October 15, 1975


Subject: EQUIPMENT AND SUPPLIES--Bedload Samplers

It has come to our attention that an increasing number of 
Districts are becoming involved in programs requiring the 
measurement of sediment moving as bedload. You should be aware 
that the Water Resources Division has not officially adopted any 
existing bedload sampler as acceptable or standard equipment for 
the measurement of bedload.

We currently have underway a research study to develop an 
acceptable bedload sampler or samplers; however, until this study 
is complete the Geological Survey cannot put its stamp of approval 
on any of the existing samplers. The research is being carried on 
at the University of Minnesota's St. Anthony Falls Hydraulics 
Laboratory. A large flume is being modified to permit the 
introduction and measurement of the rate of movement of course 
material as bedload, Various types of bedload samplers will be 
tested and calibrated in this flume, including the Helley-Smith 
sampler. The project is under the direction of Dave Hubbell, WRD, 
Denver, Colorado.

Since the development of the Helley-Smith sampler in 1971, a large 
number of samples have been collected by Luna Leopold, Bill 
Emmett, and the California District using various models of the 
sampler; however, we have not had the proper facilities to 
adequately calibrate the sampler, and therefore could not accept 
it for official use within WRD. Under the provisions of QW Branch 
Technical Memorandum No. 75.09 and WRD Memorandum No. 74.88, the 
Branch has approved the use of the Helley-Smith sampler by a few 
districts whose District Chiefs felt that the data collected were 
of high priority and have agreed to make the cooperator aware of 
the fact that the sampling efficiency of the sampler has never 
been proven.

If our research shows that the Helley-Smith sampler does perform 
adequately, we undoubtedly will adopt it as a standard Survey 
bedload sampler, and it will be made available #or purchase 
through the Federal Interagency Sedimentation project. Meanwhile, 
use of any of the current models of the Helley-Smith bedload 
sampler will be considered acceptable provided that:

1.  The cooperator is fully informed that the accuracy, or 
sampling efficiency of the sampler have not been proven, and that 
any data obtained using the sampler cannot be certified by the 
Geological Survey.

2. The district document the exact model of sampler used so that 
it can be calibrated later against the model that is selected on 
the basis of the laboratory research study.

Please contact the Chief, Operations Section (attention: Mr. Wayne 
Hammond) for information regarding purchase of Helley-Smith 
bedload samplers. Do not order any samplers through either the 
California District or Bill Emmett. This will insure that all new 
samplers conform to the best current design specifications.

The Quality of Water Branch will appreciate being kept informed 
regarding your use of the Helley-Smith Bedload Sampler or any 
other new bedload sampler.

                                      R. J. Pickering  

WRD Distribution: A, B, S, FO, PO