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Document ID ca-bc-ahhrndwhv-2025-06 Title Assessment of Human Health Risk of Nitrates in Drinking Water in the Hullcar/Clcahl Valley URL https://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/agriculture-and-seafood/agricultural-land-and-environment/soil-nutrients/nutrient-management/technical-reports/soil-nutrient-studies/assessment_of_human_health_risk_of_nitrates_in_drinking_water_in_the_hullcar_clcahl_valley_hullcar_aquifer_response_plan.pdf Jurisdiction /ca/bc Subdomain(s) Drinking water, Groundwater, Source water protection, Water quality standards Language en Status completed Analyzed at 2026-03-15 08:11:34.528255+00:00 Relevance Assesses nitrate risks and references drinking water standards and regulations.

21 Qualitative 51 Quantitative 67 Definitions

Q Qualitative Requirements (21)

Req ID	Category	Intent	Legal Status	Name	Subdomain(s)	Context	Conditions	Confidence
#Q001	monitoring	operational	recommended	Aquifer 102 Ongoing Monitoring	drinking water	Current data indicates concentrations are below the MAC, but ongoing monitoring and assessment should continue.	Aquifer 102	high
#Q002	monitoring	health	recommended	Private Well Water Quality Verification	drinking water	Residents should check with their water supplier or sample their private well water to know if their water is safe to drink.		high
#Q003	treatment	health	mandatory	Drinking Water Treatment Responsibility	drinking water	Under the Drinking Water Protection Act (DWPA), drinking water treatment is the responsibility of the water supplier for community water systems or private well owners for systems that serve only single-family residences.	Applicable to community water systems and private well owners serving single-family residences	high
#Q004	operational	health	recommended	Drink Tested and Treated Water	drinking water	To prevent adverse health effects, residents should only drink water that has been tested and treated for nitrate and other contaminants, as necessary.		high
#Q005	treatment	health	recommended	ALARA Principle for Nitrates and Nitrites	drinking water	Health Canada states that Nitrates and Nitrites should be kept as low as reasonably practicable		high
#Q006	administrative	health	mandatory	Assessment of MAC Exceedance Health Risk	drinking water	The amount by which, and the period for which, the MAC can be exceeded without posing a health risk must be assessed by considering the toxicity of the substance involved (Health Canada, 1995).	When short-term exceedances above the MAC occur	high
#Q007	operational	operational	guidance	Minimize Post-Harvest Soil Nitrate	agricultural water, drinking water	Therefore, it is prudent for agricultural producers to minimize the amount of NO3-N remaining in the soil after crop harvest, as this NO3-N may contribute to contamination of the underlying aquifer (Ministry of Agriculture and Food, 2020b).	After crop harvest	high
#Q008	monitoring	operational	mandatory	Maintain Nitrogen Management and Monitoring	agricultural water, drinking water	Though there was a marked decline, it is still imperative due to the proximity of the fields to the Aquifer 103 that proper nitrogen management practices continue and maintain monitoring (Ministry of Agriculture and Food, 2023).	Fields in proximity to Aquifer 103	high
#Q009	design	operational	recommended	Well Drilling Best Practices and Setbacks	drinking water	To help prevent contamination, private well owners should also follow best practices for well drilling including following setbacks and well depth recommendations (The BC Ground Water Association, 2017).	When drilling new wells	high
