Aquifers in the United States – Part 1

A drone photo in August 2015 shows one of Partridge Well Drilling Co. Inc.’s smaller drill rigs drilling a 3-inch-diameter rock well to about 100 total feet in Jacksonville, Florida. They were able to pump more than 50 gpm out of the well. The top of the Floridan aquifer system in this area is about 450 feet.

Part one of three: Floridan aquifer system

By Mike Price

It is overwhelming to think groundwater makes up an estimated 99% of all freshwater in the world.

Yet groundwater is “out of sight, out of mind” for most here in the United States. However, the present threat of groundwater shortages in pockets of the nation has elevated the importance of this commonly undervalued resource.

In times of drought or groundwater contamination—when people are noticeably affected—the value of water becomes clear. We’re seeing it with the years-long drought in California and the water crisis in Flint, Michigan. The principle behind what Benjamin Franklin said two centuries ago remains true today: “When the well runs dry, we shall know the value of water.”

On the heels of National Groundwater Awareness Week, held March 6-12, Water Well Journal begins a three-part series examining major aquifers in the United States.

Part one focuses on the Floridan aquifer system, which underlies the entire state of Florida as well as southern portions of Alabama, Georgia, and South Carolina. It covers 100,000 square miles and is the largest aquifer in the southeastern United States.

Florida is no doubt a water state.

The Floridan aquifer system was developed millions of years ago during the late Paleocene to early Miocene periods when Florida was underwater. The Floridan aquifer system has been divided into an upper and lower aquifer separated by a unit of lower permeability. The Upper Floridan aquifer is the principal source of water supply in most of north and central Florida.

Currently, the Upper Floridan aquifer supports nearly 10 million people as their primary source of water—used for public, domestic, and industrial water supply with almost 50% of its water being used for irrigation. The state also draws water from the St. Johns River, the Suwannee River, and the Ocklawaha River.

In the southern portion of the state, where it is deeper and contains brackish water, the aquifer has been used for the injection of sewage and industrial waste.

Location is key when drilling a water well in the Floridan aquifer system as the geological formations vary across the state. It is comprised of a sequence of limestone and dolomite, which thickens from about 250 feet in Georgia to about 3000 feet in south Florida.

Drilling Challenges

The Upper Floridan aquifer can be as deep as 600 feet and as shallow as 200 feet in northeast Florida.

“Knowing what you have to do to get to those depths and what you find above that formation makes it the challenging part,” says Merritt Partridge, vice president of Partridge Well Drilling Co. Inc. in Jacksonville, Florida.

“Whether there is an underlying rock bed above that, whether you lose drilling circulation in those formations above it, or you lose circulation in the Floridan aquifer system makes it challenging.”

Partridge Well Drilling, established in 1892 at a time when drill rigs had masts made of wood, drills by using mud rotary as far south as Key West and has completed several projects in Mississippi and Georgia. However, the majority of its work is done in northeast Florida. It also drills wells shallower than the Upper Floridan aquifer, but typically everywhere it drills, the Floridan aquifer system is present.

The Upper Floridan aquifer poses a unique drilling challenge: In some areas it is a confined artesian aquifer, which is an underground layer which holds groundwater under pressure. This causes the water level in the well to rise to a point where the pressure is equal to the weight of water putting it under pressure.

Partridge says water level and artesian pressure are key factors to consider when drilling into the Floridan. Based on their well records, Partridge can estimate if the water level will be deep in the well or free flowing at the surface, which is not uncommon in certain areas. In parts of northeast Florida, wells flow with 20 pounds of pressure or more, creating quite a gusher. He says anticipating this while addressing it when drilling is necessary along with selecting the right pump size to accommodate the varying water levels in certain parts of Florida.

Depending on the pressure after punching into the aquifer, Partridge says the quality of the mud drilling program comes into play if the ground formation begins free flowing. Depending on the flow, the well may need to be staged down and telescoped.

“If we want to drill a 2-inch well, we may have to do 8 inches at the surface, install 4-inch casing, and reduce it to 2,” Partridge says. “Therefore, if we run into problems we can backtrack or be safe above that zone because we’ve got grouted casing in place.

“Knowing how much flow, how it will affect drilling, and where the water is going to go is important. It’s not uncommon for us to get artesian wells in this area. Some of the factors we consider are elevation, location, and well logs to anticipate the flow rate.”

Caverns and sinkholes are also issues to be watchful for in central and west central Florida, where limestone is shallow (80 feet) and has karst features. The topography creates an environment where water rushes underground, eroding the sand—causing sinkholes.

According to Partridge, there are incidents of washouts but no true sinkholes in northeast Florida due to the limestone of the Upper Floridan aquifer being so deep, providing sufficient aquifer protection.

Water Quality

In parts of Florida, a misnomer is the deeper you go the better water quality you’ll find.

Partridge hears customers say this, yet it’s often not the case. Instead, Partridge explains the deeper you go the more salinity and more chlorides you’ll find.

“In certain parts of the state, especially toward the coastlines, the deeper you go the greater risk of getting saltwater in your well from saltwater intrusion,” he says, “so generally some areas you just want to scratch the surface of the Floridan aquifer system in order to avoid getting to that deeper depth where chlorides may be present.”

