Sustainability generally means the development and use of ground water in a manner that can be maintained for the present and future time without causing unacceptable environmental, economic, social, or health consequences. This is the definition stated in Louisiana Revised Statute 38:3097.2.11.
Sustainable Yields and Thresholds of Concern
Sustainable yield is that quantity of water that can be withdrawn on a continuing basis by reaching a system equilibrium without compromising the integrity of the aquifer or with respect to agreed upon criteria. (9) Sustainable yield is a critical element in identifying and designing viable water supply alternatives. With sustain-able yield defined and knowledge of total water demand in an area, an unmet demand can be calculated.
Sparta-Louisiana Sustainable Yield
‘The Sparta Groundwater Study’ Results
The Sparta Commission contracted Meyer, Meyer, LeCroix and Hixson, Inc. to determine limitations of the Sparta to meet current and future needs and to test hypothetical conservation approaches. The researchers entered well water level data, pumpage data, and information about Sparta’s hydrogeologic properties into a groundwater flow model, USGS-developed (MODFLOW) software. The study area was the Sparta aquifer in north central Louisiana and southeast Arkansas. Predictions covered the time period 2000 to 2025. The resulting ‘sustained maximum pumpage rate’ of 52 mgd was predicted to result in recovery, not to a pre-pumping state, but to a state of self-renewable stable supply, assuming the Sparta’s natural recharge and leakage rates continue close to historic rates. (2, )
The results of the study in 2001 were published in the Sparta Groundwater Study (2):
The maximum recommended pumpage from the Sparta is approximately 52 million gallons per day (mgd).
To achieve a pumpage rate of 52 mgd, pumpage must be reduced by 18 mgd, from the current pumpage rate of approximately 70 mgd.
Decreased pumping must occur across the extent of the entire Sparta region for widespread effect.
Developing alternative sources to produce an additional 12 mgd of potable water would provide for future increases in demand for potable water.
USGS Study by KcKee, Clark, and Czarnecki
Figure 26 depicts actual and optimal withdrawal rates estimated by an optimization study by McKee, Clark, and Czarnecki. (8) Components of the optimization study, including the researchers’ definition of ‘optimal withdrawal’, and their data sources, estimations, assumptions, and methods, are reported in a publication of study results (8) and a publication describing project development (9)
The researchers note that estimates of sustainable yield are affected by 1) hydraulic-head constraints (the most important factor), and 2) the distribution of managed wells. In terms of hydraulic head constraints, the researchers used for sustainable yield estimates the Arkansas ‘critical groundwater area’ criterion—water levels above the top of the aquifer. They noted that lowering the hydraulic-head constraint in Louisiana, Louisiana having no established criteria for maintaining hydraulic heads above the top of the Sparta Sand, would increase the amount of estimated sustainable yield for both Arkansas and Louisiana. Non-linear model behavior precluded reliable quantification of the increase. In terms of well distribution, the researchers used the distribution of existing wells in the Sparta aquifer. More strategic well placement might increase the sustainable yield estimates.
The response to the Sparta Commission’s request for ‘critical groundwater area’ designation for most of the Sparta region inLouisiana came in 2005 with Order No. AGC 1-05 of DNR Commissioner of Conservation. This order designated three ‘areas of groundwater concern,’ around major pumping centers in Monroe, Jonesboro-Hodge, and Ruston areas. (21) (red boxes in Figure 25). Non-domestic well owners in these areas must report monthly pumpage, purpose for use, and, if available, the static well water level. The order states, as remedies, water users ‘shall vigorously seek alternate sources of potable water’ and ‘an aggressive water conservation education program should begin as soon as possible.’
Figure 25 shows areas of Louisiana and Arkansas that meet similar criteria of groundwater stress. Arkansas designated these areas 'critical groundwater areas'. As of March, 2010 Louisiana has not designated any 'critical groundwater areas' but has designated ‘areas of groundwater concern’.
Sparta Commission Application for Designation of Critical Groundwater Area
In 2002, the Sparta Commission, following required procedures of the time, submitted to the state Groundwater Management Commission an application for designation of an area within the Sparta region a ‘critical groundwater area’. (20) [Legislative Act 225 of 2005 renamed such areas ‘areas of groundwater concern’.]
State Requirements for Designation of a Critical Groundwater Area (later Area of Groundwater Concern)
An applicant for a ‘critical groundwater area’ designation was required to state facts and supporting evidence substantiating that at least one of three criteria applied to the aquifer would, currently or in the immediate future, render the aquifer unsuitable for groundwater demands without some action taken. Criteria were: 1) water level declines, 2) salt water intrusion, 3) overall withdrawals that have exceeded the aquifer’s recharge.
