Current through Register Vol. 54, No. 50, December 14, 2024
Section 105.113 - Releases(a) The Department will impose general and special conditions regarding release rates in a permit for a dam or reservoir that it deems necessary to maintain stream flows for the purposes of protection of public health, water quality control, conservation of fisheries and aquatic habitat, improvement of recreation and protection of instream and downstream water uses. The appropriate release rates for the dams and reservoirs will be established in accordance with subsections (b) and (c).(b) For dams or reservoirs constructed after August 28, 1978:(1) The minimum release rate unless modified in accordance with paragraph (2) shall be the average consecutive 7 day flow having a recurrence interval of once in 10 years (Q 7-10) plus an additional release rate determined by the following formula: | Release rate (csm) | = | Q7-10 + PDF(.25 csm-Q7-10 csm) |
| where PDF | = | the percentage factor based on the storage capacity of the reservoir measured as percent of average annual runoff retained in the reservoir. This factor is explained in Planning Principles, State Water Plan SWP-1 (March, 1975). |
| .25 csm | = | .25 cubic feet per second of flow per square mile of watershed. |
| Q7-10csm | = | The seven-day, ten-year flow, in cubic feet per second per square mile of watershed. |
| The minimum release rate determined by this formula shall not exceed 0.25 cubic feet per square mile of watershed. |
(2) The Department may modify the minimum release rate, or provide variable schedules or releases considering the following factors:(i) The purposes stated in subsection (a).(ii) Particular stream requirements, including the particular needs of instream and downstream water uses and riparian rights.(iii) The particular uses and purposes of the dam or reservoir.(iv) The particular engineering, hydrologic and economic factors affecting the ability of the dam or reservoir to provide the releases.(c) For dams and reservoirs constructed prior to August 28, 1978, the Department will determine a reasonable schedule for release rates, considering all of the following: (1) The purposes stated in subsection (a) and the particular needs of instream and downstream water uses on the affected stream.(2) The capacity of existing release works at the dam and feasibility of potential modification of the release works.(3) The yield of the reservoir, and its capability to meet release requirements and satisfy the purposes and uses of the reservoir.(d) Every dam must at all times be operated in a manner to allow the required flow of water into the stream below the dam as established under this section, and as otherwise necessary to support fish and other aquatic life and to assure compliance with the water quality standards in Chapter 93 (relating to water quality standards) and to provide for other instream uses for the affected stream.The provisions of this § 105.113 adopted September 10, 1971, effective 9/11/1971, 1 Pa.B. 1804; amended August 11, 1978, effective 8/28/1978, 8 Pa.B. 2229; amended September 26, 1980, effective 9/27/1980, 10 Pa.B. 3843; amended January 7, 2011, effective 1/8/2011, 41 Pa.B. 219.The provisions of this § 105.113 amended under section 5 of the Dam Safety and Encroachments Act (32 P. S. § 693.5).