Mahajan, Rishab

Rishab Mahajan is currently a Senior Engineer at Geosyntec Consultants, providing clients with affordable solutions to meet their regulatory...

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About Mahajan, Rishab

Rishab Mahajan is currently a Senior Engineer at Geosyntec Consultants, providing clients with affordable solutions to meet their regulatory obligations through numerical modeling and data analysis. He currently serves as Vice Chair of Watershed Management Community

Mahajan, Rishab

Titles from this speaker

Description: Development for watershed-based strategies to eliminate phosphorus related...

Development for watershed-based strategies to eliminate phosphorus related impairments in the Fox River

Abstract

The Fox River in Illinois is one of 1,023 water bodies listed as impaired for water quality on Illinois’ Clean Water Act Section 303(d) list by the Illinois Environmental Protection Agency (Illinois EPA, 2021). Among these are impairments of aquatic life and aesthetic designated uses. Total phosphorus (TP) is listed as a cause of aquatic life and aesthetic impairments of the Fox River, and TP and dissolved oxygen (DO) are listed as causes of aquatic life impairments. The Fox River Study Group (FRSG) is a diverse coalition of stakeholders working together to preserve and enhance water quality in the Fox River watershed. The FRSG has undertaken a multi-phased approach to address water quality impairments in the Fox River. The approach includes multi-year monitoring of water quality and development of models to characterize the existing water quality related to the DO and TP conditions. This paper presents the application of the water quality model to evaluate the impact of management actions to eliminate the phosphorus-related impairments in the Fox River. The development of watershed-based strategies through the application of water quality models will be helpful to stakeholders in other large watersheds to address water quality impairments.

The following conference paper was presented at WEFTEC 2021, October 16-20, 2021. To read the full abstract, see "Abstract" tab below.

SpeakerMahajan, Rishab

Presentation time

14:14:00

14:36:00

Session time

13:30:00

15:00:00

SessionLess Nutrient Loading and Phos-For-Us

Session number311

TopicNutrients, Policy and Regulation, Watershed Management, Water Quality, and Groundwater

Author(s)

Rishab Mahajan

Author(s)R. Mahajan1; A.D. Nemura2; C. Skrukrud3;

Author affiliation(s)Geosyntec Consultants, Oak Brook, IL 1Geosyntec Consultants, Cleveland, OH2Fox River Study Group, Oswego, IL 3

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2021

DOI10.2175/193864718825158053

Volume / Issue

Content sourceWEFTEC

Word count14

Description: Fox River Implementation Plan: A Roadmap for Improved Water Quality for the Fox...

Fox River Implementation Plan: A Roadmap for Improved Water Quality for the Fox River, Illinois

Abstract

The Fox River Implementation Plan (FRIP) is a roadmap to address water quality impairments in Fox River, Illinois. The FRIP identifies four main management actions for implementation to address water quality impairments dam removal, wastewater treatment plant upgrades, upstream load reductions, and tributary load reduction. This paper discusses the overview, stakeholder engagement, implementation obstacles, and funding sources for each recommended management action. It also describes an adaptive management framework for assessing the performance of management actions and responding to potential challenges. The information presented in this paper would be useful to wastewater treatment plants and stakeholders in developing their implementation plans to address water quality issues in other larger watersheds.

The Fox River Implementation Plan (FRIP) is a roadmap for improving water quality in the Fox River, Illinois. The FRIP identifies four main recommended actions for implementation: dam removal, wastewater treatment plant upgrades, upstream load reductions, and tributary load reduction. The information presented in this paper would be useful to wastewater treatment plants and stakeholders in developing their implementation plans to address water quality issues in other larger watersheds.

