Construction sites impact Ohio's waters by:

• adding pollutants, especially sediment, to rainwater running off of construction sites during construction; and
• making long-term land use changes that alter the hydrology and pollutant loading of local streams.

To limit the negative impacts of construction projects on Ohio's waters, Ohio EPA administers a permitting program designed to document construction activity in the state and require practices that keep pollutants out of the streams. The permitting program is mandated in the Clean Water Act and is part of the NPDES (National Pollutant Discharge Elimination System) program. 

Who needs a permit?

As of March 10, 2003, if your project disturbs 1 or more acres of ground, you must get a permit to discharge storm water from your site. If your project disturbs less than 1 acre but is part of a larger plan of development or sale, you also need a permit to discharge storm water from the site.

How do I get a permit?

Most sites may get permit coverage under the general permit for discharge of storm water associated with construction activity. To get permit coverage, follow these steps, in order:

• Develop a Storm Water Pollution Prevention Plan (SWP3) for the construction site;
• Submit a Notice of Intent (NOI) requesting coverage for your discharges under the general permit;
• Wait until you receive the Ohio EPA approval letter stating that you are covered under the general permit;
• Ensure that contractors, subcontractors and staff understand their roles in carrying out the SWP3;
• Implement the SWP3;

• Proceed with construction, including regular maintenance and inspection of sediment and erosion controls and storm water management facilities.

• Construction Site Storm Water (OHC000005)

Storm Water Technical Assistance Program

The Storm Water Technical Assistance Program assists communities, developers, contractors, and consulting engineers with controlling the adverse impacts associated with new and existing development, including increased runoff, polluted storm water, stream erosion and loss of floodplain services. This section provides guidance for cost-effective and preventive measures (best management practices) that can be applied to limit these impacts during construction and after development. These practices control erosion and trap sediments during construction, treat pollutants from developed areas and reduce storm water runoff and protect downstream waters. Practice standards and specifications are available through the Rainwater and Land Development manual. Various tools are made available to facilitate compliance with Ohio’s NPDES permit requirements and other regulations. Training is offered for storm water practice design, storm water management plan review and construction site inspection.

To receive notice regarding updates to or new storm water technical assistance material, please subscribe to the Rainwater Updates by clicking here.

Stormwater Design Manuals

• Ohio's Current Rainwater and Land Development Manual
• ODOT Location & Design Manual Volume 2

Post-Construction Q&A Documents

• Post-Construction Q&A – Water Quality Volume
• Post-Construction Q&A – Water Quality Volume Drawdown
• Post-Construction Q&A – Previously Developed Areas
• Post-Construction Q&A – Small Construction Activities (< 2 acres)

Post-Construction Spreadsheets

• WQv Compliance Spreadsheet
• Runoff Reduction Spreadsheet

Forms & Checklists

• Storm Water Pollution Prevention Plan (SWP3) Check List
• Construction Site Inspection Checklist
• Ohio EPA Alternative Post-Construction BMP Submittal Form

Additional Compliance Material

• Erosivity Waiver
• Routine Maintenance Exclusion from Small Construction Activity Permitting
• Guidance on Manufactured Treatment Devices as Pretreatment for Underground Storm Water Management Systems
• Guidance on Post-Construction Storm Water Controls for Solar Panel Arrays
• Guidance on Post-Construction Storm Water Controls for Wind Turbine Facilities
• U.S. EPA Guidance for Developing SWP3 for Construction Activities
• Construction Storm Water Permit Requirements for Agricultural Projects
• Chagrin River Watershed Partners, Inc. (CRWP) has developed a model agreement that a municipality may use to ensure the long-term operation and maintenance of post-construction best management practices (BMPs). This language may need to be modified to reflect local requirements and should be reviewed by the municipality's legal council. The link below will redirect you from Ohio EPA to CRWP's website.
  • CRWP Model Long-Term Post-Construction BMP Maintenance Agreement
• Northeast Ohio Storm Water Training Council's Maintaining Storm Water Control Measures, Guidance for Private Owners and Operators

Big Darby Creek Watershed

The Big Darby Creek watershed is among the most biologically diverse stream systems of its size in the Midwest. Befitting this distinction, Ohio water quality standards regulations assign the most stringent aquatic life use designations (exceptional warmwater habitat and coldwater habitat) and the outstanding state water antidegradation category to many of the larger streams in the watershed. The watershed is home to several endangered species and Big and Little Darby Creeks are designated state and national scenic rivers.

