TO: Mayor and Commission AGENDA DATE: 8/24/2026
FROM: City Manager AGENDA ITEM: 5 - E
SUBJECT:
Title
Presentation - Theresa Basin Flood Control Study by Ardurra Group, Inc.
Body
LOCATION:
Citywide
COST:
N/A
SOURCE OF FUNDS:
N/A
ORIGINATING DEPARTMENT:
Public Works
POTENTIAL MOTION:
Recommendation
N/A
END
BACKGROUND:
Background
In September 2023, the City of Deltona entered into an agreement with Ardurra Group, Inc. to evaluate the Theresa Basin due to the impacts of Hurricanes Ian & Nicole. Hurricane Ian in September 2022, released historic rainfall in a 24-period period. Reports from surrounding cities and counties recorded between 15-20 inches of rainfall, which translated to a 500-year to 1,000-year storm event. Most City retention ponds and stormwater management facilities are designed for the 25-year storm (8.5 inches in 24-hour) for open basin with positive outfall and 100-year (11.5 inches n 24-hour) for closed basin (land-locked).
The Theresa Basin is the largest of the four (4) major watersheds in the City. The basin drainage is connected through a cascading system controlled by culverts and ditches connected in series with lakes and water bodies. The total basin area is about 35.9 square-miles (22,969 acres) of which 30.6 square-miles is land area (85.2%) and 5.3 square-miles (14.8%) are lakes and water bodies. The headwater of the basin starts in City of Lake Helen on the west side of Interstate I-4 near Old Camp Road. The basin flows from northwest to southeast direction and enters City of Deltona near Sand Lakes north of Howland Blvd and east of Interstate I-4. From there, the basin flows southeast direction through a series of interconnected lakes starting at Three Island Lakes to Dupont Lake to Angela Lake and eventually to Theresa Lake south of Newmark Drive. From Theresa Lake, the flow is directed south through the Butler Chain of Lakes and eventually into Lake Doyle, which is the southern boundary o...
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