Long Island Surface Water - Streamflow

Science Center Objects

Surface water current conditions are based on the most recent data from on-site automated recording equipment. Measurements are commonly recorded at a fixed interval of 15 to 60 minutes and transmitted by satallite uplink or telephone telemetry to the USGS every hour. Values may include "Approved" (quality-assured data that may be published) and/or more recent "Provisional" data (of unverified accuracy and subject to revision).

Out of about 250 stream sites in New York, there are 9 stream sites on Long Island that provide current data collection, which is mostly provisional. This current data collection network of streams can be found by clicking on this link, streamflow current conditions or viewed in a map interface to download data. Another interactive map known as "Water Watch" uses the data collected at these stream sites to symbolize and rank the current flow conditions based on each stations historical data collection.

Manual measurements of streamflow and gage height are used to supplement and (or) verify the accuracy of the automatically recorded observations, as well as to compute streamflow based on gage height. There are over 100 partial record stream sites with manual measurements, about 25 stream sites with annual maximum instantaneous peak streamflow and gage height data, and around 10 stream sites with historical instantaneous data on Long Island.

Statistics are computed from approved daily mean data at each site. Statistical summaries of approved historical daily values for daily, monthly, and annual (water year or calendar year) time periods are also available. There are over 22 stream sites with daily, monthly, or annual streamflow statistics available throughout Long Island (figure 19).


map of Long Island Streams and Average Flows
Figure 19. Map of stream gaging locations with average annual streamflow for the  entire period of record, on Long Island, New York(Public domain.) Click here for interactive map and data.


Table of Contents

State of the Aquifer, Long Island, New York - Introduction

Location and Physical Setting


  1. Hydrolgeologic Units
  2. Fresh and Saltwater Relations/Interactions

State of the Aquifer System

  1. Precipitation
  2. NWIS - the USGS Data Archive 
  3. Surface Water - Streamflow
  4. Groundwater Levels
  5. Water Table and Surface Maps
  6. Water Use
  7. Groundwater Budget
  8. Inflow to the Groundwater System
  9. Outflow from the Groundwater System
  1. Case Studies

Interactive Content