An Act To Update Water Quality Criteria
Maine Legislature, Session 121, LD 1485
Committee: Natural Resources
Sponsors: MARTIN, KOFFMAN, SAWYER
Amends: 38 MRSA §464, 38 MRSA §465, 38 MRSA §46

Legislative Document 
No. 1485 
S.P.491 
In Senate, March 31, 2003 
An Act To Update Water Quality Criteria 
Submitted by the Department of Environmental Protection pursuant to Joint Rule 204. 
Reference to the Committee on Natural Resources suggested and ordered printed. 
Presented by Senator MARTIN of Aroostook. 
Cosponsored by Representative KOFFMAN of Bar Harbor and 
Senator: SAWYER of Penobscot. 
Printed on recycled paper 
JOY J. O'BRIEN 
Secretary of the Senate 
Be it enacted by the People of the State of Maine as follows: 
Sec. I. 38 MRSA §464, sub-§13 is enacted to read: 
13. 
Measurement 
of 
dissolved 
oXYgen 
in 
riverine 
impoundments. 
Compliance 
with 
dissolved 
oxygen 
criteria in 
existing riverine impoundments must be measured as follows. 
A. 
Compliance with dissolved oxygen criteria may not be 
measured 
within 
0.5 
meters 
of 
the 
bottom 
of 
existing 
riverine impoundments. 
B. 
Where mixing is inhibited due to thermal stratification 
in an existing riverine impoundment, compliance with numeric 
dissolved oxygen criteria may not be measured wi thin that 
portion of 
the 
impoundment 
below 
the 
point of 
thermal 
stratification during 
the 
time 
stratification conditions 
occur, except where such stratification is caused in whole 
or in part by the operation of a dam. 
For purposes of this paragraph, 
"thermal stratification" 
means a change of temperature of at least one degree Celsius 
per meter of depth, causing water below this point in an 
impoundment to become isolated and not mix with water above 
this point in the impoundment. 
C. 
Where mixing is inhibited due to natural topographic 
features in an existing riverine impoundment" 
compliance 
with numeric dissolved oxygen criteria may not be measured 
within 
that 
portion 
of 
the 
impoundment 
that 
is 
topographically isolated. 
Such natural topographic features 
may include, but not be limited to, natural deep holes or 
river bottom sills. 
Notwithstanding 
the 
prov~s~ons of 
this 
subsection, 
dissolved 
oxygen concentrations in existing riverine impoundments must be 
~fficient to support existing and designated uses 
of these 
waters. 
For purposes of this subsection, 
"existing riverine 
impoundments" means all impoundments of rivers and streams in 
existence as of January L 
2001 and not otherwise classified as 
GPA. 
Sec. 2. 38 MRSA §465, sub-§3, 1[B, as enac ted by PL 1985, c. 
698, §15, is amended to read: 
B. 
The dissolved oxygen content of Class B 'Olaters shall 
~ 
be 
not less 
than 
parts per million or 
75% 
of 
saturation, whichever is higher, except that for the period 
from October 1st to May 14th, in order to ensure spawning 
and egg incubation of indigenous fish species, the 7-day 
Page l-LRI865(1) 
mean dissolved oxygen concentration s.Ba;J.;J. may not be less 
than 9.5 parts per million and the I-day minimum dissolved 
oxygen concentration s.Ba;J.l may not be less than 8.0 parts 
per million in identified fish spawning areas. 
Between May 
15th and September 30th, 
the number of Escherichia coli 
bacteria of human or domestic livestock origin in these 
waters 
may 
not exceed 
a 
geometric 
mean of 
per 
mil1ili ters 
or an instantaneous level of 467 2.l.2 per 100 
milliliters. 
Sec. 3. 38 MRSA §46S, sub-§4, 1(B, as affected by PL 1989, c. 
890, Pt. A, §40 ~nd amended by Pt. B, §63, is further amended to 
read: 
B. 
The dissolved oxygen content of Class C water may be not 
less than an instantaneous level of 5 parts per million or 
60% of saturation, whichever is higher, and not less than 
6.5 parts per million as a 30-day average: except that, for 
the period from October 1st to May 14th, in order to ensure 
spawning and egg incubation of indigenous salmonid species, 
the 7 -day mean dissolved oxygen concentration may not be 
less 
than 9.5 parts per million and the I-day minimum 
dissolved oxygen concentration may not be less than 8.0 
parts per million' in identified sa1monid spawning areas 
wheFe-~~--~Qality-~~-sQ~~ieieRt-~~-eRsQFe-~--e~~ 
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for the period March 1st to August 1st in order to ensure 
spawning 
and 
egg 
incubation 
of 
indigenous 
nonsalmonid 
species, the 7 -day mean dissolved oxygen concentration may 
not be less than 6.0 parts per million. 
Between May 15th 
and September 30th, the number of Escherichia coli bacteria 
of human or domestic livestock origin in these waters may 
not exceed a geometric mean of 146 126 per 100 milliliters 
or an instantaneous level of 949 2.l.2 per 100 milliliters. 
The board shall promulgate rules governing the procedure for 
designation of 
spawning areas. 
Those rules must 
include 
provision for periodic review of designated spawning areas 
and consultation with affected persons prior to designation 
of a stretch of water as a spawning area. 
Sec. 
4. 
Legislation. 
The 
Department 
of 
Environmental 
Protection shall recommend any needed changes related to the 
dissolved oxygen standard for estuarine and marine waters to the 
Joint Standing Committee 
on Natural Resources 
by January 1, 
2004. 
The Joint Standing Committee on Natural .Resources may 
report out legislation on this or related issues to the Second 
Regular Session of the 121st Legislature. 
SUMMARY 
This bill establishes requirements related to measurement of 
dissolved oxygen within riverine impoundments. 
This bill amends the bacteria criteria for Class B waters. 
This bill amends the dissolved oxygen standard and bacteria 
standard for Class C waters. 
This 
bill 
requires 
the 
Department 
of 
E:nvironmental 
Protection to 
recommend 
any needed changes 
to the dissolved 
oxygen standard for estuarine and marine waters to the Joint 
Standing Committee on Natural Resources by January 1, 2004 and 
authorizes the committee to report out related legislation to the