#Q010	administrative	health	recommended	Source Water Investigations for Pathogen Risk	drinking water	For any groundwater at risk of containing pathogens, it is best to consult a Qualified Professional and potentially a Drinking Water Officer (DWO) to undertake Source Water Investigations to identify and assess hazards to the water source (EGBC, 2019).	For any groundwater at risk of containing pathogens	high
#Q011	reporting	health	recommended	Consult Authority on Nitrate Exceedance	drinking water	If nitrate concentrations are found to be higher than the Health Canada Guidelines in the Valley, well owners should consult the Interior Health Authority.	If nitrate concentrations are higher than Health Canada Guidelines	high
#Q012	treatment	health	recommended	Treatment or Alternative Source for MAC Exceedance	drinking water	The Health Canada Guideline recommends installing treatment or using an alternative drinking water source when samples show continuous evidence of being in excess of the MAC.	When samples show continuous evidence of being in excess of the MAC	high
#Q013	monitoring	operational	recommended	Ongoing Groundwater Monitoring	drinking water	Ongoing groundwater monitoring is recommended in the Valley to ensure there is awareness and reporting of the latest data to inform corrective action decisions.		high
#Q014	monitoring	operational	recommended	Risk-Proportional Source Monitoring Frequency	drinking water	Monitoring at the source should continue at a frequency that is proportional to the risk, meaning that if long term sampling indicates concentrations of parameters are continuously below the Health Canada Guidelines, and not trending upwards, the frequency of monitoring can decrease (Ministry of Health, 2024).	If long term sampling indicates concentrations are continuously below guidelines and not trending upwards	high
#Q015	reporting	reporting	recommended	Communication of Monitoring Results	drinking water	Routine provincial monitoring should be accompanied by timely and clear communication of results.		high
#Q016	monitoring	health	recommended	Private Well Maintenance and Testing	drinking water	Private well owners in the Valley are encouraged to ensure proper well capping and routinely test their well water for pathogens, and all chemical parameters including nitrate.		high
#Q017	operational	operational	recommended	Septic System Maintenance	other	Septic owners are also encouraged to regularly check and maintain their systems to ensure groundwater is not impacted by human waste (HealthLinkBC, 2021).		high
#Q018	administrative	health	recommended	Private Well Registration	drinking water	Private well owners are also encouraged to register their well so that in the event of a health risk, they can be easily and promptly informed.		high
#Q019	operational	health	mandatory	Potable Water Microbiological Standards	drinking water	The Drinking Water Protection Regulation requires that water for drinking must meet the E. coli and total coliform bacteria water quality standards for potable water of no detectable E. Coli or total coliform bacteria per 100 ml, respectively.	All water for drinking	high
#Q020	prohibition	operational	mandatory	Manure Application Weather Restrictions	agricultural water	Producers must not apply manure in those high-risk conditions [precipitation, spring thaw/runoff, flooding, and runoff events] under the AEM Code.	During high-risk weather conditions	high
#Q021	operational	operational	mandatory	Vulnerable Aquifer Recharge Area Protective Measures	agricultural water, drinking water	The Hullcar Aquifers 103 and 102, are listed as Vulnerable Aquifer Recharge Areas within the AEM Code (Schedule B) thus are considered high-risk areas and require additional protective measures. These measures include but are not limited to: restrictions on nutrient application, monitoring, soil testing, and nutrient management planning.	Within Hullcar Aquifers 103 and 102	high

P Quantitative Requirements (51)

Req ID	Category	Intent	Legal Status	Name	Subdomain(s)	Limit Type	Limit Value	Context	Conditions	Confidence
