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environmental information > river & stream WQ monitoring > state network >

Water quality monitoring station

35A150 - Snake R @ Interstate Br

Results that exceed water quality criteria or the usual range of data (since October, 1996)

Results that exceeded water quality standards criteria

The Department of Ecology places limits on how much pollution is allowed in our rivers to protect public health and enjoyment, and to support fish, shellfish, and wildlife (WAC 173-201A). Individual results for temperature, pH, oxygen, fecal coliform bacteria, and metals (where sampled) that are higher than these criteria are listed below. (The standards do not contain criteria for other types of water quality constituents.) This table includes only results from our monthly monitoring program. Results from other monitoring, such as continuous monitoring for temperature, are not evaluated here.

Exceeding a criterion does not necessarily mean the water quality standard has been violated. Often, other �pollution� conditions must exist for a stream segment to be in violation of water quality standards. In some cases, standards require that the source of pollution be human activities rather than natural causes. Also, more than a single result exceeding a criterion may be required.

Washington's Water Quality Standards were amended in November, 2006. Data in the tables below are based on the older standards through 2008. Data collected after 2008 are based on the ammended standards, excluding supplemental temperature criteria. We are currently working on incorporating supplemental temperature criteria into our evaluation procedures.

date	time	units	criterion	result	remark	% exceed
Oxygen
9/16/2009	10:45	mg/L	8	7.9		1
8/5/2009	10:45	mg/L	8	7.6		5
8/21/2007	11:45	mg/L	8	7.9		1
7/16/2007	12:45	mg/L	8	7.5		7
8/9/2006	15:45	mg/L	8	7.9		1
8/3/2004	14:20	mg/L	8	7.7		4
pH
date	time	units	criterion	result	remark	% exceed
4/8/2009	11:05	pH	8.5	8.6		1
4/9/2008	10:45	pH	8.5	8.6		1
2/13/2008	10:50	pH	8.5	8.6		1
1/15/2008	10:55	pH	8.5	8.6		1
11/6/2007	10:30	pH	8.5	8.6		1
3/7/2007	13:35	pH	8.5	8.6		1
7/13/2005	13:30	pH	8.5	8.9		4
5/4/2005	14:45	pH	8.5	8.6		1
11/13/2002	13:30	pH	8.5	8.6		1
9/11/2002	06:50	pH	8.5	8.8		3
2/13/2002	07:10	pH	8.5	8.6		1
9/12/2001	06:55	pH	8.5	8.6		1
7/11/2001	07:30	pH	8.5	8.8		4
4/11/2001	07:15	pH	8.5	8.6	J	1
1/10/2001	07:15	pH	8.5	8.8		4
4/11/2000	10:20	pH	8.5	8.6		1
Temperature
date	time	units	criterion	result	remark	% exceed
9/16/2009	10:45	deg C	20	21.2		6
8/5/2009	10:45	deg C	20	23.3		17
9/10/2008	10:30	deg C	20	21.3		7
8/6/2008	10:45	deg C	20	22.8		14
9/4/2007	11:25	deg C	20	22.6		13
8/21/2007	11:45	deg C	20	20.7		3
7/16/2007	12:45	deg C	20	22.8		14
9/13/2006	14:45	deg C	20	20.5		2
8/9/2006	15:45	deg C	20	23.1		16
8/3/2005	13:40	deg C	20	22		10
7/13/2005	13:30	deg C	20	21.3		7
8/3/2004	14:20	deg C	20	22.5		12
7/13/2004	13:40	deg C	20	20.2		1
8/5/2003	15:10	deg C	20	22.2		11
7/8/2003	12:55	deg C	20	20.7		3
9/11/2002	06:50	deg C	20	20.1		1
8/14/2002	06:15	deg C	20	21.3		7
7/17/2002	06:15	deg C	20	22.3		12
9/12/2001	06:55	deg C	20	20.9		4
8/8/2001	07:00	deg C	20	22.8		14
7/11/2001	07:30	deg C	20	23		15
8/8/1999	14:45	deg C	20	20.5		2
8/3/1998	06:30	deg C	20	21.9		9
8/4/1997	13:05	deg C	20	23.2		16

