Ohio Integrated Water Quality Monitoring and Assessment Report

To view the draft 2014 Integrated Report, please see the 2014 tab below.

The Integrated Water Quality Monitoring and Assessment Report (also called the Integrated Report) indicates the general condition of Ohio's waters and identifies waters that are not meeting water quality goals.  The report satisfies the Clean Water Act requirements for both Section 305(b) for biennial reports on the condition of the State's waters and Section 303(d) for a prioritized list of impaired waters.  For each impaired water, Ohio EPA typically prepares a total maximum daily load (TMDL) analysis.

This current Integrated Report is available in the “2012” tab below.  U.S. EPA approved Ohio’s 2012 Section 303(d) list on May 8, 2012.

Ohio EPA submitted the final 2014 Integrated Report to U.S. EPA for approval on April 1, 2014; U.S. EPA has taken no action on the report to date. The final report as submitted is available on the "2014" tab below.

Summary of 2012 Report

Human Health Use (Fish Tissue)

The 2012 human health use (fish tissue) results are not appreciably different from the 2010 results.  Fish tissue data have been assessed in nearly every major (8 digit) hydrologic unit in Ohio.  Between one quarter and one third of the watershed assessment units assessed for human health use are in attainment of that use.  PCB contamination, primarily a result of historic industrial sources and old landfill discharges, is the cause of most of the human health use impairments.  Mercury is the second leading cause of human health use impairments after PCBs.

Recreation Use

For Lake Erie public beaches, the frequency of swimming advisories varies widely, ranging from 0% at Kelleys Island State Park beach to nearly 50% at Euclid State Park beach.  Generally, beaches located near population centers tend to have the most problems.

For inland streams, bacteria levels were low in about one in ten watersheds.  About three in ten watersheds had high levels of bacteria.  The remaining six in ten did not have enough data for evaluation.  Ohio’s 23 large rivers fare somewhat better, with about 20% having relatively low bacteria levels and 20% showing higher levels of bacteria.  About 60% did not have enough data collected in the past five years to evaluate.  High bacteria levels are often observed during periods of higher stream flows associated with heavy rains.

Aquatic Life Use

The upward trend in full attainment of the aquatic life use in both watersheds and larger streams continues.  In general, large rivers in Ohio are meeting aquatic life use goals at a much higher percentage than smaller streams.



Average Percentage of Watersheds

Attainment Percentage of Large Rivers 

Large river assessment units in Ohio reflected a slight decline in percent of monitored miles in full attainment compared to the same statistic reported in the 2010 IR.  Based on monitoring through 2010, the full attainment statistic now stands at 89% (793 of 852 assessed LRAU miles).  The slight decline in full attainment across LRAUs between the 2010 and 2012 IR cycles (93% to 89%) is largely because of new assessments in four large rivers, three of which flow through highly urbanized areas and receive large quantities of flow from wastewater treatment facilities.  The table below shows that all four of the large rivers have improved dramatically since first sampled in the early- to mid-1980s.


Year Studied

% of Stream

% of Aquatic Life Standard


























Scioto River











Great Miami
River (lower)











The following charts show the progress in attainment status of aquatic life statistics in recent years for both large rivers (upper) and watersheds (lower).

Public Drinking Water Supply Use

There are a total of 124 public water systems with 130 treatment plants using surface water (excluding Ohio River intakes).  Sufficient data were available to evaluate about one-third of the drinking water source waters for nitrate.

The only impaired areas were the Maumee River (the systems for the communities of Defiance, Napoleon, McClure and Bowling Green and the Campbell Soup system) and a portion of the Sandusky River (Fremont).  Some areas were identified for a watch list; all were located in the northwestern and central parts of the state.  It is difficult and expensive to remove nitrate from drinking water; some systems are conducting nitrate removal pilot studies, but no Ohio surface water systems currently use treatment specific for nitrate removal.  Ohio public water systems rely on blending the surface water with other sources such as ground water, selective pumping from the stream to avoid high nitrate levels by using off-stream storage in upground reservoirs, or issue public notice advisories warning sensitive populations to avoid drinking the water while nitrate levels are high.  The primary sources of elevated nitrate are nonpoint source runoff from agricultural land use and home/commercial fertilizer application, failing septic systems and unsewered areas, and wastewater plant discharges.

Pesticides could be evaluated for about 14% of the drinking water source waters.  Five of 18 areas were identified as impaired, all in southwestern Ohio: one in Brown County (Mt.  Orab), one in Miami County (Piqua), and the three sources used by the Village of Blanchester in Warren and Clinton counties.  Thirteen areas were identified for a watch list because of elevated atrazine.  The primary source of atrazine in these watersheds is nonpoint source runoff from agricultural land use.


Section 305(b) of the Clean Water Act requires states to produce "Water Quality Inventories" that assess progress in achieving the objectives of the Act.  Since the first Ohio 305(b) report was produced in 1988, the reports have evolved to reflect program advances and changes in federal guidance.

In 1990, Ohio changed the title of the report from "Water Quality Inventory" to "Water Resource Inventory."  The change reflects an ecosystems emphasis rather than reliance on water chemistry alone.  The effects of human activity on aquatic ecosystems are broad, and extend beyond water chemistry to include physical and biological impacts.  While chemical water quality remains an important component, it is necessary to consider additional impacts if the Clean Water Act goals of protecting and rehabilitating aquatic resources are to be realized.  Using the 305(b) reports, Ohio EPA prepared lists of impaired waters (Section 303(d) lists) in 1992, 1994, 1996 and 1998.

Federal guidance issued in November 2001 recommended that States prepare Integrated Reports that would satisfy the Clean Water Act requirements for both Section 305(b) water quality reports and Section 303(d) lists.  In 2002, Ohio produced its first Integrated Water Quality Monitoring and Assessment Report and continues this practice today.  Reporting on Ohio's water resources continues to develop, including more data types and more refined methodologies.  The basic framework for this report is built on four beneficial uses:

  • Aquatic life
  • Recreation
  • Human health
  • Public drinking water supply

Finding Information on This Page

The reports are organized in tabs below, described here:

  • Earlier versions of the Section 305(b) water quality reports, also known as Water Resource Inventories, are on the Ohio Water Resource Inventories tab.
  • Integrated Reports from 2002 through 2008 are combined into one tab.  For each of these report cycles, the watershed assessment unit was the 11-digit hydrologic unit.
  • The 2010 Integrated Report contained numerous changes to the methodologies and a change in the size of the watershed assessment unit from the 11-digit hydrologic unit to the 12-digit hydrologic unit.  A summary of the changes made, as well as access to the report, are available in the 2010 tab.
  • The 2012 Integrated Report contains the most current approved 303(d) list of impaired waters and is on the 2012 tab.