Water quality and water treatment, the issue focus of this month’s Water Well Journal, is a major part of Partridge Well Drilling, which installs water treatment systems. They have customers who believe wells in northeast Florida have the staining mineral iron and sulfur. Again, Partridge says more often than not iron is not present. Typically, the Upper Floridan aquifer can have a high presence of sulfur but it can be easily treated.

“We guarantee our customers not to have iron staining present in their water,” he says, “which is a big advantage for us and a good thing to be able to promise our customers because they’re concerned about that.

“The shallower wells typically do have iron, but we can drill customers a well in the Upper Floridan aquifer and get them good, quality water. The city water in our area is drawn from Upper Floridan aquifer wells, so they’re comforted with the idea their water will be of similar quality.”

Iron can sometimes be present in rock, gravel pack, and shallow wells. Partridge Well Drilling does not recommend treating irrigation water for iron. But if iron staining is a concern, the company recommends drilling an Upper Floridan aquifer or intermediate well (3- or 4-inch-diameter well at 220-320 feet).

The U.S. Geological Survey and U.S. Department of the Interior found the quality of groundwater in the Upper Floridan aquifer to be among the nation’s best, according to their circular paper, Water Quality in the Upper Floridan Aquifer and Overlying Surficial Aquifers, Southeastern United States, 1993–2010.

Fewer than 1 in 20 water samples collected from drinkingwater wells in the Upper Floridan aquifer contained a constituent at a concentration that exceed a human-health benchmark. Radon exceeded its human-health benchmark most frequently.

Water Well Permitting

All wells in Florida require a permit from one of the state’s five water management districts. Each district has a different way of permitting certain diameter wells.

Partridge Well Drilling, established in 1892, has about 40 employees. Pictured are most of Partridge Well Drilling’s managers. Merritt Partridge is second from left. Photos courtesy Partridge Well Drilling.

Partridge Well Drilling, located in the northeastern part of the state, operates in the St. Johns River Water Management District.

Over the last few years the Florida Department of Environmental Protection (DEP) has focused on increasing efficiency and statewide consistency of water-related permitting in Florida. The focus is on the Consumptive or Water Use Permitting (CUP/WUP) program and the Environmental Resource Permitting program. The Consumptive Use Permitting Consistency Initiative—commonly known as “CUPcon”— addresses the CUP/WUP program, where a 2012 state law began efforts to make the Environmental Resource Permitting program more consistent.

The DEP, along with the five water management districts, which are responsible for implementing the program, has been working on CUPcon since 2011. The CUP/WUP program is one of the regulatory programs created by Florida’s Water Resources Act, passed in 1972.

Water management districts are directed to regulate the use of groundwater and surface water by requiring permits for the withdrawal and consumptive use of larger quantities of water—quantities exceeding specified threshold amounts. But over the years each district created different rules regulating the CUP/WUP program despite all districts operating under the same statutory authority for the program.

Soon after Governor Rick Scott became governor in 2011, he directed the DEP to carry out its legal obligation to supervise the districts to achieve greater statewide consistency, which led to CUPcon. The DEP and districts worked toward a more cohesive system and increased consistency by meeting with stakeholders, organizing workgroup meetings for stakeholders to develop solutions, and distribute amendments to the rules implementing the CUP/WUP program. All five water management districts adopted more consistent Consumptive Use Permit rules in 2014.

The current state of well permitting sits squarely on the mind of Partridge, who is serving as this year’s president of the Florida Ground Water Association. The association was organized in 1935 and currently has more than 600 members.

Partridge is struggling to make sense of consistency efforts regarding applying a rule of a large diameter well (6 inches or larger at land surface) to all size wells drilled throughout the districts. There is more paperwork required to file a permit application for a large sized well, he says, so this may create a lengthy process, whereas a well less than 6 inches in diameter currently requires a one-page permit application.

In Partridge’s area, you may have to drill a well with 6- inch casing at the surface to obtain a 3-inch well into the aquifer. He says the well should be permitted based on the restricting factor, which is the smallest water-bearing casing, not the casing at the surface.

“The governor is really pushing consistency throughout the state in permitting regulations,” Partridge says, “and we support that to an extent, but because of the difference in geology and the difficulties in certain areas and uniqueness of drillers with the way they do things throughout the state, it’s hard to say a one size fits all application is really beneficial.

“There is a happy medium between the two and we’re struggling to find that.”

On behalf of the FGWA, Partridge spoke with the DEP and all the water management districts earlier this year.

“We’re on board with consistency,” he says, “but at some point, the returns on consistency do not make sense if it makes it more difficult for the contactor who is really the person you’re trying to be consistent for.

“We’re trying to get everyone on the same page and a lot of people have opinions they’ve held on to for quite a bit of time, and it’s hard to change those opinions. The governor’s office is also putting influence on the DEP and those government bodies to make things happen. Some people are going the direction they want to with that.”

