Executive Summary — February 2002
The current average daily outflow of water from the Sparta Aquifer exceeds the existing inflow. Accordingly, water level measurements show continuing average annual declines in areas of significant pumpage. Furthermore, water levels in the aquifer are below the top of the formation in significant portions of seven parishes in the sixteen parish Sparta Groundwater Conservation District. The average annual water level declines and the lowering of aquifer water levels below the top of the formation, in certain areas, places the aquifer in a stressed condition.
Being in a stressed condition does not necessarily mean that broad-based failure is impending. Based on the historical performance of the aquifer, it is reasonable to assume that time is available in which to implement corrective actions towards restoration and preservation of this natural resource for future generations.
The MODFLOW model predicts that significant restoration of the aquifer is possible by the year 2025, assuming that major efforts to establish alternative sources of surface supply are undertaken over the next three to five years. Any delays in the development of alternative sources of supply will exacerbate the declining water levels in the Sparta aquifer.
The areas of greatest pumpage and drawdown stress are shown to exist in all or part of the parishes of Bienville, Claiborne, Jackson, Lincoln, Ouachita, Union and Webster.
Of addition concern, though not in the scope of this study are the indications that saltwater, on the eastern side of the Sparta formation is moving westward at an undertermined rate. The United States Geological Survey (USGS) has recently initiated action to further analyze and report on this saltwater movement.
This study was undertaken with the intent to examine the Sparta aquifer on an areal extent basis. The grid system utilized in the MODDLOW model was set to examine known areas of high pumpage rates (from USGS records). The scope of the study did not provide for model capability to examine in detail finite areas located within the boundaries of the SGCD. Accordingly, the results and recommendations are intended to derive from, and be applicable to, the entire Sparta aquifer area in Louisiana. Conservation measures should be adopted and applied across the entire Sparta formation. The recommended 18 mgd reduction in pumpage and the 18 mgd alternative surface supply should be applied across the entire aquifer. A localized rapid response recovery would no doubt result from a reduction of pumpage of 18 mgd in the West Ouachita Parish area, but other stressed areas of the aquifer would not see an equivalent response from such a localized action.
The current condition of the aquifer did not develop over a short period of time and, because of such inherent characteristics as variable transmissivity, it will not respond to restoration over a short period of time. However, restoration will begin concurrently with the herein recommended significant reductions in Sparta aquifer pumpage. SPARTA AQUIFER STUDY: At A Glance
Sparta Aquifer Description:
- Location in southern Arkansas and northern Louisiana
- Sixteen (16) parishes in Louisiana's Sparta Groundwater Conservation
District
Problem: The current average daily outflow of water from the Sparta
Aquifer exceeds the existing inflow. Factors that place the aquifer
in a stressed condition are:
1) continuing annual declines in water level in areas of significant
pumpage.
2) water levels below the top of the aquifer in significant portions
of seven (7) parishes
3 ) indications that saltwater, on the eastern side of the Sparta
formation is moving westward
Six Highest Consumption Sparta Aquifer Parishes (year 2000):
The consumption of these six parishes represents 87% of the total Sparta
Aquifer consumption.
| PARISH | CONSUMPTION as *MGD | |
| Ouachita | 23.682 | |
| Bienville | 12.344 | |
| Lincoln | 9.164 | |
| Webster | 6.484 | |
| Union | 6.074 | |
| Claiborne | 3.043 | |
| (Jackson Parish also significantly stressed) | ||
| *Million Gallons Per Day | ||
Prognosis with Correction:
Significant restoration of the aquifer is possible by the year 2025,
assuming that major efforts to
establish alternative sources of surface supply are undertaken over
the next three to five years.
Correction:
A. 18 mgd reduction of pumpage from aquifer, in specified areas,
is expected to effect significant
restoration of the aquifer by 2025 assuming 1) there is no new consumption
of aquifer water and 2)
17 mgd of aquifer pumpage is replaced by surface water pumpage by 2005.
B. Summary of Pumpage Requirements in Sparta Aquifer Area:
| Current & Proposed Sparta Pumpage | Proposed Pumpage: All Sources | |||||||
|
|
70 mgd | Future Sparta Pumpage |
|
|||||
| Recommended Reduction by 2025 | 18 mgd | *Surface Replacing Sparta Pumpage |
|
|||||
| Future Sparta Pumpage | 52 mgd | *New Surface Pumpage for Growth |
|
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| Total Planned Available Future Water |
|
|||||||
| * i.e. Provision should be made for consumption of water from surface sources to increase 30 mgd. | ||||||||
C. Some Potential Sources of Surface Water, ranked highest to
lowest*:
Ouachita River-W. Monroe,
Bayou D'Arbonne Lake,
Ouachita River-Bastrop,
Caney Creek Lake,
Lake Bistineau.
Lake Claiborne could be considered, esp. in terms providing for regional
economic growth
(*Citeria: Design capacity, Areas of most stress, water use, demographic
projections, salt water intrusion, cost)
Sparta Aquifer Study for Sparta Groundwater Conservation District by
Meyer, Meyer, LaCroix and Hixson,
Inc., 2001