Trends of Withdrawals and Heads

The base simulation includes withdrawal data from wells that became inactive over time. Only three wells are active in the area at the end of the simulation; however, pumping in the Rio Grande water-bearing zone as a whole increases slightly between 1980 and 2013 (fig. 6). Generally, pumping increases in HBA 27 and decreases in HBA 25 in the base simulation (figs. 6A, 6E). In both HBA 25 and HBA 27, the nominal and optimal water-loss scenarios indicate that projected pumping would be fairly steady through 2040 (figs. 6B, 6F). Under the optimal water-loss scenario, withdrawals would decrease slightly over time. The full allocation scenario indicates that projected withdrawals would increase by 186 percent for HBA 25 and 393 percent for HBA 27 (table 2) in comparison to the reported pumping in 2013 used in the base simulation (figs. 6A, 6E).

The base simulation includes withdrawal data from wells that became inactive over time. Only three wells are active in the area at the end of the simulation; however, pumping in the Rio Grande water-bearing zone as a whole increases slightly between 1980 and 2013 (fig. 6). Generally, pumping increases in HBA 27 and decreases in HBA 25 in the base simulation (figs. 6A, 6E). In both HBA 25 and HBA 27, the nominal and optimal water-loss scenarios indicate that projected pumping would be fairly steady through 2040 (figs. 6B, 6F). Under the optimal water-loss scenario, withdrawals would decrease slightly over time. The full allocation scenario indicates that projected withdrawals would increase by 186 percent for HBA 25 and 393 percent for HBA 27 (table 2) in comparison to the reported pumping in 2013 used in the base simulation (figs. 6A, 6E).

For HBA 25, withdrawals decline in the first part of the base simulation, then spike in 1989 and an increase over several years in the mid-2000s (fig. 6A). After an initial spike in 2015, the reported pumping after the end of the base simulation is less than the projected pumping (fig. 6A). The response in heads shown in figure 6B reflects an inverse relation to the pumping. The large decline in the minimum head in 1994 reflects pumping in a well that is only included in the model for that stress period. Even though projected withdrawals decrease slightly in the optimal water-loss scenario (fig. 6A), there is still a slight decline in the heads for all three statistics (median, 10th percentile, and minimum) in HBA 25 (fig. 6B), likely reflecting an increase in pumping in the underlying Atlantic City 800-foot sand. In the full allocation scenario, the heads immediately decline sharply in response to the increased withdrawals and then continue to decline over time starting to level out by the year 2040 (fig. 6B).

For HBA 26, there is a general decline of heads over time across all three scenarios even though there are no pumping wells in the area (fig. 6D). The decline in heads reflects increased pumping in the underlying Atlantic City 800-foot sand and (for the full allocation scenario) in the adjacent budget areas (fig. 6D).

For HBA 27, overall, the heads shown in figure 6F decline slightly in the base simulation, despite a slight recovery starting around 1998 and a two-year spike upward in the 1990s when the area had no withdrawals (fig. 6E). For the nominal and optimal water-loss scenarios, all head statistics slightly decline over time, corresponding with a slight increase in pumping (fig. 6F). In the full allocation scenario, the heads, especially the minimum, decline quickly and then more gradually over time. The decline continues through until the end of the simulation in 2040 (fig. 6F).

Simulated Heads and Drawdown in 2040

Figure 7A shows the simulated head distribution in 2040 for the Rio Grande water-bearing zone based on the nominal water-loss scenario. The large area with heads below −40 feet reflects a pumping center (area where wells are clustered) in the underlying Atlantic City 800-foot sand aquifer. The simulated head map for the nominal water-loss scenario looks very similar to that of the optimal water-loss scenario (fig. 7B). For the full allocation scenario, a noticeable decrease in the head surface can be seen on the map; the cone of depression around the main pumping wells are visible with the heads lower than −80 feet (fig. 7C).

Figure 8A shows the simulated drawdown in the Rio Grande water-bearing zone from the end of 2013 through 2040 based on the nominal water-loss scenario. The drawdowns around the pumping wells are evident in figure 8A because the contour interval is smaller than the interval used in figure 7A. Note that, for the well closest to the coast in HBA 25 on the map, the head change is positive (fig. 8A) because the withdrawals from the well were projected to decrease (fig. 6A) so there is recovery rather than drawdown. The drawdown based on the optimal water-loss scenario is smaller compared to the nominal water-loss scenario (fig. 8B; table 3). For the full allocation scenario, the drawdown is generally much larger than the other two scenarios (fig. 8C; table 3). Most of the aquifer ranges from 15–50 feet of drawdown (change of head from the end of 2013 through 2040 is negative) with even larger amounts around the two largest pumping wells. In addition to effects from the pumping, the drawdown in the Rio Grande water-bearing zone is also being impacted by pumping in the Atlantic City 800-foot sand aquifer below.

