thumbnail

Nitrogen Load Estimates From Six Nonpoint Sources on Long Island, New York, From 1900 To 2019

Scientific Investigations Report 2024-5047
National Water Quality Program
By: , , and 
https://doi.org/10.3133/sir20245047

Links

Abstract

Estimates of nitrogen loading from nonpoint sources on Long Island, New York, at or just below the land surface, are essential for assessing the current and future effects of nitrogen on the island’s drinking water and fresh and marine surface receiving waters. Annual estimates of nitrogen loading for the 120 years from 1900 to 2019 for major nonpoint nitrogen sources—septic systems, residential fertilizer, agricultural fertilizer, livestock waste, pet waste, and atmospheric deposition—were made by using a geographic information system to analyze, visualize, and process data sources, and format output data. This analysis provided spatial and temporal estimates of nitrogen loading derived from each nonpoint source at a 500- by 500-foot gridded resolution and represents the total mass of nitrogen applied on, or just below, the land surface annually from 1900 to 2019. These mass estimates are considered unattenuated as they do not reflect the various mechanisms of nitrogen loss, such as plant uptake, overland runoff, and chemical transformations in the soil and unsaturated zones that likely reduce the amount of nitrogen that reaches the water table.

Island-wide and countywide summaries of the estimated nitrogen loading were analyzed to describe the long-term average nitrogen totals and the contributions from the six nonpoint sources. The island-wide average annual nitrogen load from 1900 to 2019 was 14.92 million kilograms (Mkg) nitrogen, which represents the aggregate of individual contributions from septic systems (4.15 Mkg), residential fertilizer (3.28 Mkg), agricultural fertilizer (3.19 Mkg), livestock waste (1.22 Mkg), pet waste (0.98 Mkg), and atmospheric deposition (2.10 Mkg). The island-wide average annual nitrogen load, normalized by area, was 4,100 kilograms nitrogen per square kilometer (kg N/km2), which represents the aggregate of individual contributions from septic systems (1,100 kg N/km2), residential fertilizer (910 kg N/km2), agricultural fertilizer (880 kg N/km2), livestock waste (340 kg N/km2), pet waste (270 kg N/km2), and atmospheric deposition (580 kg N/km2).

Suggested Citation

Monti, J., Jr., Walter, D.A., and Jahn, K.L., 2024, Nitrogen load estimates from six nonpoint sources on Long Island, New York, from 1900 to 2019: U.S. Geological Survey Scientific Investigations Report 2024–5047, 40 p., https://doi.org/10.3133/sir20245047.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Method and Approach
  • Description of Datasets Used in the Analysis
  • Estimating Nitrogen Loads
  • Trends in Nitrogen Load From Nonpoint Sources
  • Uncertainties and Limitations
  • Summary
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Nitrogen load estimates from six nonpoint sources on Long Island, New York, from 1900 to 2019
Series title Scientific Investigations Report
Series number 2024-5047
DOI 10.3133/sir20245047
Year Published 2024
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) New York Water Science Center
Description Report: vi, 40 p.; Data Release
Country United States
State New York
Other Geospatial Long Island
Online Only (Y/N) Y
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details