Water-Resources Investigations Report 01-4030 -- Table 25

WRIR 02-4030: Streamflow and Water-Quality Data for Selected Watersheds in the Lake Tahoe Basin, California and Nevada, through September 1998	Table of Contents
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Table 25. Trends, P values, and probability plot correlation coefficient (PPCC) values from Seasonal-Kendall and ESTIMATOR results for 10 primary and 10 secondary LTIMP stations in the Lake Tahoe Basin, California and Nevada

[Symbols: *, P value <.05 = significant trend; **, P value >.05 to <.10 = less-significant trend; ***, P value >.10 = no significant trend; --, no significant trend]

Constituent	Seasonal Kendall trend	Seasonal Kendall P value	Estimator trend	Estimator P value	PPCC
Third Creek near Crystal Bay
Dissolved nitrite + nitrate	--	0.102***	positive	0.866***	0.99
Dissolved ammonia	negative	.005*	negative	.000*	.99
Total nitrogen	negative	.021*	negative	.000*	.98
Soluble reactive phosphorus	--	.423***	--	.303***	.99
Total phosphorus	negative	.021*	--	.296***	.99
Biologically reactive iron	negative	.002*	positive	.000*	.98
Suspended sediment	negative	.070**	positive	.000*	.99
Incline Creek near Crystal Bay
Dissolved nitrite + nitrate	negative	.003*	negative	.813***	.98
Dissolved ammonia	negative	.011*	negative	.004*	.99
Total nitrogen	negative	.051**	positive	.000*	.98
Soluble reactive phosphorus	negative	.019*	negative	.002*	.81
Total phosphorus	--	.260***	--	.107***	.99
Biologically reactive iron	--	.535***	negative	.001*	.97
Suspended sediment	--	.110***	negative	.000*	.98
Incline Creek at Highway 28
Dissolved nitrite + nitrate	negative	.002*	--	.526***	.98
Dissolved ammonia	negative	.013*	--	.488***	.98
Total nitrogen	negative	.002*	negative	.000*	.97
Soluble reactive phosphorus	negative	.088**	--	.720***	.96
Total phosphorus	negative	.009*	negative	.000*	.97
Biologically reactive iron	negative	.003*	negative	.000*	.96
Suspended sediment	negative	.036*	negative	.000*	.98
Incline Creek above Tyrol Village
Dissolved nitrite + nitrate	negative	.000*	--	.608***	.98
Dissolved ammonia	negative	.002*	negative	.010*	.98
Total nitrogen	negative	.001*	negative	.000*	.97
Soluble reactive phosphorus	negative	.001*	negative	.026*	.95
Total phosphorus	negative	.000*	negative	.001*	.94
Biologically reactive iron	negative	.001*	negative	.057**	.94
Suspended sediment	negative	.002*	negative	.000*	.98
Glenbrook Creek at Glenbrook
Dissolved nitrite + nitrate	negative	.002*	negative	.048*	.96
Dissolved ammonia	negative	.001*	negative	.000*	.99
Total nitrogen	negative	.000*	negative	.000*	.96
Soluble reactive phosphorus	--	.304***	--	.217***	.98
Total phosphorus	negative	.025*	negative	.001*	.96
Biologically reactive iron	negative	.037*	negative	.001*	.96
Suspended sediment	--	.713***	negative	.010*	.98
Logan House Creek near Glenbrook
Dissolved nitrite + nitrate	--	.168***	--	.444***	.98
Dissolved ammonia	negative	.003*	negative	.000*	.92
Total nitrogen	negative	.009*	negative	.000*	.98
Soluble reactive phosphorus	negative	.001*	negative	.000*	.74
Total phosphorus	negative	.000*	negative	.000*	.99
Biologically reactive iron	negative	.008*	negative	.021*	.97
Suspended sediment	negative	.005*	negative	.000*	.86
Edgewood Creek at Stateline
Dissolved nitrite + nitrate	negative	.052**	--	.262***	.96
Dissolved ammonia	--	.187***	--	.626***	.99
Total nitrogen	negative	.002*	negative	.000*	.99
Soluble reactive phosphorus	negative	.011*	--	.192***	.98
Total phosphorus	negative	.011*	negative	.060**	.95
Biologically reactive iron	negative	.004*	negative	.077**	.94
Suspended sediment	negative	.065**	negative	.007*	.97
Edgewood Creek at Palisade Drive
Dissolved nitrite + nitrate	negative	.008*	--	.134***	.99
Dissolved ammonia	negative	.004*	--	.375***	.99
Total nitrogen	negative	.017*	negative	.000*	.95
Soluble reactive phosphorus	negative	.007*	negative	.053**	.93
Total phosphorus	negative	.001*	negative	.000*	.91
Biologically reactive iron	negative	.001*	negative	.008*	.92
Suspended sediment	negative	.004*	negative	.000*	.95
Eagle Rock Creek near Stateline
Dissolved nitrite + nitrate	negative	.080**	negative	.071**	.99
Dissolved ammonia	negative	.004*	negative	.023*	.98
Total nitrogen	--	.552***	negative	.000*	.85
Soluble reactive phosphorus	--	.159***	negative	.066**	.92
Total phosphorus	negative	.011*	--	.863***	.80
Biologically reactive iron	--	.216***	negative	.007*	.84
Suspended sediment	negative	.074**	negative	.000*	.89
Trout Creek at South Lake Tahoe
Dissolved nitrite + nitrate	--	.479***	negative	.000*	.99
Dissolved ammonia	--	.115***	negative	.000*	.99