Results that contrast strongly with historical data

Results exceeding the usual range of data (defined as 2 standard deviations beyond the mean value for a station based on data from the same three-month period over the previous six years) are shown below. A certain percentage of results will always be listed in this report. Inclusion here does not necessarily indicate something unique is occurring in the watershed.

date	time	units	result	remark	QMEAN	QSD	QDP
Ammonia-Nitrogen
4/9/2008	10:45	mg/L	0.045		1.933333E-02	1.280165E-02	18
1/10/2007	13:55	mg/L	0.043		1.472222E-02	7.010962E-03	18
11/15/2006	14:10	mg/L	0.229		1.861111E-02	1.746977E-02	18
2/8/2006	15:30	mg/L	0.069		1.472222E-02	7.010962E-03	18
1/11/2006	15:30	mg/L	0.039		1.472222E-02	7.010962E-03	18
12/13/2000	07:00	mg/L	0.078		0.016	0.011	17
9/12/1999	15:45	mg/L	0.033		0.015	0.007	18
8/8/1999	14:45	mg/L	0.062		0.015	0.007	18
7/11/1999	14:50	mg/L	0.038		0.015	0.007	18
4/7/1997	13:25	mg/L	0.078		0.026	0.024	17
12/2/1996	12:15	mg/L	0.041		0.016	0.011	17
Barometric Pressure
date	time	units	result	remark	QMEAN	QSD	QDP
12/8/2004	14:10	mm/Hg	715.518		738.865	7.03566	18
6/15/2004	13:50	mm/Hg	752.602		735.815	6.195481	18
12/17/2002	13:20	mm/Hg	718.312		742.3479	4.407835	18
6/5/2002	06:40	mm/Hg	726.948		739.9087	5.155893	18
4/10/2002	07:20	mm/Hg	726.186		739.9087	5.155893	18
2/13/2002	07:10	mm/Hg	729.742		745.382	6.502	17
Conductivity
date	time	units	result	remark	QMEAN	QSD	QDP
2/4/2009	10:30	umhos/cm	496		356.4445	48.8566	18
7/9/2008	10:45	umhos/cm	137		260.4445	60.59336	18
4/9/2008	10:45	umhos/cm	310		176.8333	54.94088	18
12/7/2005	14:40	umhos/cm	402		340.8333	28.35956	18
4/6/2005	14:00	umhos/cm	332		170.2222	51.92025	18
9/12/2001	06:55	umhos/cm	385	J	252.556	65.756	18
2/3/1997	12:00	umhos/cm	174		338.111	70.382	18
Fecal Coliform Bacteria
date	time	units	result	remark	QMEAN	QSD	QDP
3/4/2009	09:55	#/100ml	15		4	5.213106	18
1/7/2009	10:40	#/100ml	25		4	5.213106	18
9/10/2008	10:30	#/100ml	100		14.94444	13.74761	18
12/3/2007	10:40	#/100ml	47		8.222222	8.835461	18
12/6/2006	13:00	#/100ml	20		2.777778	2.390067	18
11/15/2006	14:10	#/100ml	14		2.777778	2.390067	18
10/4/2006	14:10	#/100ml	35		2.777778	2.390067	18
3/8/2006	15:20	#/100ml	6		2	1.644957	18
1/11/2006	15:30	#/100ml	23		2	1.644957	18
12/7/2005	14:40	#/100ml	15		2.777778	2.390067	18
10/5/2005	15:30	#/100ml	14		2.777778	2.390067	18
1/5/2005	13:40	#/100ml	8		2	1.644957	18
11/3/2004	15:45	#/100ml	10		2.333333	1.847096	18
9/15/2004	13:20	#/100ml	45		8.666667	8.331372	18
8/3/2004	14:20	#/100ml	27	J	8.666667	8.331372	18
7/13/2004	13:40	#/100ml	45		8.666667	8.331372	18
1/13/2004	13:42	#/100ml	7		1.777778	1.060275	18