Budget Analysis

Figure 9 and table 4 show the budget components for HBA 25 and are discussed below. The outflow from HBA 25 is split between withdrawals from wells (58–83 percent) and flow to the Atlantic City 800-foot sand aquifer below (16–28 percent). Lateral flow from offshore is the largest inflow (61–66 percent) to HBA 25. Most of the rest of the inflow is lateral flow from updip (16–26 percent); this is water from the unconfined part of the Kirkwood-Cohansey aquifer system that flows through the confining unit updip from where the Rio Grande water-bearing zone pinches out. There is a small amount of inflow from HBA 26 (7–12 percent) and flow leaking through the confining unit above (4–5 percent). The budget components for HBA 25 are similar among the base simulation and nominal and optimal water-loss scenarios. For the full allocation scenario, the magnitude of outflow to wells is more than twice the amount of the other scenarios; the higher outflow to wells is balanced mostly by increased lateral inflow from offshore and from the adjacent HBA 26. Although there is likely ample freshwater offshore and there is no indication that there would be an issue on the time frame of the scenario, pumping at the level simulated in the full allocation scenario would eventually draw in salty water.

Most outflow from HBA 26 (85–95 percent) goes to the confining unit below (and eventually to the Atlantic City 800-foot sand aquifer) with small amounts of water flowing out into HBA 25 (2–4 percent) and HBA 27 (3–10 percent) (fig. 10; table 5). Roughly half of the inflow (50–53 percent) is from the confining unit above HBA 26. There is close to equal amounts of inflow coming from offshore lateral flow (19–21 percent) and the confining unit updip from where the Rio Grande water-bearing zone pinches out (25–27 percent). The relative amounts of the budget components are similar among the base simulation and three scenarios although in the full allocation scenario, the magnitude of the inflows and outflows are generally higher.

The outflow from HBA 27 is almost entirely (80–99 percent) to the well with only a small amount (1–19 percent) of leakage to the Atlantic City 800-foot sand aquifer below (fig. 11; table 6). Most of the inflow for HBA 27 is divided between lateral flow from the unconfined aquifer updip (38–49 percent) and from the offshore boundary that corresponds to the 250 mg/L isochlor (37–39 percent). A small amount of flow (12–16 percent) comes from HBA 26, which lies to the north of HBA 27. Comparing the scenarios, the relative amounts of the budget components are similar although the magnitude of the flows are higher for the full allocation scenario. In the full allocation scenario, there is some inflow (6 percent) from the underlying Atlantic City 800-foot sand in contrast to the base simulation and other two scenarios where water flows out of HBA 27 from the underlying confining layer.

Trends of Withdrawals and Heads

Figure 12 shows withdrawal trends and trends of median, 10th percentile, and minimum heads from the base simulation and withdrawal scenarios for each budget area. Table 2 shows a summary of the past and projected withdrawals in each budget area. The well locations are shown in figure 13.

Most of the withdrawals in the Atlantic City 800-foot sand are in HBA 2 (table 2). Some pumping occurs in HBA 1 in the north, mainly concentrated in the communities along the Atlantic Coast.

Pumping in the base simulation increases from 1980 onwards, although pumping begins to decline in 2010 (fig. 12A). The nominal water-loss scenario indicates that pumping would increase 9-percent for HBA 1, be near steady for HBA 2, and decrease 34-percent in HBA 3 (where water quality is potentially an issue). The optimal water-loss scenario indicates that projected withdrawals would be lower in comparison, with a 3-percent increase in HBA 1, a 5-percent decrease in HBA 2, and a 38-percent decrease in HBA 3 (table 2). The full allocation scenario indicates withdrawals across all three HBAs would increase: 80 percent in HBA 1, 48 percent in HBA 2, and 70 percent in HBA 3 (table 2). When comparing the projected pumping for the first two scenarios to the reported pumping from 2014–2020, the actual numbers reflect the general trend of the scenarios in HBA 1 and HBA 3; however, the actual pumping is considerably less than the projected withdrawals in HBA 2 (fig. 12).

In the base simulation, head is shown to generally decline in all three budget areas in the Atlantic City 800-foot sand aquifer (fig. 12). In HBA 1, heads appear to have nearly leveled off in response to declining withdrawals at the end of the base simulation beginning around 2005 (figs. 12A, 12B). The simulations project the decline in head continues in HBA 1 for all three scenarios (fig. 12B). The nominal and optimal water-loss scenarios indicate that the decline is close to linear over time (fig. 12B). The full allocation scenario indicates that the simulated heads drop quickly in response to the step change in pumping and then continue declining approaching a steady state by 2040 (fig. 12B).