Total nitrogen	--	.227***	negative	.236***	.98
Soluble reactive phosphorus	--	.374***	--	.662***	.96
Total phosphorus	negative	.044*	negative	.000*	.98
Biologically reactive iron	--	.112***	--	.832***	.96
Suspended sediment	--	10.00***	negative	.000*	.99
Trout Creek at Pioneer Trail
Dissolved nitrite + nitrate	negative	.038*	-negative	.055**	.98
Dissolved ammonia	negative	.014*	negative	.020*	.99
Total nitrogen	negative	.060**	negative	.000*	.93
Soluble reactive phosphorus	negative	.020*	--	.816***	.98
Total phosphorus	negative	.016*	negative	.000*	.89
Biologically reactive iron	negative	.011*	negative	.000*	.91
Suspended sediment	negative	.003*	negative	.000*	.97
Trout Creek at U.S. Forest Service Rd. 12N01
Dissolved nitrite + nitrate	negative	.000*	negative	.076**	.99
Dissolved ammonia	negative	.007*	negative	.000*	.99
Total nitrogen	negative	.001*	negative	.000*	.98
Soluble reactive phosphorus	negative	.029*	negative	.918***	.97
Total phosphorus	negative	.000*	negative	.003*	.95
Biologically reactive iron	negative	.045*	negative	.000*	.87
Suspended sediment	negative	.001*	negative	.000*	.93
Upper Truckee River at South Lake Tahoe
Dissolved nitrite + nitrate	negative	.000*	negative	.000*	.99
Dissolved ammonia	--	.136***	negative	.000*	.99
Total nitrogen	negative	.006*	negative	.000*	.98
Soluble reactive phosphorus	negative	.036*	negative	.000*	.99
Total phosphorus	negative	.005*	negative	.000*	.98
Biologically reactive iron	--	.404***	--	.385***	.96
Suspended sediment	negative	.005*	negative	.000*	.98
Upper Truckee River at Highway 50 above Meyers
Dissolved nitrite + nitrate	negative	.000*	negative	.000*	.98
Dissolved ammonia	negative	.036*	--	.198***	.98
Total nitrogen	negative	.000*	negative	.000*	.97
Soluble reactive phosphorus	negative	.000*	negative	.000*	.97
Total phosphorus	positive	.000*	negative	.000*	.95
Biologically reactive iron	negative	.000*	negative	.000*	.94
Suspended sediment	negative	.000	negative	.000	.96
Upper Truckee River at South Upper Truckee Road
Dissolved nitrite + nitrate	negative	.001*	--	.528***	.99
Dissolved ammonia	negative	.041*	negative	.006*	.98
Total nitrogen	negative	.001*	negative	.000*	.97
Soluble reactive phosphorus	--	.193***	--	.628***	.97
Total phosphorus	negative	.001*	negative	.000*	.96
Biologically reactive iron	negative	.028*	negative	.000*	.94
Suspended sediment	negative	.000*	negative	.000*	.98
General Creek near Meeks Bay
Dissolved nitrite + nitrate	--	.935***	negative	.002	.99
Dissolved ammonia	negative	.003*	negative	.000*	.97
Total nitrogen	--	.893***	--	.565***	.99
Soluble reactive phosphorus	--	.603***	--	.556***	.99
Total phosphorus	negative	.004*	--	.182***	.83
Biologically reactive iron	positive	.003*	positive	.000*	.97
Suspended sediment	positive	.000*	positive	.000*	.99
Dissolved nitrite + nitrate	--	.279***	negative	.001*	.89
Blackwood Creek near Tahoe City
Total nitrogen	--	.447***	--	.136***	.99
Dissolved ammonia	negative	.000*	negative	.000*	.79
Soluble reactive phosphorus	--	.396***	positive	.000*	.99
Total phosphorus	negative	.020*	negative	.003*	.97
Biologically reactive iron	positive	.018*	positive	.000*	.99
Suspended sediment	positive	.000*	positive	.000*	.99
Ward Creek at State Highway 89
Dissolved nitrite + nitrate	negative	.041*	negative	.000*	.99
Dissolved ammonia	negative	.044*	negative	.000*	.98
Total nitrogen	--	.893***	negative	.013	.99
Soluble reactive phosphorus	--	.462***	--	.962***	.83
Total phosphorus	negative	.007*	negative	.000*	.96
Biologically reactive iron	positive	.004*	positive	.000*	.99
Suspended sediment	positive	.058**	positive	.000*	.98
Ward Creek at Stanford Rock Crossing
Dissolved nitrite + nitrate	negative	.035*	negative	.000	.99
Dissolved ammonia	negative	.084***	--	.796***	.99
Total nitrogen	negative	.043*	negative	.000	.98
Soluble reactive phosphorus	negative	.050*	--	.992***	.97
Total phosphorus	--	.154***	--	.507***	.98
Biologically reactive iron	negative	.060**	negative	.000	.98
Suspended sediment	--	.238***	negative	.072**	.98
Ward Creek below confluence
Dissolved nitrite + nitrate	--	.154***	negative	.000*	.98
Dissolved ammonia	--	.822***	positive	.082**	.99
Total nitrogen	negative	.060**	negative	.000*	.97
Soluble reactive phosphorus	negative	.084**	negative	.003	.98
Total phosphorus	--	.154***	negative	.098**	.91
Biologically reactive iron	--	.940***	--	.234***	.96
Suspended sediment	--	.822***	negative	.001	.98

Trend summary	Number
Both negative	77
Both positive	6
Both undetected	16
1 negative / 1 undetected	35
1 positive / 1 undetected	2
1 positive / 1 negative	4
Total	140