dennis demcheck, scott mize, & stan skrobialowski usgs louisiana water science center in...
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Dennis Demcheck, Scott Mize, & Stan SkrobialowskiDennis Demcheck, Scott Mize, & Stan Skrobialowski
USGS Louisiana Water Science CenterUSGS Louisiana Water Science CenterIn cooperation with the U.S. Army Corps of EngineersIn cooperation with the U.S. Army Corps of Engineers
June 13, 2008June 13, 2008
New Orleans District
Water-Quality Effects of the April 11-May 8 2008 Bonnet Carre’ Spillway Diversion on
Lake Pontchartrain
NASA MODIS image, 4/29/08
The Rigolets
Crossover 7
Crossover 2
Chef Menteur Pass
Spillway at Hwy 61
Schedule
• Weekly for the first 8 weeks
• Bi-weekly through September– Outgoing tide at The
Rigolets and Chef Menteur Pass
– Spillway sampling ended May 20
Spillway: May 20
Constituents sampled• Field parameters (water temp. D.O.,
Sp. Cond., salinity, & pH) taken at three depths during all site visits
• Hourly field parameters and nitrate at one depth at CO-7
• Major ions (silica, sodium, chloride, sulfate, alkalinity, etc)
• Nutrients – tot. & diss. forms of N & P – Organic nitrogen– Nitrate + nitrite– Ammonia– Total & diss. phosphorus– Orthophosphate
• Tot. suspended solids• Tot. organic carbon• Chlorophylls• Triazine herbicides• Phytoplankton collected & preserved
QW processing
• Mobile lab• Onsite processing when mobile lab is
unavailable
Crossover 7, 3.9 miles from the south shore
Nitrate analyzer &
Sp. Cond. results: 4/8-29/08
Causew ay crossover #7 Nitrate and Sp. Conductance
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Date
0
2
4
6
8
10
12
Nitrate mg/L
SpCond mS/cm
NASA “Aqua” photo: 4/29/08 250-meter resolution
Crossover 7: 4/08-5/23
0
2
4
6
8
10
12
Date
Sp
ec
ific
co
nd
uc
tan
ce
, in
m
illis
iem
en
s p
er
ce
nti
me
ter
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Nit
rate
, in
mill
igra
ms
pe
r lit
er
Specific Conductance, in millisiemens per centimeter
Nitrate, in milligrams per liter
Hourly multiparameter readings at Crossover 7
4/08-5/23/08
depth: 10 ft.
0
5
10
15
20
25
30
Water Temp, in degrees Celsius
Specif ic Conductance, in millisiemens percentimeterDissolved Oxygen, in milligrams per liter
pH, in units
Nitrate, in milligrams per liter
Crossover 7 hourly nitrate compared to Crossover 2 weekly samples
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
4/2 4/7 4/12 4/17 4/22 4/27 5/2 5/7 5/12 5/17 5/22 5/27
Date
Nit
rate
, in
mil
lig
ram
s p
er l
iter Nitrate at CO-7
Nitrate at CO-2
Anabaena sp. at CO-2
Onsite investigation of algal blooms
Tangipahoa R. below Bedico Creek:
May 12-June 12, 2008
Contacts
• General water-quality questions: Dennis Demcheck [email protected] 225-298-5480, ext. 3214
• Nitrate analyzer operation; [email protected]
• Tangipahoa River nitrate real-time datahttp://waterdata.usgs.gov/la/nwis/uv/?
site_no=07375690&PARAmeter_cd=00065,72020,00060
• NASA satellite imagry– http://rapidfire.sci.gsfc.nasa.gov/subsets/index.php?
subset=AERONET_Stennis.2008160.aqua.250m