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NPDES Permit Program Basics Home

 

NPDES Topics Alphabetical Index Glossary About NPDES

NPDES Permit Program Basics
Frequently Asked Questions

The following is a list of Frequently Asked Questions for NPDES Permit Program Basics organized from general questions about the NPDES Program to more technical questions about NPDES Permit Program Basics. Click here to search for other program-specific FAQs or to display a list of all NPDES FAQs. Please check back periodically for updates!


What is an NPDES permit?

The Clean Water Act prohibits anybody from discharging "pollutants" through a "point source" into a "water of the United States" unless they have an NPDES permit. The permit will contain limits on what you can discharge, monitoring and reporting requirements, and other provisions to ensure that the discharge does not hurt water quality or people's health. In essence, the permit translates general requirements of the Clean Water Act into specific provisions tailored to the operations of each person discharging pollutants.

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What is a pollutant?

The term pollutant is defined very broadly in the Clean Water Act because it has been through 25 years of litigation. It includes any type of industrial, municipal, and agricultural waste discharged into water. Some examples are dredged soil, solid waste, incinerator residue, sewage, garbage, sewage sludge, munitions, chemical wastes, biological materials, radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt and industrial, municipal, and agricultural waste. By law, a pollutant is not sewage or discharges incidental to the normal operation of an Armed Forces vessel, or water, gas, or other material injected into an oil and gas production well.

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What is a point source?

The term point source is also defined very broadly in the Clean Water Act because it has been through 25 years of litigation. It means any discernible, confined and discrete conveyance, such as a pipe, ditch, channel, tunnel, conduit, discrete fissure, or container. It also includes vessels or other floating craft from which pollutants are or may be discharged. By law, the term "point source" also includes concentrated animal feeding operations, which are places where animals are confined and fed. By law, agricultural stormwater discharges and return flows from irrigated agriculture are not "point sources".

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What is a water of the United States?

The term water of the United States" is also defined very broadly in the Clean Water Act and after 25 years of litigation. It means navigable waters, tributaries to navigable waters, interstate waters, the oceans out to 200 miles, and intrastate waters which are used: by interstate travelers for recreation or other purposes, as a source of fish or shellfish sold in interstate commerce, or for industrial purposes by industries engaged in interstate commerce.

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Do I need an NPDES permit?

It depends on where you discharge pollutants. If you discharge from a point source into the waters of the United States, you need an NPDES permit. If you discharge pollutants into a municipal sanitary sewer system, you do not need an NPDES permit, but you should ask the municipality about their permit requirements. If you discharge pollutants into a municipal storm sewer system, you may need a permit depending on what you discharge. You should ask the NPDES permitting authority.

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Where do I apply for a NPDES permit?

NPDES permits are issued by states that have obtained EPA approval to issue permits or by EPA Regions in states without such approval. The following map illustrates the states with full, partial, and no NPDES Authority. This file in PDF format provides the status of state NPDES Programs.

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Is it legal to have wastewater coming out of a pipe into my local receiving water (e.g., lake, stream, river, wetland)?

As long as the wastewater being discharged is covered by and in compliance with an NPDES permit, there are enough controls in place to make sure the discharge is safe and that humans and aquatic life are being protected. To find out if a discharge is covered by an NPDES permit, call the EPA Regional office or the state office responsible for issuing NPDES permits.

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How do NPDES permits protect water?

An NPDES permit will generally specify an acceptable level of a pollutant or pollutant parameter in a discharge (for example, a certain level of bacteria). The permittee may choose which technologies to use to achieve that level. Some permits, however, do contain certain generic 'best management practices' (such as installing a screen over the pipe to keep debris out of the waterway). NPDES permits make sure that a state's mandatory standards for clean water and the federal minimums are being met.

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Typically, how long are NPDES permits effective?

The Clean Water Act limits the length of NPDES permits to five years. NPDES permits can be renewed (reissued) at any time after the permit holder applies. In addition, NPDES permits can be administratively extended if the facility reapplies more than 180 days before the permit expires, and EPA or the state regulatory agency, which ever issued the original permit, agrees to extend the permit.

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Is there any information available to me on permits in my area?

Yes, there is a national system that provides certain permitting information called the Permits Compliance System (PCS). You can find out more about your local watershed through EPA's "Surf Your Watershed".

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Can the general public participate in NPDES permitting decisions?

