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Penn State Extension: Total Maximum Daily Loading Plan - A Watershed Stewardship Opportunity

By Scott A Sjolander, Associate Educator in Renewable Natural Resources and Kinorea Tigri, Master Gardener Coordinator

Total Maximum Daily Loads, or TMDLs, can be considered to be a daily watershed pollutant budget to reduce pollutant loading over a schedule and meet water quality standards.


The 1972 Federal Clean Water Act (CWA) Part 303(d) was passed to restore and maintain the chemical, physical, and biological integrity of the Nation's waters.

The U.S. Environmental Protection Agency (EPA) issued regulations in 1985 requiring states to set appropriate water quality standards and test all water bodies within their boundaries against those standards.

CWA Part 305(b) requires more inclusively that States report on the overall condition of all aquatic resources, assigning them a status of attaining, impaired, or unassessed.

The report must prioritize the assessment of those remaining “unassessed" and addressing those listed as “impaired."

Federal Regulatory Code Title 40, Subpart 130.7. details the calculations of Total Maximum Daily Loads (TMDLs) in planning recovery of waters listed as “impaired," having failed to meet quality standards.

States lack the resources to meet the Act's intensive testing and mitigation schedule and need dedicated citizen stewards to participate in complying.

Around 2000, PA Department of Environmental Protection (DEP) began to address surface water runoff, termed non-point sources through the Unassessed Waters Initiative.

In the 2020 PA Integrated Water Quality Monitoring Report, 85,146 miles of streams and rivers connecting more than 700,000 acres of lakes, bays, and wetlands are recognized, although not all have been assessed.

What Is a TMDL?

Pennsylvania uses a comprehensive watershed approach to addressing water quality. A watershed is composed of land surface that drains to one point, like a bathtub. Total Maximum Daily Loads, or TMDLs, can be considered to be a daily watershed pollutant budget to reduce pollutant loading over a schedule and meet water quality standards.

Waters classified as “impaired" fail to meet quality standards, even though regulatory and technical practice controls may be in place. The Clean Water Act requires TMDLs be developed to reduce pollutant levels in “impaired" waters unless a TMDL alternative exists.

Ranked lists of “impaired" waters and proposed TMDLs are submitted for approval to U.S. Environmental Protection Agency (EPA) every April 1st of even-numbered years with the state’s 305(b) and 303(d) attainment reports.

The TMDL process allocates the amounts of pollutants that a waterway or water body can take in from all pollutant sources and categories. The TMDL does not specify how impaired watersheds must reduce a particular load to meet the standard.

DEP's Office of Water Resources Planning works through regional commissions, county conservation districts, watershed associations, conservancies, colleges, and other citizen scientists in preparing best strategies.

Remedial measures often include educating watershed residents and the general public of improving practices, as well as requiring changes in land use and other protective measures.

Managing Mitigation Through Programs

Point source waste load allocations, such as those emitted from an identified industrial plant pipe are managed through established state regulations under the National Pollutant Discharge Elimination System (NPDES) permit program.

These permits set limits on the amounts of pollutants that can be discharged, and still protect water quality during critical low-flow periods.

Existing tools have enabled DEP to complete point source discharge TMDL recoveries in most watersheds.

Non-point source load allocations, from field erosion and stormwater runoff, are not subject to the same regulations as point sources.

The critical exposure period for non-point load assessment is during high-flow periods when rainfall washes pollutants from the land into waters. Baseline water quality data is lacking for waters already impaired when first assessed.

DEP, therefore, calculates TMDLs using load data from events in reference watersheds similar to the impaired watershed.

Pennsylvania's Erosion and Sedimentation (E&S) Pollution Control Program, established by the PA Clean Streams Law and the Chapter 102 Erosion Control regulations, exemplifies a non-point regulatory program.

The E&S program requires planning, along with implementing practices and measures, to minimize soil erosion from all earthmoving activities, including farming, construction, and timber harvesting.

Municipal ordinances that address zoning, land use, and stormwater runoff are examples of local programs intended to reduce polluted runoff.

Since 1987, Clean Water Act Section 319(h) funds are provided to designated state and tribal agencies to implement approved non-point source management programs.

This regulation provides state funding for third party non-governmental organizations and citizens to define a mitigation plan or implement a measure through DEP Growing Greener Grants.

Third-Party Steward Roles

Although the Clean Water Act and federal regulations have required TMDLs for several years, budget constraints have delayed developing the standards. Tools developed by EPA to carry out requirements involve enormous sampling and data commitments.

In Pennsylvania, these efforts often rely on carefully vetted third-party professionals and volunteers.

Watershed-based activities can only be completed when local stakeholders take ownership. A third party, once approved by the Commonwealth, and federal EPA, works under lead agency supervision.

The third party can be a watershed group, municipal wastewater or stormwater discharger organization, industrial discharger entity, other unit of government (such as a county, city, municipality, or land management agency).

 Further, it may be a non-point source organization (such as a farm bureau, irrigation, and drainage district, or landowner).

DEP needs and encourages public participation in the TMDL process. Watershed coordinators in each region’s DEP regional office keep citizens and organized watershed groups informed of TMDL activities.

Early in the process, watershed residents can submit data or other information about the watershed that DEP can use in preparing the TMDL.

Later, DEP holds a formal public comment period and informational public meetings to present, discuss, and amend each TMDL draft as necessary to meet water quality standards.

For more information, call the DEP regional office in your area or visit their website

Citizens with time and desire to contribute can take part in a Penn State Master Watershed Steward program.

To participate in this kind of needed effort, learn more about the Master Watershed Steward Program.

[Learn more about TMDLs by visiting DEP’s PRP/TMDL Plans webpage.]

How Clean Is Your Stream?

DEP’s Interactive Report Viewer allows you to zoom in on your own stream or watershed to find out how clean your stream is or if it has impaired water quality using the latest information in the draft 2020 Water Quality Report.

Resource Links:

-- 319 Grant Program for States and Territories. US EPA.

-- 2020 Pennsylvania Integrated Water Quality Monitoring and Assessment Report. PA Department of Environmental Protection. 2021.

-- Nonpoint Source PA. PA Department of Environmental Protection. 2021.

-- Overview of Total Maximum Daily Loads (TMDLs). US Environmental Protection Agency.

-- PA Department of Environmental Protection. Fact Sheet "Watershed Management and TMDLs".

-- Pennsylvania's TMDL Program, Restoring Water Quality. PA Department of Environmental Protection.

-- US EPA. Summary of the Clean Water Act.

(Reprinted from the latest Penn State Extension Watershed Winds newsletterClick Here to sign up for your own copy.)

Related Article -TMDL:

-- DEP Invites Comments On Total Maximum Daily Load Plan For Brush Valley Creek In Northumberland County Covering Sediment Pollution

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-- Penn State Extension: Take A Walk With A Master Watershed Steward And Learn About Your Watershed

-- Spring Creek Watershed Group Creates Watershed Atlas To Educate The Public In Centre County

-- Penn State Extension Water Team Invites You For Stormwater BMP Walk In Cumberland, Westmoreland Counties

-- Penn State Extension Water Team Goes Live On Facebook (And On Demand)

-- Learn How To Certify Your Property As Watershed-Friendly

-- Penn State Extension: Circle Traps Work To Destroy Spotted Lanternflies

[Posted: April 22, 2021]


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