The DEP holds workgroup meetings in conjunction with the FGWA’s quarterly membership meetings throughout the state. Water well contractors, the five water management districts, some county health departments, the Florida Department of Health, and the DEP all have representatives present.

“These meetings are extremely valuable to the water well drilling industry,” Partridge says. “The workgroup discusses everything from permitting, rules and regulations for water wells, and other issues that could impact Florida’s groundwater.

“We recently started to have discussions regarding consumptive use permitting consistency. While the discussions have been productive, we have not come to a consensus yet.”

As these efforts continue, the Southwest Florida Water Management District in Tampa is unique in it is the only district to have a Well Drillers Advisory Committee. It was created in 1970 to provide two-way communication between the district and the water well contractors.

Every revision to the district’s regulation of water well rules is provided to the WDAC at meetings for discussion and approval. The district views water well contractors as their “eyes and ears” of the Floridan aquifer system, according to David N. Arnold, PG, well construction manager, Water Use Bureau, for the Southwest Florida Water Management District in Tampa.

Arnold says he’s heard interest from other water management districts in creating similar advisory committees.

Central Florida Water Initiative

In 2013, the Central Florida Water Initiative was created to protect, conserve, and restore water resources in a 5300- square-mile area.

A variety of stakeholders are involved with the initiative, including the DEP, the Florida Department of Agriculture and Consumer Services, and the state’s three largest water management districts (Southwest Florida Water Management District, St. Johns River Water Management District, South Florida Water Management District).

In central Florida, water pumped from the Floridan aquifer system serves about 2.7 million residents and also supports a large tourist industry, farming operations, and a business community. The population in some areas is projected to increase by almost 50% by the year 2035.

However, as the central Florida population increased by more than 1 million people over the past 15 years, the overall water use has basically stayed the same, according to the Central Florida Water Initiative. The CFWI says much of that is due to good water conservation and more efficient practices, including the use of reclaimed, or recycled, water.

Today, the average total water use is about 800 million gallons per day. It is estimated the CFWI planning area will need approximately 300 mgd of additional water supplies by 2035.

About 50 mgd of additional fresh groundwater can be made available through management strategies such as changes to wellfield operations and increases in aquifer recharge. The remaining 250 mgd will have to be met through expanded water conservation and other alternative sources.

A total of 150 potential projects—more than enough to meet the region’s 250 mgd increase—were identified throughout its plan development process in 2014. Aquifer storage and recovery will have its part to play among some of these projects.

Aquifer Storage and Recovery

Florida has 29 active aquifer storage and recovery (ASR) facilities, ranging from a single well to 21 wells, according to Joe Haberfeld, PG, administrator, Aquifer Protection Program, for the Florida Department of Environmental Protection in Tallahassee.

The Peace River Manasota Regional Water Supply Authority ASR system in southwest Florida is the largest wellfield in the state with a combined recovery capacity of 10 to 20 mgd.

ASR is a mechanism made for storing water underground through an injection well to be withdrawn in the future. Water is typically stored in reservoirs during times of excess supply for use when supplies are limited. However, natural evaporation and limited capacity during heavy rainfall limit the ability to efficiently store excess water, Haberfeld says.

ASR wells are capable of storing treated drinking water as well as groundwater, reclaimed water, or surface water.

“The level of treatment required after storage depends on the use of the water,” Haberfeld says, “whether for public consumption, surface water augmentation, wetlands enhancement, irrigation, saltwater intrusion barrier, etc. Because ASR provides for the storage of water that would otherwise be lost to tide or evaporation, it represents a crucial water supply management strategy for Florida’s future.”

Public health protection is provided by local ordinances, deed restrictions, easements, and other methods to prevent access to groundwater in the vicinity of the ASR projects by other parties.

Water utilities are required to meet appropriate water quality standards prior to distribution of recovered water from recharged aquifers. Florida’s water utilities are showing increased interest in the use of ASR to supplement their water supplies and preserve Florida’s groundwater.

Partridge has heard much about ASR projects in the state but not seen any requests for proposals come across his desk. Then again, the threat of a water shortage is not as pressing as it is in central Florida.

A sixth-generation well driller, the 29-year-old Partridge is devoted to doing what he can to help protect the Floridan aquifer system and move the industry forward in his state. The FGWA Annual Convention & Trade Show in May will include workshop sessions on water well construction compliance and enforcement as well as a water management district panel discussion.

“There is a lot of information out there, both good and bad. What may be true in a certain region of the Floridan aquifer system may not be true in another area,” says Partridge, who also serves on the National Ground Water Association Board of Directors.

“Associations like the Florida and National Ground Water Association can help craft a unified message while keeping in perspective the unique challenges of each region. It’s important for professionals like the licensed drilling contractors who work with the Floridan aquifer system every day to be a big part of the effort to protect and promote the responsible use of this resource.”

Mike Price is the senior editor of Water Well Journal. In addition to his WWJ responsibilities, Price produces NGWA’s newsletter and contributes to the Association’s quarterly scientific publication. He can be reached at

Part two of this aquifer series will spotlight the Ogallala Aquifer in the May issue of Water Well Journal, which focuses on irrigation and groundwater.