North Creek Water Quality

Prepared by Jon Rogers and Carie McCoy

Dr. Jaffe’s Environmental Chemistry Lab Class

January 21st – February 3rd, 2005

North Creek• Adjacent to the

UWB/CCC Campus in the Sammamish Valley of King County, WA

• Approximate latitude and longitude: 47o 45’ 21” N 122o 11’ 20”W

• Upstream Site: East of exit number 24 off I-405

• Downstream Site: Past the Boardwalk in the UWB/CCC Wetlands

Goals

• Determine if the wetland helps contribute to improved water quality.

• To determine if North Creek complies with state standards.

Study Parameters• pH: effects chemical and biological processes which occur in an

aquatic environment• Conductivity: measures ionic potential of the waterway• Temperature: influences rates of chemical and biological processes • Dissolved Oxygen (DO): concentration of oxygen which is in a

dissolved form in the water• Stream Flow: volume of water moving over a designated point at a

fixed period of time• Turbidity: measured amount of suspended sediments in the water• Nitrates: measure of nitrogen as nitrate (N03-N) in the water

• Phosphates: measure of phosphorous as phosphate (PO4-P) in the water

Effects of Parameters• pH: if pH is too acidic or alkaline than the water becomes

inhabitable by aquatic life (desired pH range 6.5-8.0)• Conductivity: effects the buffering capacity of the water• Temperature: influences amount of DO (optimal <20o)• DO: form of oxygen available for aquatic life• Stream Flow: help determine amount of impervious surface area in

the watershed• Turbidity: increased turbidity may cause damage to fish gills,

suffocating them• Nitrates: can determine amount of fertilizer runoff entering the

stream (septic runoff is also a source)• Phosphates: corallites with the amount of soaps and detergents in

the water

Profiling a stream

• Measure the width of the stream channel

• At equal intervals of width (0.5 m) measure stream death

• Post a reference point for future depth measurements

Significant Results• Flow

– Statistically significant difference (P=.01) in flow from the two sites

– Greater stream flow at the upstream site than downstream

– Possible reason is the water absorbing quality of the wetland

– Rain event prior to data collection and approximately 0.03 cm of precipitation during our survey

Upstream Site

-60.0

-50.0

-40.0

-30.0

-20.0

-10.0

0.00.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0

width (cm)

dept

h (c

m)

profile 1-21profile 1-24profile 1-27profile 1-28profile 1-31profile 2-3

Downstream Site

-45.0

-40.0

-35.0

-30.0

-25.0

-20.0

-15.0

-10.0

-5.0

0.00.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0

width (cm)

dept

h (c

m)

profile 1-21profile 1-24profile 1-27profile 1-28profile 1-31profile 2-3

Statistical Runner Up

• Conductivity– Using a paired T-test

we verified a P value of P=0.065

– Almost a significant difference. Desire P<0.05

– What if the study had a longer duration?

– Is there an outlier?

Comparison of Conductivity on an Upstreamand Downstream site

90

100

110

120

130

140

150

160

170

180

0 2 4 6 8

Collection number

Con

duct

ivity

(µs)

Upstream

Dow nstream

Conductivity

0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

160.00

180.00

200.00

Mea

n va

lue

(µs)

Upstream

Dow nstream

Conclusions

• We found the wetland does help absorb runoff during rain events

• At the time of our study, the area of North Creek we evaluated does comply with Washington State Department of Ecology Standards for a class A stream

• Stream quality may change during other seasons

Questions?