SpeakerMahajan, Rishab

Presentation time

09:00:00

09:15:00

Session time

08:30:00

10:00:00

SessionLet Me Know About BMPs

Session locationRoom S405 - Level 4

TopicIntermediate Level, Small Communities and Decentralized Systems, Utility Management and Leadership, Watershed Management, Water Quality, and Groundwater

Author(s)

Mahajan, Rishab

Author(s)R. Mahajan 1; A. Nemura 2 ; R. Mahajan 1; C. Skrukrud 3;

Author affiliation(s)Geosyntec Consultants 1; Geosyntec Consultants 2 ; Fox River Watershed Group 3;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159154

Volume / Issue

Content sourceWEFTEC

Word count16

Description: NARP: A Novel Watershed-Based Permitting Approach To Address Nutrient-Related...

NARP: A Novel Watershed-Based Permitting Approach To Address Nutrient-Related Impairments

Abstract

BACKGROUND
Efforts to reduce nutrient loading from point sources (such as wastewater treatment plants and municipal separate storm sewer systems or MS4s) and non-point sources (stormwater runoff, agriculture) are being used to address the Gulf of Mexico hypoxia, harmful algal blooms in Western Lake Erie, and numerous other nutrient-related impairments in local water bodies. These efforts are picking up pace across the U.S.. The US Environmental Protection Agency (EPA) has been working with states, U.S. territories, and tribes (hereinafter referred to as 'states') to adopt numeric nutrient criteria (NNC) for total phosphorus (TP) and total nitrogen (TN) since 2000. These NNC are then used to develop effluent limits for National Pollution Discharge Elimination System (NPDES) permits for point source discharges. EPA released new guidance to help states adopt NNC for lakes and reservoirs in 2021 (EPA, 2021). Few states, however, have been able to develop NNC for all lakes/reservoirs due to the complexity of the relationship between stressors (nutrients) and response (algae blooms, dissolved oxygen, pH, etc.). The development of NNC for streams has proved to be even more challenging. For example, Illinois's Nutrient Science Advisory Committee (NSAC) developed recommended NNC for streams and rivers (Illinois NSAC, 2021). However, these criteria have not been adopted by Illinois. Illinois EPA received numerous comments that the NSAC's recommendations were unsupportable, did not account for site-specific conditions, and were unnecessarily stringent. The complexity of nutrient impacts on receiving water requires adoption of innovative strategies for nutrient load reduction planning and implementation. The strategies involve watershed approaches which include load reductions from both point and non-point sources and other measures.
NUTRIENT ASSESSMENT REDUCTION PLAN
Illinois EPA had proposed a total phosphorus effluent standard of 1.0 milligrams per liter (mg/L) for major publicly owned treatment works (POTWs). Environmental non-governmental organizations (ENGOs) were concerned that an effluent limitation of 1 mg/L would not address phosphorus-related impairments or protect local waterways and instead proposed an effluent limitation of 0.1 mg/L. The Illinois Association of Wastewater Agencies (IAWA) was concerned that the ENGOs' proposed 0.1 mg/L would impose significant financial burdens on ratepayers and would not necessarily achieve measurable water quality benefits due to site-specific conditions. This disagreement created a substantial permitting backlog in Illinois. Illinois EPA, IAWA, and the ENGOs negotiated the Nutrient Assessment Reduction Plan (NARP) permit requirement in 2018 to overcome the permitting backlog, make progress towards reducing phosphorus loads at POTWs, and restoring local water bodies. The NARP requirements apply to POTWs discharging to downstream segments of water bodies which are impaired related to phosphorus loads or at risk of eutrophication. These major POTWs are required to develop a NARP to address phosphorus-related impairments in streams. The purpose of the NARP is to identify phosphorus input reductions and other measures needed to help ensure that numeric dissolved oxygen (DO) criteria and narrative criteria for offensive conditions (aquatic algae and plants) are met in the respective segments of the water body. The POTW can work with other stakeholders in the watershed to develop the NARP or develop a stand-alone NARP. This unique watershed-based approach has resulted in several POTWs forming watershed groups to develop the NARP. Currently, there are 90 major POTWs that are part of six major watershed groups. These watershed groups have embarked on multi-year monitoring and modeling efforts to identify phosphorus reductions and other measures needed to eliminate phosphorus-related impairments. In addition to the POTWs participating in the watershed groups, Illinois EPA has put the NARP requirements in 53 other major POTWs and the agency is currently in the process of determining the status of the NARP requirement for another 33 major POTWs. Figure 2 shows the status of NARP requirements for major POTWs in Illinois.
METHODOLOGY FOR DEVELOPING A NARP
Illinois EPA has provided flexibility to POTWs on developing a NARP since each watershed is different. Figure 2 shows a suggested NARP development process. A key requirement of the NARP is to establish site-specific water quality targets or adopt the NSAC's statewide recommendations. The NARP needs to identify point source reductions, non-point source reductions, and other measures to eliminate the impairments. Illinois EPA acknowledges that it is possible that the NARP may not recommend point source reductions. Finally, the NARP needs to include an implementation schedule.
CASE STUDIES ON NARP
This presentation will provide case study descriptions of different approaches to develop a NARP. The case studies will include examples of stand-alone NARPs including a large regional utility developing a PARP (Phosphorus Assessment Reduction Plan) for a network of receiving water bodies and a POTW located in headwaters of a watershed. The case studies will also include several different examples of watershed groups that are developing NARPs to address impairments throughout a watershed.
RELEVANCE
The complexity of nutrient impacts on receiving waters requires the use of watershed-based approaches to eliminate impairments. Illinois' novel strategy of allowing POTWs to develop watershed-based NARPs, including site-specific NNC, will be helpful to stakeholders in other states to address nutrient-related impairments in receiving waters.

