The U.S. Geological Survey (USGS) has been measuring the flow in the Nation's rivers since 1889. This graph (Slide 1) shows the number of active USGS continuous record streamgages in operation from 1901 through 2004. The number of streamgages in operation rose steadily from 1901 for nearly 7 decades, reaching a peak number in operation in 1968 of 8,221 active streamgages. From 1968 until 1981 the number of active streamgages fell slightly to about 7,770 streamgages, then the number declined rapidly to about 7,000 streamgages by 1984 where it stayed relatively stable for nearly 15 years until 1998 when the number of active streamgages again climbed to about 7,530 streamgages by 2003. In 2001, NSIP received a funding increase to help sustain the increasing network size, although most of the streamgages added by NSIP were reactivations of previously discontinued streamgages. Because of level funding for both NSIP and the Cooperative Water Program, and inflationary cost increases to operate streamgages averaging 3 to 4 percent, 2004 and 2005 both showed a decline in the total number of active streamgages resulting in about 7,360 streamgages active at the end of 2005.

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