@misc{indiciae33022c6a7069,
  title = {Water-quality trends in the nation's rivers},
  author = {Richard A. Smith and Richard B. Alexander and M. G. Wolman},
  year = {1987},
  doi = {10.1126/science.235.4796.1607},
  url = {https://pubs.usgs.gov/publication/70015321},
  note = {Source identifier: 70015321}
}