Percentage of Surface Drinking Water from Intermittent,
Ephemeral, and Headwater Streams in New York
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15
30
60
90
120

Legend: This map highlights regional patterns of dependence on intermittent, ephemeral, and headwater streams
for surface drinking water in New York. In New York, 10,436 total miles of streams provide water for surface
water intakes supplying public drinking water systems; of this, 5,728 miles, or 55%, are intermittent, ephemeral, or
headwater streams. Over 11 million people in New York receive drinking water from public drinking water
systems that rely at least in part on intermittent, ephemeral, or headwater streams. This analysis compared the
stream length of intermittent, ephemeral, and headwater streams to total stream length within all mapped Source
Protection Areas (SPAs) for each county. A SPA is an area upstream from a drinking water source or intake that
contributes surface water flow to the drinking water intake during a 24-hour period. This is based on data that
generally do not include streams less than one mile in length. Intermittent streams are streams containing water
for only part of the year. Ephemeral streams flow in response to precipitation events. First-order streams have
been used to represent headwater streams.
Data Sources: National Hydrography Dataset Plus at medium resolution; Federal Safe Drinking Water
Information System 4th Quarter 2006 Data.

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