Is Stormwater Harming Our Streams?

STREAMS?harming our

STORMWATERIs

urbanizedwatersheds

stormwater

METALS

Long-term stream monitoring

King County, WA

Toxicity

ToxicityBaseflow comparison

ToxicityBaseflow comparisonTrends over time

ToxicityBaseflow comparisonTrends over timePollutant sources

33 sites

Seattle

Tacoma

1993-2010

grabsamples

2-6x/yr

after 24h dry & ¼” rain

ICP-MS

24 metalstotal & dissolved

Toxicity

Human health (WA Water Quality Stds)

rare:

Nickel Thallium

widespread:

Arsenic

Human health (WA Water Quality Stds)

Aquatic life (WA Water Quality Stds)

rare:

Copper Lead

common:

Mercury

Aquatic life (WA Water Quality Stds)

Salmonids (draft screening values)

Copper Lead

Salmonids (draft screening values)

Cadmium

Zinc

common towidespread:

Silver

???:

Baseflowcomparison

Baseflowcomparison2001-2003

Total concentrationshigher in stormflow:

As Cd Cr Cu Ni Pb Sb V Zn

Toxics:

Others:

Ba Be Co Fe

Total concentrations and dissolvedhigher in stormflow:

As Cd Cr CuNi Pb Sb V Zn

Ba Be Co Fe

Toxics:

Others:

Trends

Cr Cu Ni Pb Zn

Some toxics decreased

Cr Cu Ni Pb Zn

Some toxics decreased

Hardness increased

protectiveCa Mg

Sources

weathering

Iron as tracer

weathering

most metals

most streams

weathering

total

dissolved

Iron correlations

tota

l copper

(µg/L

)

total iron (µg/L)

Iron correlations

tota

l copper

(µg/L

)

total iron (µg/L)

tota

l copper

(µg/L

)

total iron (µg/L)

Iron correlations

Mill Creek:to

tal m

eta

l (µ

g/L

)

total iron (µg/L)

Mill Creek: Old industrial dumpto

tal m

eta

l (µ

g/L

)

total iron (µg/L)

Toxicity concerns:mercurycopper, lead, zinc

Trends were improving.

Weathering was amajor source.

Photo credits:• Stream sampling: King County DNRP• Lake Union aerial: Jelson25 (Wikipedia)• Stormwater outfall: Blake Feist (NOAA Fisheries)• Blacksmith: NBC News• Rain: Tuncay (Flickr)• ICP: Wblanchard (Wikipedia)• Toddler in lake: King County DNRP• Nickel: US Mint• Thallium: Rob Lavinsky irocks.com (Flickr)• Arsenic: Tomihahndorf (Wikipedia)• Aquarium: Angelo Juan Ramos (Flickr)• Copper: Jonathan Zander (Wikipedia)• Lead: KBD Photography (Flickr)• Mercury: Dedvedev (Wikipedia)• Salmon migrating: J Armstrong (UW)• Zinc: Raysonho (Wikipedia)• Cadmium: W Oelen (Wikipedia)• Silver: Elekes Andor (Wikipedia)• Seattle waterfront: Seattle DOT• Seattle historic Third Ave. construction: Seattle Municipal Archives