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Section 7 Environmental Effects of the Selected Plan

EAA Storage Reservoirs Revised Draft PIR and EIS February 2006

7-3

7.3 FLOOD PROTECTION LEVEL OF SERVICE

7.3.1 Flood Protection Level of Service

The original drainage design for the EAA was nominally based on a rainfall

event with a return frequency of 10 years. The capacity of the primary pump

stations serving the Miami, North New River, Hillsborough and West Palm

Beach Canals is 20,645 cfs. The service area has decreased from approximately

591,755 acres to about 499,800 acres as a result of removing the Rotenberger

and Holey Land WMAs, as well as construction of STAs. Pump stations G-370

and G-372, replacing the roles of S-7 and S-8 in draining the EAA, also act to

increase the total drainage pump capacity.

Flood protection in the EAA would be improved by ensuring the major canals are

adequate to take advantage of the increased drainage rate resulting from

improvements in the EAA. Increasing the capacity of the Bolles and Cross

Canals will improve flood protection during localized rain events by allowing

more efficient movement of water between the Miami, North New River,

Hillsboro, and West Palm Beach Canal basins. The rate of inflow into the STAs

will continue to be limited by the capacity of the inflow pump stations and

internal control structures.

As an additional benefit, canal improvements will increase the storage capacity

within the canals themselves. Increasing the width of the Miami, North New

River, Bolles, and Cross Canals’ conveyance will create additional storage. This

will help attenuate flows at the beginning of storm events.

The proposed storage reservoir, canal improvements, and STA would add to the

storage capacity for area flood waters. The system also would introduce

additional flexibility in developing plans for extreme events such as a hurricane.

Thus, there is a beneficial impact of the proposed action upon flood protection

level of service.

7.4 CLIMATE

The proposed action is not expected to significantly impact the general climate of

the EAA. There may be some minor impacts on local microclimates as a result of

the presence of a large body of water or the dikes containing the reservoir. This

will take the form of altered wind directions, slightly moderated temperatures,

and an increased likelihood of fog formation. The proposed action may

significantly lessen the impact of stormwater from hurricanes and other storms.

The reservoir may be used to help control floodwaters and related environmental

damage. Replacement of crops with open water will act to increase

evapotranspiration, which may have a minor, very local effect.

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Wenger 72944 Spezifikationen Seite 269