d.c. water lead levels below federal limits consumers urged to continue precautions
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D.C. Water Lead Levels Below Federal Limits Consumers Urged to Continue Precautions By D'Vera Cohn Washington Post Staff Writer Wednesday, May 11, 2005; - PowerPoint PPT PresentationTRANSCRIPT
D.C. Water Lead Levels Below Federal Limits Consumers Urged to Continue Precautions
By D'Vera Cohn Washington Post Staff Writer Wednesday, May 11, 2005;
Lead levels in the District's drinking water have fallen substantially in recent months and dropped below the federal action limit for the first time in four years, the general manager of the D.C. Water and Sewer Authority said yesterday.
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By Pierre Home-Douglas
FIRST, MARC EDWARDS DISCOVERED HIGH LEVELS OF LEAD IN WASHINGTON, D.C.'S, DRINKING WATER, THEN HE HAD TO PERSUADE THE BUREAUCRACY TO GET THE WORD OUT.
It was a problem that had baffled civil engineer Marc Edwards for a decade. By the time the Virginia Tech professor finally figured out the answer, he had stumbled across a health issue that ended up pitting him against the Environmental Protection Agency (EPA) and the utility that supplies Washington, D.C., with its drinking water. The resulting battle and stress affected his health, but Edwards persevered and was finally vindicated, assisted by three graduate students he credits with helping him through the ordeal.
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GAS WORKS PARK
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Lake Nyos
Solution lakes and streams
Scale formation in pipes
Stalactites
Stalagmites
FeS2 + 4O2 + 3H20 H2SO4 + Fe(OH)3
Hood Canal, Washington, USA
Newton, UW-APL
, pet waste, lawns, pet waste, lawns
Onsite Septic N ProjectState Legislature Appropriation to the PSAT
M. Brett et al
The objective of this project is to measure nitrogen removal rates from septic system drainfield plumes for OSSs located in the Hood Canal watershed. These data are needed to estimate the potential N loading to the Hood Canal from OSSs …. project report with the state legislature by the end of June, 2007.
Well Installation and Sampling
HouseS
1
2
34
5
6
7
8
11
13
12
9
Drainfield
KIT02
cutbank
125 34
XX
Tap
From: W.T. Edmondson (1994) Lake & Reservoir Management 10: 75-84.
The impact of waste water diversion on Lake Washington phosphorus loading
0
25
50
75
100
125
Dis
solv
ed P
Inp
uts
(met
ric
tons
yr.
-1)
1965 1970 1975 1980 1985 1990
Year
Watershed Loading
Sewage Effluent
From: W.T. Edmondson (1994) Lake & Reservoir Management 10: 75-84.
Change in Lake Washington phytoplankton composition and biomass
0
1
2
3
Phy
to. B
iovi
ol. (
mm
3 L-1)
1965 1970 1975 1980 1985 1990
Year
Other Phytoplankton
Cyanobacteria
0
25
50
75
100
125P
erce
nt o
f 19
64 V
alue
1965 1970 1975
Year
Phytoplankton
Phosphate
Nitrate
Inorganic Carbon
From: W.T. Edmondson (1991) The Uses of Ecology.
Change in Lake Washington nutrient concentrations, and phytoplankton biomass after waste water diversion
From: W.T. Edmondson (1994) Lake & Reservoir Management 10: 75-84.
The impact of waste water diversion on Lake Washington water clarity
0
5
10
15
20
Dap
hnia
L-1
0
2
4
6
8
10
Sec
chi (
m)
1965 1970 1975 1980 1985 1990
Year
Secchi Depth
Daphnia
Trophic Equilibrium
Global average temperature
1860 1880 1900 1920 1940 1960 1980 2000
0.8
0.4
0
-0.4
-0.8
degr
ees
Cel
sius
Consequences of Global Warming for the PNW
Shorter ski seasons More winter flooding Increased landslide risk due to rain on snow events Reduced summer flows Water supply shortages More catastrophic forest fires Agricultural water shortages in Eastern W Further-stressed salmon runs
1928
2000
The South Cascade glacier retreated dramatically in the 20th century
Courtesy of the USGS glacier group
Decrease Increase
Mote 2003(b)
Decrease Increase
As the West warms,winter flows rise and summer flows drop
Figure by Iris Stewart, Scripps Inst. of Oceanog. (UC San Diego)
Northwest warming
44
45
46
47
48
49
50
51
52
53
54
1900
s
1920
s
1940
s
1960
s
1980
s
2000
s
2020
s
2040
s
Deg
rees
F warmest scenarioaverage coolest scenarioobserved
Questions?