In the base simulation, the head in HBA 2 is generally in decline (fig. 12D). The nominal and optimal water-loss scenarios indicate that the decline in head in 2040 is slight over most of HBA 2: a median of 3.9 feet and 1.7 feet, respectively (fig. 12D). However, the drawdown (minimum head in fig. 12D) in HBA 2 continues linearly to reach a maximum of 31.1 feet in the nominal water-loss scenario and 24.3 feet in the optimal water-loss scenario (table 7). The optimal water-loss scenario indicates that the number of cells in HBA 2 with drawdown of at least a foot in 2040 drops to 68 percent compared to 99 percent of the cells in the nominal water-loss scenario (table 7). The full allocation scenario indicates that the heads drop quickly in response to the step change in pumping and then continue declining, approaching steady state by 2040 (fig. 12D). The median drawdown across HBA 2 is 23.4 feet with the maximum reaching 69.3 feet by 2040 for the full allocation scenario (table 7).

In HBA 3, heads are generally declining in the base simulation, especially after withdrawals start in the area in 1998. Once they start, the withdrawals are fairly consistent, and the head declines at a fairly consistent rate (figs. 12E, 12F). There is minimal difference in the statistics across HBA 3 (table 7), likely because there are only two active wells during the base simulation. The nominal and optimal water-loss scenarios (wherein withdrawals are projected to decline [fig. 12E]) indicate that heads continue to decline slightly before recovery begins (fig. 12F). By the end of the simulations in 2040, the simulated heads are at a similar level to simulated heads in 2013 for both of those scenarios (table 7). The full allocation scenario indicates that simulated heads drop quickly in response to the step change in pumping and then continue declining at a lessening rate until 2040. The median drawdown across HBA 3 is 18.0 feet and the maximum is 19.7 feet by 2040 for the full allocation scenario (table 7).

Simulated Heads and Drawdown in 2040

Figure 13A shows the simulated head distribution in 2040 for the Atlantic City 800-foot sand aquifer based on the nominal water-loss scenario. In the map, an area with low heads surrounds the largest pumping well in Atlantic County. An area of low heads can also be seen along the coast where many of the wells are located. Moving inland to the unconfined Kirkwood-Cohansey aquifer, heads increase. A similar pattern is seen in figures 13B and 13C, which show the optimal water-loss scenario and the full allocation scenario, respectively; however the overall head is slightly higher in the optimal water-loss scenario and lower in the full allocation scenario.

Figure 14A shows the simulated drawdown in Atlantic City 800-foot sand aquifer from the end of 2013 through 2040 based on the nominal water-loss scenario. The largest area of drawdown appears in central Atlantic County around the high-capacity wells. The map shows minimal drawdown in HBA 3 and a small part of HBA 2 in the lower part of Cape May County. In the northeastern tip of HBA 1, water levels are shown recovering in response to declining projected withdrawals. The relative pattern of drawdown for the optimal water-loss scenario, which appears in figure 14B, is similar to the nominal water-loss scenario but with smaller values (table 7). Additional areas of head recovery can be seen in figure 14B in HBA 3 and an area in HBA 2 about halfway up the coast.

For the full allocation scenario, the drawdown is generally much larger than the other two scenarios (fig. 14C; table 7). Drawdown in most of the aquifer ranges from 20–50 feet (head change of −20 to −50 feet). All the cells in the HBA defined in the Atlantic City 800-foot sand are simulated to have at least 1 foot of drawdown in the full allocation scenario (table 7).

Budget Analysis

Figure 15 and table 8 show the budget components for HBA 1 and are discussed below. The outflow from the budget area is primarily (greater than 80 percent) withdrawals from wells. There is a small amount (7–11 percent) of outflow south into HBA 2 where the high-capacity wells are located. About half of the inflow to HBA 1 is lateral flow from offshore; and then most of the rest is from the unconfined part of the Kirkwood-Cohansey aquifer system updip. There is some inflow coming up through the confining layer from the Piney Point aquifer below (11–13 percent). Smaller amounts are leaking through the confining unit above from the Rio Grande water-bearing zone (11–13 percent) or flowing in laterally from HBA 2 (2–4 percent). The budget components are similar among the four runs with the exception being the full allocation scenario where the well withdrawal is higher and balances the inflow that comes mostly from lateral flow offshore and updip.