This presentation will provide an overview and case-studies of a novel approach being adopted in Illinois to address nutrient-related impairments in downstream local waters bodies. The case studies will include stand-alone NARPs as well as examples of watershed groups developing NARPs to address impairments throughout a watershed.

SpeakerMahajan, Rishab

Presentation time

15:35:00

15:50:00

Session time

15:30:00

17:00:00

TopicIntermediate Level, Nutrients, Watershed Management, Water Quality, and Groundwater

Author(s)

Mahajan, Rishab

Author(s)Rishab Mahajan1; Adrienne Nemura2

Author affiliation(s)Geosyntec Consultants, Oak Brook, IL1; Geosyntec Consultants, Valley City, OH2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2022

DOI10.2175/193864718825158693

Volume / Issue

Content sourceWEFTEC

Word count11

Nutrient Reduction Planning: Illinois' Journey and Lessons Learned

Abstract

INTRODUCTION:
Efforts to reduce nutrient loading from both point sources and non-point sources are intensifying to tackle major environmental issues. These issues include hypoxia in the Gulf of Mexico, harmful algal blooms in Western Lake Erie, and various nutrient-related problems in local water bodies across the U.S. The Illinois Nutrient Loss Reduction Strategy aims for a 45% reduction in total phosphorus and nitrogen loading by 2045. A key tool in this strategy is the Nutrient Assessment Reduction Plan (NARP), which is a special condition included in National Pollutant Discharge Elimination System permits for major wastewater treatment plants with a design flow of one million gallons per day.

OBJECTIVE:
The primary purpose of the NARP is to identify phosphorus input reductions and other necessary measures to address phosphorus-related impairments. The NARP special condition requires permittees to develop an implementation plan and schedule for the identified measures to address water quality impairments effectively. The WWTPs are required to achieve an annual geometric mean effluent TP target of 0.5 mg/L by 2030. The NARP determined whether a local TP effluent target was required to address the phosphorus-related impairments in receiving waters

IMPLEMENTATION STRATEGIES:
The NARP development NARP was tailored to the unique characteristics of each wastewater treatment plant (WWTP) and watershed. At WEFTEC 2022, various approaches to NARP development were presented (Mahajan et al., 2022). This presentation will cover implementation plans for three completed NARPs: one for a headwater stream by a single WWTP, another by a large regional utility for a network of receiving water bodies, and a watershed-wide NARP by a group of WWTPs.

