Natural organic matter (NOM) is present in all raw water supplies and is the major precursor to chlorinated disinfection by‐products (DBPs). Reducing the amount of NOM entering treatment plants and better understanding the character of NOM in raw water supplies are essential for optimizing treatment and meeting more‐stringent regulations. A study of the unfiltered New York City (NYC) water supply system evaluated the extent to which alternative raw water selection strategies could reduce finished water DBP concentrations. A two‐year monitoring program was conducted to establish spatial and temporal patterns of DBP precursors in NYC's upstate reservoirs. System operations modeling was driven with a statistically generated, long‐term time series of dissolved organic carbon concentrations for each reservoir as a proof‐of‐concept evaluation of alternative operating rules to minimize precursor transport to terminal reservoirs. Results found that DBP precursors varied widely among reservoirs and over time but that modified reservoir operations could substantially reduce finished water DBP concentrations.

New York City has one of the most fascinating water systems in the world. Raw water is supplied from a network of 19 reservoirs and three controlled lakes in a 5,120 square kilometer watershed that extends 200 kilometers north and west of the City. About 90% of the supply, roughly 3.4 billion liters per day, comes from the Catskill/Delaware System, which consists of six source water and two balancing reservoirs. The only treatment provided is disinfection with free chlorine, corrosion control, and fluoridation – this is the largest unfiltered supply in the United States. While the quality of the raw water is extremely high, there are concerns about meeting the more stringent requirements of the United States Environmental Protection Agency's Stage 2 Disinfection Byproduct Regulations for haloacetic acids (HAAs). A comprehensive study was conducted by the New York City Department of Environmental Protection to evaluate a number of potential NOM/DBP control options including filtration, magnetic ion exchange resin treatment, converting to chloramines, and modifying reservoir operations. The purpose of this paper is to present the results of modifying reservoir operations with the goal of minimizing HAA levels in the City's water supply.

This article discusses a survey conducted by the New York City Department of Environmental Protection to assess the city's options for complying with the U.S. Environmental Protection Agency's Stage 2 Disinfectant and Disinfection Byproducts Rule. The survey asked 13 major U.S. water utilities to report their history of chloramine use, facilities used, dosages and chemicals used, operational procedures, environmental review required, public health impacts, advantages and disadvantages, and source water quality.

The new Peekskill (New York) Water Treatment Plant faced several design complexities, including connecting the new facility and high‐service pumps to the existing clearwell without interrupting service; installing a new intake; and managing a project site underlain with bedrock, requiring costly excavation. An award‐winning approach was used to optimize the conventional dissolved air flotation (DAF) process and include a pump station that allowed the plant to be constructed at grade, minimizing excavation.