Little Miami River Watershed

Little Miami River watershedThe Little Miami River watershed is located in southwestern Ohio.  It drains a total of 1,758 square miles and flows through all or part of 11 counties.  Major municipalities partially or fully in the watershed include Xenia, Beavercreek, Wilmington, and Cincinnati and some of its suburbs.

The eastern portion of the watershed is predominantly comprised of cultivated crops with pockets of forest and pasture and hay lands.  The western portion of the watershed is a mixture of forest, hay and pasture lands and urban development.

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Little Miami River (upper) Watershed

Little Miami River (upper) watershedThe Little Miami River (LMR) is located in southwestern Ohio in the Ohio River drainage basin.  The LMR (upper) watershed includes the catchment area upstream from, and including, the Caesar Creek subbasin.  Covering portions of six counties (Clark, Greene, Warren, Clinton, Montgomery, and Madison) and draining approximately 657 square miles, the topography of this northern section has been influenced by glaciation which left distinctive land forms and thick deposits of silt, sand, and gravel.  In addition to Caesar Creek (drainage area of 242 square miles), major tributaries include Massie Creek and Beaver Creek.  Impoundments in the watershed include Caesar Creek Reservoir (6,110 acres) and Lake Shawnee (190 acres) on Caesar Creek and the Clifton dam (RM 89.15) and Corwin lowhead dam (RM 55.3) on the LMR mainstem.

Designated a State and National Scenic River, the Little Miami River main stem contains some of Ohio’s most scenic and diverse riverine habitat and is a popular recreational resource.  Additionally, the LMR flows atop a buried valley aquifer composed of highly permeable sands and gravel.  This aquifer is the major water source for the area and has been designated a Sole Source Aquifer by the U.S. EPA.  The City of Wilmington, located outside the study area, also utilizes water from Caesar Creek Reservoir.

Excluding the Dayton-Xenia corridor where population density and urban land use is highest, land use is comprised mostly of agriculture.  Residential and commercial development pressures, however, continue to rapidly increase throughout much of the watershed.  This change in land use is reflected in both point and nonpoint source impacts to the watershed.


The Little Miami River is located in southwest Ohio.  The upper portion of the watershed was studied during 2011 as follow-up to the 2002 TMDL report.  The Little Miami River flows into the Ohio River at Cincinnati in Hamilton County.  The Little Miami River (upper) watershed’s southwestern boundary is in Warren County.  The upper watershed is divided into five subwatersheds, as follows:

  • 05090202 01 Headwaters Little Miami River
  • 05090202 02 Massies Creek-Little Miami River
  • 05090202 03 Anderson Fork
  • 05090202 04 Caesar Creek
  • 05090202 05 Sugar Creek-Little Miami River

The Upper Little Miami River Total Maximum Daily Load (TMDL) report was approved by U.S. EPA on July 2, 2002.  TMDLs identify and evaluate water quality problems in impaired water bodies and propose solutions to bring those waters into attainment.

The primary causes of impairment in the upper Little Miami River watershed are nutrient enrichment, low instream dissolved oxygen, sedimentation, and habitat degradation.  TMDLs were calculated for total phosphorus and sediment.  Habitat degradation and dissolved oxygen depletion are not load based quantities; however, the regulations provide for these types of impairing causes and ‘TMDL’ numbers were calculated for these as well.  The Little Beaver Creek sub-basin is uniquely impaired by metals and organic compounds in addition to the causes listed above.  TMDL endpoints for these additional pollutants were also calculated.

The final report reflects comments made during the first and second public comment periods; the significant differences from the second draft of the report are:

  • the margin of safety discussion was expanded and clarified

  • the POTW suggested implementation plan was included

  • some of the NPDES language was clarified

  • Appendix E includes the comments from the second draft period as well as the first

The first draft was different from the original document that was public noticed in early 2001; it was changed in the following ways: elimination of total nitrogen allocations, addition of permit limits for point sources, and more detail on implementation.

