WATER QUALITY--Sampling: Pesticides June 19, 1975 QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM NO. 75.25 Subject: WATER QUALITY--Sampling: Pesticides Enclosed for your information is a copy of "Guidelines on Sampling and Statistical Methodologies for Ambient Pesticide Monitoring," which was compiled by the Monitoring Panel of the Federal Working Group on Pest Management. Input from the Geological Survey to the compilation of these guidelines, particularly to the section on the Hydrologic Environment, was provided by Herman Feltz, our representative on the Monitoring Panel. Although these guidelines are generally consistent with the Division's procedures for sampling and analysis of pesticides in the hydrologic environment, as defined in recent instructional memoranda and in the Survey's TWRI on analysis of organic substances, there are some differences due to the general nature of the guidelines. In the past, samples collected by Division personnel as part of the National Pesticide Water Monitoring Program have not been shipped in a chilled condition as called for in the guidelines (p. IV-8). This was due in part to the lack of suitable containers for shipping glass bottles in an iced condition without breakage, and in part to the persistent nature of the pesticides that we were monitoring initially. The Operations Section currently is working on a design for a container in which we can safely ship the iced bottles. Until an acceptable container is developed, we recommend that the bottles be kept chilled before and after shipping on the premise that the persistent pesticides for which we are analyzing will not seriously degrade by being raised to ambient temperature during the few days required for shipment. We further recommend immediate extraction and chilling of the extracts when the samples arrive at the laboratory. Section III of the guidelines calls for freezing of soil samples. Plans are being completed for additional research by Division personnel on the advantages and disadvantages of preservation of water samples by freezing. At the present time, we do not recommend that water or sediment samples be frozen. I hope you will find the guidelines useful in field operations. Please route them to personnel under your supervision as appropriate. Questions concerning the guidelines should be addressed to the Chief, Quality of Water Branch. R. J. Pickering Chief, Quality of Water Branch Enclosure WRD Distribution: A,B,FO-LS,PO