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Background and Purpose
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The Stevenson Creek basin encompasses
approximately 6,000 acres in central Pinellas County, approximately
4765 acres of which lie within the limits of the
City of Clearwater. The remainder of the basin, which consists
of the upper reaches of the Spring Branch Subbasin, falls primarily
within the limits of the City of Dunedin.
The primary objective of the
project is to develop a watershed management plan for the Stevenson
Creek basin, in accordance with a cooperative agreement between
the Southwest Florida
Water Management District and the City
of Clearwater. It will be used as a tool in the planning,
regulation, and management of Stevenson Creek for future development,
and as a basis for determining and prioritizing capital improvements.
This objective will be met in part, by conducting an analysis
of the watershed in order to characterize the existing watershed
conditions and recommend improvements for flood protection,
natural systems, habitat, water quality, erosion control, public
awareness and involvement, regulatory control, and capital improvements.
The second objective is to coordinate the development of the
management plan for the freshwater portion of the basin with
limited evaluation of the estuarine saltwater portion of the
basin, to be performed in conjunction with the U.S. Army Corps of
Engineers as the lead agency, as may be required.
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| Springtime Avenue between Brook
Avenue and Stevenson Avenue |
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INFORMATION COLLECTION AND
MANAGEMENT Literature Search
The project will perform a literature search to
review and assimilate available information pertinent to the study area under
four major categories; flood protection, water and sediment quality, natural
resources and drainage problems
Evaluate and Define
Deficiencies of Existing Data
Existing available data shall be
evaluated by the consultant to identify any missing data that are
necessary to the study. Additionally, conflicting data will be
identified. Missing or conflicting data will be evaluated to determine
the appropriate method of obtaining the needed data or resolving
conflicts.
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| City Official Sampling Water for its Quality |
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Gage Installation in Spring
Branch at King’s Highway
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FIELD WORK AND
DATA ANALYSIS
Field Work
Field investigations will be conducted to identify the drainage ways
and tributaries and of existing drainage and stormwater management
systems
Biological Resources
Parsons ES biologists are conducting an
evaluation of the Stevenson Creek watershed in order to determine the
existing conditions of the natural resources. Any undeveloped property
and property already in public ownership will be assessed for potential
use as wildlife habitat, stormwater retention and treatment or
preferably, a combination of these uses. The assessment will determine
the presence of essential habitat that needs preservation for endangered
or threatened species, wetlands that are in need of hydrological or
vegetative restoration, or highly disturbed areas that may be optimal
for wetland creation. This provides the City of Clearwater with a
"big picture" approach to watershed management, allowing the
City’s resources to be put to use in the best manner possible.
Cooperative funding mechanisms will be evaluated for potential capital
improvement projects such as regional stormwater facilities, mitigation
banks, bridge improvements and similar projects.
Two (2)
automatic streamflow and water quality sampling stations will
be installed within the study area near the mouths of
Stevenson Creek and Spring Branch. Each installation consist
of an ISCO automatic sampler, water level recorder, and a
recording precipitation gage. The stage, rainfall, and flow
monitoring data will serve as the basis for calibration and
verification of the hydrologic and hydraulic models of the
watershed. A streamflow rating curve will be developed for
each of the sites by obtaining a minimum of ten (10) separate
flow measurements using a flow velocity meter. Additional
rainfall data will be provided by the CITY from its other
stations located near or within the study area.
The two
sampling stations are installed at the freshwater flow
monitoring locations near the mouths of Stevenson Creek and
Spring Branch. Flow-weighted composite samples will be
collected for up to ten (10) separate storm events and six (6)
ambient (baseflow) events during the period of study at each
of the sampling stations and analyzed for the following water
quality constituents
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Total Suspended Solids
Total Dissolved Solids
Biochemical Oxygen Demand
Chemical Oxygen Demand
Total Organic Carbon
Nitrogen (NH3, TKN, NO2/NO3)
Phosphorus (Total P, Ortho-P)
Oil and Grease
Total Petroleum Hydrocarbons
Total Hardness
Metals (Aluminum, Arsenic,
Cadmium,
Chromium, Zinc, Nickel,
Copper, and Lead)
Fecal coliforms/ABA |
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WATER QUALITY & NATURAL SYSTEMS
CONDITIONS
Parsons ES
will inventory existing land uses for use in developing data
for the storm water model. Parsons ES will summarize
existing land use plans and policies developed by
Clearwater, Dunedin, Pinellas County, and regional planning
agencies to gauge future development potential.
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SWFWMD
1995 Land Use/Cover |
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POLLUTANT LOADING ANALYSIS
Pollutant Loading Model
- Identify chemicals of concern
- Develop pollutant loading model
- Calculate gross pollutant loads generated at
each sub-basin.
- Estimate existing water quality treatment
capabilities
- Calculate net pollutant loads discharged from
each sub-basin.
- Determine Water Quality Levels of Service
- Assess system deficiencies
Existing Conditions Water Quality
Level of Service
WATERSHED MODELING (COMPUTER
MODELING)
The model will be used to analyze the processes
associated with flood control. The system will include the development of the
runoff hydrographs and the routing of the hydrographs through the creek and the
stormwater conveyance structures. The applicable Levels of Service for flood
control will be established by the TEAM.
IDENTIFICATION OF
PROBLEMS AND POTENTIAL SOLUTIONS
Evaluate Existing Conditions
The methods to be used for this
task will include field studies, data analysis, and computer
model simulations. The data analysis will include the approved
Level of Service criteria to identify those areas where the
existing system does not provide an acceptable Level of Service.
Develop and Evaluate Potential
Solutions
After compiling and evaluating the existing
conditions the development of potential solutions to address the identified
flooding, sediment, and water quality problem conditions in the watershed. The
identification of these potential solutions will take into account existing
watershed development conditions.
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| Salvage
yard - Potential Pollution Source |
- Floodplain, water quality
and water quantity regulations and programs
- Maintenance practices and
programs
- Non-point source pollutant
load source reduction measures
- Base flow management and
restoration
- Wetland restoration,
enhancement, and creation
- Conservation and restoration
of natural waterways
- Vegetated buffers along
stream corridors and riparian areas
- Lined and unlined channels
- Selected or limited
structure improvements
- Regional detention and
retention facilities
- Non-structural improvements
and methods, including source reduction programs
- Multi-use facilities
- Proposed revisions to
designated land use or zoning
- Minimization of mitigation
to that absolutely necessary to construction
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EVALUATION AND
PRIORITIZATION OF POTENTIAL SOLUTIONS
The potential solutions and
projects will be evaluated and prioritized based on the City’s
Level of Service evaluation criteria. The potential solutions
shall include assessment of: |
| Lake on tributary 18-02-05, east of King’s Highway, looking at control weir inside skimmer structure.
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- Drainage problems (erosion,
sedimentation)
- Flooding (frequency: 10-,
25-, 100-yr, and severity: streets, yards, homes)
- Water quality (measurable
and cost-effective improvements)
- Public safety and welfare
- Construction costs
- Relative benefits
- Requirements for
right-of-way
- Operation and maintenance
- Permitability
- Public acceptance
- Economic support
- Land use
- Regulatory Enhancement
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