  • Final Report (April 2002  (posted 9/18/02)
    • Figure 1 - Summary of the 1998 Waterbody Assessment Results
  • Appendix A - Model Development for the Upper Little Miami River TMDL Project
  • Appendix B - Qualitative Habitat Evaluation Index scores for the Upper Little Miami basin
  • Appendix C - Target Development for Total Phosphorus
  • Appendix D - Additional Documentation of Reasonable Assurances
  • Appendix E - Responsiveness Summary to Public Comments, updated September 2002
  • Appendix F - The Little Beaver Creek Pollutant Load Analysis Report
    • Figure 1 - Little Beaver Creek watershed
    • Figure 2 - Little Beaver Creek sub-watershed boundaries

Little Miami River (lower) Watershed

Little Miami River (lower) watershedThe lower Little Miami River watershed is located in southwest Ohio.  The 602-square-mile TMDL project area encompasses the Little Miami River watershed from below Caesar Creek to the mouth, excluding the East Fork Little Miami River.

Land use in the watershed is predominantly agriculture (40% cropland, 11% pasture) and forest (30%).  About 17% of the watershed is developed or urban land, mostly in the southern portion when current land development is most rapid.









Water quality monitoring in 2007 identified impairments of aquatic life and recreational uses.  The Little Miami River itself displayed exceptional quality, while the tributaries were generally of a lower quality.  Overall, aquatic communities met water quality goals at 66% of the sites surveyed, partially met standards at about 26%; approximately 9% of the sites did not meet any of the quality goals.  About 30% of the sites failed to meet bacteria water quality standards. 

The two primary causes of aquatic life impairment are the high proportion of fine sediment in the channel and the extremely low water levels due to a drought year.  Other stressors include degraded habitat from agricultural drainage and the "armoring" of the stream channel in urban areas; nutrient enrichment from wastewater plant effluent and cropland runoff, and oxygen demanding substances from inadequately treated storm water at the former ABX Airpark and combined sewer discharges within the Metropolitan Sewer District (MSD).  Sources of bacteria are wastewater emanating from sanitary sewer and combined sewer overflows, inadequate treatment from home septic systems, and runoff of bacteria-laden crop fields where manure or sludge are likely applied.

According to the 2012 Integrated Report, the watershed will next be monitored in 2022.

The lower Little Miami River Watershed Total Maximum Daily Load (TMDL) report was approved by U.S. EPA on March 28, 2011.  TMDL reports identify and evaluate water quality problems in impaired water bodies and propose solutions to bring those waters into attainment with water quality standards.

TMDLs are calculated for E. coli bacteria, total phosphorus, chemical oxygen demand, total suspended solids, and sedimentatiion and habitat.

Recommendations include point source controls on the airpark, MSD’s combined sewer system, and the Blanchester wastewater treatment plant.  Nonpoint source actions include improving home septic systems and implementing conventional management practices that are designed to abate pollutant loading from cropland and urban landscapes.

Final TMDL Report without appendices

  • TMDL Fact Sheet
  • Biological and Water Quality Study of the Lower Little Miami River and Selected Tributaries including the Todd Fork Subwatershed, 2007.  Clermont, Clinton, Hamilton, and Warren Counties, Ohio.

The following implementation projects have been completed in the watershed.

East Fork Little Miami River

East Fork Little Miami RiverThe East Fork Little Miami River watershed is primarily located in Clermont and Brown counties.  Portions are also located in Clinton, Highland, Warren and Hamilton counties.  The predominant land uses are cultivated crops (almost 45%) and forested land (just over 32%), with 11.1% of land being developed.  Blanchester is partially located in the watershed and uses surface water for public drinking water supplies.











The East Fork Little Miami River is located in southwest Ohio.  The entire watershed is being studied during 2012.  The East Fork Little Miami River flows into the Little Miami River at Milford in Clermont County.  The East Fork Little Miami River watershed is divided into four subwatersheds, as follows:

  • 05090202 10 Headwaters East Fork Little Miami River
  • 05090202 11 Fivemile Creek-East Fork Little Miami River
  • 05090202 12 Cloverlick Creek-East Fork Little Miami River
  • 05090202 13 Shayler Run-East Fork Little Miami River

There is no TMDL information available at this time.

  • Link to Study Plan [PDF 491K]
  • 1994 Biological and Water Quality Study of the Little Miami River and Selected Tributaries, Clark, Greene, Montgomery, Warren, Clermont and Hamilton Counties, Ohio