Technology Assessment Division

Sources and Impacts of Pollution in Lake Pontchartrain

Background

Lake Pontchartrain's geography and hydrology are such that it receives inflow from numerous inputs. These inputs carry pollutant loadings from myriad urban, commercial, industrial, and agricultural sources, affecting the Lake across a wide spectrum of impacts. Neither the cumulative historical nor current total annual pollutant loadings in Lake Pontchartrain are known. Numerous authorities, agencies, foundations, and groups contacted said the annual pollutant loading into the Lake would be a valuable piece of information they would all like to have. All acknowledged that obtaining the necessary data would be a substantial project requiring a considerable commitment of resources beyond that which is allocated to Lake monitoring today.

 

Various components of the overall pollutant loading picture of the Lake are known or have recently been estimated from data that is available. For example, there are quite a few spot or point analyses of pollutant levels at most of the significant inflows into the Lake, such as at municipal discharge points and mouths of major tributaries. Generally lacking at these points to establish pollutant loading levels are volume flow measurements and a statistically significant number of samples over an extended period of time. Also notably lacking are measurements of non-point source inputs along the perimeter of the Lake.

 

Though lacking adequate information and data to fully define the pollutant loadings into the Lake and all of the impacts caused by these pollutants, significant data and information do exist to define most of the important factors that impact the Lake and characterize its overall picture. The remainder of this report attempts to summarize some of the major facets that predominate concerning sources of pollution and their impacts. These are features that stood out after reviewing the literature and interviewing on the telephone about 30 environmental, academic, regulatory, and conservation authorities.

 

The following is a consolidated list that summarizes most of the various sources of pollution and types of impacts on the Lake:

Urban Runoff

Lake Pontchartrain's entire south shore is adjacent to the state's largest metropolitan area. Several population centers are adjacent to the north shore, and the runoff from other communities north of the Lake drains into it. Additionally, several major highways cross the lake (i.e., Pontchartrain Causeway, U.S. 11, and I-10) or run along one of its shores (e.g., I-10, I-55 and U.S. 90). Oil and grease deposited on highways and streets washes off with each rain and drains into the Lake. Urban residential, commercial, and industrial land use generate many types of pollutants that find their way into Lake Pontchartrain via storm water that runs off into streams and canals.

 

Jefferson Parish Discharges into Lake Pontchartrain

Comprehensive data on pollutant loadings from urban runoff around the Lake is lacking. Examining an urban runoff source that has been quantified, though, gives an idea of the magnitude of the overall picture. In order to apply for its NPDES Storm Water Permit from the U.S. Environmental Protection Agency, Jefferson Parish had to estimate pollutant loading of all storm water discharges from the parish. Table 3 provides a summary of these discharges that enter Lake Pontchartrain.

Comprehensive, detailed data on these discharges has not been collected; hence, the preceding pollutant loadings had to be calculated based on storm water drainage models and data that was available. Jefferson Parish employed the engineering firm Montgomery Watson to perform this task.

Pleasure Craft

A surprise revelation was finding out how much 2-cycle outboard motors pollute. The following summarizes the unburned hydrocarbon emission characteristics of 2-cycle engines and an estimate of the amount of oil and gasoline pleasure craft release into Lake Pontchartrain.

• 2-cycle marine engines release 25 to 40% of their fuel/oil mixture unburned into the water.8,9,10,11

 

• Based on boating activity on Lake Pontchartrain, pleasure craft with 2-cycle engines are estimated to release between 206 and 2475 gallons per day of fuel/oil mixture.

 

• The estimate for an average weekend day, not a real busy weekend day, is 1238 gallons.

 

• The estimated annual release of unburned oil and gasoline into Lake Pontchartrain from the operation to 2-cycle engine pleasure craft is 150,000 gallons per year.

 

• It should be noted that these estimates ignore fuel/oil/grease pollution from spillage and bilge discharges from both 2-cycle and 4-cycle engine recreational boats.

 

• This compares to the approximately 227,000 gallons of oil and grease (1.326 million pounds in Table 3) discharged by Jefferson Parish.

 

• To put things into perspective, the largest and only recent leak from an oil and gas well in the Lake (the UNIFED well that was being plugged a few years ago on a lease in West Lake Pontchartrain Block 38) is estimated by officials to have spilled 10 barrels or 420 gallons into the lake. Nearly all of it was contained and removed.