10/7/2003	14:00	#/100ml	8		2.333333	1.847096	18
9/9/2003	13:35	#/100ml	25		7.888889	7.33957	18
9/12/2000	13:15	#/100ml	27		7.765	8.92	17
Flow
date	time	units	result	remark	QMEAN	QSD	QDP
7/6/1998	07:50	CFS	64600		24508.67	14840.44	15
10/6/1997	08:40	CFS	33500		17850	7084.635	18
7/7/1997	12:15	CFS	54400		24508.67	14840.44	15
6/2/1997	14:10	CFS	127000		54200	33899.2	15
3/3/1997	12:30	CFS	71500		28292.86	15093.83	14
2/3/1997	12:00	CFS	84000		28292.86	15093.83	14
1/13/1997	12:25	CFS	59000		28292.86	15093.83	14
Nitrate+Nitrite-Nitrogen
date	time	units	result	remark	QMEAN	QSD	QDP
11/5/2008	10:20	mg/L	3.35		0.6398889	0.1059877	18
9/10/2008	10:30	mg/L	0.524		0.296	0.1104824	18
4/9/2008	10:45	mg/L	0.714		0.3005556	0.1692145	18
4/6/2005	14:00	mg/L	0.714		0.2910556	0.1694876	18
11/3/2004	15:45	mg/L	0.499		0.7459444	0.1197298	18
10/6/2004	13:50	mg/L	0.476		0.7459444	0.1197298	18
11/5/2003	14:10	mg/L	0.5		0.7459444	0.1197298	18
Nitrate-Nitrite
date	time	units	result	remark	QMEAN	QSD	QDP
9/12/1999	15:45	mg/L	0.614		0.302	0.133	18
9/14/1998	06:25	mg/L	0.603		0.302	0.133	18
9/8/1997	13:00	mg/L	0.641		0.302	0.133	18
Oxygen
date	time	units	result	remark	QMEAN	QSD	QDP
7/16/2007	12:45	mg/L	7.5		8.732223	0.5479648	18
6/18/2007	11:30	mg/L	9		10.62778	0.6572273	18
7/13/2005	13:30	mg/L	9.9		8.732223	0.5479648	18
8/3/2004	14:20	mg/L	7.7		8.758333	0.5220463	18
2/14/2001	06:45	mg/L	14.2		12.856	0.614	18
4/4/1999	17:15	mg/L	12		10.683	0.623	18
pH
date	time	units	result	remark	QMEAN	QSD	QDP
11/6/2007	10:30	pH	8.6		8.333529	9.924346E-02	17
7/13/2005	13:30	pH	8.9		8.319412	0.2130279	17
2/13/2002	07:10	pH	8.6		8.122	0.193	18
7/11/2001	07:30	pH	8.8		8.333	0.119	18
1/10/2001	07:15	pH	8.8		8.122	0.193	18
11/16/1999	11:25	pH	7.4		8.306	0.135	18
12/6/1998	16:40	pH	8		8.306	0.135	18
9/14/1998	06:25	pH	7.6		8.333	0.119	18
6/8/1998	06:15	pH	7		8.1	0.305	18
2/2/1998	07:25	pH	7.6		8.122	0.193	18
12/8/1997	06:45	pH	7.1		8.306	0.135	18
11/3/1997	07:10	pH	7.4		8.306	0.135	18
6/2/1997	14:10	pH	7.2		8.1	0.305	18
Phosphorus, Sol Reactive
date	time	units	result	remark	QMEAN	QSD	QDP
11/5/2008	10:20	mg/L	0.003	U	0.0536	1.248807E-02	18
9/10/2008	10:30	mg/L	0.0773		3.941111E-02	1.655909E-02	18
9/4/2007	11:25	mg/L	0.0674		0.03575	1.559099E-02	18
4/12/2006	15:35	mg/L	0.0533		2.342778E-02	8.865651E-03	18
2/8/2006	15:30	mg/L	0.0884		4.606667E-02	9.288703E-03	18
10/5/2005	15:30	mg/L	0.0846		5.568333E-02	0.0144101	18
1/5/2005	13:40	mg/L	0.0701		4.606667E-02	9.288703E-03	18
9/12/2001	06:55	mg/L	0.0562		0.023	0.011	18
8/8/2001	07:00	mg/L	0.047		0.023	0.011	18
3/14/2001	07:10	mg/L	0.027		0.049	0.011	18
12/13/2000	07:00	mg/L	0.095		0.05	0.012	18