However, recent studies document declines in water quality and stream habitat, some of which have been found to be directly related to construction activity. Among the most visible and widely publicized future threats to the Big Darby Creek watershed is conversion of farm land to suburban and commercial land uses, especially in Franklin County.

As a result, Ohio EPA has developed specific watershed conditions, found in Appendix A of OHC000005, for storm water associated with construction activity within the Big Darby Creek watershed. Appendix A implements many of the basic recommendations regarding the programs, activities and Best Management Practices developed through the Total Maximum Daily Load process and the State Water Quality Management Plan and 208 Plan. Ohio EPA believes implementation of these recommendations is necessary to protect the unique water quality and biological integrity of the Big Darby Creek system. 

Permit Compliance Materials

• Big Darby Creek Watershed Map
• Ground-Water Recharge Table-Applicability Map
• Land Use Map
• Hydrologic Soil Group Data

Related Documents

• Big Darby Creek Watershed TMDL Report
• State Water Quality Management Plan
  • Appendix 9-3. 208 Plan Prescriptions for Water Quality Protection within the Big Darby Creek Watershed

GIS Data for Download

Save the following .zip files to your computer's hard drive and use a program such as PKZIP or WINZIP to extract the files.

• Land Use Data from TMDL (grid) [ZIP 390K]
• Watershed Boundaries (shapefile) [ZIP 402K] 
• Ground-Water Recharge Table-Applicability (shapefile) [ZIP 165K]

Olentangy River Watershed

Draining 543 miles of Central Ohio landscapes, the Olentangy River watershed provides drinking water, recreation, agricultural drainage and other public goods for over 250,000 watershed residents. Its waters and habitats are home to unique and diverse communities of fish, mussels and other aquatic life. Recent studies document declines in its water quality and stream habitat. Among the most visible and widely publicized threats to the Olentangy’s water quality and habitats is the conversion of farm and forest acreage to residential and commercial land uses at an exceptionally rapid pace. 

The river system drains Ohio’s first and sixth most rapidly populating counties - Delaware and Morrow, respectively. Delaware County’s most rapidly developing townships - Delaware, Liberty and Orange - overlap the river’s State Scenic River section. Areas of the Whetstone Creek subwatershed, located within Morrow County, are designated as Exceptional Warmwater Habitat (EWH) with two tributaries being designated as Coldwater Habitat (CWH). Approximately two miles of the Olentangy River is designated as EWH within Franklin County. This area is currently receiving the greatest pressure for development within Franklin County’s portion of the watershed.

As a result, Ohio EPA has developed an alternative general permit for storm water associated with construction activity specific for portions of the Olentangy River watershed. This alternative permit implements many of the basic recommendations regarding the programs, activities and Best Management Practices developed through the Total Maximum Daily Load process. Ohio EPA believes implementation of these recommendations is necessary to protect the unique water quality and biological integrity of the Olentangy River watershed.

Ohio EPA’s Statewide Construction Storm Water General Permit (OHC000005) incorporates the Big Darby Creek watershed and Portions of the Olentangy River watershed requirements as appendices. These two watersheds’ previous specific alternative general permit conditions, that exceed the standard statewide conditions, have been included as appendices in OHC000005. This has combined all three general permits into one. 

Permit Compliance Materials

• Olentangy River Watershed Map 

• Figure 1: Olentangy River Mainstem Riparian Setback

• Figure 2: Perennial Streams Riparian Setback

• Figure 3: Intermittent Streams Riparian Setback

• Figure 4: Ephemeral Streams Riparian Setback

Related Documents

• Olentangy River Watershed TMDL Report

What is a Municipal Separate Storm Sewer System (MS4)?

A conveyance or system of conveyances (including roads, catch basins, curbs, gutters, ditches, man-made channels, or storm drains):

• Owned or operated by a public body
• Designed and used for collecting storm water
• Is not a combined sewer
• Is not part of a Publicly Owned Treatment Works (POTW)

The U.S. EPA's storm water program addressed storm water runoff in two phases. Phase I addressed storm water runoff from large and medium MS4s. Large municipalities with a separate storm sewer system serving a population greater than 250,000 and medium municipalities with a service population between 100,000 and 250,000 had to obtain NPDES permits. Initial application deadlines for large and medium municipalities were November 16, 1992 and May 17, 1993, respectively. As part of their individual NPDES permit applications, the large and medium MS4s had to develop a storm water management program (SWMP).

