In Reply Refer To: March 27, 1992 Mail Stop 412 OFFICE OF WATER QUALITY TECHNICAL MEMORANDUM 92.08 Subject: PROGRAMS AND PLANS--Nutrient Sample Size Reduction On April 10, 1992, the National Water Quality Laboratory (NWQL) will begin replacing 250 mL brown nutrient bottles and 1 mL mercuric chloride ampoules with 125 mL brown nutrient bottles and 0.5 mL mercuric chloride ampoules. The purpose of this change is to reduce the amount of mercuric chloride that is being used in the field and that, subsequently, must be disposed of by the NWQL. Efforts continue towards replacing mercuric chloride with another preservation method during Fiscal Year 1993. By this memorandum, we request Districts to place orders (by edoc to DENSUPPLY) for replacement bottles and ampoules as soon as possible. Order a supply that will cover your needs for the next six months only. Districts initially will be billed for the orders, but will be reimbursed for the costs of both bottles and ampoules when the obsolete 1 mL mercuric chloride ampoules are returned to NWQL for disposal. The 250 mL bottles are not to be returned to NWQL (only the 1 mL ampoules). Districts can dispose of the 250 mL nutrient bottles as they see fit. NWQL expects the exchange of supplies to take about one month, and beyond that, an additional month will be allowed for receipt of any outstanding 250 mL nutrient samples for analysis. After that time, the 250 mL bottles will no longer be accepted by the Login Section. The exact sample acceptance cutoff date will be set by the NWQL after the exchange of supplies is completed and will be announced in the QWTALK Continuum. Further details and instructions will be distributed by NWQL in the coming weeks. David A. Rickert This memorandum does not supersede any previous Office of Water Quality Technical Memorandum. Key Words: Nutrients, preservative, mercuric chloride Distribution: A, B, S, FO, PO