9/12/2000	13:15	mg/L	0.055		0.023	0.011	18
9/12/1999	15:45	mg/L	0.049		0.023	0.011	18
1/5/1998	08:00	mg/L	0.022		0.049	0.011	18
Phosphorus, Total
date	time	units	result	remark	QMEAN	QSD	QDP
9/12/2001	06:55	mg/L	0.081		0.039	0.016	18
12/13/2000	07:00	mg/L	0.11		0.065	0.018	18
9/12/2000	13:15	mg/L	0.083		0.039	0.016	18
9/12/1999	15:45	mg/L	0.08		0.039	0.016	18
11/3/1997	07:10	mg/L	0.106		0.065	0.018	18
10/6/1997	08:40	mg/L	0.11		0.065	0.018	18
4/7/1997	13:25	mg/L	0.283		0.073	0.063	17
1/13/1997	12:25	mg/L	0.198		0.074	0.036	18
Suspended Solids
date	time	units	result	remark	QMEAN	QSD	QDP
3/4/2009	09:55	mg/L	22		5.388889	2.852015	18
11/5/2008	10:20	mg/L	1	U	3.833333	1.150447	18
10/10/2007	10:25	mg/L	7		3.833333	1.150447	18
7/12/2006	15:40	mg/L	21		5.888889	2.323509	18
1/11/2006	15:30	mg/L	12		4.611111	2.476689	18
7/13/2005	13:30	mg/L	11		5.888889	2.323509	18
6/3/2003	13:20	mg/L	105	J	26.72222	23.01357	18
7/7/1997	12:15	mg/L	19		6.056	4.795	18
6/2/1997	14:10	mg/L	97		22.222	22.967	18
2/3/1997	12:00	mg/L	21		7	6.088	18
Temperature
date	time	units	result	remark	QMEAN	QSD	QDP
2/4/2009	10:30	deg C	6.9		4.316667	0.9338409	18
6/18/2007	11:30	deg C	17.5		11.23889	2.466276	18
3/16/2005	13:00	deg C	6.6		3.783333	1.372953	18
6/15/2004	13:50	deg C	15.7		10.72222	2.180544	18
Total Persulf Nitrogen
date	time	units	result	remark	QMEAN	QSD	QDP
11/5/2008	10:20	mg/L	3.37		0.792	9.535753E-02	18
9/10/2008	10:30	mg/L	0.804		0.4767222	0.1362553	18
4/9/2008	10:45	mg/L	0.99		0.4503889	0.194868	18
3/7/2007	13:35	mg/L	0.937		1.201177	0.1234849	17
1/11/2006	15:30	mg/L	1.51		1.201177	0.1234849	17
4/6/2005	14:00	mg/L	0.891		0.4543889	0.2175414	18
11/3/2004	15:45	mg/L	0.613		0.9002222	0.1307964	18
10/6/2004	13:50	mg/L	0.619		0.9002222	0.1307964	18
9/12/1999	15:45	mg/L	0.872		0.458	0.15	15
9/14/1998	06:25	mg/L	0.85		0.458	0.15	15
9/8/1997	13:00	mg/L	0.788		0.458	0.15	15
Turbidity
date	time	units	result	remark	QMEAN	QSD	QDP
3/4/2009	09:55	NTU	16		3.961111	2.446399	18
11/5/2008	10:20	NTU	0.5	U	1.905556	0.6681601	18
2/14/2007	13:15	NTU	8.9		3.683333	2.562685	18
7/12/2006	15:40	NTU	20		2.572222	0.9975296	18
6/3/2003	13:20	NTU	30		13.27222	7.481098	18
8/3/1998	06:30	NTU	13		2.694	1.711	18
7/7/1997	12:15	NTU	6.4		2.694	1.711	18
1/13/1997	12:25	NTU	40		7.906	9.821	18

Note: QMEAN, QSD, and QDP are the quarterly mean, standard deviation, and number of data points for the last six years, where available, for the station shown.

Washington State Department of Ecology

Data users please read disclaimer.

Questions or comments on content may be sent to Dave Hallock
Questions or comments on presentation may be sent to Steve Barrett.