Thresholds

Analyse water quality data from a set of given station/sites for appropriate parameter guideline thresholds and threshold exceedances

The exceedance analysis entails determining the appropriate parameter guideline threshold values for a given time-series dataset (e.g. data for set of parameters for each station/site) and then comparing the time-series data against the established guideline thresholds for each parameter. Guideline thresholds are established provincially by the BC Ministry of Environment (http://www2.gov.bc.ca/gov/topic.page?id=044DD64C7E24415D83D07430964113C9) and nationally by the Canadian Council of Ministers of the Environment (CCME; http://www.ccme.ca/en/resources/canadian_environmental_quality_guidelines/index.html). Provincial guidelines are used if there are (differing) guideline thresholds for a parameter. Note: apparently the federal guidelines are machine readable.

There are 44 established provincial guidelines. Some guideline thresholds are static (e.g. comparing data against a single value for a single use). However, the coding will likely involve creation of individualized functions for some parameters that have guideline thresholds that are different depending on the use of water (e.g. drinking water, aquatic life, wildlife, livestock watering, and irrigation) and/or relative (e.g. dependent on value of 1 or 2 other parameters). See http://www.ec.gc.ca/indicateurs-indicators/default.asp?lang=en&n=3786D3FD-1 for an example set of water quality parameter guideline thresholds for aquatic life for British Columbia. The current vision is to have a set of functions that return the appropriate guideline thresholds to be used for a given data set and given water use (e.g. maybe by adding a column to the source data) and then feed this ‘new’ data into the further analyses below. Guideline thresholds required or commonly used for the WQI analysis are to be coded/included first; the contract monitor will work with MoE water quality staff and the vendor to prioritize subsequent parameter guideline thresholds.

Guidelines Dataset

The guidelines information is stored in a .csv file in wqcb/data-raw/guidelines.csv. The advantage of a cvs file is that it can be read by a range of programs, is straightforward to input into R and is a text file so can be version controlled using git.

The file has a number of columns which are described in the help file. To view the guidelines help file build and load the package and then type ?guidelines for more information and summary(guidelines) to get a summary.

Approved

we can only include thresholds for parameters where the guideline document is final (e.g. not "working" or "draft" -http://www2.gov.bc.ca/gov/topic.page?id=1ED7413D20E54AC0AF9965293832C117). If it is not included in the bc_pdf document then I believe we don't have an official guideline for BC (yet). Also, please only use the "new" bc gov pages as your references (http://www2.gov.bc.ca/gov/topic.page?id=500E145665274DB980A7B61735E5C55F or anything that is in that format or starts with www2.gov.bc.ca). Or, alternatively, confirm any values from 'old' web pages before using.