Julieta Gomez-Fragoso Yanire Martinez-Martinez 20260330 publication https://doi.org/10.5066/P13YAAPN The U.S. Geological Survey (USGS), in cooperation with the Puerto Rico Department of Natural and Environmental Resources (PRDNER), has been collecting surface water-quality data for over 20 years across the island of Puerto Rico. These data are used for numerous purposes, including to meet the mandates of the Clean Water Act, provide government agencies and public corporations up-to-date data on the quality of surface waters, and maintain a data base of water-quality information to assess the general water-quality at selected sites throughout Puerto Rico. The PRDNER continues progressing in the development of a water-quality management plan to reduce point source and non-point source water pollution across the island of Puerto Rico. To understand how the water-quality conditions have changed over time, the USGS, in cooperation with the PRDNER, conducted an analysis to identify water quality trends for selected sites and parameters (major ions, metals, nutrients, physical and other parameters). Mann-Kendall and Seasonal Kendall trend analyses were done using the open-source R software (R Core Team, 2024) and water quality data obtained from the Water Quality Portal (www. waterqualitydata.us) that were collected between the 1958 and 2022 water years. The trend analysis evaluated the full length of record at each site and included three schemes: the Mann-Kendall and Seasonal Mann-Kendall trend tests using non-flow adjusted data, and the Seasonal Mann-Kendall trend test using flow-adjusted data. The Mann-Kendall trend analysis also included three additional time periods (water years 2008-2022, and 2013-2022). This data release and its child items contain the input data that were used for trend analysis, the output files from the trend analysis, and the accompanying R scripts for data screening and trend analysis. A README file also is available with a description of the files that were included in the data release and steps to follow to run the scripts. Reference Cited: R Core Team, 2024, R – A language and environment for statistical computing: R Foundation for Statistical Computing website, accessed February 9, 2024, at http://www.R-project.org. The purpose of this data release is to describe the input data that were used for trend analysis at selected sites throughout Puerto Rico together with documentation of the R script used for conducting the trend analysis. The data release also contains output files from the trend model, summarizing the results of the trend analysis. The main purpose of this study is to identify water quality trends at selected sites and parameters that could be potential indicators of impairment in water quality. 1958 2022 ground condition Complete None planned World -67.3242 -65.1874 18.6827 17.7801 ISO 19115 Topic Category biota Water quality trends Mann Kendall Trend test Seasonal Kendall trend test Major ions Ammonia Temperature, water Specific conductance Nitrite Inorganic nitrogen (nitrate and nitrite) Phosphorus Copper Lead Magnesium Cadmium Chromium Stream flow, instantaneous Dissolved oxygen Total nitrogen Selenium USGS Metadata Identifier USGS:65aa9acdd34ef34c35062d11 Common geographic areas Puerto Rico Caribbean Islands None. Please see 'Distribution Info' for details. None. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Julieta M Gomez-Fragoso U.S. Geological Survey, SOUTHEAST REGION Civil Engineer mailing address

B Street, Lot 38

Bayamon PR 00961 US 787-749-7479 787-749-7401 jgomez-fragoso@usgs.gov Water Quality Portal (www.waterqualitydata.us) No formal attribute accuracy tests were conducted. Data were checked for duplication and expected ranges. This data set represents surface-water-quality data retrieved from the Water Quality Portal. Users are advised to read the rest of the metadata record for additional details. No formal positional accuracy tests were conducted. No formal positional accuracy tests were conducted. This data release contains the input data that were used for trend analysis, documentation of the R scripts used for preparing data and conducting trend tests, and the output files from the trend model. 2024 GS ScienceBase U.S. Geological Survey mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. Digital Data https://doi.org/10.5066/P13YAAPN None 20260330 Julieta M Gomez-Fragoso U.S. Geological Survey, SOUTHEAST REGION Civil Engineer mailing address

B Street, Lot 38

Bayamon PR 00961 US 787-749-7479 787-749-7401 jgomez-fragoso@usgs.gov FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata FGDC-STD-001.1-1999