MANASOTA & PEACE RIVER BBDs Meeting Notebook 10-21-09.docx

H088
Dona Bay Water Supply Development and Management Project
Project Type WS&R Dev.
AOR(s)
Water Supply, Flood Protection, Water Quality, Natural Systems
Basin(s) General Fund (District), Peace River, Manasota
Cooperator(s)
Sarasota County
Project Manager MORRIS, LISANN
Task Manager(s)
HEYL, MIKE
Status Ongoing
Description
This cooperative funding application proposes a multi-phase implementation plan for the Dona Bay Watershed
Management Plan (DBWMP), previously cooperatively funded by the basin under L493. The project proposes to divert,
store and transport excess freshwater flows from Cow Pen Slough prior to discharging them into the Dona Bay Estuary
providing an alternative water supply in the SWUCA as well as environmental benefits to the bay. The water would be
ultimately transported to the County's Carlton Facility for treatment and distribution. The potential capacity is estimated
in 3, 5, 10, and 15 mgd phases. The DBWMP was finalized in June 2007, and as design has progressed, the
implementation plan has evolved. The project covers initial elements including design, permitting and construction for
a new weir structure in the Cow Pen Slough canal near the historic ridge line, the phased adaptation of the Venice
Minerals site to a reservoir (first 3 mgd), a conveyance system from the proposed weir to join the future Venice
Minerals site, the West Pinelands wetlands restoration, and a pilot treatment study to determine the most efficent and
effective way to treat surface and groundwater in that area. Because of uncertainties such as water supply demands,
the Albritton reservoir that is part of future phases is not included in the project at this time. Certain initial project
components will be sized to accommodate the increased capacities once Albritton is brought online. The County,
District and Authority staff are working through several funding issues such as Authority involvement in the project,
and the most suitable water treatment system for the project through the Dona Bay Work Group. Currently the MOU
between the County and Authority agreeing to work together to develop a Dona Bay Project agreement is scheduled to
go before County and Authority Boards for approval in July 2009.
Benefits
The objective is to decrease excess freshwater flows to Dona Bay. The elements listed in the FY2010 application, the
new weir, West Pinelands mitigation area, conveyance to the future Venice Minerals reservoir and initial adaptation of
the Venice Minerals site could increase the watershed hydro period and storage capacity. The County has been
working with District staff and has provided an estimate of approximately 5 tons/yr of nitrogen removed from the bay if
Venice Minerals is used as a retention pond and an additional 9 tons/yr of nitrogen removal if surface water is utilized
for water supply. If the pilot test proposed in phase 1 of the project determines intermediate groundwater is the most
effective source for the intial 3-5 mgd, the environmental benefits to the Bay from this withdrawal will not be realized .
Costs
The request for FY2010 funding of $1,800,000 would be split between the Governing Board for $900,000, the Peace
River Basin Board for $243,000 and the Manasota Board $657,000. The County has already begun design\permitting
for West Pinelands restoration, the new weir in Cow Pen Slough, phased modifications of the Venice Minerals mine to
a reservoir, and the conveyance from the new weir to Venice Minerals. These FY2010 funds would be used to finish
design\permit tasks not started in FY2009 and\or begin initial work such as area excavation for the modification of
Venice Minerals. Another option discussed at the Dona Bay Work Group was to proceed with the pilot treatment test
as a partnership between the Authority and the County. The total project cost is estimated at approximately $53
million at this time. The District share is requested to be 50 percent, or approximately $26.5 million. As previously
mentioned, the County and Authority continue to discuss options for sharing the water from this project regionally. If an
agreement can be reached that meets the intent of District Policy 130-4, then Governing Board funding may be
available for the project.
Additional Information
The current Dona Bay watershed has been significantly impacted by man-made drainage activities, which increased
the efficiency and volume of freshwater being discharged to its tidal estuary. In addition, historical maps indicate that a
significant portion of the current watershed may have been diverted to Dona Bay by the man-made Cow Pen Slough
canal. Towards this outcome, Sarasota County has acquired lands that are strategically located in the watershed and
initiated monitoring of freshwater flows to, and natural system and water quality indicators in, the tidal portions of Dona
Bay. The Dona Bay Watershed Management Plan (DBWMP) (L493) was cooperatively funded during FY2006 and
FY2007 as a comprehensive watershed plan for the Dona Bay watershed.
021 - Manasota Basin 238