Figure 16 and table 9 show the budget components for HBA 2 and are discussed below. The outflow from the budget area is almost entirely from withdrawals from wells (95–98 percent). Minor amounts of input come from storage (3 percent in the base simulation) and lateral flow from offshore and HBA 1. The largest inflow (58–61 percent) comes from lateral flow from offshore. The next largest inflow (19–21 percent) is lateral flow from the unconfined part of the Kirkwood-Cohansey aquifer system updip. There is also inflow (10–12 percent) that leaks downward through the confining unit from the Rio Grande water-bearing zone above. Some minor amounts (less than 5 percent) of inflow enters the budget area from the Piney Point aquifer below and from the adjacent budget areas. The budget components are similar among the four runs with the exception being the full allocation scenario where the inflows and outflows are generally higher.

Figure 17 and table 10 show the budget components for HBA 3 and are discussed below. The outflow from the budget area is split between flow to wells (51–65 percent) and lateral flow northward into HBA 2 (35–49 percent). Most of the inflow (97–98 percent) to the budget area is lateral flow from the 250 mg/L chloride isochlor indicating that water quality could worsen in this area (note this entire HBA is already beyond the 250 mg/L isochlor).

Trends of Withdrawals and Heads

Figure 18 shows withdrawal trends and trends of median, 10th percentile, and minimum heads from the base simulation and withdrawal scenarios for each budget area in the Piney Point aquifer. Table 2 shows a summary of the past and projected withdrawals in each budget area in the Piney Point aquifer.

Over the period of the base simulation, there has been a general increase in pumping over time in the Piney Point aquifer, although there has been a decline in pumping since around 2005. In HBA 4, the nominal and optimal water-loss scenarios both indicate withdrawals would decline (fig. 18A) 20 percent and 25 percent, respectively, by 2040 (table 2). In HBA 5, the nominal and optimal water-loss scenarios both indicate withdrawals increase (fig. 18C) 20 percent and 14 percent, respectively (table 2). For both HBA 4 and HBA 5, the full allocation scenario indicates withdrawals increase 62 and 119 percent (table 2), respectively.

In the base simulation, both budget areas in the Piney Point aquifer saw a slight decline in heads (figs. 18B, 18D). The head in areas near wells has fluctuated by 50 to more than 100 feet reacting to changes in pumping as reflected in the maximum head change (figs. 18B, 18D).

In HBA 4, the base simulation shows the median and 10th percentile heads slowly declining over time with a slight recovery after 2009 in response to declining pumping (figs. 18A, 18B). The nominal and optimal water-loss scenarios, although the total withdrawals for HBA 4 are projected to decline, indicate the head response is generally flat although the head continues to decrease at the model cell where simulated head is minimum in HBA 4 (fig. 18B). The scenarios show a median cell in HBA 4 recovers by 0.1 feet for both the nominal and optimal water-loss scenarios, with the maximum drawdown being 5.0 and 2.6 feet, respectively (table 11). The full allocation scenario indicates that heads quickly decline but then level out within 10 years (fig. 18B). The median drawdown in 2040 is 7.6 feet and the maximum is 122.1 feet for the full allocation scenario (table 11).

In HBA 5, the withdrawals are projected to increase in all three scenarios. For the nominal and optimal water-loss scenarios, the simulated heads only decline slightly in response to the additional pumping (fig. 18D). For the nominal water-loss scenario in 2040, the median drawdown for all cells in HBA 5 is 4.9 feet and the maximum drawdown is 19.7 feet (table 11). For the optimal water-loss scenario in 2040, the median drawdown for all cells in HBA 5 is 3.4 feet and the maximum drawdown is 15.3 feet (table 11). The heads do not level out as quickly under the full allocation scenario as in HBA 4 but are close to steady at the end of the simulation. The median drawdown for cells in HBA 5 in the full allocation scenario is 19.8 and the maximum is 120.3 feet (table 11). The maximum drawdown is less, however, than the maximum simulated from 2007–2009 in the base simulation.

Simulated Heads and Drawdown in 2040

The general features of the head distribution in the Piney Point aquifer are similar for the three scenarios (fig. 19). The highest heads are on the updip boundary. The lowest heads are around the pumping centers in the northeast and southwest, and in an area on the southern part of the boundary between HBA 4 and HBA 5. This area, which has no pumping wells and low head, is where the confining layer between the Piney Point aquifer and the Atlantic City 800-foot sand above is relatively thin (fig. 1) and there is heavy pumping in the Atlantic City 800-foot sand (fig. 14).

The heads are in recovery over the northern part of the aquifer, especially in the far northeast along the coast, in response to declining withdrawals in the area (fig. 20A). In the southern part of the aquifer, the largest areas of drawdown are around the pumping wells. The relative pattern of drawdown for the optimal water-loss scenario, which appears in figure 20B, is similar to the nominal water-loss scenario although the magnitude is slightly less (table 11). For the full allocation scenario, there are large areas with greater than 20 feet of head decline with cones of more than 50 feet of head decline in the vicinity of some wells, including the northeast where the other two scenarios simulate head recovery (fig. 20C). The area around the southern part of the boundary between HBA 4 and 5 also shows substantial head decline in response to increased pumping in the Atlantic City 800-foot sand (fig. 14). Even in the full allocation scenario, there remains some areas of slight head recovery. These areas have a strong connection to the unconfined aquifer, so the recovery likely reflects the small difference between the recharge in the last stress period of the base simulation and that used in the scenarios.