#P001	chemical	health	guideline	nitrate (NO3-)	drinking water	MAC	45 mg/L	Health Canada Guideline for nitrate established a MAC of 45 mg/L		high
#P002	chemical	health	guideline	nitrate-nitrogen (NO3-N)	drinking water	MAC	10 mg/L	The Guideline for Canadian Drinking Water Quality for nitrate-nitrogen (nitrate-N) has set a Maximum Acceptable Concentration (MAC) of 10 mg/L.	developed to protect the health of bottle-fed infants	high
#P003	chemical	health	guideline	nitrite (NO2-)	drinking water	MAC	3 mg/L	Health Canada established a MAC of 3 mg/L for nitrite		high
#P004	chemical	health	guideline	nitrite-nitrogen (NO2-N)	drinking water	MAC	1 mg/L	equivalent to 1 mg/L of nitrite-nitrogen		high
#P005	microbiological	health	mandatory	E. coli	drinking water	requirement	0 per 100 ml	The Drinking Water Protection Regulation requires that water for drinking must meet the E. coli and total coliform bacteria water quality standards for potable water of no detectable E. Coli		high
#P006	microbiological	health	mandatory	total coliform bacteria	drinking water	requirement	0 per 100 ml	water quality standards for potable water of no detectable E. Coli or total coliform bacteria per 100 ml		high
#P007	chemical	health	guideline	lead	drinking water	MAC	0.005 mg/L	Health Canada has recently revised their drinking water quality guideline for lead to a MAC of 0.005 mg/L		high
#P008	chemical	health	guidance	Cadmium TDI	drinking water	requirement	0.0008 mg/kgBW-day	Health Canada TDI based on chronic exposure primarily through food resulting in renal tubular dysfunction	chronic exposure	high
#P009	chemical	health	guidance	Trivalent Chromium TDI	drinking water	requirement	1.5 mg/kgBW-day	TDI based on chronic exposure through diet; considered non-toxic essential element	chronic exposure	high
#P010	chemical	health	guidance	Hexavalent Chromium TDI	drinking water	requirement	0.0022 mg/kgBW-day	TDI based on chronic exposure in drinking water resulting in gastrointestinal toxicity	chronic exposure	high
#P011	chemical	health	guidance	Copper TDI	drinking water	requirement	0.426 mg/kgBW-day	TDI based on 9-month study of human exposure through drinking water resulting in gastrointestinal toxicity	chronic exposure	high
#P012	chemical	health	guidance	Lead TDI	drinking water	requirement	0.0005 mg/kgBW-day	TDI based on human studies resulting in neurodevelopmental toxicity	chronic exposure	high
#P013	chemical	health	guidance	Mercury TDI	drinking water	requirement	0.0003 mg/kgBW-day	TDI based on subchronic rat studies and irreversible neurological symptoms	subchronic exposure	high
#P014	chemical	health	guidance	Nickel Chloride TDI	drinking water	requirement	0.011 mg/kgBW-day	TDI based on studies of perinatal lethality in rats	perinatal exposure	high
#P015	chemical	health	guidance	Selenium TDI (Adults)	drinking water	requirement	0.0057 mg/kgBW-day	Upper level TDI for adults 20 years and older based on chronic epidemiological diet studies	20 years and older	high
#P016	chemical	health	guidance	Zinc TDI (Adults)	drinking water	requirement	0.57 mg/kgBW-day	Upper level TDI for adults 20 years and older based on subchronic human exposure	20 years and older	high
#P017	chemical	health	guidance	Arsenic Oral Slope Factor	drinking water	requirement	1.8 (mg/kgBW-day)^-1	Slope factor for chronic exposure resulting in various cancers	chronic exposure	high
#P018	operational	health	guidance	Manure harvest wait time (grain or corn)	agricultural water	requirement	90 days	Wait time between applying manure and harvesting crops like grain or corn	Canadian Organic Growers standards	high
#P019	operational	health	guidance	Manure harvest wait time (root crops)	agricultural water	requirement	120 days	Wait time between applying manure and harvesting root crops	Canadian Organic Growers standards	high
