By 2041, Sarasota County expects water demand to have increased by 5 million gallons per day

County Commission approves updated report to Peace River Manasota Regional Water Supply Authority, which provides most of county’s drinking water

This chart shows projections for increases in demand for drinking water for county customers. Image courtesy Sarasota County

In 2018, Sarasota County’s water demand was 19.81 million gallons per day (mgd). By 2041, that is projected to grow to 28.94 mgd, the county’s Public Utilities Department staff has estimated.

For this year, the figure is expected to be 23.48 mgd.

At the same time, the number of the county’s water customers is anticipated to rise from about 235,000 to approximately 290,000, based on The Sarasota News Leader’s review of a graph provided by county staff.

In conjunction with the terms of the county’s Master Water Supply contract with the Peace River Manasota Regional Water Supply Authority, the County Commission on Feb. 4 unanimously approved the county water demand projections from 2021 to 2041. The item was on the board’s Consent Agenda of routine business matters that day.

Commissioner Alan Maio, who is a member of the Peace River Authority Board, reported in December 2019 to his fellow commissioners on steps the Authority is taking to increase its water storage capability. No one — including Maio — offered comments on the Feb. 4 agenda item.

This graph shows trends in population growth and water customer growth. ‘BEBR’ stands for the Bureau of Economic and Business Research of the University of Florida

A county staff memo provided to the board in advance of the meeting explained, “Based on current population growth projections and the current water supply sources, Sarasota County will meet its water supply demands through 2025 without adding new water supply sources.” However, the memo added, “Based on the 20-year water use projections, the County needs to start adding additional water supply sources gradually beginning in 2025 to meet the additional 5 MGD average day demand increase projected in 2041.”

That memo also noted that a water supply agreement Sarasota County has with Manatee County “is set to expire in 2025.” That contract calls for Manatee County to supply Sarasota County 5 million gallons of water per day. Thus, the memo continued, county Public Utilities Department staff members have been holding discussions with their Manatee counterparts “to develop an amended Water Supply Agreement to extend several years beyond the current expiration date.”

If staff cannot achieve a successful conclusion to those talks, the memo pointed out, Sarasota County would need extra capacity from its Carlton Wellfield.

This chart shows the annual population changes in Florida from 1970 to 2017. Image courtesy of BEBR

A 2007 report produced by Sarasota consulting firm Kimley-Horn and Associates — which focused on the management of the Dona Bay watershed — explains that the Carlton Wellfield is located in the central part of the county, east of the Myakka River. It then consisted of 14 production wells, “with depths varying from 400 feet to 715 feet.” As that time, the county had a permit to withdraw 7.303 mgd, on a daily average. The peak daily average, over a month, was permitted at 9.625 mgd, the report noted.

A 2017 Drinking Water Quality Report for Sarasota County said the Carlton Wellfield had expanded to 16 wells, and it was producing 10% of the county’s drinking water in the calendar year of 2017.

This chart is included in the 2018 Sarasota County Drinking Water Quality Report. Image courtesy Sarasota County

The 2018 report showed the amount of the drinking water supply had fallen to 9% for that calendar year.

That report is the most recent the News Leader found available on the county website.

The Feb. 4 staff memo noted that the Public Utilities Department “is in the process of rehabilitating the Carlton Water Treatment Plant to maintain its current capacity as part of the overall strategy to meet future demands.” In conjunction with that, the memo continued, the County Commission in late 2018 approved the department’s proposed budget for construction contracts associated with the replacement of the treatment equipment. Phase 1 of that process is under construction and should be completed in early 2021, the memo said. The design of Phase 2 has commenced, the memo added, and is anticipated to be finished in 12 months. “The construction of Phase 2 is expected to be completed in 2023,” the memo noted. Afterward, the memo said, the Carlton Water Treatment Plant will have a capacity of 15 mgd.

The Feb. 4 staff memo further noted that the University Wellfield gives the county an extra 2 mgd of capacity under its operating permit, but the water the county receives from Manatee County is needed “for blending purposes to meet water quality requirements.”

The Dona Bay Watershed report explained that the University Wellfield is located near Sarasota County’s northern boundary. It consists of seven production wells that vary in depth from 580 to 640 feet.

The Feb. 4 staff memo also pointed out that the updated water demand projections include what is called the GAP Water Supply of 4 mgd. However, the memo said, that supply is not intended for daily use, “but rather as an emergency supply, used by the region, on an as-needed basis. Further discussions will be required to amend the current agreement with Peace River and the Southwest Florida Water Management District for this particular supply.”