Combined 2018/2020 Integrated Report

The Combined 2018/2020 Integrated Report (IR) assesses the quality of the surface waters in the state and identifies waterbodies that are not meeting water quality standards. These standards support the designated beneficial uses that protect water quality for drinking water, recreation, aquatic life, and agriculture. Waterbodies that do not meet one or more of their beneficial uses are classified as impaired in the IR and placed on the Clean Water Act 303(d) list.

The water quality data used for the Combined 2018/2020 IR cover the period between October 1, 2010, and September 30, 2018. DWQ held a public comment period from November 7, 2018, to December 21, 2018, on the 303(d) assessment methods. These assessment methods are included in the IR but are outside the scope of the current public comment period.

The Draft Combined 2018/2020 Integrated Report was open for a 60-day public comment period that began on October 21, 2020, and ended on December 21, 2020. DWQ responded to public comments on February 9, 2021, and in some cases edited the IR based on feedback. DWQ’s response to comments, the 305(b) report, and 303(d) listing decisions were submitted to EPA for approval on February 25, 2021. EPA approved the Combined 2018/2020 Integrated Report on August 8, 2021.

The Combined 2018/2020 Integrated Report (IR) compiles all existing, credible, and readily available data to determine whether water quality is sufficient to meet the beneficial uses assigned to Utah’s waters. The report is divided into four main sections:

  • Executive Summary: Overview of the IR
  • Chapter 1: Assessment methods (previously released for public comment)
  • Chapter 2: Assessments specific to lakes and reservoirs
  • Chapter 3: Assessments specific to rivers and streams.

The IR helps DWQ prioritize limited resources to address water quality problems efficiently and effectively. Remediation plans such as total maximum daily loads (TMDLs) and nonpoint source projects are developed to help impaired waters meet water quality standards and support beneficial uses.

A river or stream, for purposes of the integrated Report (IR), is defined as flowing surface water moving under the force of gravity. Flowing surface waters include perennial, intermittent, and ephemeral surface waters, springs, and seeps, provided they are flowing and connect, contribute, or are influencing water quality in a downstream river or stream. Canals are also included in this assessment if they are identified in site-specific numeric criteria or named on the list of waters with designated beneficial use classifications in state regulation.

Utah assesses surface waters of the state at the monitoring-site level and then summarizes the site-level assessments up to a larger spatial scale (i.e., the Assessment Unit (AU) scale). Flowing surface waters of the state and canals are delineated by specific rivers or one or more surface water reaches in subwatersheds.

Lakes and reservoirs, for the purposes of the Integrated Report (IR), are inland bodies of standing fresh or saline water that are generally too deep to permit submerged aquatic vegetation to take root across the entire waterbody. Expanded parts of a river or natural lake, a reservoir behind a dam, or a natural or excavated depression containing a waterbody without a surface water inlet and/or outlet are included in this assessment type.

Utah assesses surface waters of the state at the monitoring-site level and then summarizes the site-level assessments up to a larger spatial scale (i.e., the Assessment Unit (AU) scale). Lakes, reservoirs, and ponds have been delineated as individual AUs, and their size is reported in acres.

Map Instructions

Click the assessment unit polygons for draft assessment information. Hover over the layers button to turn on and off assessment category polygons. The “Reset View” button will set the map to its original bounds around the state of Utah. Use the “Search” box to look up assessment units by name or assessment unit ID.

By the Numbers

Data Reviewed

  • Number of data records downloaded from EPA’s Water Quality Portal: 1.36 million
  • Number of data records that passed screening and data preparation checks for assessment: 432,280
  • Number of data records rejected during the secondary review process: 35,281
  • Number of data records in the core assessment dataset for the period of record following screening, secondary review, and daily aggregation: 348,003
  • Number of unique assessments by site, use, parameter, and criterion: 61,388

Assessment Totals (Flowing Surface Waters of the State, Canals, Lakes, Reservoirs, and Ponds)

  • Total AUs reported on: 913
  • Total AUs fully supporting (Category 1): 80
  • Total AUs partially supporting (Category 2): 133
  • Total AUs with insufficient data (Category 3): 321
  • Total AUs with a plan in place (Category 4): 32
  • Total AUs impaired (Category 5): 347

Questions and Comments

Jodi Gardberg (
Watershed Protection Section Manager
(801) 536-4372