Waterbody Measurements
Water level and streamflow can help explain changing river conditions. Temperature, oxygen, and other measurements reveal other information regarding the waterbody.
Detailed Water Information
Understanding Your Water
Water affects our health, ecosystems, and communities. AquaNY brings public water measurements into one place. This guide will help you understand what the measurements on the map page mean, and how they affect you.
About Measurements
When you click a measurement value in AquaNY, you will see its explanation here. Try using these example readings.
These are examples for explanation, not our current Hudson River observations.
Why water data matters
A river's condition changes with weather, runoff, seasons, and human activity. Drinking-water systems are tested for substances that may affect health over time. Public agencies collect this information, but the results can be difficult to find or interpret.
Water Contaminants
Laboratory tests can identify chemicals such as PFAS, arsenic, or nitrate. Knowing what a substance is helps you ask better questions about a result.
Context Matters
One measurement is not indicative of the entire location. Location, date, units, detection limits, and the type of sample matter as well.
AquaNY's Data Sources
What's been observed in a waterway?
AquaNY displays recent USGS monitoring-station readings where confidently associated with a waterbody, alongside older observations and historical environmental sampling results.
Important: A river measurement is tied to a particular station and time. It does not represent the entire river, nor does it establish current swimming or drinking safety directly.
What's been reported for a public water system?
AquaNY shows historical NYSDOH contaminant summaries for named public water systems. The records are just annual or quarterly summaries, not live readings from your faucet; while they give a good overview, do more research before taking action.
Important: Some records can refer to untreated or inactive sources. Confirm your actual water supplier and consult its latest official water quality report.
What do river measurements mean?
Not every measurement is a pollutant. Many describe the physical or chemical conditions at a USGS station. AquaNY only labels parameters it can identify reliably.
Streamflow
ft³/sMeasures how much water passes a location each second. Higher streamflow often occurs after rainfall or snowmelt and can indicate stronger currents or increased flood risk. There is no universal good or bad streamflow value; it depends on the river's normal conditions.
← Back to mapGage height
ftMeasures water-surface height relative to a station's reference point. A rising gage height may indicate increasing flood risk, especially when approaching local flood thresholds. The number alone does not tell you whether flooding will occur, but can be useful combined with other factors.
← Back to mapWater temperature
°F / °CAffects aquatic organisms and how much oxygen water can hold. Warmer water generally holds less dissolved oxygen and can stress cold-water fish such as trout. Temperatures above 68°F (20°C) may be stressful for some cold-water species, but there is no single safe temperature for every waterbody.
← Back to mapDissolved oxygen
mg/LMeasures oxygen available in the water, which is used fish and other aquatic life. Higher values are generally more favorable. Concentrations below 5 mg/L can stress many fish, while levels below 3 mg/L are particularly concerning. Different species have different oxygen requirements, so different ecosystems require different levels.
← Back to mappH
Measures how acidic or basic water is. A pH of 7 is neutral, below 7 is acidic, and above 7 is basic. A commonly used EPA freshwater aquatic-life reference range is 6.5–9.0. Values outside this range may stress organisms and affect how other chemicals behave in the water.
← Back to mapTurbidity
FNU / NTUMeasures cloudiness caused by suspended particles. Higher turbidity can reduce sunlight penetration and affect aquatic habitats. Sudden increases above a river's normal level may indicate runoff, sediment, or algae. Other causes include rainstorms, spring snowmelt, bank erosion, bottom-feeding fish stirring up sediment, and natural algae or plankton growth. There is no NTU or FNU cutoff that defines poor water quality universally.
← Back to mapSpecific conductance
µS/cmIndicates how well water conducts electricity, which is related to its concentration of dissolved ions. Examples of such include calcium, magnesium, sodium, and chloride. Higher values may reflect more dissolved salts or minerals from road salt, runoff, or natural geology. Unusually high readings compared with a station's normal values may warrant investigation, but there is no universal harmful threshold.