#P020	chemical	health	guidance	Selenium TDI (Infant 0-0.5y)	drinking water	requirement	0.0055 mg/kgBW-day	Health Canada established age-specific upper level TDI for selenium based on chronic diet studies	Ages 0 to <0.5 years	high
#P021	chemical	health	guidance	Selenium TDI (Child 0.5-5y)	drinking water	requirement	0.006 mg/kgBW-day	Health Canada established age-specific upper level TDI for selenium based on chronic diet studies	Ages 0.5 to <5 years	high
#P022	chemical	health	guidance	Selenium TDI (Child 5-12y)	drinking water	requirement	0.0063 mg/kgBW-day	Health Canada established age-specific upper level TDI for selenium based on chronic diet studies	Ages 5 to <12 years	high
#P023	chemical	health	guidance	Selenium TDI (Youth 12-20y)	drinking water	requirement	0.0062 mg/kgBW-day	Health Canada established age-specific upper level TDI for selenium based on chronic diet studies	Ages 12 to <20 years	high
#P024	chemical	health	guidance	Zinc TDI (Infant 0-0.5y)	drinking water	requirement	0.49 mg/kgBW-day	Health Canada established age-specific upper level TDI for zinc based on subchronic human exposure	Ages 0 to <0.5 years	high
#P025	chemical	health	guidance	Zinc TDI (Child 0.5-5y)	drinking water	requirement	0.48 mg/kgBW-day	Health Canada established age-specific upper level TDI for zinc based on subchronic human exposure	Ages 0.5 to <5 years	high
#P026	chemical	health	guidance	Zinc TDI (Child 5-12y)	drinking water	requirement	0.51 mg/kgBW-day	Health Canada established age-specific upper level TDI for zinc based on subchronic human exposure	Ages 5 to <12 years	high
#P027	chemical	health	guidance	Zinc TDI (Youth 12-20y)	drinking water	requirement	0.54 mg/kgBW-day	Health Canada established age-specific upper level TDI for zinc based on subchronic human exposure	Ages 12 to <20 years	high
#P028	microbiological	health	mandatory	E. coli	drinking water	requirement	0 per 100 ml	The Drinking Water Protection Regulation requires that water for drinking must meet standards of no detectable E. Coli per 100 ml		high
#P029	microbiological	health	mandatory	total coliform bacteria	drinking water	requirement	0 per 100 ml	Water quality standards for potable water require no detectable total coliform bacteria per 100 ml		high
#P030	chemical	health	guidance	Arsenic Acute Oral MRL	drinking water	unknown	0.005 mg/kgBW-day	ATSDR acute oral exposure minimal risk level	acute oral exposure	high
#P031	chemical	health	guidance	Arsenic Chronic Oral MRL	drinking water	unknown	0.0003 mg/kgBW-day	ATSDR chronic oral exposure minimal risk level	chronic oral exposure	high
#P032	chemical	health	guidance	Cadmium Subchronic Oral MRL	drinking water	unknown	0.0005 mg/kgBW-day	ATSDR subchronic oral exposure minimal risk level	subchronic oral exposure	high
#P033	chemical	health	guidance	Cadmium Chronic Oral MRL	drinking water	unknown	0.0001 mg/kgBW-day	ATSDR chronic oral exposure minimal risk level	chronic oral exposure	high
#P034	chemical	health	guidance	Chromium(VI) Subchronic Oral MRL	drinking water	unknown	0.005 mg/kgBW-day	ATSDR subchronic oral exposure minimal risk level	subchronic oral exposure	high
#P035	chemical	health	guidance	Chromium(VI) Chronic Oral MRL	drinking water	unknown	0.0009 mg/kgBW-day	ATSDR chronic oral exposure minimal risk level	chronic oral exposure	high
#P036	chemical	health	guidance	Copper Acute Oral MRL	drinking water	unknown	0.02 mg/kgBW-day	ATSDR acute oral exposure minimal risk level	acute oral exposure	high
#P037	chemical	health	guidance	Copper Subchronic Oral MRL	drinking water	unknown	0.02 mg/kgBW-day	ATSDR subchronic oral exposure minimal risk level	subchronic oral exposure	high
#P038	chemical	health	guidance	Mercury Acute Oral MRL	drinking water	unknown	0.002 mg/kgBW-day	ATSDR acute oral exposure minimal risk level	acute oral exposure	high