Budget Analysis

As shown in figure 21 and table 12, the outflow from HBA 4 is mostly to the pumping wells (45–66 percent) and through the overlying confining layer (28–46 percent). The inflow is mostly (85–87 percent) from the overlying confining layer with a small component of lateral flow from offshore (5–10 percent), updip (3–5 percent), and HBA 5 (1–2 percent). Compared to the base simulation, there is less pumping and consequently less inflow from the overlying confining layer for the nominal and optimal water-loss scenarios and more pumping and inflow from the overlying confining layer for the full allocation scenario.

Figure 22 and table 13 show the budget components for HBA 5 and are discussed below. The largest component (49–61 percent) of outflow in HBA 5 is flow to the overlying confining layer. The other main components of outflow are withdrawals from wells (20–36 percent) and flow to the underlying confining layer (11 percent). The inflow is mostly from the overlying confining layer (85–86 percent) with a small component of lateral flow from offshore (including some from the 250 mg/L isochlor), updip, and from HBA 4. The additional pumping from wells in the full allocation scenario is almost entirely offset by additional inflow from the overlying aquifer.

Trends of Withdrawals and Heads

The trend in withdrawals in HBA 6 is fairly constant over the base simulation despite some variability from year to year (fig. 23A). The nominal and optimal water-loss scenarios both project a modest increase in withdrawals into the future. The increase is within the variability reported (and used in the base simulation) between 1980 and 2013; it does not represent a large change compared to historical withdrawals. Reported pumping from 2014-2020 is mostly lower than the projected pumping, however, it is within the historical variability simulated in the base simulation.

In HBA 7, reported withdrawals in the base simulation begin in 1999 (fig. 23C). The withdrawals are small overall and show a lot of variability. Both the nominal and optimal water-loss scenarios project an increase in pumping. The full allocation scenario represents a near doubling of the current pumping; however even that is a relatively small amount.

Most of the pumping in the three unconfined budget areas is from HBA 30. In the nominal and optimal water-loss scenarios, there is no change in the pumping amounts for all the unconfined wells. The level of pumping in the full allocation scenario is higher than the other two scenarios, however it falls within the variability of historical pumping.

In the base simulation, the heads have been fairly constant over time (fig. 23B). This is due the narrow extent of the aquifer and proximity to the outcrop area. The simulated hydraulic conductivity is lower than some of the other aquifers, so what pumping exists can locally have bigger effects on the heads compared to aquifers with higher hydraulic conductivity.

In HBA 6, the median head is almost constant through the base simulation and all three scenarios (fig. 23B). The 10th percentile head is nearly constant as well, although heads increase (or recover) in the nominal and optimal water-loss scenarios despite the increase in total withdrawals projected through 2040 (fig. 23A). After a decline and quick recovery from 1980 to 1994, minimum head in HBA 6 continues a more gradual recovery in the nominal and optimal water-loss scenarios even though overall withdrawals increase (Figure 23B); this recovery reflects reduced pumping from wells in the areas with the most drawdown. Considering all the model cells, the maximum drawdown is simulated to be 12.0 feet for the nominal water-loss scenario and 8.4 feet for the optimal water-loss scenario (table 14). The full allocation scenario indicates the 10th percentile and minimum heads in HBA 6 are lower in comparison to the other scenarios (fig. 23B) with the maximum drawdown reaching 39.6 feet (table 14).

In HBA 7, the effects of pumping are limited to areas in close proximity to the wells (Fig. 24). Although the areal extent is not large, the drawdown in response to pumping can be large in areas near the wells. This pattern can be seen in the plots of head over time in figure 23D. The lines are nearly flat for both the median and 10th percentile heads in the base simulation and the scenarios, whereas the minimum fluctuates by more than 100 feet and has a downward trend. The maximum drawdown values are also large for all three scenarios—135.4 feet for the nominal water-loss scenario, 121.8 feet for the optimal water-loss scenario, and 176.9 feet for the full allocation scenario (table 14).

Simulated Heads and Drawdown in 2040

The general pattern of the simulated heads in the Vincentown aquifer is similar in all three scenarios: higher heads in the unconfined areas where the recharge occurs and lower heads in the vicinity of the pumping wells (fig. 24). There are two areas where prominent cones of depression show up around the pumping wells: one in the southwest and the other in the northeast. The one in the southwest is much more defined, as the simulated hydraulic conductivity is less there. There is a low area of head along the border of Camden and Burlington Counties in response to pumping in the underlying Wenonah-Mount Laurel aquifer. In the full allocation scenario, there are a few more wells with tight cones of depression around them.

