ABSTRACT
Many California counties document the 1950’s as the beginning of large scale instream gravel extractions within the active channel. These larger scale operations began at approximately the same time as the construction of the Interstate Highway System. The San Benito River provided aggregate for the construction of highways and also had an annual gravel extraction rate since 1952 (87,000 m3 to 132,000 m3) which far exceeded the estimated annual replenishment of sediment (18,000 m3 to 45,000 m3). The degradation downstream and head cutting upstream as seen in Figure 2.