← Back to mapSalinity
PSUMeasures dissolved salts in water. Freshwater generally has salinity below about 0.5 PSU, while seawater is around 35 PSU. Elevated salinity can harm freshwater organisms, although higher values are normal in tidal estuaries such as parts of the Hudson River.
← Back to mapWater-surface elevation
ftMeasures water elevation relative to a reference datum (agreed upon reference level), such as NAVD88. Higher elevations may result from tides, storms, or increased river levels. Whether a value is concerning depends on local flood thresholds and the reference datum.
← Back to mapWhat are the contaminants?
A contaminant is a substance measured in a water sample. Note, detection does not automatically mean a health standard was exceeded. Keep in mind that standards and interpretations depend on the substance, amount, source, and regulatory limits.
PFAS: PFOA and PFOS
PFAS (commonly known as "forever chemicals") are a large family of manufactured chemicals used in industrial processes and consumer products. PFOA and PFOS are two widely studied examples. They can persist in the environment, and long-term exposure to certain PFAS has been associated with health concerns.
Often reported in ng/L (approximately parts per trillion in water) ← Back to mapNitrate
A form of nitrogen that may enter water through fertilizers, wastewater, and natural processes. The U.S. EPA limit for nitrates is 10ppm. Elevated nitrate in drinking water is a particular concern for infants.
Usually recorded in ppm (parts per million) ← Back to mapArsenic
A naturally occurring element that can enter groundwater from rocks and minerals. Long-term consumption of elevated concentrations in drinking water can pose health risks.
Often reported in µg/L ← Back to mapOther detected contaminants
Water-system summaries may also include disinfection byproducts, solvents, radionuclides, and other substances. AquaNY displays selected detected analytes, but its card list is not the full monitoring history.
Use “View all contaminant summaries” for more records ← Back to map
About PFAS standards
New York regulates PFOA and PFOS in public drinking water. Regulatory thresholds and compliance schedules can change. For current standards and official guidance, consult the New York State Department of Health rather than treating an AquaNY card as a complete determination.
How to read a result
Check where
Is it a specific USGS station, an environmental sampling location, or a public water system? A nearby station may not be matched to the waterbody you searched.
Check when
Look at the observation timestamp or reporting period. “Latest available” can still be months or years old. Annual and quarterly summaries may overlap.
Check what
Read the parameter name, unit, and detection status. “Nondetect” means not detected under the applicable testing method, not necessarily zero.
Mean and Maximum
In AquaNY's drinking-water cards, mean is a summary average and maximum is the highest summarized value for the selected reporting period. These are not necessarily individual tap samples. “No published measurement,” meaning a measurement was not recorded, is different from “Nondetect,” usually meaning a low or undetectable level.
Common questions
Does a detected contaminant mean my drinking water is unsafe?
Not necessarily. A detection tells you a substance was measured, not whether a threshold was exceeded or whether there is a health risk. Check the water supplier's official report and public notices.
Can I drink or swim in a river based on AquaNY readings?
No, while they are a good starting point, streamflow, temperature, oxygen, pH, and historical pollutant sampling alone cannot establish current drinking or recreational safety. Consult local health advisories and official beach or waterbody notices.
Why does a station on the map have data while a river search shows none?
The station map includes individual USGS stations. The waterbody view shows readings only where stations have been confidently associated with a particular waterbody. Some nearby stations are not yet matched, to ensure valid data for each waterbody.
Why are some station measurements missing?
Most USGS stations do not record all supported values, and AquaNY only provides values it can determine are reliable.
Where can I find the latest information about my tap water?
Confirm your supplier using your water bill or local utility website, read its latest annual Consumer Confidence Report (water quality report), and check official advisories from your water supplier or health department.
Explore the official sources
While AquaNY helps make publicly reported measurements easier to discover, government agencies and water suppliers are still the authoritative sources for standards and health information.