STAKEHOLDER ROLE:
The Water Research Foundation Project #4974 has identified three pillars for nutrient management: Practice, Policy, and Partnerships (Clark et al., 2023). Partnerships with relevant stakeholders are a critical aspect of nutrient reduction efforts and are often overlooked. The NARP development included many stakeholders, including government agencies, municipalities, non-profits, environmental groups, and the community. This presentation will discuss the role of different stakeholders in the NARP development, and the strategies used to solicit input from them. Example strategies utilized in the NARP development included public meetings, watershed group meetings, surveys, and workshops. Engaging stakeholders ensures that diverse perspectives are considered, and collaborative solutions are developed.

OBSTACLES TO IMPLEMENTATION:
The NARPs were due by the end of 2024. This presentation will discuss the obstacles to the NARP implementation recommendations. These include, but are not limited to:
1. Financial Constraints: Many WWTPs in Illinois, especially smaller ones, face financial constraints in meeting the NARP TP effluent limits of 0.5 mg/L. The State Revolving Fund (SRF) in Illinois does not have enough funds to assist with upgrading all the major WWTPs to meet the effluent TP target of 0.5 mg/L. Another example is the funding for dam removal recommended in some NARPs for addressing phosphorus-related impairments.
2. Technical Constraints: An example of a technical constraint is the inability of a large WWTP to meet the effluent TP target of 0.5 mg/L due to the industrial nature of a large proportion of its effluent. This presents a significant challenge in achieving the desired nutrient reduction goals.
3. Uncertainty about the Role of Environmental Groups' Comments for NPDES Permit Renewal: Environmental groups were part of the NARP development process. However, they provided comments urging the Illinois EPA to set the target effluent TP concentrations to 0.1 mg/L or below. It remains to be seen how the Illinois EPA will respond to these comments during the NPDES permit renewal process, adding a layer of uncertainty to the implementation.
4. Public Engagement: During the NARP development, WWTPs found it challenging to engage with the public on wastewater topics. This is likely to remain a challenge for implementation, as it is difficult to generate public interest and excitement about 'wastewater' issues. Effective public engagement strategies are essential for gaining community support and ensuring successful implementation.

PATH FORWARD: This presentation will discuss the recommended path forward to overcome the described obstacles. Adaptive management is an iterative process that involves continual monitoring to assess the performance of management actions and enable responsiveness to potential challenges. The NARP implementation would need to include adaptive management to address the implementation challenges. The NARP implementation will also focus on the three Ps of nutrient management: incorporating technological advancements and cost-efficient WWTP upgrades, flexible regulatory policies that encourage innovation, and continuing to foster partnerships to achieve the nutrient reduction goals. By adopting an adaptive management approach, stakeholders can ensure that the NARP implementation remains effective and responsive to changing conditions and new information.

SIGNIFICANCE:
The lessons learned from the development of Illinois NARPs will be invaluable to stakeholders in other states as they address nutrient-related impairments in receiving waters.

This paper was presented at WEFTEC 2025, held September 27-October 1, 2025 in Chicago, Illinois.

Presentation time

16:00:00

16:30:00

Session time

15:30:00

17:00:00

SessionBalancing Act: Nutrients, Water Quality, and Ecosystems

Session locationMcCormick Place, Chicago, Illinois, USA

TopicWatershed Management

Author(s)

Mahajan, Rishab, Nemura, Adrienne

Author(s)R. Mahajan1, A. Nemura1

Author affiliation(s)Geosyntec Consultants1

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Sep 2025

DOI10.2175/193864718825159982

Volume / Issue

Content sourceWEFTEC

Word count9

Base text size -

Mahajan, Rishab

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