Tier II Review

The purpose of the Tier II antidegradation review is to protect and maintain Tier II high quality waters from degradation. The Tier II review is required for new or modified National Pollutant Discharge Elimination System (NPDES) permit applications, Nontidal Wetlands and Waterways permits, and activities requiring a 401 Water Quality Certification (also issued by the MDE Nontidal Wetlands and Waterways Program). Additionally, the review is required for Water and Sewer Plan Amendment reviews. Other MDE environmental reviews that may result in future permitting, for example Interagency Clearinghouse Reviews, may also identify related projects that may need to undergo a Tier II review, and potentially require Tier II review information at that time. The Tier II review is applicable to applications and approvals for local, state, and federal entities and projects.

The Tier II review is implemented on a watershed basis using an upstream approach intended to protect downstream water quality. This means that regulated activities occurring anywhere within a Tier II watershed area may require a Tier II review. Using a science-based implementation strategy, the review identifies common impacts associated with a given regulated activity, and provides where appropriate, comments to help address those impacts. Permits and approvals may include special conditions and requirements to address antidegradation issues

In the diagram, the vertical arrow on left represents Tier II water quality. The midline value of “0” represents no net change in water quality. The horizontal arrow represents the progression of the Tier II review for each project.

No net change is the overarching goal of the Tier II review. This is achieved by reducing environmental water quality impacts (the dark purple box) as much as is possible. If mitigation is not possible, remaining impacts should be justified before being permitted. This process is called a ‘social and economic justification’.

Overall Review Process

All analyses described below are applicable to all areas of the whole and complete project within a Tier II watershed. It is recommended that applicants provide MDE with a final “Tier II Review Antidegradation” Report that organizes responses to questions, forms, and other supporting documentation used to support the final review determination. Once the Tier II review is complete for the project, this report documentation can be used for other related MDE permits and approvals related to that project. If the permitted activity is modified, then at that time MDE may initiate further review to determine if changes will impact Tier II water quality.

Step 1: Identify Impacts

Impacts vary depending upon the proposed activity requiring MDE permits or approvals. When evaluating potential Tier II impacts consider all MDE permit or approval necessary, i.e. nontidal wetlands permit, wastewater treatment permit, etc., and how each may affect in-stream water quality, or, how implementing the proposed activity may affect resources that support in-stream water quality.

Common impacts related to wastewater treatment can include changes in dissolved oxygen, pH, temperature, or other pollutants such as copper or ammonia found in effluent. If applying for modifications to existing permits, on-going compliance issues are also considered during the course of the review. Other reviews, such as a review for a nontidal wetlands or waterways construction permit, will consider landscape changes that contribute to declines in biological water quality, such as land-use conversion from forest to non-forest, modification or removal of stream buffers, or increasing impervious surfaces.

Permit renewals, with no change in treatment process, flow capacity, or no increase in impacts to Tier II or other regulated resources, generally do not undergo Tier II review unless there is an on-going compliance issue or other special concern.

There are several common situations related to landscape changes that generally do not require Tier II review. Such situations include emergency work and repairs, habitat restoration, rehabilitation, and stabilization, and minor activities like road resurfacing. While MDE permits or approvals may be required for such activities, there may be little to no Tier II resource impacts. Therefore, applicants are given the opportunity to provide adequate documentation to support a determination that no Tier II review is necessary.

Information to help to determine if a portion of your activity may not require Tier II review can be downloaded here.

Step 2: Avoidance Alternatives Analysis

The avoidance, or ‘no-discharge’ alternatives analysis determines whether or not an applicant can implement the permitted activity without impacting Tier II waters. This may be achieved by modifying wastewater treatment, relocating outfalls to places outside of Tier II watersheds, rerouting other support infrastructure such as roads, pipelines, powerlines, etc. to avoid intersecting Tier II watersheds, and evaluating alternative sites. If a reasonable alternative is identified, it is then required as a condition of the permit or approval, and the Tier II review ends. If not, the next step is minimization.

There are several instances where there are no options for avoidance, including restrictions due to site specific repairs or restoration, funding incentives, financing limitations, phased projects, certain military projects, or other special cases. During the no-discharge alternatives analysis, applicants are given the opportunity to provide adequate documentation to support an exemption from the no-discharge alternatives analysis.

Click here to download the Tier II No-Discharge Alternatives Analysis form.