 

Concluding Observation

Many activities release pollutants that have made their way into Lake Pontchartrain over the years and continue to do so. The preceding indicates that there are primarily two activities, though, that have had significant deleterious effects that compromise the quality and usability of Lake Pontchartrain. These are agricultural operations (e.g., animal herding and dairy farming) on North shore tributaries and untreated human waste, principally on the South shore. These activities have necessitated the health advisories listed in Table 1 against swimming and water contact sports on beaches and near-shore areas of the Lake. These sources of pollution still exist with the advisories remaining in effect. Progress on correcting these problems is being made, but is slow.

 

Cited References

¹1994 Louisiana Water Quality Inventory, Louisiana Department of Environmental Quality: Baton Rouge, LA, 1994, pp. 43-49.

 

²Advisories in Louisiana, Louisiana Department of Health and Hospitals, Environmental Epidemiology: New Orleans, LA, November 20, 1992 update.

 

³State Health Officer Discourages Swimming in Lake Pontchartrain, Press Release, Louisiana Department of Health and Human Resources: New Orleans, LA, July 1, 1985.

 

⁴1982 Lake Pontchartrain Bacterial Pollution Study, Louisiana Department of Health and Human Resources, Office of Health Services and Environmental Quality: New Orleans, 1982.

 

⁵Environmental Characteristics of the Pontchartrain - Maurepas Basin and Identification of Management Issues, Prepared for the Lake Pontchartrain Task Force, Louisiana Department of Energy and Natural Resources, Coastal Management Division: Baton Rouge, LA, October 1984, pp. 3-16 to 3-20.

 

⁶State of Louisiana Water Quality Management Plan, Volume 5, Part B, Water Quality Inventory 1994, Louisiana Department of Environmental Quality: Baton Rouge, LA, 1994.

 

⁷NPDES Storm Water Permit - Part 2, Permit Application, Volume A, for Jefferson Parish Louisiana, prepared by Montgomery Watson, Inc.: Metairie, LA, May 1993.

 

⁸Banse, Tim, Boating '95 Future Shock, The EPA Says Good-bye to Straight 2-Stroke and 4-Stroke Engines. Here's What '95 and Beyond Look Like in Marine Power, Popular Mechanics, Feb. 1995, pp. 47 - 52.

 

⁹Control of Air Pollution; Emission Standards for New Gasoline Spark-ingition and Diesel Compression-ignition Marine Engines, 40 CFR Parts 89 and 91 Notice of Proposed Rulemaking, U.S. Environmental Protection Agency, Federal Register, Vol. 59, No. 216: Washington, DC, November 9, 1994, pp. 55930 - 55966.

 

¹⁰EPA Goes after Motorboats, Watercraft in Air Cleanup, The Energy Report, Pasha Publications Inc.: Arlington, VA, November 7, 1994, p. 788.

 

¹¹Revelt, Jean Marie, The Effects of Marine Engine Exhaust Emissions on Water Quality: Summary of Findings of Various Research Studies, U.S. Environmental Protection Agency, Engine and Vehicle Regulations Branch Memorandum: Ann Arbor, MI, Nov. 15, 1994.

 

OTHER REFERENCES

Houck, Oliver A., Fritz Wagner, and John B. Elstrott, To Restore Lake Pontchartrain, a Report to the Greater New Orleans Expressway Commission on the Sources, Remedies, and Economic Impacts of Pollution in the Lake Pontchartrain Basin, April 28, 1989.

 

Environmental Regulatory Code, Part IX. Water Quality Regulations, Louisiana Department of Environmental Quality: Baton Rouge, LA, August 1994.

 

Englande, Jr., A.J., Storm Water Characterization and Design Considerations for an Artificial Wetlands Treatment System for New Orleans East Runoff, prepared for Burk-Kleinpeter, Inc.: New Orleans, LA, May 1984. Page 9

Credits

April 6, 1995

Memorandum

To:	Mineral Board Lake Pontchartrain Study Committee

From:	Mike French, Director, Technology Assessment Division

Subject:	Sources and Impacts of Pollution in Lake Pontchartrain