Yes. The NPDES administrative procedures require that the public be notified and allowed to comment on NPDES permit applications. When EPA authorizes a state to issue NPDES permits, EPA requires that the state provide the public with this same access.

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How can I find out about a proposed permit for a facility near me so that I can participate in the permitting process?

If a facility near you has applied for an NPDES permit, the permitting authority or company will have provided notice in a major local newspaper, usually in the legal section of the classified ads, or in an official publication such as the Federal Register. You also may call the appropriate state regulatory agency for information on applications for permits. For more information, refer to the Permitting Contacts section of this web site.

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How are the conditions in NPDES permits enforced by EPA and the states?

There are various methods used to monitor NPDES permit conditions. The permit will require the facility to sample its discharges and notify EPA and the state regulatory agency of these results. In addition, the permit will require the facility to notify EPA and the state regulatory agency when the facility determines it is not in compliance with the requirements of a permit. EPA and state regulatory agencies also will send inspectors to companies in order to determine if they are in compliance with the conditions imposed under their permits.

Federal laws provide EPA and authorized state regulatory agencies with various methods of taking enforcement actions against violators of permit requirements. For example, EPA and state regulatory agencies may issue administrative orders which require facilities to correct violations and that assess monetary penalties. The laws also allow EPA and state agencies to pursue civil and criminal actions that may include mandatory injunctions or penalties, as well as jail sentences for persons found willfully violating requirements and endangering the health and welfare of the public or environment. Equally important is how the general public can enforce permit conditions. The facility monitoring reports are public documents, and the general public can review them. If any member of the general public finds that a facility is violating its NPDES permit, that member can independently start a legal action, unless EPA or the state regulatory agency has taken an enforcement action.

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What is the NPDES Permit Backlog?

The Clean Water Act specifies that NPDES permits may not be issued for a term longer than five years. Permittees that wish to continue discharging beyond the five year term must submit a complete application for permit renewal at least 180 days prior to the expiration date of their permit. If the permitting authority receives a complete application, but does not reissue the permit prior to the expiration date, the permit may be "administratively continued. "Permits that have been administratively continued beyond their expiration date are considered to be "backlogged." Where information is available, facilities awaiting their first NPDES permits are also considered part of the NPDES permit backlog.

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What are the Backlog Reduction Goals?

The goals established by EPA acknowledge some minimal backlog levels, but strive to keep permit issuance at an acceptable rate. Because backlog reduction, the NPDES program's long-term viability, and protection of human health and the environment are inherently linked, EPA has established the following quantitative targets for reducing the backlog:

  • The backlog of NPDES permits for major facilities will be reduced to 10 percent in all states by the end of calendar year 2001.
  • The backlog of NPDES permits for major and minor facilities will be reduced to 10 percent by the end of calendar year 2004.

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What are the Current Backlog Rates?

The chart on the left shows the current NPDES permit issuance and backlog rates. As of July 31, 2000, 68 percent of NPDES permits are current. This represents an improvement of 13 percent from the backlog measured in November 1998 (54 percent).

Over the last 22 months EPA Headquarters has provided assistance to states and EPA Regions to clean up invalid records in PCS. Other states were encouraged to improve PCS on their own initiative. This effort has been very successful.

Since the EPA and states began focusing on cleaning up PCS data, the overall universe of permittees in PCS has declined 18 percent. Records in PCS that were listed as not having a permit expiration date have been reduced by 56 percent. Now, EPA is able to more accurately track the backlog of facilities with individual permits on a national basis. EPA is now working with states and EPA Regions to better characterize facilities that are covered by non-stormwater and stormwater permits.

While EPA is encouraged by the positive trends, permit issuance trends data compiled since November, 1998 continue to show that accelerated permit issuance rates are necessary to meet backlog reduction goals for many states. At the same time that states and EPA Regions are being encouraged to accelerate permit issuance rates, EPA HQ is examining ways to improve the quality of NPDES permits and bring about changes in policy to improve the permit issuance process.

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What is the National Pollutant Discharge Elimination System (NPDES) Stormwater Program?

Polluted stormwater runoff is a leading cause of impairment to the nearly 40 percent of surveyed U.S. water bodies which do not meet water quality standards. Over land or via storm sewer systems, polluted runoff is discharged, often untreated, directly into local water bodies. When left uncontrolled, this water pollution can result in the destruction of fish, wildlife, and aquatic life habitats; a loss in aesthetic value; and threats to public health due to contaminated food, drinking water supplies, and recreational waterways.

