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Title:	Endangered Species Act Supplemental Biological Assessment, Everglades Restoration Transition Plan : Appendix C, G-3273 Constraint Relaxation/S-356 Field Test and S-357N Operational Strategy Environmental Assessment
Authors:	United States. Army. Corps of Engineers. Jacksonville District.
Keywords:	Environmental protection Endangered species Everglades (Fla.) Hydrology
Publisher:	United States. Army. Corps of Engineers. Jacksonville District.
Abstract:	The overarching project need is to increase the availability of S-333 to increase water deliveries from WCA 3A to ENP through NESRS for the benefit of natural resources. A small incremental step toward achieving that goal is to reduce the number of times S-333 discharges are limited by the existing G-3273 stage constraint of 6.8 feet NGVD. G-3273 lies within eastern ENP, directly west of the 8.5 SMA. The G-3273 constraint of 6.8 feet, NGVD exists as a flood protection measure. A stage of 6.8 feet NGVD at this gage has been used since 1985 as a trigger to cease S-333 discharges from flowing south into NESRS as a protective measure for residential areas to the east, particularly the 8.5 SMA. Since many of the MWD features have been built, including the protective levee around the 8.5 SMA and much of the C-111 South Dade Project detention areas to the south, there are more opportunities to begin relaxation of the G-3273 constraint and subsequent increased water deliveries from WCA 3A into NESRS. The releases from S-333 are part of a regulation schedule for WCA 3A and are typically dependent on the Interim Operational Procedure for Restricted Rain-Driven Water Deliveries to ENP via NESRS (Rainfall Plan) outlined in the WCAs-ENP-SDCS Water Control Plan (USACE 2012c). This Rainfall Plan consists of a rainfall-based delivery formula that specifies the amount of water to be delivered to ENP in weekly volumes through the S-333 and S-12s. Currently, the flow distribution is 55% through S-333 into NESRS and 45% through the S-12s into ENP west of the L-67 extension levee; however, during the dry season non-regulatory target flows are 80% through S-333 and 20% through the S-12 structures. Releases through the S-333 are limited by the constraint at G-3273 under the current WCAs-ENP-SDCS Water Control Plan (USACE 2012c). Therefore, when G-3273 is below 6.8 feet NGVD, 55% of wet season and 80% of dry season Rainfall Plan target flow is released into NESRS. However, when G-3273 is above 6.8 feet NGVD, S-334 is used to pass all or partial S-333 flows through SDCS, thereby preventing water from entering NESRS. When S-333 is closed and partial flows cannot be passed through S-334, the volume of flow that could not be delivered at S-333 shifts to the S-12s. In this manner, the G-3273 constraint limits the volume of water entering NESRS. The proposed modification to the G-3273 constraint is anticipated to reduce the number of times that S-333 discharge is reduced and increase the number of times the maximum (i.e. 55% of wet season or 80% of dry season) Rainfall Plan deliveries from WCA 3 through S-333 into NESRS are achieved. The current WCAs-ENP-SDCS Water Control Plan (USACE 2012c) does not contain water management operating criteria for the planned spillway (S-357N) located in the 8.5 SMA upstream of S-357, at the intersection of C-357 and the newly constructed seepage collection canal (C-358). The 2012 Design Refinement for the 8.5 SMA EA did not address water management operating criteria for S-357N or C-358 and stated that all gates would be in the closed position until a new operational protocol is developed for the MWD Project (USACE 2012a). Interim water management operating criteria for the planned 8.5 SMA gated culvert S35N will be implemented in conjunction with Increment 1. Information obtained from Increment 1, if successful with achievement of field test goals and objectives will be codified within the current WCAs-ENP-SDCS Water Control Plan (USACE 2012c). In addition, information obtained through Increment 1 will be used to support development of a second field test (Increment 2) and subsequent consideration of future incremental modifications to the current WCAs-ENP-SDCS Water Control Plan (USACE 2012c).
URI:	http://hdl.handle.net/11681/26405
Appears in Collections:	Environmental Documents