Individual MS4 permits for discharge of storm water

• City of Dayton
• City of Toledo
• City of Akron
• City of Columbus

The Phase II regulations address storm water runoff of MS4s serving populations less than 100,000, called small MS4s. More particularly, small MS4s located partially or fully within urbanized areas (UAs), as determined by the U.S. Bureau of the Census, and also on a case-by-case basis for those small MS4s located outside of UAs that Ohio EPA designates into the program. Automatically designated Small MS4s, those in UAs, were required to apply for permit coverage and develop and submit a SWMP by March 10, 2003.

U.S. EPA developed a Fact Sheet [PDF 239K] explaining how urbanized areas affect water quality through increased runoff and pollutant loads and what homeowners can do to prevent storm water pollution.

Ohio EPA developed two general permits that were issued to Phase II Small MS4 communities under the first generation permitting in 2003. The Baseline General Permit allowed a full 5 years for SWMP development/implementation; whereas, the Alternative General Permit for MS4s Located within Rapidly Developing Watersheds required development/implementation of the Construction and Post-Construction minimum control measures within 3 years. The alternative general permit was issued to a select group of MS4s that Ohio EPA considered being located within rapidly developing watersheds. All MS4s will now be covered under the general permit renewal that was issued on January 31, 2009

USEPA developed a set of digitized maps which display detailed urbanized area maps. See the following link:

USEPA Urbanized Area Maps

Ohio EPA developed a set of digitized maps which display detailed area maps for watersheds that Ohio EPA has identified as being rapidly developing. See the following link:

Rapidly Developing Watersheds

• Ohio EPA MS4 Workshops
• USEPA Storm Water Phase II Fact Sheets 
• USEPA National Menu of Best Management Practices
• USEPA Measurable Goals Guidance for Phase II Small MS4s
• USEPA Storm Water Phase II Compliance Assistance Guide [PDF 1,466K]
• OEPA Guidance Brochure for Phase II Small Municipal Separate Storm Sewer System (MS4) Operators [PDF 95K]
• USEPA Storm Water Case Studies
• USEPA Nonpoint Source Outreach Toolbox

Required for use by Small MS4 operators to submit annual reports. Small MS4 annual reports are due on April 1.

Regulated Small MS4s’ 2019 annual reports are due, on or before, April 1, 2020.  Beginning February 1, 2017 these reports can be submitted electronically via Ohio EPA’s eBusiness Center.  For a step-by-step walkthrough on entering and submitting the electronic report view the MS4 Annual Report Quick Guide.  If you have any questions on submitting your Small MS4 annual report electronically, please contact the following:

• Paper Annual Report Form  

• MS4 General Permit
• Ohio Storm Water Rules
• Example Model Ordinances
  • Chagrin River Watershed Partners, Inc.
  • Stormwater Manager's Resource Center (see Ordinance)
  • Northeast Ohio Areawide Coordinating Agency
• USEPA Educational Outreach Materials
• Illicit Discharge Detection And Elimination Manual by New England Interstate Water Pollution Control Commission
• MS4 Program Evaluation Guidance Documents
  • MS4 Program Evaluation Guidance with Appendix A
  • MS4 Program Evaluation Guidance with Appendices B-D
• Illicit Discharge Detection and Elimination Program Manual - A Guidance Manual for the State of Ohio
• Chagrin River Watershed Partners, Inc. (CRWP) has developed a model agreement that a municipality may use to ensure the long-term operation and maintenance of post-construction best management practices (BMPs). This language may need to be modified to reflect local requirements and should be reviewed by the municipality's legal council. The link below will redirect you from Ohio EPA to CRWP's website.
  • CRWP Model Long-Term Post-Construction BMP Maintenance Agreement

• Ohio Environmental Education Fund
• Ohio Water Pollution Control Loan Fund
• Storm Water Utility Information
  • Stormwater Manager's Resource Center (see Program Resources)
  • An Internet Guide to Financing Stormwater Management
  • Guidance For Municipal Stormwater Funding [PDF]
• Catalog of Federal Funding Sources for Watershed Protection