Mandated by Congress under the Clean Water Act, the NPDES Stormwater Program is a comprehensive two-phased national program for addressing the non-agricultural sources of stormwater discharges which adversely affect the quality of our nation's waters. The program uses the National Pollutant Discharge Elimination System (NPDES) permitting mechanism to require the implementation of controls designed to prevent harmful pollutants from being washed by stormwater runoff into local water bodies.

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Whom should entities regulated under the NPDES Stormwater Program contact to obtain permit coverage?

Regulated entities should contact their NPDES permitting authority, which will be either their state or EPA Regional Office, depending on the type of entity and its location. For regulated entities located in areas where EPA is the NPDES permitting authority, all information and forms needed to obtain permit coverage are available through visiting any one of the three regulated stakeholder areas (MS4s, industrial activity, construction activity) or the Resources section of this web site.

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Construction: Who must seek permit Coverage Under an EPA construction General Permit?

See Stormwater Phase II Final Rule-Small Construction Program Overview (Fact Sheet 3.0) for more information on both the small and large construction programs.

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

The regulatory definition of an MS4 (40 CFR 122.26(b)(8)) is "a conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains): (i) Owned or operated by a state, city, town, borough, county, parish, district, association, or other public body (created to or pursuant to state law) including special districts under state law such as a sewer district, flood control district or drainage district, or similar entity, or an Indian tribe or an authorized Indian tribal organization, or a designated and approved management agency under section 208 of the Clean Water Act that discharges into waters of the United States. (ii) Designed or used for collecting or conveying stormwater; (iii) Which is not a combined sewer; and (iv) Which is not part of a Publicly Owned Treatment Works (POTW) as defined at 40 CFR 122.2."

In practical terms, operators of MS4s can include municipalities and local sewer districts, state and federal departments of transportation, public universities, public hospitals, military bases, and correctional facilities. The Stormwater Phase II Rule added federal systems, such as military bases and correctional facilities by including them in the definition of small MS4s.

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MS4: Which MS4s are regulated by the NPDES Stormwater Program?

For regulatory purposes, EPA's NPDES Stormwater Program regulates "medium," "large," and "regulated small MS4s."

A medium MS4 is a system that is located in an incorporated place or county with a population between 100,000 - 249,999.

A large MS4 is a system that is located in an incorporated place or county with a population of 250,000 or more.

In addition, some MS4s that serve a population below 100,000 have been brought into the Phase I program by an NPDES permitting authority and are treated as medium or large MS4s, independent of the size of the population served.

A regulated small MS4 is any small MS4 located in an "urbanized area" (UA), as defined by the Bureau of the Census, or located outside of a UA and brought into the program by the NPDES permitting authority.

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MS4: Is a permit required for regulated MS4s?

Yes. A National Pollutant Discharge Elimination System (NPDES) permit must be obtained by the operator of an MS4 covered by the NPDES Stormwater Program.

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What are Sanitary Sewer Overflows?

Sanitary Sewer Overflows (SSOs) are discharges of raw sewage from municipal sanitary sewer systems. SSOs can release untreated sewage into basements or out of manholes and onto city streets, playgrounds and into streams before it can reach a treatment facility. SSOs are often caused by blockages in sewer lines and breaks in the sewer lines.

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What design flow is appropriate for calculating limits for nutrients (nitrogen and phosphorus)?

This question is not entirely specific to nutrients, and therefore, is answered the same as for any other water quality criteria. Design flows for effluent limit calculations are based on treatment design flows at individual facilities. Please refer to 40 CFR 122.45(b) Exit EPA Site and Chapter 6 of the NPDES Permit Writers' Manual [PDF - 222 KB - 28 pp] for more information on determining appropriate effluent design flow.

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What monitoring requirements for nutrients (nitrogen and phosphorus) are necessary in permits?

This question is not entirely specific to nutrients, and therefore, is answered the same as for any other water quality criteria. In general, monitoring requirements in permits must effectively ascertain compliance with effluent limits. Please refer to 40 CFR 122.44(i) Exit EPA Site and Chapter 8 of the NPDES Permit Writers' Manual [PDF - 132 KB - 29 pp] for more information.

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Can a new source or a new discharger be authorized in water bodies that are currently listed as impaired for nutrients (nitrogen and phosphorus)?

