( NOTICE: This is an excerpt from the the rules and regulations intended to carry out the purposes of the Dam Safety Law of 1967. If you wish to view the full text under SubChapter K, please go to an unofficial site for N.C. Administrative Code, or view it at the Division of Land Resources, Dam Safety Program site. )

( NOTE: The Division of Environmental Management (DEM) was reorganized, and the relevant agency is now the Division of Water Quality (DWQ). )

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SECTION .0500 - MINIMUM STREAM FLOWS TO MAINTAIN AQUATIC HABITAT 

.0501 DEFINITIONS

(a) Aquatic habitat shall be divided into three classes -
"poor," "moderate," and "good." 
(1) Streams with poor aquatic habitat are those which have
a "poor" fish assemblage rating, and which are rated "poor"
for at least two of the following three characteristics: 
(A) Substrate; 
(B) Cover; and 
(C) Macro-invertebrate organisms. 
(2) Streams with moderate aquatic habitat are those which
exhibit physical conditions and biota which are intermediate 
between the poor and good categories. 
(3) Streams with good aquatic habitat are those which
receive at least two "good" ratings when the substrate, 
cover, and macro-invertebrate organism characteristics are 
evaluated. The fish assemblage also must receive a "good"
rating. 
(b) Cover means objects within or overhanging the stream
channel which provide shelter for aquatic organisms.  "Good"
cover occurs when cover is widespread and diverse.  "Poor" 
cover occurs when the amount of cover is small or non-existent. 
(c)   Substrate means the predominant particle size of the
material which makes up the stream bed.  "Good" substrate is 
composed of at least 50 percent silt free substrate with gravel
or cobble.  "Poor" substrate is composed of at least 80 percent
silt, sand, or smooth bedrock. 
(d)   The macro-invertebrate organisms of the affected reach
are rated as "good" if the affected reach is rated good or
excellent in the Division of Environmental Management's (DEM)
biological monitoring database, or by a site-specific survey
according to Standard Operating Procedures for Biological
Monitoring, 1995, Division of Environmental Management as 
defined in 15A NCAC 2B .0103(b).  Macro-invertebrates are rated
"poor" if the reach is rated fair or poor in DEM's biological
monitoring database, or by a site-specific survey according to
Standard Operating Procedures for Biological Monitoring, 1995,
Division of Environmental Management as defined in 15A NCAC 2B
.0103(b).
(e)   The fish assemblage rating shall be based on the North
Carolina Index of Biotic Integrity (IBI).  Existing ratings
from the DEM biological monitoring database shall be used where
available.  If no rating exists, then a site-specific survey
shall be conducted according to Standard Operating Procedures
for Biological Monitoring, 1995, Division of Environmental
Management as defined in 15A NCAC 2B .0103(b).  The fish
assemblage shall be rated as "good" if the IBI rating is good,
good-excellent, or excellent.  The fish assemblage shall be 
rated as "poor" if the IBI rating is poor or lower. 
(f)   The affected reach of stream means that section of a
stream downstream of a dam which experiences significant changes
in hydrology.  The exact delineation of the affected reach shall
be site-specific and depend on factors including, but not
limited to: 
(1) volume of storage in the impoundment; 
(2) upstream and downstream hydrologic characteristics of
the stream; 
(3) withdrawals from the impoundment; and 
(4) downstream point source discharges to the stream. 
For the purpose of evaluating aquatic habitat, the affected
reach of a stream does not include any portion which is in the
backwater of a downstream dam when the level of that downstream
impoundment is at normal pool.
(g)   "Special case" streams are those which exhibit at least
one of the following characteristics: 
(1) supplemental classification as an Outstanding Resource
Water as defined in 15A NCAC 2B .0101(e)(4) and .0216;  
(2) populations of aquatic species listed as threatened or
endangered by the U.S. Fish and Wildlife Service, or species
which are listed as threatened or endangered by  the N.C.
Wildlife Resources Commission; 
(3) self-sustaining populations of wild trout; or  
(4) exceptional non-game or fishery resources as determined
by the Wildlife Resources Commission. 
(h)   The use of the regression equations in Rule .0502 of
this Section shall depend on the geographic region of the
state in which the stream is located.  The geographic region
shall be determined from the North Carolina Atlas, edited by
Clay, Orr, and Stuart, published by the University of North
Carolina Press, 1975. 
(i)   A continuous stream gage record means a continuous
record of daily flows from a stream gage which: 
(1) has at least 15 years of continuous daily records; 
(2) has no significant hydrological effects caused by
upstream regulation, withdrawals, or discharges; 
(3) is no less than one-half and no more than one and
one-half times the drainage area of the site in question; and 
(4) has low flow and average flow yields which are comparable
to the site in question. 
(j)   A site-specific instream flow study conducted by the
applicant or his consultants, which is subject to approval by
the Department, means a study performed according to the 
following conditions: 
(1) A plan of study shall be developed in consultation with
the Department and submitted to the Department for review and
approval prior to commencement of the study. 
(2) The plan of study shall identify the aquatic habitat
parameters to be evaluated by the study.  The selection of
these parameters shall depend on factors including, but not 
limited to: 
(A) the aquatic species being evaluated; 
(B) the habitat quality of the affected reach; and 
(C) existing or potential water shortages or water use
conflicts. 
(3) The Department shall have the option of participating in
the collection of all field data, and shall be notified prior
to collection of any set of data. 
(4) The results of the study shall accurately determine the
parameters identified during study design. 
(5) The Department may review the field data and results of
these studies to determine the stream flow needed to maintain
aquatic habitat. 

History Note: Statutory Authority G.S. 143-215.24; 43-215.25;
 143-215.31; 143-215.32; 143-215.33; 143-215.36; 
Eff. December 1, 1994; 
Amended Eff. April 1, 1995. 

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