Nitrate

Issaquah Water System

Nitrate, a fertilizer chemical, frequently contaminates drinking water due to agricultural and urban runoff, and discharges from municipal wastewater treatment plants and septic tanks. Excessive nitrate in water can cause oxygen deprivation in infants and increase the risk of cancer. Click here to read more about nitrate.

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Samples

Samples exceeding legal limit (MCL)

Samples exceeding
health guidelines

Testing results - average by year

Year	Average result	Samples taken	Detections	Range of results
2013	N/A	0	0	N/A
2014	0.320 ppm	4	3	ND - 0.510 ppm
2015	0.313 ppm	4	3	ND - 0.490 ppm
2016	0.315 ppm	4	3	ND - 0.540 ppm
2017	0.393 ppm	4	3	ND - 0.640 ppm
2018	0.450 ppm	4	4	0.1000 ppm - 0.660 ppm
2019	0.415 ppm	4	4	0.190 ppm - 0.640 ppm

ppm = parts per million

State and national drinking water standards and health guidelines

EWG Health Guideline 0.14 ppm

The EWG Health Guideline of 0.14 ppm for nitrate was defined by EWG . This health guideline protects against cancer and harm to fetal growth and development.

EPA Maximum Contaminant
Level (MCL) 10 ppm

The legal limit for nitrate, established in 1962, was developed to protect infants from acute methemoglobinemia, a life-threatening disorder of oxygen transport in the body. This limit does not fully protect against the risk of cancer and harm to the developing fetus.

ppm = parts per million

All test results

Date	Lab ID	Result
2014-05-19	21604	0.430 ppm
2014-05-19	21605	0.340 ppm
2014-05-19	21606	ND
2014-05-19	21603	0.510 ppm
2015-05-29	24210	0.430 ppm
2015-05-29	24209	0.490 ppm
2015-05-29	24211	0.330 ppm
2015-05-29	24212	ND
2016-07-25		0.490 ppm
2016-07-25		0.540 ppm
2016-07-25		ND
2016-07-25		0.230 ppm
2017-08-15		0.310 ppm
2017-08-15		ND
2017-08-15		0.640 ppm
2017-08-15		0.620 ppm
2018-08-29		0.660 ppm
2018-08-29		0.650 ppm
2018-08-29		0.390 ppm
2018-08-29		0.1000 ppm
2019-08-05		0.190 ppm
2019-08-05		0.190 ppm
2019-08-08		0.640 ppm
2019-08-08		0.640 ppm