This question is not entirely specific to nutrients, and therefore, is answered the same as for any other water quality criteria. New sources and new dischargers can be authorized in water bodies currently listed as impaired. If a TMDL has been developed, the permit writer must demonstrate that there are remaining pollutant load allocations to allow for the additional loads and compliance schedules designed to bring the impaired water body into compliance with applicable water quality standards. When a TMDL has yet to be developed, the new source or new discharger can obtain a permit when certain conditions are met such as when the dischargers do not contain the pollutant causing the impairment, or other pollutant source reductions will offset the new discharge. For more information, refer to 40 CFR 122.4(i) Exit EPA Site and page 38 of EPA's decision on the Chesapeake Bay Foundation petition [PDF - 500 KB - 64 pp].

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Should WQBELs apply only if a water is determined to be impaired by nutrients (nitrogen and phosphorus)?

This question is not entirely specific to nutrients, and therefore, is answered the same as for any other water quality criteria. The permitting authority must include a WQBEL in a permit if nutrients or any pollutant cause, contribute to, or have the reasonable potential to cause or contribute to an excursion of a water quality standard. In other words, even if a waterbody is not currently impaired for nutrients, a permit writer must include a WQBEL if a discharge has the reasonable potential to cause or contribute to an excursion of the nutrient criteria. For more information on WQBELs, please refer to 40 CFR 122.44(d) Exit EPA Site.

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When determining reasonable potential for nutrient (nitrogen and phosphorus) NPDES permits, are dynamic models appropriate, and if so, which models?

This question is not entirely specific to nutrients, and therefore, is answered the same as for any other water quality criteria. The decision to use dynamic models (time variable models) depends on the waterbody system to be modeled. The factors one considers to determine when to use a time variable model are found in a suite of technical guidances related to modeling the fate and transport of contaminants for the purposes of developing wasteload allocations that OW published between 1983 and 1990. Citations for these documents are as follows:

USEPA (U.S. Environmental Protection Agency). 1983a. Technical Guidance Manual for Developing Total Maximum Daily Loads: Book 2, Rivers and Streams, Chapter 2: Nutrient/Eutrophication Impacts. EPA 440/4-84-021. U.S. Environmental Protection Agency, Office of Water, Washington, DC.

USEPA. 1983b. Technical Guidance Manual for Performing Waste Load Allocations: Book 4, Lakes and Impoundments, Chapter 2: Nutrient/Eutrophication Impacts [PDF - 1.8 MB - 177 pp]. EPA 440/4-84-019. U.S. Environmental Protection Agency, Office of Water, Washington, DC.

USEPA. 1990a. Technical Guidance Manual for Performing Waste Load Allocations: Book 3, Estuaries, Part 2: Application of Estuarine Waste Load Allocation Models [PDF - 2.5 MB - 173 pp]. EPA 823/R-92-003. U.S. Environmental Protection Agency, Office of Water, Washington, DC.

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How can new nutrient (nitrogen and phosphorus) criteria be implemented in existing NPDES permits?

This question is not entirely specific to nutrients, and therefore, is answered the same as for any other water quality criteria. The permitting authority may be able to modify an existing permit (a new nutrient standard may be an allowable cause for modification) during the existing permit term, wait until the end of the permit term, or use an overlay permit that captures multiple facilities and provides additional flexibility. Permitting authorities are encouraged to consider a watershed-based permitting approach, which allows for the coordinated reissuance of permits with applicable limits throughout a watershed and may expedite implementation of new criteria while lowering administrative burden. The Virginia Chesapeake Bay and the Connecticut Long Island Sound Permits are examples where states have utilized the overlay permit to implement new nutrient criteria. Refer to 40 CFR 122.62 Exit EPA Siteand Chapter 11 of the NPDES Permit Writers' Manual [PDF - 84 KB - 19 pp] for regulatory requirements and information on reopening a permit.

For more information on examples of overlay permits, refer to "Case Study 1-General Permit for Nitrogen Discharges" and "Case Study 13-Chesapeake Bay Watershed, Virginia: Watershed-based General Permit for Nutrient Discharges and Nutrient Trading" located on EPA's Watershed-Based Permitting publications page.

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What options are available when treatment technology does not exist to enable dischargers to meet the WQBEL?

This question is not entirely specific to nutrients, and therefore, is answered the same as for any other water quality criteria. If dischargers cannot meet the WQBEL based on existing water quality standards, states have the option of changing the water quality standards through variances or changes to designated uses, which would result in a different WQBEL that could be met. In other instances, dischargers may be able to meet the WQBELs based on existing water quality standards through options such as offsets from point and nonpoint sources (e.g., land based BMPs) and water quality trading, and watershed analysis.

