Project #4747

Chemical Management of Hydrilla For Drinking Water Utilities

Principal Investigator
Research Manager
Mrs. Alice E Fulmer
Hazen and Sawyer
Reservoir Management
Source Water Protection
Utility Management
Risk Assessment


Hydrilla, a federally listed noxious weed, is a high priority risk for multi-use reservoir systems. Hydrilla infestation can impact water quality, aquatic habitat, and recreational uses. The species forms dense mats of vegetation, outcompeting native species, reducing dissolved oxygen, and raising pH. Hydrilla is a challenge in many parts of the United States and is currently present in New Croton Reservoir, which is management by the New York City Department of Environmental Protection (DEP). This project evaluated management strategies through the following project objectives:

  • Assessing the state of knowledge of fluridone application for the management of hydrilla in drinking water reservoirs and its impacts on treatability, water quality, and human and environmental health
  • Reviewing lessons learned from prior hydrilla management efforts
  • Assessing potential impacts associated with DEP’s current method of managing hydrilla, particularly related to fluridone treatment
  • Providing recommendations for mitigation of impacts associated with hydrilla management
  • Developing a communications fact sheet and final report

Research Partner: New York City Department of Environmental Protection.

Published in 2018.