Suggested citation for smwrGraphs:

  Lorenz, D.L. Kiekoff, A.L, smwrGraphs--An R package for graphing
  hydrologic data, Version 1.1.2: U.S. Geological Survey Open File
  Report 2016-1188

A BibTeX entry for LaTeX users is

  @TechReport{,
    title = {smwrGraphs--An R package for graphing hydrologic data, Version 1.1.2},
    author = {Dave Lorenz and Aliesha L. Diekoff},
    institution = {U.S. Geological Survey},
    series = {Open File report},
    year = {2016},
  }