NOR_01_CMP12 - Sediment sampling/analysis in response to herbicide treatments (2,4-D and Endothall) on Little St. Germain Lake.


Granular herbicide treatments to control curly leaf pondweed and eurasian water milfoil have taken place over the last seven years on Lttle St Germain lake. We are begining to collect residual data on how long the herbicides (2,4-D) remain in the water column and at what concentrations. Little residual work has been done on lake sediment. We want to determine if these herbicides (2,4-D/Endothall)accumulate in the sediments over the long term; how quickly to they break down?; Do granular herbicides settle into the sediment before they dissolve in the water column? Possible toxicity problems? We will deploy sediment porewater equiliabrators (peepers) at 3 locations (one control, 2 treatment sites) on Little St Germain Lake. They will be deployed prior to treatment, the day of treatment, 2-3 weeks post, 4-6 weeks post and 8 weeks post. The peepers will be allowed to equilibrate for 10 -14 days under each sampling event. The porewater will be analyzed for Endothall and 2,4-D using the immunoassay technique. All samples will be sent to the US ARMY ERDC Lab in Gainesville, Florida under our existing CRADA agreement.


Project Justification: We are spending thousands of dollars a year through our grant program to fund herbicide treatments. We are begining to learn how these herbicides behave in the water column (residual monitoring) in terms of concentrations and exposure times. We have learned a lot. Little work has been conducted on lake sediment monitoring to determine the fate of these herbicides.


Performance Measures: These are milestones that will be reported on in the Division Quarterly Report. 1) Number of sample sites associated with the project 3 (one control, 2 treatment sites) sample sites. 2) Number of sampling events associated with project - 5. 3) Estimated date when sample collection will be complete - July /August 2011. 4) Estimated date when all data will be entered into appropriate database - May 2012. 5) Estimated date when final report will be complete - June 30 2012.

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