Water Quality Assessment and Environmental Compliance in Brazil R package tikatuwq version 0.9.0 Tools to import, clean, validate, and analyze freshwater quality data in Brazil. Implements water quality indices including the Water Quality Index ('WQI'/'IQA') using the weighted geometric mean following 'CETESB' methodology, the Trophic State Index ('TSI'/'IET') after Carlson (1977) <doi:10.4319/lo.1977.22.2.0361> and Lamparelli (2004) <https://teses.usp.br/teses/disponiveis/41/41134/tde-20032006-075813/publico/TeseLamparelli2004.pdf>, and the National Sanitation Foundation Water Quality Index ('NSF WQI', Brown (1970)). The package also checks compliance with Brazilian standard 'CONAMA' Resolution 357/2005 <https://conama.mma.gov.br/?id=450&option=com_sisconama&task=arquivo.download> including the legal frequency rule (Art. 15, 80% conformity over six or more samples per year), and provides seasonal analysis with regional flow-season calendars, pollutant load computation, exceedance probability estimation, 'IET' visualization, and multivariate 'PCA' tools for routine monitoring workflows. The example dataset ('wq_demo') is a real subset from 'INEMA' monitoring data from a river in Bahia, Brazil (2020-2024). Software Depends: R (>= 4.1) Imports: dplyr, readr, tibble, rlang, stats, utils, ggplot2, tidyr, lubridate, stringr, glue, scales, broom, purrr, tools Suggests: testthat (>= 3.0.0), spelling, rmarkdown, knitr, pkgdown, leaflet, withr Vinicius Saraiva Santos <vinisaraiva@gmail.com> Comprehensive R Archive Network (CRAN) Vinicius Saraiva Santos [aut, cre] (ORCID: <https://orcid.org/0009-0007-1387-7927>) MIT + file LICENSE (https://CRAN.R-project.org/package=tikatuwq/LICENSE) 2026-06-09 application/tgz https://CRAN.R-project.org/package=tikatuwq doi:10.32614/CRAN.package.tikatuwq en-US