N EW Y ORK S TATE D EPARTMENT OF E NVIRONMENTAL C ONSERVATION H UDSON R IVER E STUARY P ROGRAM Telling Hudson River Stories with Graphs 1. WATER LEVELS Iona Island Marsh near Bear Mountain

Changes in water levels can be shown using line graphs. Where? When? How high? Source: USGS Hudson River Salt Front website

Interpreting graphs: What is the story that each graph tells? Answer these questions when looking at each graph: 1. What time period is shown in this graph? 2. What is being measured in this graph? 3. Where was the information gathered? 4. What happens to it over the time period shown? 5. What is your hypothesis about what caused this to happen? 6. Measurements of what other parameters would help you test and verify your hypothesis? If you have Internet access, you can go to the Hudson Environmental Conditions Observing System website to check other parameters and test your hypothesis.Hudson Environmental Conditions Observing System website

How do changes in water level differ at these two Hudson River sites? Source: USGS Current Conditions for New York: Surface Waters Create a hypothesis to account for the different plots at these sites.

From the city of Troy south, the surface of the Hudson is at sea level – the same level as the surface of the ocean. At Sandy Hook on the Atlantic Ocean, is the sea’s surface always at the same level, or does it rise and fall? Why? 2013 Source: New York Harbor Observing & Prediction System

Because the Hudson is at sea level from Troy to the ocean, tides make the river rise and fall here. How many high tides occur daily at any spot on the river? How many low tides? How long does it take to go from low tide to the next high tide? From a low tide to the next low? Troy Source: Hudson River Environmental Conditions Observing System

Low and high tides occur in a cycle. Based on this graph, predict the times of high and low tides at Poughkeepsie on November 19.

Source: Hudson River Environmental Conditions Observing System 2013 This graph shows tides at Poughkeepsie and at Albany during the same time period. How are tides different at the two locations?

What is the tide doing on the Hudson now…. … at the Battery in Manhattan? Visit the National Oceanic & Atmospheric Administration’s Battery tide gauge website. Battery tide gauge … near where you live? Visit the HRECOS web page to find the station nearest your home. Go to the Current Conditions page, select that station. Choose the Depth or Water Elevation parameters; click on Plot.HRECOS web page Want to know when the tide will be high or low tomorrow? Next week? Months from now? Visit the National Oceanic & Atmospheric Administration’s tide predictions website for New York, scroll down to the list of Hudson River stations, and click on the one nearest you.tide predictions

N EW Y ORK S TATE D EPARTMENT OF E NVIRONMENTAL C ONSERVATION For more information, contact: Steve Stanne, Education Coordinator NYSDEC – Hudson River Estuary Program/New York Water Resources Institute – Cornell University 21 South Putt Corners Road New Paltz, NY