There is a large area with minimal change in head corresponding to the unconfined parts of the aquifer and in areas away from the high-capacity wells (fig. 25); this largely reflects the change from the base simulation’s recharge value in the final stress period to the average value used in the scenarios. The larger area of recovery along the downdip edge in the northeast is due to reduced pumping in a well that is located beyond the downdip limit of the aquifer. Some areas around the wells have a large amount of head decline, indicating that the cones are not just artifacts of the historical pumping but that the magnitudes of the cones of depression will increase under these scenarios. This pattern appears in all the scenarios, but the magnitude is greatest in the full allocation scenario with the maximum drawdown reaching 176.9 feet (table 14). Cones of depression can be seen in areas without pumping in the Vincentown aquifer where the confining unit is relatively thin and there are high-capacity wells in the underlying Wenonah-Mount Laurel aquifer.

Budget Analysis

The largest component of the outflow (55–58 percent) from HBA 6 is flow out to the underlying confining layer above the Wenonah-Mount Laurel aquifer (fig. 26; table 15). Other components of outflow include lateral flow out to the unconfined HBA 30 (17–20 percent) and flow to wells (10–21 percent). The main component of inflow (99–100 percent) to HBA 6 is water leaking in from the unconfined Kirkwood-Cohansey aquifer system above through the confining layer.

Almost all the inflow (96–98 percent) in HBA 7 of the Vincentown aquifer is from the overlying confining layer and the Kirkwood-Cohansey aquifer system above (fig. 27; table 16). Much of that flow passes down through the Vincentown aquifer and out through the underlying confining unit (89–92 percent). In contrast to many of the other HBAs, only a small amount (1–2 percent) of the total outflow is to wells.

The main budget components in the unconfined areas of the Vincentown aquifer are inflow from recharge (92–97 report) and outflow to streams (fig. 28, table 17; fig. 29, table 18; fig. 30, table 19). There are some minor amounts (5 percent or less) of flow between adjacent HBAs to and from the underlying Wenonah-Mount Laurel aquifer.

Trends of Withdrawals and Heads

Pumping in HBA 8 in the period of the base simulation fluctuated by over 400 gallons per day until the mid-1990s when restrictions from the Critical Area 1 designation took effect (fig. 31A). From that point forward, there is a slight increase through the end of the base simulation. This increase is projected to continue at a reduced rate in the nominal (9 percent) and optimal (4 percent) water-loss scenarios. The full allocation scenario represents a 132-percent increase in withdrawals from 2013 (table 2).

Pumping in HBA 9 declines from 1990 through the end of the base simulation (fig. 31C). In contrast, the nominal water-loss scenario projects an increase of 5.2 percent, and the optimal water-loss scenario projects a decrease of 1.4 percent (fig. 31D). The actual reported withdrawals from 2014 through 2020 have continued the general trend that was seen in the base simulation, declining by 28.6 percent over that time period, suggesting that the nominal and optimal water-loss scenarios may be overestimates. The full allocation scenario indicates a 101.5 percent increase from the 2013 pumping amount in HBA 9 (table 2).

Pumping in HBA 10 is fairly level from the mid-1980s through the mid-1990s, after which pumping increased by 300 percent (fig. 31E). A fairly steady decrease follows and continues through the end of the base simulation to 2020. Rather than reflecting this decline, both the nominal and optimal water-loss scenarios project a slight increase in pumping (6.1 and 1.8 percent, respectively). The full allocation scenario indicates an increase of 89.4 percent (table 2).

Withdrawals in HBA 11 increase until approximately 1998, at which time they level out and then start to decrease around 2005 (fig. 31G). The withdrawals are fairly steady from 2014 to 2020. Both the nominal and optimal water-loss scenarios indicate increasing withdrawals in HBA 11 (11.5 percent and 6.3 percent, respectively; table 2). The full allocation scenario indicates that withdrawals increase 121.9-percent compared to the last stress period of the base simulation in HBA 11 (table 2).

Withdrawals in HBA 12 increase fairly steadily through the period of the base simulation (fig. 31I). Both the nominal (−1.4 percent) and optimal (−6.1 percent) water-loss scenarios indicate withdrawals would see a small decline (table 2). The full allocation scenario indicates withdrawals would increase 107.9 percent over the last stress period of the base simulation in HBA 12 (table 2).

There is minimal pumping in the unconfined parts of the Wenonah Mount Laurel aquifer (table 2). This includes HBAs 33–37.

