( 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. )

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SECTION .0500 - MINIMUM STREAM FLOWS TO MAINTAIN AQUATIC HABITAT 

.0503 REQUIRED MINIMUM FLOW FOR SMALL HYDROELECTRIC PROJECTS 

(a) This Rule shall apply only to a dam operated by a small
power producer, as defined in G.S.  62-3(27a), that diverts
water from 4,000 feet or less of the natural stream bed.  The
length of the bypassed reach shall be measured from the toe
of the dam to the point where the diverted water re-enters
the natural channel, following the centerline of the natural
channel. 
(b)   The minimum release for a hydroelectric project
subject to this Rule shall be determined according to the
procedures described in Subparagraphs (1)-(5) of this
Paragraph.  If at any time the inflow just upstream of the
dam is less than the minimum flow required in the bypassed
reach, then the minimum flow may be reduced to a level
equal to this inflow. 
(1) If the aquatic habitat in the bypassed reach is rated poor,
then the minimum release to the bypassed reach shall be
determined as follows:  
(A) If the 7Q10 is less than or equal to 10 percent of the
mean annual daily flow, then the minimum release to the
bypassed reach shall be the 7Q10 flow. 
(B) If the 7Q10 is greater than 10 percent of the mean
annual daily flow, and there are no existing point  source
discharges of wastewater to the bypassed reach, then the
minimum release to the bypassed reach shall be 0.8 times
the 7Q10. 
(C) If the 7Q10 is greater than 10 percent of the mean
annual daily flow, and one or more existing point source
discharges of wastewater enter the bypassed reach, then the
minimum release to the bypassed reach shall be the 7Q10
flow. 
(2) If the bypassed reach does not have an aquatic habitat
rating of "poor," is not on a special case stream, and is
located in the piedmont region, as defined in Rule .0501(h)
of this Section, then the minimum release to the bypassed
reach shall be determined as follows: 
(A) If the 7Q10 is less than or equal to six percent of the
mean annual daily flow, then the minimum release to the
bypassed reach  shall be 3.0 times the 7Q10 flow. 
(B) If the 7Q10 is greater than six percent of the mean
annual daily flow, and less than or equal to 10 percent of the
mean annual daily flow, then the minimum release to the
bypassed reach shall be 2.2 times the 7Q10 flow. 
(C) If the 7Q10 is greater than 10 percent of the mean
annual daily flow, then the minimum release to the 
bypassed reach shall be 1.2 times the 7Q10 flow. 
(3) The minimum flow determined by the procedures
described in Subparagraphs (1) and (2) of this Paragraph
may be adjusted downward by the Department if that
adjustment would not result in significant loss of aquatic
habitat.  This adjustment may be based on factors including: 
(A) the type of aquatic habitat present in the bypassed
reach; 
(B) the length of the bypassed reach. 
(4) If the applicant or owner disputes the minimum flow
determined by the procedures described in Subparagraphs
(1) and (2) of this Paragraph, he may undertake a
site-specific field study, as defined in Rule .0501(j) of this
Section, subject to the review and approval of the
Department.  The final minimum release required will not
exceed the amount determined by the procedures described
in this Section. 
(5) The minimum flow for a dam on a special case stream,
or on a stream located in the mountain region, as defined in
Rule .0501(h) of this Section, which does not exhibit poor
aquatic habitat; shall be determined by a site-specific
instream flow study, as defined in Rule .0501(j) of this
Section.  This study shall be conducted by the applicant or
his consultants, and shall be subject to approval by the
Department. 
(c)   A dam operated by a small power producer, as defined
in G.S. 62-3(27a), which was operating to produce power
as of October 13, 1994, and which is not under the
jurisdiction of the Federal Energy Regulatory Commission,
shall not be required by this Rule to increase its minimum
flow above the amount required on October 13, 1994. 

History Note: Statutory Authority G.S. 143-215.24;
143-215.25; 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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