For information on variances, refer to EPA's Water Quality Standards Handbook. For information on changing designated uses, please refer to 40 CFR 131.10(g) Exit EPA Site. For information on offsets, trading, and watershed analysis, refer to the Watershed-Based Permitting website and the Water Quality Trading website.

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How can watershed-based permitting strategies, trading, or other novel permitting strategies be utilized to "meet" water quality standards?

The answer to this question is not specific to nutrients. EPA promotes using a NPDES watershed approach and water quality trading as innovative tools that may provide low cost implementation solutions for meeting water quality standards. For more information on these tools, please refer to the Watershed-Based Permitting website and the Water Quality Trading website.

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How do technology-based effluent limits affect the need for water-quality based effluent limits (WQBELs) in permits?

This question is not entirely specific to nutrients, and therefore, is answered the same as for any other water quality criteria. Water quality-based effluent limitations are needed where technology-based effluent limitations are not stringent enough to meet applicable water quality standards. Refer to 40 CFR 122.44(d) Exit EPA Site and Chapter 6 of the NPDES Permit Writers' Manual [PDF - 222 KB - 28 pp] for more information on WQBELs.

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Can a permit require chemical and biological sampling at points other than the discharge outfall?

This question is not entirely specific to nutrients, and therefore, is answered the same as for any other water quality criteria. Biological sampling may be appropriate to effectively monitor the discharge status and ensure compliance. One practice for collecting ambient monitoring is described in EPA's Interim Guidance for Performance-based Reductions of NPDES Permit Monitoring Frequencies [PDF - 87 KB - 23 pp], which states that the permit authority can grant reductions in effluent monitoring for a permittee with a history of good compliance and permitting performance in exchange for ambient monitoring. In an attempt to test some of the ideas in the 1996 Interim Guidance, performance track facilities have been piloting programs to strike a balance between ambient monitoring and end-of-pipe monitoring. Specifically, Kodak Colorado Division and other dischargers near Kodak on the Cache la Poudre River have formed an ambient water quality monitoring group. This group was formed in cooperation with the Colorado Department of Public Health & Environment (CDPHE) to monitor the ambient water quality of the receiving water body.

More information about this ambient monitoring group is located on EPA's National Environmental Performance Track website. Also refer to Chapter 8 of the NPDES Permit Writers' Manual [PDF - 132 KB - 29 pp] for information on including special studies and additional monitoring in NPDES permits.

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In the absence of a TMDL, do permitting authorities have the flexibility to use a watershed approach similar to a TMDL analysis? Does EPA have guidance on an appropriate margin of safety for nutrient (nitrogen and phosphorus) TMDLs associated with the wasteload allocation/load allocation (WLA/LA) to ensure that water quality standards are met when implemented into permit limits?

This question is not entirely specific to nutrients, and therefore, is answered the same as for any other water quality criteria. Yes, in the absence of a TMDL, permitting authorities have the flexibility to use a watershed approach similar to a TMDL analysis. One such approach is watershed-based permitting, which may be valuable where a TMDL is not available or as a tool to implement a TMDL. However, unless the watershed-based permitting effort includes all of the required elements of a TMDL or a TMDL alternative, a waterbody impaired by nutrients should remain on the 303(d) list until it meets standards or has an actual TMDL established or approved by EPA. The Chesapeake Bay implemented a watershed-based permitting approach for controlling nutrient discharges [PDF - 196 KB - 3 pp]. You can find more information on the Watershed-Based Permitting website. For information on determining the margin of safety for nutrient TMDLs, refer to Chapter 9 of EPA's Protocol for Developing Nutrient TMDLs [PDF - 2.5 MB -137 pp].

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Are seasonal water quality-based permit limits for nutrients (nitrogen and phosphorus) appropriate?

The answer to this question is specific to nutrients. Seasonal water quality-based permit limits are not explicitly specified in the NPDES regulations under 40 CFR 122 Exit EPA Site. However, seasonal permit limits may be acceptable if they are consistent with applicable water quality standards, and with the assumptions and requirements of the wasteload allocation of any approved TMDL (40 CFR 130.7(c) Exit EPA Site). For example, if the water quality standards for nutrients provide for seasonal limits, permits can include seasonal limits. See the memorandum, discussing nitrogen and phosphorus annual permit limits [PDF - 444 KB - 5 pp] implemented to protect the Chesapeake Bay.

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