Thomas Fuller said "we never know the worth of water until the well goes dry." In the Florida Keys, only a handful of wells have ever produced any semblance of drinking water, so islanders have known its worth since they arrived. As early as the 1860s, settlers were trying new sea water desalination technology (simply distillation) in Key West and the Dry Tortugas. Since that time, cisterns became very common for most households. Yet, arid conditions during much of the year kept water supplies very tenuous. Businesses also had higher demands for more reliable water supply. Deep wells didn’t produce fresh water in Key West. Wells produced limited supply on Big Pine Key and in the upper and middle keys.

A temporary solution was to haul water in large tanks from the mainland on the Overseas Railway that Henry Flagler built in the early 1900s. The water also assisted with the construction of the railway itself; especially for concrete mixing.

The Navy had keen interest in the development of a reliable water supply to meet the needs of its Key West base In 1917, Major John Hughes began a strong campaign to build an 18-inch diameter pipeline from Dade County to Key West. However, World War 1, Florida's land boom collapse in 1926 and the Great Depression kept the pipeline from materializing for many years.


Florida Keys Aqueduct Authority and the Navy

In 1937, the legislature of the state of Florida created the Florida Keys Aqueduct Commission, the predecessor to the Florida Keys Aqueduct Authority. The Commission was charged with the responsibility of obtaining, supplying and distributing potable water to the Florida Keys.

Then in 1939, the Navy Base in Key West reopened and once again the need for a reliable water supply was brought into focus. With agreement from the state of Florida to pay 1/3 the cost, Congress provided 2/3 the cost to build the pipeline from the mainland to Key West along with the necessary wellfield, treatment and pumping infrastructure. Land (353 acres) was acquired in Florida City for a wellfield and eventual treatment plant. In 1941, installation of the 18-inch transmission main began from Florida City to Key West. Steel pipe, wrapped and coated, was the material of choice for this pipeline.


Florida East Coast Railway flat cars with cypress wood tanks. (Monroe County Library)

In 1970, the Authority (Florida Keys Aqueduct Authority) was established by the state legislature to succeed the Commission. The Authority currently operates under Special Legislation 76-441, Laws of Florida, as amended, as a special district of the state with a Board of Directors appointed by the governor.

The Authority is the sole provider of potable water for all the residents of the Florida Keys (Monroe County). The Authority also provides wastewater collection and treatment in most unincorporated areas of the Monroe County. The Florida Keys extend approximately 130 miles from the Florida mainland and are connected by 43 bridges. The Authority provides service to over 48,000 customers throughout the Florida Keys.

The Authority has made significant improvements to its infrastructure over the years to provide expanded service and accommodate increased demand. Dramatic increases in population and tourism began after World War II. As a result, the capacity of the system was soon maxed out and during the late 1960s and 1970s, water pressure decreased and delivery was not as reliable. Planning, engineering and financing were conducted in the late 1970s for a new transmission pipeline and associated infrastructure. During this time, an oil-fueled flash plant was built in Key West for added supply. The Authority replaced the aging flash plant with a seawater reverse osmosis plant while the construction of this major transmission project began in the early 1980s.

The initial phase of the transmission line replacement was completed in the mid-1980s. The new transmission system included important upgrades to the water booster pump stations and system control. The Authority then established a long-range capital improvement master plan to address anticipated future water demands and other operational features for system improvements; this included an upgrade of the Lime-softening Water Treatment Plant (WTP) from 6 million gallons per day (MGD) to 23.79 MGD. The plan was updated in 2006 in conjunction with the development of a strategic water supply plan that identified future water supplies. As a result, a new brine 6 MGD reverse osmosis system was designed and operational by 2009, adjacent to the existing WTP.


Pipeline crossing Jewfish Creek (1942, Authority archives)


Water Supply and Treatment

The Authority draws its primary raw water supply from the Biscayne Aquifer through ten wells with average depths of fifty to sixty feet for treatment through the lime-softening WTP; and five Floridan Aquifer wells with depths of about 1,500 feet through the Reverse Osmosis WTP. The well field is adjacent to the outskirts of Everglades National Park and is within an environmentally protected Pine Rockland. The location of the well field, along with restrictions enforced by state and local regulatory agencies, contribute to the unusually high quality of the raw water, which meets all federal and state finished drinking water standards prior to any treatment.


