Fraction of organisms ingested that initiate infection (*r* value) | | | | |

*Giardia* | rg | Unitless | Empirical (2.5th = 0.009798; 12.5th = 0.01336; 25th = 0.01584; 50th = 0.0198; 75th = 0.02466; 87.5th = 0.02845; 97.5th = 0.03582) | 44; calculated based on likelihood confidence intervals |

*Cryptosporidium* | rc | Unitless | Empirical (5th = 0.0074; 25th = 0.0227; 50th = 0.0539; 75th = 0.1197; 95th = 0.3044) | 62 |

Incidental sediment ingestion rate | IR_{sed} | mg/day | Triangular | Selected based on a |

Recreator | | | Minimum = 25, mode = 100, maximum = 200 | review of sediment |

Visitor | | | Minimum = 25, mode = 50, maximum = 95 | ingestion rates |

Homeless person | | | Minimum = 25, mode = 200, maximum = 350 | provided in regulatory guidance and recent health assessments |

Exposure frequency | EF | Days/yr | Triangular | Selected based on a |

Recreator | | | Minimum = 1, mode = 12, maximum = 95 | review of sediment |

Visitor | | | Minimum = 1, mode = 2, maximum = 12 | ingestion rates |

Homeless person | | | Minimum = 1, mode = 24, maximum = 150 | provided in regulatory guidance and recent health assessments. Maximum number of days limited by meteorological factors such as precipitation and temperature |

Incidental water ingestion rate, swimming (for bacterial calculations) | IR_{swim} | ml/day | Triangular (minimum = 10, mode = 16, maximum = 100) | 20 |