Treatment of Legacy Nitrogen as a Compliance Option to Meet Chesapeake Bay TMDL Requirements

Abstract

In efforts to combat eutrophication, the U.S. Environmental Protection Agency has established aggressive nitrogen, phosphorus, and sediment reduction goals for states and regulated dischargers within the Chesapeake Bay watershed. Chesapeake Bay jurisdictions are struggling to meet the nutrient (N, P) reduction goals. This paper evaluates the efficacy of removing legacy N from groundwater as a compliance strategy for three potential classes of “buyers” of N reductions in the Chesapeake Bay watershed: permitted point sources, permitted municipal stormwater systems (called MS4s), and state nonpoint source (NPS) managers. We compare denitrifying spring bioreactors with conventional agricultural and urban NPS removal technologies using evaluative criteria important to each of these buyers. Results indicate that spring bioreactors compare favorably to other N removal technologies based on cost effectiveness, administrative costs, and certainty of N removal performance. Most conventional NPS technologies provide greater ancillary benefits. On balance, denitrifying spring bioreactors add a valuable compliance option to those tasked with achieving Bay N reduction goals.

Confronting our Agricultural Nonpoint Source Control Policy Problem

“…2021; Stephenson et al. 2021). From a strictly financial perspective, agricultural producers will not install and operate a technology with few on‐farm benefits and that costs them money (even if cost‐shared).…”

“…Consider a BMP that produces little agronomic benefit to a producer's operation, promises significant low-cost nutrient reductions but requires substantial upfront capital investment and ongoing operation and maintenance expenditures. BMPs such as stream buffers, denitrifying bioreactors, stream fencing, and manure storage/treatment can generate substantial nutrient reductions at relatively low costs (Price et al 2021;Stephenson et al 2021). From a strictly financial perspective, agricultural producers will not install and operate a technology with few onfarm benefits and that costs them money (even if cost-shared).…”

Distribution and Homogenization of Multiple Mercury Species Inputs to Freshwater Wetland Mesocosms

“…Strategies to control aquatic pollution typically consider the pollutant mass loading into the impacted waterway and, in some cases, the initial speciation of the chemical input. − For example, water quality management at the ecosystem scale leverages discharge permit controls at specific sources (e.g., point source discharge) to establish pollution credits and incentives to address other more diffuse sources (e.g., surface runoff). , Additionally, different “buyers” in a pollution credit system might implement a range of technologies and management best practices based on the efficacy of reducing total pollutant load, including the potential impact on other chemical or physical constituents of concern like nitrogen, phosphorus, and sediment. − If this approach were applied to Hg pollution, then discharge allocations would need to account for the relative risks of each Hg input with respect to mass loading and bioavailability . Furthermore, such accounting needs to consider natural cycling processes within the ecosystem that lead to the homogenization of the various Hg inputs.…”

A Process‐Based Model to Track Water Pollutant Generation at High Resolution and Its Pathway to Discharge

“…Regulators initially attempted to restrict discharge concentrations to improve the basins’ water environment, with limited success (B. Wang et al., 2023). The total maximum daily load and other projects have optimized control strategies to confine the discharge loads so that nutrients input from additional anthropogenic sources can match the self‐purification capacity of water bodies, and achieved certain results (Stephenson et al., 2021). However, the generation pattern of water pollutant loads at high resolution remains blank, and the detailed pathway between generation and discharge has not been clarified, resulting in the potential substantial gap between the two processes has not been considered (S. Li et al., 2017; J. Zhang et al., 2019).…”