The simulated heads from the base simulation recover in the northeastern part (HBAs 8 and 9) likely reflecting restrictions in Critical Area 1. In the southwestern part (HBAs 10, 11, and 12) of the Wenonah-Mount Laurel aquifer heads decline (fig. 31) likely reflecting increased withdrawals in response to restrictions in the deeper aquifers in Critical Area 2. Across the aquifer, the nominal and optimal water-loss scenarios indicate that simulated heads are relatively stable in comparison to changes in the base simulation (fig. 31).

In HBA 8, the median head is almost constant through the later part of the base simulation and remains nearly constant for the nominal and optimal water-loss scenarios (figs. 31A, 31B). Figure 31B shows a general recovery in 10th percentile and minimum heads in HBA 8 since the early 1990s (with a few spikes downward) in response to the large decrease in withdrawals. Even with a slight increase in withdrawals, the nominal and optimal water-loss scenarios indicate there is still a small, continued recovery in simulated heads. The increase in projected withdrawals leads to modest drawdown increases of 1.3 feet for the nominal water-loss scenario, 0.1 feet for the optimal water-loss scenario in the 90th percentile drawdown, and 5.2 feet and 3.3 feet, respectively, for the maximum drawdown in HBA 8 (table 20). The full allocation scenario leads to decreasing heads and therefore increasing drawdowns to a maximum of 42.3 feet (table 20).

The heads are fairly stable in the latter part of the base simulation and continue to be stable for the nominal and optimal water-loss scenarios for most of the cells in HBA 9 (fig. 31D). The minimum head in HBA 9 increases from the early 1990s to the end of the base simulation, but the scenarios indicate that minimum head levels off for the nominal and optimal water-loss scenarios (fig. 31D). The drawdown numbers from table 20 tell a similar story, however, comparing the maximum drawdown values to the 90th percentile of the cells shows that there are areas where drawdown increases. The scenarios indicate the maximum drawdown for model cells in HBA 9 is 18.6 feet for the nominal water-loss scenario and 17.2 feet under the optimal water-loss scenario (table 20). The full allocation scenario indicates there are areas of substantial head declines. The heads quickly decline with the step increase in withdrawals and then continue a more gradual decline based on the 10th percentile and minimum heads of model cells in HBA 9 (fig. 31D). In this scenario, the maximum drawdown is 77.2 feet (table 20).

In HBA 10, the heads initially decline in the base simulation and then mostly level off starting around the year 2000, as the median and 10th percentile heads show (fig. 31F). The nominal and optimal water-loss scenarios indicate that the trend of mostly stable heads in HBA 10 continues. The cell with the minimum head in HBA 10 is more variable but there is no discernable trend, a pattern that continues in the nominal and optimal water-loss scenarios (fig. 31F). The maximum drawdown is 16.6 feet for the nominal water-loss scenario and 13.1 feet for the optimal water-loss scenario (table 20). The full allocation scenario indicates there is a decline in heads with the maximum drawdown reaching 73.1 feet in HBA 10 (table 20).

For HBA 11, heads recover in the last part of the base simulation in response to declining withdrawals (figs. 31G, 31H). The nominal and optimal water-loss scenarios indicate that some withdrawal increases are large enough to reverse that recovery and result in an overall slight decline in heads—although at the cell with the minimum head there is a small increase in head for the optimal water-loss scenario (fig. 31H). There are areas where localized drawdown happens in response to the projected withdrawals from the nominal and optimal water-loss scenarios (table 20). The scenarios indicate that the maximum drawdown in HBA 11 reaches 42.3 feet for the nominal water-loss scenario, 37.9 feet for the optimal water-loss scenario, and 111.5 for the full allocation scenario (table 20).

In HBA 12, there is a general decline in heads over the base simulation (fig. 31J). All three scenarios indicate heads continue to decline based on all three statistical measures except minimum head under the nominal and optimal water-loss scenarios where there is some recovery in HBA 12 (fig. 31J). Although the heads are projected to decline in HBA 12, the scenarios indicate that drawdowns are generally small by most of the statistical measures in comparison to the other confined budget areas in the Wenonah-Mount Laurel aquifer (table 20).

Simulated Heads and Drawdown in 2040

Figure 32 shows the simulated head distribution in 2040 for the Wenonah-Mount Laurel aquifer. The general pattern of simulated heads in the Wenonah-Mount Laurel aquifer is high along the outcrop areas and low in the downdip areas and especially where there are pumping wells. Note that the highest heads are in the confined part of the aquifer in HBA 8, indicating that the overlying confining layer’s properties do not isolate the aquifer from the unconfined system above. The lowest areas of head in the Wenonah-Mount Laurel aquifer are along the coast in Monmouth and Ocean Counties and around a cluster of pumping wells in Gloucester and Camden Counties. There are several other areas of depressed heads around pumping wells.