Authority treatment plants (RO in foreground, lime softening in background) in Florida City

The Authority is permitted by the South Florida Water Management District (SFWMD) to withdraw its supply of water from the Biscayne and Floridan Aquifers for a total allocation of 23 .98 MGD. The Authority's water use permit allows for an annual average daily withdrawal from the Biscayne Aquifer of 17.79 MGD, yet limits the average daily withdrawal to 17 MGD during the dry season. For the remaining allocation, the permit allows extraction from the deeper Floridan aquifer, a brackish water source, to treat through reverse osmosis. This alternative water supply is used to meet high demands and to replenish supply from the dry season limitation on the Biscayne aquifer withdrawal. The permit is effective until 2028, yet the Authority may request additional allocations if water supply demands increase beyond expectations and permit allocations.

The primary water treatment process consists primarily of lime softening, filtration, disinfection and fluoridation. In the Reverse Osmosis process, brackish water is forced through membranes to remove chlorides and impurities. Water treated through the two WTP facilities is then blended and disinfected before entering the transmission system.

Adjacent to these treatment facilities are water storage tanks, high service pumping equipment, emergency diesel generators, a control center for transmission telemetry, and a state-certified water quality testing laboratory.

The Authority also maintains seawater reverse osmosis facilities in Stock Island and Marathon capable of producing two MGD and one MGD, respectively. These facilities were constructed primarily for emergency operations in the event of a major transmission main break.


Water Transmission and Distribution Systems


The Authority maintains approximately 190 miles of transmission main and 700 miles of distribution lines. The transmission main ranges in size from 36 inches leaving the water treatment plant in Florida City, to 18 inches at the end of the line in Key West, to 12 inches at the end C-905 with redundant lines in some areas. The transmission system runs at a relatively high pressure (typically 100-250psi) for delivery along the long stretch of pipeline.

The Authority operates transmission pump stations at the water treatment plant in Florida City, Key Largo, Long Key, Marathon, and Ramrod Key. These pump stations boost the water pressure to meet water demands throughout the service area. A pumping station on Stock Island just outside of Key West can also pump water in the opposite direction in the event of a transmission main break east of Key West.

All stations have pumps with electric variable speed drives as well as diesel engine drives for emergencies. All stations are equipped with instrumentation to provide monitoring and control provisions to the Authority's operations at both Key West and Florida City.


New 36-inch transmission main being assembled on new Jewfish Creek bridge to provide parallel pipe reliability

The Authority also operates 20 distribution pump stations located throughout the service area to maintain water pressure in the distribution system.

Strategic locations and volume of water storage is also an important part of the Authority's water supply system. When full, the tanks hold a combined volume of 47 million gallons, which equates to over two days of storage capacity.


Future Considerations

Bold islanders imagined and then built an incredible water system in very difficult conditions through the Florida Keys nearly eighty years ago. It was a remarkable accomplishment and shows the critical driving force of water for survival and that of a good supply of potable water for an enhanced quality of life. The Authority continues to maintain, improve and enhance this unique water supply infrastructure.

Challenges for continued future operation of a resilient water supply include environment and economic issues. With higher demands throughout Monroe and south Miami-Dade County, the withdrawals from the Biscayne and Floridan Aquifers will continue to increase. At the same time, sea level rise will place added constraints on the balance of water demand in the low• lying area where the Authority's wellfield is located. Wellfield protection will take more sensing, tracking and monitoring of the dynamics of water in the region to be able to adjust and make necessary changes to deal with environmental changes that will affect the water supply. At the same time, energy demands and infrastructure repair/replacement in the harsh environment require a keen focus and strong financing to provide a reliable and resilient water supply for current customers to future generations.


References


1. Florida Keys Sea Heritage Journal, by Carston Heinlein, Fall 2000
2.  
2. History of the Florida Keys Aqueduct Authority, Jerry Wilkinson, 2009
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3. Florida Keys Aqueduct Authority 20-Year Water System Capital Improvement Master Plan, 2006

4. Chapter 76-441, Laws of Florida, Enabling Legislation of the Florida Keys Aqueduct Authority
5. Florida Keys Aqueduct Authority Comprehensive Annual Financial Report, Fiscal Years Ended 2014 and 2013

Click here to see the article in the Florida Engineering Society Journal