In this section
2012 Water quality status and trends report
2011 Water quality status and trends report
CLW (Lake Weir)
Location: latitude 29°01’01.563”, longitude 81°56’15.019”, GPS datum—WGS-1984 Station CLW is located at the center of Lake Weir.
Point sources: There are no wastewater treatment facilities within a five-mile radius or within the drainage basin of this water quality site.
Lake Weir is a beautiful lake covering approximately 5,685 acres, located in Marion County in central Florida. It is a very popular lake for fishing and boating of all types. The lake is overlooked by tall hills to the east and south that were once covered with citrus groves. More and more of the groves are being sold and private residences are being built that offer magnificent views of Lake Weir.
The lake’s shorelines are covered with private residences on three sides. There is a public boat ramp that has nice facilities and plenty of parking for vehicles and trailers and it is located on the southwestern side of the lake. There is a private beach club located on the south side of the lake as well. Boaters should be alert for amphibious aircraft (sea planes) that do take off and land on the lake, especially the north end.
The community of Oklawaha is located on the northern shore of Lake Weir and has local folklore concerning the criminal Ma Barker Gang who used to hang out in the area. Lake Weir is not far from the scenic waters of the Ocklawaha River to the northeast. The southwestern lobe of the lake is known as Little Lake Weir.
All of the maps and charts shown below were created using a customized GIS data summary tool, with the watershed generated by Arc Hydro for this monitoring station. More information about Arc Hydro can be found by going to the Technical background page. From that page, a description of the customized GIS data summary tool can be accessed.
Spatial data summaries
Population data is collected by the Census Bureau every 10 years and is used to show the distribution of population in a number of ways. Population density has a direct impact on land use, which effects water quality in areas around or near water bodies. This map displays the 2000 population density per square kilometer within this surface water catchment. The legend shows the area for each class in square kilometers and the percentage of area in descending order. More complete metadata can be found by clicking on the metadata link for the 2000 population density.
Land use, which is usually derived from aerial photography by photo interpreters, shows the distribution of land and how it is used. Land use affects the water quality of water bodies through water runoff within a surface water catchment. This map displays the distribution of eight categories of general land use within this surface water catchment. The legend shows the area for each category in square kilometers and the percentage of area in descending order. More complete metadata can be found by clicking on the metadata link for general land use 2000.
The geology of the state of Florida was delineated by the Florida Geological Survey. Water quality is impacted by the underlying geology of streams and lakes. This map displays the underlying geological formations within this surface water catchment. The legend shows the area for each type of formation in square kilometers and the percentage of area in descending order. More complete metadata can be found by clicking on the metadata link for geology.
Physiography describes the earth’s exterior physical features. These are divided into general groups and then subgroups containing features such as uplands, hills, ridges, plains, valleys, karst, etc. Water quality is affected through water runoff by physiography. This map displays the more detailed physiographic subdistricts within this surface water catchment. The legend shows the area for each subdistrict in square kilometers and the percentage of area in descending order. More complete metadata can be found by clicking on the metadata link for physiographic divisions.
Rainfall data comes from radar imaging as well as rainfall gauge surveys. Rainfall affects water quality through runoff within the surface water drainage basins. This map displays the total daily rainfall in inches for each pixel for 2004 within each surface water catchment. The legend shows the area for each rainfall range in square kilometers and the percentage of area in descending order. More complete metadata can be found by clicking on the metadata link for 2004 rainfall.
The St. Johns River Water Management District (SJRWMD) purchases lands that are in environmentally sensitive areas to protect the water resources on, beneath or adjoining the property. Water quality is affected in water bodies adjacent to these protected lands. This map displays the lands owned, jointly owned, being considered for purchase, or lands through which SJRWMD has an easement. The legend shows the area of these lands in acres and the percentage of area in descending order. More complete metadata can be found by clicking on the metadata link for SJRWMD and public lands.
Soils drainage characteristics can also impact surface water runoff, a source of nonpoint pollution for adjacent water bodies, which effects water quality. This map displays water bodies and soil drainage characteristics. The legend shows the area of these soils in square kilometers and the percentage of area in descending order. More complete metadata can be found by clicking on the metadata link for soils drainage.
Land elevation influences rainfall runoff, which effects the surface water quality, as water moves through the landscape to the rivers, streams, and lakes. This map with accompanying legend displays the maximum (MAX), minimum (MIN), range, standard deviation (STD) and mean of 5-foot elevations within the surface water drainage area (watershed). More complete metadata can be found by clicking on the metadata link for 5-foot elevation-DEM (Digital Elevation Model).