#P039	chemical	health	guidance	Mercury Subchronic Oral MRL	drinking water	unknown	0.00001 mg/kgBW-day	ATSDR subchronic oral exposure minimal risk level	subchronic oral exposure	high
#P040	chemical	health	guidance	Selenium Chronic Oral MRL	drinking water	unknown	0.005 mg/kgBW-day	ATSDR chronic oral exposure minimal risk level	chronic oral exposure	high
#P041	chemical	health	guidance	Zinc Subchronic Oral MRL	drinking water	unknown	0.3 mg/kgBW-day	ATSDR subchronic oral exposure minimal risk level	subchronic oral exposure	high
#P042	chemical	health	guidance	Zinc Chronic Oral MRL	drinking water	unknown	0.3 mg/kgBW-day	ATSDR chronic oral exposure minimal risk level	chronic oral exposure	high
#P043	design	health	recommended	Minimum recommended depth for dug wells	drinking water	requirement	>= 15 m	Dug (or excavated) shallow wells, usually less than 15 m deep are typically not recommended as they are more vulnerable to contamination and more susceptible to drought than deeper wells.	Applies to new well construction	high
#P044	operational	operational	recommended	Nitrate sampling frequency	drinking water	requirement	4 times per year	Typical recommendations are for quarterly sampling for nitrates to monitor effects of seasonality.	Recommended for monitoring seasonal fluctuations	high
#P045	chemical	health	guideline	Chromium acute toxicity threshold	drinking water	requirement	1 mg/L	Acute toxicity is possible but not observed at concentrations below 1 mg/L	Based on Health Canada 1986 technical document	high
#P046	chemical	health	guideline	Arsenic acute effect threshold	drinking water	requirement	> 1.2 mg/L	Other health effects from acute drinking water exposure can occur at concentrations greater than 1.2 mg/L based on human studies	Acute drinking water exposure	high
#P047	microbiological	health	guidance	E. coli infective dose	drinking water	unknown	10 - 1000 organisms	The estimated infective dose for E. Coli	Based on US EPA 2004 as cited in section 11.3.1	high
#P048	microbiological	health	guidance	Cryptosporidium infective dose	drinking water	unknown	10 - 1000 oocysts	Infective dose of Cryptosporidium from cattle may range from 10 to 1,000 oocysts	Based on US EPA 2004 as cited in section 11.3.3	high
#P049	chemical	health	guidance	Nitrate threshold for methaemoglobinemia association	drinking water	unknown	> 220 mg/L	Health Canada found that the majority of methaemoglobinemia cases (80%) were associated with nitrate concentrations in drinking water greater than 220 mg/L nitrate.	Infantile exposure	high
#P050	physical	operational	guidance	Groundwater elevation threshold for nitrate concentration (OW 409)	drinking water	requirement	> 501.5 masl	Generally, it appears groundwater elevations at Observation Well 409 greater than 501.5 metres above sea level (masl) correspond to below-guideline dissolved nitrate concentrations	Observation Well 409	high
#P051	chemical	treatment	guidance	Post-harvest soil nitrate survey benchmark	agricultural water	requirement	< 100 kg NO3-N/ha	Eighty-four percent of the land area sampled (43 of 50 fields) had soil nitrate levels in the 0-90 cm soil profile less than 100 kg NO3-N/ha; these results support the hypothesis that majority of fields fall below 100 kg NO3-N/ha.	0-90 cm soil profile after crop harvest	high

D Definitions (67)

Req ID	Name	Context	Confidence
#D001	BC	British Columbia	high
#D002	AEM Code	Code of Practice for Agricultural Environmental Management	high
#D003	DALY	Disability Adjusted Life Year	high
#D004	DWO	Drinking Water Officer	high
#D005	DWPA	Drinking Water Protection Act	high
#D006	DWPR	Drinking Water Protection Regulation	high
#D007	EMS	Environmental Monitoring System	high
#D008	GWELLS	Groundwater Wells and Aquifers Database	high
#D009	IHA	Interior Health Authority	high
#D010	MAC	Maximum Acceptable Concentration	high
#D011	masl	Metres above sea level	high
#D012	mbgl	Metres below ground level	high
