Regulation No.31 - The Basic Standards and Methodologies for Surface Water

Oct 4, 2026

Uploaded by iuabcfuw

Water quality standards in effect for Clean Water Act purposes are provided, including a framework of basic standards, an antidegradation rule, and procedures for classifying Colorado surface waters. The regulation sets out how beneficial use categories and numeric tables define conditions to maintain and attain those uses. It describes assignment of classifications through proper processes such as public hearings, allowance for additional numeric standards, and implementation through mechanisms like control regulations, TMDLs, Waste Load Allocations, antidegradation reviews, and permits, while detailing oversight and review at least every three years.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages280

Reading Time11 h 46 min

AccessFree to download

31.1 Authority and Scope

31.2 Purpose

31.3 Introduction

31.4 Deleted

31.5 Definitions

Presented below are water quality standards that are in effect for CleanWater Act purposes. EPA is posting these standards as a convenience to users and has madea reasonable effort to assure their accuracy.Additionally,EPA has madea reasonable effort to identify parts of the standards that are notapproved,disapproved,or are otherwise not in effect for Clean WaterAct purposes. January 28,2025 Regulation No.31-The Basic Standards and Methodologies for Surface Water Effective November 25,2024 The following provisions are in effect for Clean Water Act purposes with these few exceptions: EPA has taken no action on: July 12,2023 · Other“phased application”WQS provisions which narrow the universe of circumstances whereadoption of standards for TN and TP may be considered prior to December 31,2027. ·Non-substantive(formatting only)changes to the river/stream TVS for TN and TP in Table VI. o The non-substantive changes included:a)relocation of the values from 31.17(b)and(c)toTable VI,b)changes in terminology(e.g.,the term“TVS”was adopted as a replacement forthe term“interim value”),and c)changes to the informational/explanatory footnotes toTable VI. December 31,2021 ·Section 31.7(4)(c)provisions as EPA determined those provisions are not WQS,except for the firstsentence that reads“A discharger-specific variance applies only to the point source discharge andpollutant(s)specified in the variance”,which was approved. ·Section 31.9(4)provisions as EPA determined those provisions are not WQS. July 14,2016 ·Total Phosphorus and Total Nitrogen interim values for rivers and streams(31.17(b)and(c)).o Note that EPA's 2023 Approval moved these items,but EPA stillhas not taken action. ·Phased application provisions(31.17(e),(f),and(g)) o Note that EPA's 2023 Approval moved these items,but EPA still has not taken action. EPA has disapproved: December 8,2011 ·The 300μg/Lmolybdenum table value for the protection of agriculture uses. COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT Water Quality Control Commission REGULATION NO.31-THE BASIC STANDARDS AND METHODOLOGIES FOR SURFACE WATER 5 CCR 1002-31 [Editor's Notes follow the text of the rules at the end of this CCR Document.] # 31.1 AUTHORITY AND SCOPE This requlation is promulgated pursuant to 25-8-101 et seq..and in particular.25-8-203 and 25-8-204. C.R.S.It provides basic standards,an antidegradation rule and implementation process,and a system:for classifying state surface waters;for assigning water quality standards;for granting temporarymodifications and for periodic review of the classifications and standards. # 31.2 PURPOSE This regulation establishing basic standards and an antidegradation rule and implementation process andestablishing a system for classifying state surface waters,for assigning standards,and for grantingtemporary modifications(hereinafter referred to as “Regulation”)is the foundation for the classification ofthe state surface waters of Colorado,as prescribed by the Colorado Water Quality Control Act. It is intended to implement the state Act by maintaining and improving the quality of the state surfacewaters.This regulation is based on the best available knowledge to insure the suitability of Colorado'swaters for beneficial uses including public water supplies,domestic,agricultural,industrial andrecreational uses,and the protection and propagation of terrestrial and aquatic life. It is further intended to be consistent with the 1983 and 1985 goals and objectives of the federal Act.Thisregulation shall be constructed in a manner consistent with these purposes and shall be considered partof the implementation of the 1983 and 1985 goals and objectives. # 31.3 INTRODUCTION This regulation presents a classification system which establishes beneficial use categories together withbasic standards (section 31.11),an antidegradation rule (section 31.8),and numeric tables which definethe conditions generally necessa

FAQs

What standards and rules are established by Regulation No. 31 for Colorado surface waters?

The regulation establishes basic standards, an antidegradation rule, and numeric tables defining conditions necessary to maintain and attain beneficial uses.

How are water quality classifications and standards assigned under this regulation?

Classifications are assigned by applying the system to specific state surface waters using proper procedures, including public hearings, and then assigning additional numeric standards when appropriate.

How often must water quality classifications and standards be reviewed?

Water quality standards, temporary modifications of numeric standards, and classifications must be reviewed at least once every three years and revised where appropriate.

Oct 4, 2026

Uploaded by iuabcfuw