1. (1) The average 24-hour temperature gradient displayed during the 1961-1966 period may be interpolated from the following table, which is based on available records:

   Zone 2
   Date	RM 133.4 to 108.4	RM 108.4 to 95.0	RM 95.0 to 78.8
   (1)	(2a)	(2b)	(3a)	(3b)	(4a)	(4b)
   	°F	°C	°F	°C	°F	°C
   Jan. 1	37	2.8	41	5.0	42	5.6
   Feb. 1	35	1.7	35	1.7	36	2.2
   March 1	38	3.3	38	3.3	40	4.4
   April 1	46	7.8	46	7.8	47	8.3
   May 1	58	14.4	58	14.4	58	14.4
   June 1	71	21.7	71	21.7	72	22.2
   July 1	79	26.1	79	26.1	80	26.7
   Aug. 1	81	27.2	81	27.2	81	27.2
   Sept. 1	78	25.6	79	26.1	78	25.6
   Sept. 15	76	24.4	77	25.0	76	24.4
   Oct. 1	70	21.1	70	21.1	70	21.1
   Nov. 1	59	15.0	61	16.1	60	15.6
   Dec. 1	46	7.8	50	10.0	50	10.0
   Dec. 15	40	4.4	45	7.2	45	7.2

   (d) Zone 5.

   The induced increase above ambient temperature shall not exceed 4°F (2.2°C) from September to May and 1.5°F (0.8°C) from June to August, or a maximum of 86°F (30.0°C), whichever is less, which temperatures shall be measured outside of designated heat dissipation areas as described in subdivision (f) of this section.

   (e) Zone 6.

   The induced increase above ambient temperature shall not exceed 4°F (2.2°C) from September to May and 1.5°F (0.8°C) from June to August, or a maximum of 85°F (29.4°C), whichever is less, which temperatures shall be measured outside of designated heat dissipation areas as described in subdivision (f) of this section.

   (f) Heat dissipation areas.

   The limitations specified above may be exceeded by special permit in heat dissipation areas designated on a case-by-case basis, subject to the following conditions:

2. (1) Zones 1A, 1B and 1C.

   1. (i) Maximum length. As a guideline, heat dissipation areas shall not be longer than 1,000 feet, or 20 times the average width of the stream, whichever is less, measured from the point where the waste discharge enters the stream.
   2. (ii) Maximum width. Heat dissipation areas shall not exceed a maximum width of one-half the surface width of the stream or the width encompassing one-half of the entire cross-sectional area of the stream, whichever is less. Within any one heat dissipation area only one shore shall be used in determining the limits of the area.

3. (2) Zones 1D and 1E.

   1. (i) Maximum length. As a guidelines, heat dissipation areas shall not be longer than 3,500 feet, or 20 times the average width of the stream, whichever is less, measured from the point where the waste discharge enters the stream.
   2. (ii) Maximum width. Heat dissipation areas shall not exceed a maximum width of one-half the surface width of the stream or the width encompassing one-half of the entire cross-sectional area of the stream, whichever is less. Within any one heat dissipation area only one shore shall be used in determining the limits of the area.

4. (3) Zones 2, 3 and 4.

   1. (i) Maximum length. As a guideline, heat dissipation areas shall not be longer than 3,500 feet, measured from the point where the waste discharge enters the stream.
   2. (ii) Maximum width. Heat dissipation areas shall not exceed a maximum width of two-thirds the surface width measured from shore to shore at any stage of tide. Within any one heat dissipation area only one shore shall be used in determining the limits of the area.
   3. (iii) Maximum cross-section. Heat dissipation areas shall not exceed a maximum of one-quarter of the cross-sectional area of the stream.
5. (4) Zones 5 and 6. Maximum length. As a guideline, heat dissipation areas shall not be longer than 3,500 feet, measured from the point where the waste discharge enters the stream.

6. (5) All other zones.

   1. (i) Maximum length. As a guideline, heat dissipation areas shall not be longer than 1,000 feet, or 20 times the average width of the stream, whichever is less, measured from the point where the waste discharge enters the stream.
   2. (ii) Maximum width. Heat dissipation areas shall not exceed a maximum width of one-half the surface width of the stream or the width encompassing one-half of the entire cross-sectional area of the stream, whichever is less. Within any one heat dissipation area only one shore shall be used in determining the limits of the area.
7. (6) Adjacent heat dissipation areas. Where waste discharges would result in heat dissipation areas in such close proximity as to impair protected uses, additional limitations may be prescribed to avoid such impairment.

8. (7) Other considerations.

   1. (i) The rate of temperature change in designated heat dissipation areas shall not cause mortality of fish or shellfish.

   2. (ii) The determination of heat dissipation areas in tidal waters shall take into special consideration the extent and nature of the receiving waters so as to meet the intent and purpose of the criteria and standards, including provisions for the passage of free-swimming and drifting organisms so that negligible or no effects are produced on their populations.

      (g) Definitions.

9. (1) Ambient temperature is the temperature of a water body unaffected by the heated waste discharge or waste discharge complex.
10. (2) Natural temperature is the temperature of a water body unaffected by artificial sources of waste heat.
11. (3) Stream temperature is the temperature of the stream outside of the heat dissipation area.

(a) Trout waters.

In waters classified for trout use the discharge of waste effluent shall not increase the ambient temperature of the receiving waters by more than 5°F (2.8°C) until stream temperatures reach 50°F (10.0°C), nor by more than 2°F (1.1°C) when stream temperatures are between 50°F (10.0°C) and 58°F (14.4°C), nor shall such discharge result in stream temperature exceeding 58°F (14.4°C), which temperatures shall be measured in the stream outside of heat dissipation areas as described in subdivision (f) of this section.

(b) Other nontidal waters.

In nontidal waters other than described in subdivision (a) of this section, the discharge of waste effluents shall not increase the ambient temperature of the receiving waters by more than 5°F (2.8°C), nor shall such discharge result in stream temperature exceeding 87°F (30.6°C), which temperatures shall be measured in the stream outside of heat dissipation areas as described in subdivision (f) of this section.

(c) Zones 2, 3 and 4.

The induced temperature increase shall not exceed 5°F (2.8°C) above the average 24-hour temperature gradient displayed during the 1961-1966 period, or a maximum of 86°F (30.0°C), whichever is less, which temperatures shall be measured outside of designated heat dissipation areas as described in subdivision (f) of this section.