#D013	mg/L	Milligrams per Litre	high
#D014	MW	Monitoring Well	high
#D015	OW	Observation Well	high
#D016	SSWD	Steele Springs Waterworks District	high
#D017	TDI	Tolerable Daily Intake	high
#D018	US EPA	United States Environmental Protection Agency	high
#D019	WTN	Well Tag Number	high
#D020	the Valley	Clcahl/Hullcar Valley	high
#D021	Health Canada Guidelines	Guidelines for Canadian Drinking Water Quality	high
#D022	HARP Report	Hullcar (Clcahl) Aquifer Response Plan	high
#D023	Methaemglobinemia	a condition caused by exposure to high concentrations of nitrates to infants less than six months of age.	high
#D024	N	nitrogen	high
#D025	potable	safe to drink	high
#D026	aesthetic objectives	refer to taste, odour, and appearance	high
#D027	mineralization	soil bacteria break down organic nitrogen sources, such as livestock manure or soil organic matter, into ammonium.	high
#D028	nitrification	soil bacteria convert the ammonium into nitrite and then into nitrate.	high
#D029	blue-baby syndrome	a condition caused by exposure to high concentrations of nitrates to infants less than six months of age.	high
#D030	BC	British Columbia	high
#D031	AEM Code	Code of Practice for Agricultural Environmental Management	high
#D032	DALY	Disability Adjusted Life Year	high
#D033	DWO	Drinking Water Officer	high
#D034	DWPA	Drinking Water Protection Act	high
#D035	DWPR	Drinking Water Protection Regulation	high
#D036	EMS	Environmental Monitoring System	high
#D037	GWELLS	Groundwater Wells and Aquifers Database	high
#D038	IHA	Interior Health Authority	high
#D039	MAC	Maximum Acceptable Concentration	high
#D040	masl	Metres above sea level	high
#D041	mbgl	Metres below ground level	high
#D042	mg/L	Milligrams per Litre	high
#D043	MW	Monitoring Well	high
#D044	OW	Observation Well	high
#D045	SSWD	Steele Springs Waterworks District	high
#D046	TDI	Tolerable Daily Intake	high
#D047	US EPA	United States Environmental Protection Agency	high
#D048	WTN	Well Tag Number	high
#D049	the Valley	Clcahl/Hullcar Valley	high
#D050	Health Canada Guidelines	Guidelines for Canadian Drinking Water Quality	high
#D051	HARP Report	Hullcar (Clcahl) Aquifer Response Plan	high
#D052	Methaemglobinemia	a condition caused by exposure to high concentrations of nitrates to infants less than six months of age.	high
#D053	TRVs	used to quantify health risks associated with exposure to environmental contaminants.	high
#D054	TDIs	tolerable daily intakes for threshold substances	high
#D055	MRLs	estimate the acute, sub chronic, or chronic exposure limits where health risks are not detectable	high
#D056	hormonal growth promoters	can include estrogen, androgen, progesterone, and thyroid hormones.	high
#D057	personal care and pharmaceutical products	products from human sources, referred to as personal care and pharmaceutical products may also be present from residential sources	high
#D058	FPT CDW	Federal-Provincial-Territorial Committee on Drinking Water	high
#D059	slope factors	for non-threshold substances	high
#D060	nitrate-N	nitrate-nitrogen	high
#D061	Faecal coliforms	a general indicator of faecal contamination	high
#D062	Veterinary medicines	including antibiotics and antiparasitic agents.	high
#D063	Mineral salts	minerals salts in animal waste include sodium, calcium, magnesium, chloride, sulphate, bicarbonate, and carbonate	high
#D064	The Report	POLIS Recommendations Report, 'From Crisis to Solutions: Towards Better Source Water Protection and Nutrient Management in the Hullcar Valley' (Brandes et al., 2017)	high
#D065	Aquifer 102	a deep, confined aquifer located in the Clcahl/Hullcar Valley	high
#D066	Aquifer 103	a shallow, unconfined aquifer located in the Clcahl/Hullcar Valley	high
#D067	N-fixing crops	crops that convert atmospheric nitrogen into ammonia through a symbiotic associated with root biota, which is then converted into organic nitrogen within plant tissue	high