Document: NRC Regulatory Guide
Document ID: 0b3f08e9-b342-468d-a869-a00f19278ecb
Document Type: regulatory_guide
Title: Normal Water Level and Discharge at Nuclear Power Plants
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740143.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.135
CFR Part: 
CFR Title: 

Content:
le if longer records do not exist and it can be demonstrated that the period used in cludes major wet and dry periods. 5. Regulated Lakes and Reservoirs Normal water level should be the designated nor mal pool elevation. There may be different designated normal pool elevations at different times of the year. If the reservoir contains flood control space, the normal water level during the flood season should be the median of the flood levels attained dur ing the life of the reservoir. 6. Oceans For events of short duration (a half hour or less), normal water level should be the median tide based on a 20-year period of record. If the event may have a longer duration, normal water level should be the me dian higher high tide or median lower low tide based on a 20-year period of record. Choice of higher high or lower low tide should be the most conservative for the event being considered and its consequences. 7. Estuaries Normal water level should be the median level based on a 20-year period of record. For longer duration events, median higher high or lower low tide based on a 20-year period of record should be sub stituted for median tide level. 8. Ground Water Normal ground water level should be the median level based on 20 years of data. If permanent lower ing of the ground water level by using underdrains is planned, normal level should be the design lowered level. 9. Availability of Data If the minimum periods of record specified in the foregoing positions are not available, standard methods may be used to transpose or extend the available data. Full explanations of the methods used for such procedures should be furnished. D. IMPLEMENTATION The purpose of this section is to provide informa tion to applicants regarding the NRC staffs plans for using this regulatory guide. Except in those cases in which the applicant proposes an acceptable alternative method for com plying with specified portions of the Commission's regulations, the method described herein will be