LOUISIANA: NATCHITOCHES PARISH
Sibley Lake Watershed Drinking Water Protection Program
Background
Sibley Lake serves as a drinking water supply for the City of Natchitoches, and 37 surrounding
water systems. It is also an important economic and recreational resource for the area, which is used
extensively for fishing, boating and swimming. The watershed surrounding the lake consists of 40
square miles of urban and rural land. The entire watershed is located within Ward 1 of Natchitoches
Parish.
Although the lake serves as the drinking water supply source for the City of Natchitoches, most of
the watershed is located outside of the City limits. While this is obviously a very beneficial
circumstance for the lake's water quality in many ways, the fact that the bulk of the watershed area
is beyond the city's sewer collection infrastructure presents a significant problem. The area
immediately surrounding the lake has a significant amount of residential development, most of
which is served by individual sewage treatment systems, in varying degrees of repair and operational
condition. Many of these systems are located within only a few hundred feet of the lake or its
tributaries. In some cases, direct discharges of sewage into the lake, which may be insufficiently
treated, are continuing in spite of ordinances prohibiting such discharges. Approximately 100% of
the watershed has on-site individual sewage treatment systems.
Priority Contamination Threat
Inefficient or defective individual sewage treatment systems present significant nutrient, solids, and
pathogen loading problems for the lake. Nutrient enrichment is a primary concern for Sibley Lake,
as it results in nuisance algal blooms that cause taste and odor problems, accelerate lake
eutrophication, and impair water quality for recreational uses. The lake is being severely impacted
by nutrient loading, creating eutrophic conditions and adversely affecting water quality. Individual
sewage treatment systems are significant contributing sources of nutrients to the lake.
Local Involvement and Developing the Protection Plan
The citizens that live in the watershed that feeds Sibley Lake, the approximate 25,000 people that
drink the water from Sibley Lake (which includes those in the watershed), and the officials of the
City of Natchitoches that supply the drinking water are all stakeholders.
The project is being funded by a Section 319 Federal Grant with the grantee being the City of
Natchitoches. The city provides a 40% match of in kind services to 60% federal funds. The amount
awarded to the city is $167,000 with $100,300 being federal funds and a match of $66,700.
Office of Water (4606M) 816F100014 January 2010
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Management Measures
Phosphorus and bacterial problems in the lake can be immediately reduced significantly by a more
rigorous sewage treatment system maintenance program, including the establishment of a program to
supplement the cost of replacing and/or repairing malfunctioning systems.
Under this proposed project, the following will be accomplished:
• An inventory and inspection of all individual sewage treatment systems within a half mile of
Sibley Lake will be conducted, using GPS equipment, and all pertinent information
on each system will be entered into the City's GIS database.
• Areas will be ranked based on proximity to the lake and potential threat posed by faulty
sewage treatment systems.
• Based on the rankings, funds will be made available to sewage treatment system owners to
supplement the cost of upgrading or replacing their systems. To the extent permitted by time
and funding, additional areas beyond a half mile of the lake which are immediately adjacent
to lake tributaries will go through the same process, beginning with areas demonstrating the
greatest concentration of individual sewage treatment systems. The system owner will be
required to provide a 50% match. In individual cases based upon demonstrated financial
need, the matching requirement of the system owner may be waived or reduced.
Post implementation of the plan, the City will continue to perform inspections of the
repaired/replaced systems to ensure continued compliance with operation and maintenance
requirements.
Contingency Planning
The City of Natchitoches and other public water supply systems located in the watershed are
responsible for maintaining its water supply. This includes providing for alternate sources of
drinking water in the event of a disruption in drinking water supply. In the event of a severe
disruption and/or loss of service, the Louisiana Department of Health and Hospitals will provide
technical assistance and support for restoring a drinking water supply for the area.
Measuring Program Effectiveness
The Louisiana Department of Environmental Quality's Drinking Water Protection program staff
maintain contact with the City of Natchitoches source water protection staff. Occasional site visits
are conducted to ensure that program goals and objectives are being achieved.
For further information, contact:
Office of Water (4606M) 816F100014 January 2010
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Howard Fielding, Chief
Aquifer Evaluation & Protection Section
Louisiana Department of Environmental Quality
(225)219-3510
Howard.Fielding@la.gov
Office of Water (4606M) 816F100014 January 2010
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