1. Dennis Demcheck, Scott Mize, & Stan Skrobialowski USGS Louisiana Water Science Center In cooperation with the U.S. Army Corps of Engineers June 13, 2008 New Orleans District Water-Quality Effects of the April 11-May 8 2008 Bonnet Carre’ Spillway Diversion on Lake Pontchartrain

2. NASA MODIS image, 4/29/08 The Rigolets Crossover 7 Crossover 2 Chef Menteur Pass Spillway at Hwy 61

3. 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

4. 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

5. QW processing Mobile lab Onsite processing when mobile lab is unavailable

6. Crossover 7, 3.9 miles from the south shore

7. Nitrate analyzer & Sp. Cond. results: 4/8-29/08 NASA “Aqua” photo: 4/29/08 250-meter resolution

8. Crossover 7: 4/08-5/23

9. Hourly multiparameter readings at Crossover 7 4/08-5/23/08 depth: 10 ft.

10. Crossover 7 hourly nitrate compared to Crossover 2 weekly samples

11. Anabaena sp. at CO-2 Onsite investigation of algal blooms

12. Tangipahoa R. below Bedico Creek: May 12-June 12, 2008

13. Contacts General water-quality questions: Dennis Demcheck ddemchec@usgs.gov 225-298-5480, ext. 3214 ddemchec@usgs.gov Nitrate analyzer operation; svmize@usgs.govsvmize@usgs.gov Tangipahoa River nitrate real-time data http://waterdata.usgs.gov/la/nwis/uv/?site_no=07375690&PARAme ter_cd=00065,72020,00060 NASA satellite imagry –http://rapidfire.sci.gsfc.nasa.gov/subsets/index.php?subset=AER ONET_Stennis.2008160.aqua.250m