Maine Legislature, Session 121, LD 1137
Committee Amendment CA_A_H350 (House)
Amends: 38 MRSA §464

COMMITTEE AMENDMENT ,,/J(, to H.P. 840, L.D. 
Regarding Riverine Imp!.f~ents" 
1137, Bill, "An 
Amend the bill by striking out everything after the enacting 
clause and before the summary and inserting in its place the 
following: 
'Sec. 1. 38 MRSA §464, sub-§13 is enacted to read: 
13. 
Measurement 
of 
dissolved 
o~gen 
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 below the 
higher of: 
(1) 
The point of thermal stratification when 
such 
stratification occurs; or 
(2) 
The 
point 
proposed 
by 
the 
department 
as 
an 
alternative depth for a specific riverine impoundment 
based 
on 
a11 
factors 
included 
in 
section 
466, 
subsection ll-A 
and 
for 
which 
a 
use 
attainability 
analysis is conducted if reguired by the United States 
Environmental Protection Agency. 
COMMITTEE AMENDMENT 
COMMITTEE AMENDMENT ,j)r. to H,P, 840, L.D. 1131 
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 topographical 
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 
sufficient to support existing and designated uses of these 
waters. 
For purposes of this subsection, 
"existing riverine 
impoundments" means all impoundments of riyers and streams in 
existence as of January L 
2001 and not otherwise classified as 
~' 
SUMMARY 
This 
amendment 
establishes 
requirements 
related 
to 
measurement of dissolved oxygen within riverine 
impoundments. 
The 
amendment provides that compliance with dissolved oxygen 
criteria in riverine impoundments may not be measured within .5 
meters of the bottom of the riverine impoundment. 
Where mixing 
is inhibited due 
to 
thermal stratification, 
compliance with 
numeric dissolved oxygen criteria may not be measured below the 
higher of the point of 
thermal stratification or the point 
proposed by the Department of Environmental Protection as an 
alternative depth based on all factors that would be included in 
a use attainability analysis and for which a use attainability 
analysis 
is 
conducted 
if 
required 
by 
the 
United 
States 
Environmental Protection Agency. 
Where mixing is inhibited due 
to natural topographical features in a 
riverine 
impoundment, 
compliance with numeric dissolved oxygen criteria may not be 
measured within the portion that is isolated. 
COMMITTEE AMENDMENT