SI-2F (2/23/05 version)
Environmental Targets And Priorities, Stream Integrity, Stream/Watershed Components: Lakes


There are approximately 50,000 lakes and small ponds in Ohio with a total surface area of about 200,000 acres (ODNR, unpublished). About 2200 of these lakes are 5 acres or greater with a total surface area of 134,000 acres (ODNR, 1980). These 2,200 lakes include both public and private lakes. The USEPA estimated (from an electronic file generated from 1:100,000 scale maps) that Ohio has 5,130 lakes totaling 188,461 acres (USEPA 1991). The difference in number of lakes estimated by USEPA and ODNR is likely related to numerous small ponds (high number, small acreage) not detected on the 1:100,000 scale maps.

There are 447 lakes with public access and 5 or more acres of surface area in Ohio. Lakes (51) where public fishing is available are listed at

Of the 447 public lakes, there are 186 public reservoirs of 2 hectares (5 acres) or larger. Among these are 125 tributary reservoirs, 57 upground reservoirs, and 6 canal lakes. Small impoundments, less than 82 hectares (203 acres), are either tributary or upground reservoirs.

Current Situation

The Ohio Lake Management Society (OLMS) , a State Chapter of the North American Lake Management Society (NALMS), is a non-profit organization dedicated to the protection of Ohio lakes and their watersheds.

Whether man-made, the result of damming a river for flood control, or naturally occurring, the focus of lake management in Ohio is on recreational uses, and, in some cases, as a drinking water supply. The negative impact of NPS on these uses is often significant. In some cases, the management of lake outflow (and the water quality of that outflow) through a dam can have profound effects on downstream ability to assimilate NPS pollutants and to support designated aquatic life uses.

There is no consistent protocol that has been used to assess the condition of all of Ohio Lakes over time. However, a number of assessment tools, as outlined below have been used for a sub-set of Ohio lakes. The indicators used are dependent on the water resource use that is being evaluated.

  • Citizen Lake Awareness and Monitoring (CLAM).

    Per a February 2005 status report on the Ohio Water Resources Council (OWRC) 4-year Strategic Plan, 117 citizen volunteers monitor 40 Ohio lakes regularly for color and clarity using secchi disk depth readings. Unfortunately, the destiny of the citizen monitoring program is uncertain due to lack of funding and diminishing in-kind contributions from current and former project partners.

  • Reservoir Sampling Program

    In 2003, the Ohio Department of Natural Resources, Division of Wildlife, implemented a standardized sampling program (Inland Management System) (PDF 242kb) to assess the status of primary sportfishes in Ohio reservoirs. The focus of this sampling program is to provide data to support maintenance of the inland sport fishery in Ohio.

    A standard set of data is collected on a small subset of reservoirs every year (reference reservoirs) and all remaining reservoirs (systematic reservoirs) at varying frequencies during a six-year cycle. In addition, the creel survey program was recently revised and streamlined to allow for data collection at approximately 30 reservoirs annually, using a similar "reference" and "systematic" reservoir approach. All data are recorded in a centralized database (Ohio Fisheries Information System), (PDF 1825kb). In 2005, a lower trophic level sampling program will be added.

  • Lake Conditions Index (LCI)

    Historically, Section 314 of the Clean Water Act required that each state report on the overall condition of its public lakes including trophic state, impaired/threatened uses, impact from toxic chemicals, and status and trends of water quality. Specifically, lakes were to be classified into one of five possible use attainment categories: 1) insufficient data, 2) full use attainment, 3) full use attainment, but threatened, 4) partial use, non- attainment, and 5) impaired use, non-attainment.

    To meet the above-mentioned requirements, Ohio EPA developed and applied the Lake Condition Index (LCI) to characterize overall lake health and to assess beneficial use status of all 447 public lakes, documenting the results in the 1996 Section 305(b) report (PDF 1738kb). For each Ohio public lake, separate use assessments were made for: 1) aquatic life use support, 2) recreational use support, 3) public drinking water supply use support and 4) fish tissue consumption use support.

    From 1996 to the present, Ohio EPA has monitored 53 lakes, but LCI scores have not been calculated. Although the LCI methodology was later revised to address changes in the interpretation of the threatened use and the full use attainment categories, the current implications of identifying a lake as impaired with the necessity of a TMDL were not anticipated. Thus, uncertainty exists about how a lake sampled in the early 1990s and characterized as "threatened" should be categorized under the present regulations and guidance on Section 303(d) listings.

    Water quality in lakes will be evaluated as TMDLs are developed for various WAUs that have inland lakes. Some examples include, Grand Lake St. Marys (includes HUC codes 05120101-020 (PDF 9kb) and 05120101-030 (PDF 9kb) and Alum Creek/Hoover Reservoir (includes HUC codes 05060001-130 (PDF 9kb) and 05060001-150 (PDF 9kb).

    For more details, see Section 6.2.3 "Inland Lakes and Reservoirs" of the 2004 Integrated Water Quality Report.

  • Wetlands Assessment

    Many natural inland lakes in Ohio have extensive wetland communities around their perimeters, or are shallow enough that the entire "lake" is a jurisdictional wetland. Therefore, Ohio EPA uses the Ohio Rapid Assessment Method for Wetlands and Vegetation Index of Biotic Integrity for Ohio Wetlands to assess the condition and regulatory protection category of these waters.

NPS Related Lake Assessment Findings