EQUIPMENT & SUPPLIES: DH-75 Suspended-Sediment Sampler January 17, 1977 QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM NO. 77.03 Subject: EQUIPMENT & SUPPLIES: DH-75 Suspended-Sediment Sampler The Federal Interagency Sedimentation Project recently has introduced the DH-75 series of suspended-sediment samplers. The DH-75 sampler was first described in an article by Steven H. Hindall in the April-June 1974 WRD Bulletin as the "Hindall Sampler." The sampler was designed specifically for sampling under ice using the standard pint sample bottle. Hindall's original design was modified by the Sedimentation Project to hold a plastic 500-ml bottle (DH-75P). They then developed two other models that hold 1000 ml (DH-75Q) and 2000 ml (DH-75H) containers. These samplers were listed for sale in their 1977 Fiscal Year price list. All models are intended for use on a wading rod for sampling under ice. The purpose of this memo is to inform you that all three of these models are acceptable for use within WRD for sampling under ice. Also, the 500 ml and the 1000 ml models may be used for the collection of samples in open waters by wading or from a boat when a wading rod can be utilized. The DH-75H (2000 ml ,model) is not recommended for the collection of water-sediment samples in open waters except for low velocity flow where no silt-or sand-size particles are in suspension. The reason for this is because the unsampled zone is about 50 percent greater for the DH-75H than for the DH-48; therefore, the DH-75H data are not comparable to DH-48 data for the silt plus sand fractions. No attempt should be made to suspend any of the DH-75 samplers from a reel and cable. The Sedimentation Project currently is attempting to develop a satisfactory large-volume sampler for general water-quality and suspended-sediment sampling under extreme low temperature conditions. As soon as such a sampler is available the field offices will be notified. R. J. Pickering Chief, Quality of Water Branch WRD Distribution: A, FO, PO