Figure 33 shows the simulated drawdown from the end of 2013 through 2040 in the Wenonah-Mount Laurel aquifer for the three withdrawal scenarios. In the northeastern part of the aquifer, heads recover over the nominal and optimal water-loss scenarios. This recovery is mostly in response to decreased withdrawals as a result of Critical Area 1 restrictions. There are some other areas of recovery in those scenarios in response to local decreases in pumping. Areas of drawdown exist in the vicinity of some of the pumping wells in HBA 9, HBA 10, and HBA 11, with the largest areas of drawdown occurring through the center of HBA 11.

In the full allocation scenario, there are many areas where the drawdown is greater than 20 feet throughout the aquifer. The largest amount of drawdown in HBA 10 and HBA 11 is greater than 50 feet of head decline. Across the unconfined areas and in a small area along the coast, there is a small (less than two feet) increase in heads across the simulation.

Budget Analysis

Figure 34 and table 21 show the net components of flow in and out of HBA 8 and are discussed below. For HBA 8, the primary source of inflow (57–59 percent) is from the overlying aquifer. Flow to and from the adjacent unconfined HBA 33 consists of 38–40 percent of total inflow and 42–48 percent of total outflow. The wells in HBA 8 account for less than ten percent of the outflow in the budget area. Other components of outflow include flow through the underlying confining layer to the Englishtown aquifer system (23–29 percent) and lateral flow to HBA 9 (17–19 percent). The components are similar between the scenarios, except for the full allocation scenario, in which there is more inflow from the overlying aquifer and outflow to the underlying aquifer and wells.

Figure 35 and table 22 show the budget components for HBA 9 and are discussed below. The two main components of inflow to HBA 9 are flow from the overlying aquifer (71–73 percent) and lateral flow from HBA 8 (18–20 percent). The main outflow of water (78–82 percent) is lateral flow to the unconfined HBA 34. Minor amounts of outflow are to the wells (5–10 percent), flow to the overlying confining unit (6–7 percent) and leakage to the underlying confining layer (4–6 percent). The near-zero components include flow to the offshore areas, lateral flow to HBA 10, and storage. The relative amounts of the budget components were similar among the base simulation and three scenarios.

Figure 36 and table 23 show the budget components of flow in and out of HBA 10 and are discussed below. The main component of inflow (95–96 percent) to HBA 10 is flow from the overlying aquifer. The outflow is to the unconfined HBA 35 (49–58 percent), to wells (18–28 percent), and to the overlying confining layer (18–22 percent). Under the full allocation scenario there is increased leakage through the overlying confining layer to supply increased outflow to the wells. The net flows to the other components are small.

Figure 37 and table 24 show the budget components of flow in and out of HBA 11 and are discussed below. The main component of inflow (83–90 percent) to HBA 11 is from the overlying confining layer with minor components from offshore (3–6 percent), HBA 10 (2–3 percent), and HBA 12 (4–6 percent). The largest outflow is to the unconfined HBA 36 (48–63 percent). Most of the other outflow is to the wells (26–44 percent). For the full allocation scenario, the outflow to the wells in HBA 11 is approaching that of flow to the unconfined HBA 36.

Figure 38 and table 25 show the budget components of flow in and out of HBA 12 and are discussed below. The inflow is primarily (94–95 percent) from the overlying confining layer in HBA 12; some water also flows out to the overlying confining layer (13–17 percent). The largest component of outflow (48–57 percent) in HBA 12 is lateral flow to the unconfined HBA 37. The wells are the second largest component of outflow (13–25 percent) from HBA 12. The full allocation scenario has close to double the flow to wells both by magnitude and percentage. There is some outflow (4–5 percent) to the Delaware River where the model simulates a connection to the Wenonah-Mount Laurel aquifer in Salem County (fig. 38). There is some lateral outflow to HBA 11 (4–8 percent) and a small amount of outflow to areas offshore (2–3 percent).

The budgets for the unconfined hydrologic budget areas in the Wenonah-Mount Laurel aquifer are presented in figures 39–43 and tables 26–30. For all these unconfined budget areas, the main component of inflow is recharge (58–85 percent) and the main component of outflow is to the streams (39–95 percent). The second biggest inflow is from the adjacent confined HBA (11–29 percent). This reflects the leaky nature of the overlying confining unit in that the confined aquifer transmits part of the general recharge to discharge system. In HBA 33, the flow leaking to the confining layer below (36–37 percent) is only slightly less than the amount of flow to the modeled streams (39–41 percent). In the other HBA, there is some amount of flow in and out of the underlying confining layer that accounts for less than 10 percent of the total inflow and outflow.