Step 3: Minimization Alternatives Analysis

The minimization alternatives analysis identifies options, that when implemented, minimize impacts to Tier II waters. These options can include treatment modification, design modification to reduce impacts, and mitigation to offset unavoidable impacts. At this time applicants may also use strategies to avoid certain impacts, such as leaving an unused area vegetated rather than clearing. MDE may also identify other project, site-specific, or compliance concerns that may require the development of management or action plans, stream monitoring, biological monitoring of fish and benthics, or studies, as special conditions.

During this step it is important that impacts to Tier II streams, stream buffers, forest cover, and changes in impervious cover area, are accurately calculated. All identified impacts are classified as either avoidable or unavoidable. Unavoidable impacts are due to existing infrastructure, buildings, stormwater management, or other requirements for construction to meet standards and regulations, such as those pertaining to minimum right-of-way or design standards. All other impacts should be minimized to the greatest extent feasible. Any actions related to design, siting, treatment configuration, etc. previously incorporated into the activity to reduce water quality impacts can be accounted for in this portion of the review. If an applicant has done a thorough feasibility and impact analysis prior to the submitting the permit application or MDE review, much of this can be considered during the course of the Tier II review.

Mitigation is an integral part of the minimization process. While certain losses are unavoidable, those losses could be mitigated either on-site or elsewhere within the Tier II watershed impacted by the activity. For land disturbing activities, the preferred mitigation method is ‘in-kind’. This means that the amount of forest restored within the Tier II watershed should equal the amount of net forest lost due to the permitted activity. Buffer impacts can be mitigated on-site by increasing widths where possible to account for permanent changes within the basic 100-foot targeted stream buffer. Areas identified for Tier II mitigation should be protected in perpetuity.

Applicants are allowed the opportunity to revise and resubmit all information required during the Tier II review. Generally, once the applicant adequately completes the minimization analysis, including mitigation, and there is some assimilative capacity remaining in the Tier II water, the Tier II review ends. If there is no assimilative capacity in the Tier II water, i.e. MDE has determined that the stream has degraded below Tier II standards, a more substantial justification for remaining impacts is required before the Tier II review is satisfied.

Click here to download the Tier II Minimization Alternatives Analysis form.

Click here to download the Tier II Mitigation Analysis form.

Click here to download the Construction Stormwater Antidegradation Checklist form.

Step 4: Social and Economic Justification (SEJ) for Unavoidable Impacts

If impacts cannot be fully avoided, minimized, or mitigated, the applicant may have to provide MDE with an SEJ. The SEJ must demonstrate that an economic hardship and/or public benefit overrides the value of the ecological services or water quality benefit that the Tier II water segment provides. Before MDE can consider the SEJ in a decision, the applicant must first provide documentation to show that all reasonable avoidance, minimization, and mitigation alternatives have been considered, and where economically feasible, implemented. The SEJ is usually required when the Tier II stream effected has no remaining assimilative capacity. However, if the impacts associated with the project are widespread, or are likely to cause substantial impacts due to significant clearing, grading, hydrologic modification, temperature, etc., MDE may require an SEJ even when there is remaining assimilative capacity. At a minimum, each SEJ should include the economic contributions of the project such as job creation, tax revenue, as well as other social benefits gained by the affected community located in the watershed of the Tier II water. The SEJ should also discuss the loss in value of the Tier II water as well as the economics of restoration of lost water quality. Different aspects of economic information are required for public vs private entities, and outlines for each are provided below.

Click here to download the Social and Economic Justification (Public Entities) Outline.

Click here to download the Social and Economic Justification (Private Entities) Outline.

The Tier II Review process, by permit/approval type:

Click here to return to the Maryland Tier II Waters homepage.

Contact Information:

Please direct any questions or comments concerning Maryland's Antidegradation program to Angel Valdez at angel.valdez@maryland.gov.

This page was last updated 02/2022.

Maryland Department of the Environment

High Quality Waters Related Links

Tier II Review

Overall Review Process

Step 1: Identify Impacts

Step 2: Avoidance Alternatives Analysis

Step 3: Minimization Alternatives Analysis

Step 4: Social and Economic Justification (SEJ) for Unavoidable Impacts

Contact Information:

​​​​​High Quality Waters Related Links​

​Tier II Review

Overall Review Process

Step 1: Identify Impacts

Step 2: Avoidance Alternatives Analysis

Step 3: Minimization Alternatives Analysis

Step 4: Social and Economic Justification (SEJ) for Unavoidable Impacts

Contact Information:

High Quality Waters Related Links

Tier II Review