The Sparta Commission contracted Meyer, Meyer, LeCroix, and Hixson, Inc. to conduct the Sparta Groundwater Study to identify areas that met the specified conditions. The Sparta Commission specified three conditions that satisfied Louisiana's 'critical groundwater area' criteria of the time and, for the advantages of bi-state cooperation, also satisfied 'critical groundwater area' criteria established by Arkansas law, Endnote 7 namely:
‘areas where the drawdown exceeded one-foot per year over a study period (a recognition that continued present pumping and the possibility of new wells will continue to exacerbate the existing adverse situation areas);
areas where the water surface had dropped below the top of the Sparta aquifer (a recognition that to allow this to continue violates the long-range goal of saving and restoring the Sparta aquifer for long-term future use as a major water supply source),
possible areas where salt water intrusion is becoming a problem (a recognition that a moving salt water interface from East to West will materially affect water quality in the Sparta).’ (20)
Figure 24 is a Sparta Groundwater Study (2) map of 2001 showing the area where the drawdown had exceeded one-foot per year over 20 years, and, overlapping in places, the area where the water surface had dropped below the top of the Sparta aquifer. Authors noted that further study was required to better define salt water intrusion areas. (2)
In 1999, the Louisiana legislature created the Sparta Groundwater Conservation District Commission (Sparta Commission) to study characteristics of the Sparta aquifer and how best to manage activities in the Sparta region that impact current and future Sparta use. The 19 member commission is composed of representatives of Sparta region parishes, municipalities, and industries, who help fund the work of the commission. The state helped pay for the Sparta Groundwater Study. Other funding is provided by private donations. Members of the Sparta Commission and the Union County (Arkansas) Water Conservation Board have shared information and mutual concerns in bi-state cooperation since a meeting in Ruston in 1997. Both boards work to fulfill their similar mission ‘to conserve, protect, restore, and maintain the Sparta Formation Aquifer as a continuing source of high quality, potable water for current and future consumers by promoting conservation measures and the develop-ment of alternate sources of fresh water, pursuant to the authority and responsibility granted by the state.’
Prior to 2001, there was no statewide groundwater law, other than a 1972 law authorizing the Department of Transportation and Development (DOTD) Dept. of Public Works to regulate (registration, reporting, well construction and sealing) wells drawing more than 50,000 gallons per day . [This DOTD authority was transferred to Louisiana Department of Natural Resources (LDNR) in 2009]. A 1974 law created the Capital Area Groundwater Conservation District and gave it permitting and funding authority within five parishes surrounding Baton Rouge.
In 2001, Act 449 provided for a commission and a task force to develop comprehensive groundwater law. Act 449 also defined ‘critical groundwater area’ and provided for a process for designation of these areas.
In 2003, Act 49 (Louisiana Revised Statutes 38:3097.1-3097.6) modified or eliminated provisions of earlier laws and became the basis for groundwater law in Louisiana. Act 225 of 2005 replaced Act 49’s definition of ‘critical groundwater area’ with a new definition and created a new category, ‘area of groundwater concern’.
LDNR Commissioner of Conservation is ‘empowered and responsible for the administration of all matters related to the management of the state’s groundwater resources’.
‘Sustainability’ is defined as ‘the development and use of ground water in a manner that can be maintained for the present and future time without causing unacceptable environmental, economic, social, or health consequences’.
An ‘area of groundwater concern’ is defined as an ‘area in which, under current usage and normal environmental conditions, sustainability of an aquifer is not being maintained due to either movement of a salt water front, water level decline, or subsidence, resulting in unacceptable environmental, economic, social, or health impact, or causing serious adverse impact to an aquifer, considering the areal and temporal extent of all such impacts’. Well owner(s) may apply. After public hearings, the Commissioner may issue an order designating an area of concern, which must contain a plan for protection of the area.
A ‘critical area of groundwater concern’ is defined: ‘An area of ground water concern, declared pursuant to R.S. 38:3097.6, shall be designated a critical area of ground water concern when the commissioner finds that sustainability cannot be maintained without withdrawal restrictions’.
First priority use is assigned to human consumption in 'critical areas of groundwater concern’.
Well owners, with some exceptions, must notify the Commissioner 60 days before drilling a new well.
Restrictions are placed on regulating groundwater withdrawal: for large volume wells (greater than 8" diameter exterior encasement) and wells in a ‘critical groundwater area’, the Commissioner may order allowable production, spacing, and metering, otherwise, the Commissioner may regulate spacing.
Orders of the Commissioner of Conservation include the following:
designation of ‘areas of groundwater concern’ in Sparta pumping centers (AGC 1-05 of 2005);
required reporting of water source and volume used in hydraulic fracturing operations (2009);
establishment of uniform regulations for Haynesville Shale operations in urban areas (2009).
Louisiana legislature Act 437 of 2009 transferred responsibility for water well registration, licensing, and regulation from DOTD to DNR, effective January 1, 2010. DNR Office of Conservation tracks the number and use of water wells in the state. [http://dnr.louisiana.gov/cons/groundwater/]
Statewide Comprehensive Groundwater Management Plan
The Louisiana Groundwater Resources Commission, on which the Sparta Commission is represented, is preparing a statewide groundwater management plan, which is projected to be complete by the end of 2010.