the monitoring start date applicable to the system's size.
004.06 Failure to collect any required source
water sample in accordance with the sampling schedule, sampling location,
analytical method, approved laboratory, and reporting requirements is a
monitoring violation.