PPT Slide

This graph shows a set of streams in the Long Island, New York region, 2 of which have been developed (Valley Stream and Pines Brook). As impervious cover has increased, dry weather flow has steadily declined and is now only a fraction of its pre-developed condition. The other, predominantly agricultural watersheds have been able to sustain flow during dry weather.

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Notes:

This often means that a headwater stream that was once perennial now becomes intermittent.

One example is a set of streams in the Long Island, New York region. The graph shows the predominantly agricultural watersheds that have been able to sustain flow during dry weather. Two streams, the Valley Stream and Pines Brook shown on the bottom, have steadily developed over time. As impervious cover has increased, dry weather flow in the streams has steadily declined and is now only a fraction of its pre-developed condition.