The data set contains a summary of all measurements that were collected at the cottage grove reservoir over the time period of the study. This dataset is associated with the following publication: Eckley, C., T. Luxton, J. Goetz, and J. McKernan. Water-level fluctuations influence sediment porewater chemistry and methylmercury production in a flood-control reservoir.. David Carpenter, and Eddy Zeng ENVIRONMENTAL POLLUTION. Elsevier Science Ltd, New York, NY, USA, 222: 32-41, (2017).