In some areas of SJRWMD, the Floridan aquifer is at or near land surface and is vulnerable to pollutants that threaten our drinking water supply. It is especially important to preserve surface water quality in these areas. This map displays recharge to the Floridan aquifer in inches per year (in/yr) within this surface water drainage catchment. Discharge, where the potentiometric surface is greater than the land surface elevation, is also shown. The area for each class is shown in square kilometers and the percentage of area in descending order. More complete metadata can be found by clicking on the metadata link for recharge 1995.
The map below contains selected features from the St. Johns River Water Management District (SJRWMD) Arc Hydro geodatabase. The introduction of the SJRWMD Arc Hydro geodatabase made the creation of these fact pages possible, by providing improved geographic information system (GIS) data that has been combined into a GIS network. This hydrologically based network does for water resources what the commonly used mapping websites (such as MapBlast, MapQuest and GoogleMaps) have done for travel planning, except that instead of interstates, highways and roads, this hydrologic network shows streams, rivers, lakes and wetlands. Similar to transportation mapping sites, information about water resources has been related, or linked, to the GIS network and can be easily accessed. The legend to the right of the map includes the Arc Hydro network, Arc Hydro Polygon Feature Classes and HydroPoints. The features included in the Arc Hydro Network exist to establish relationships based on surface water flow. The lines (HydroEdges) may represent streams or rivers, which are commonly displayed as lines on maps. The lines may also represent, in a “shorthand” way, the concept of surface water flow through a lake or a wetland, which are not routinely displayed as lines. The features in the Arc Hydro Polygon Feature Classes and HydroPoints represent some of the water resources information that has been linked to the Arc Hydro GIS network. HDS in the map legend below refers to the District’s Water Resource Information program and NWIS refers to the National Water Information System, which is part of the United States Geological Survey (USGS). See Technical Background for a more detailed explanation of the SJRWMD Arc Hydro technology and its features.
Clicking on the Methodology link will direct you to information about how water quality samples were collected, analyzed, and summarized for this fact page. View the most recent Water Quality Status and Trends Report.
Lake Weir, located in southern Marion County, is sampled every other month, at the lake’s center, as part of the ambient monitoring program. The lake is about 6.6 meters deep at the sample site and has a typical temperature range. When compared to other lakes, conductivity is low with correspondingly low major ion concentrations, resulting in soft water. The median dissolved oxygen concentration is typical for a lake in the District. The lake has poor buffering capacity and a neutral pH. Total organic carbon, color, total suspended solids, turbidity, total nitrogen, total phosphorus, and chlorophyll concentrations are lower than those typically found in lakes within the District. Secchi depth, chlorophyll, and total nitrogen concentrations indicate eutrophic conditions, under Forsberg–Ryding criteria, while the total phosphorus concentration indicates an oligotrophic condition. Coliform counts were typical. The lake has good water quality, according to the trophic state index.
|Analytes||Data Yrs||N Data||Min||Q1||Median||Q3||Max||Range|
|Water temperature (°C)||15||141||11.00||18.90||23.30||28.17||31.47||mid|
|Secchi disc transparency (meters)||15||141||0.30||1.25||1.40||1.60||3.70||high|
|Color (platinum-cobalt units)||15||141||5.00||10.00||10.00||15.00||50.00||low|
|Specific conductance (µhmhos/cm @ 25° C)||15||140||173.00||185.00||194.00||204.50||224.00||mid-lo|
|Sample collection depth (meters)||15||141||0.50||0.50||0.50||0.50||0.53||mid-hi|
|Dissolved oxygen analysis by probe (mg/L)||15||137||5.87||7.67||8.29||9.02||11.56||mid|
|pH (standard units)||15||140||6.10||7.28||7.49||7.74||8.59||mid-lo|
|Total alkalinity (mg/L as CaCO3)||15||139||10.50||12.18||13.17||15.00||114.00||low|
|Total nonfiltrable residue (mg/L)||15||139||0.50||4.00||5.00||6.00||17.00||mid-lo|
|Total nitrogen (mg/L as N)||15||135||0.55||0.77||0.83||0.90||1.21||low|
|Total phosphorus (mg/L as P)||15||139||0.00||0.01||0.01||0.02||0.03||low|
|Total organic carbon (mg/L as C)||15||138||2.00||6.90||7.40||8.10||43.00||low|
|Total calcium (mg/L as Ca)||15||138||3.90||4.40||4.69||5.00||6.43||low|
|Total magnesium (mg/L as Mg)||15||138||3.60||4.50||4.80||5.00||5.56||mid-lo|
|Total sodium (mg/L as Na)||15||138||17.90||20.60||22.05||23.30||26.25||mid|
|Total potassium (mg/L as K)||15||138||2.00||2.90||3.08||3.20||4.13||mid-lo|
|Total chloride (mg/L)||15||141||30.00||36.00||39.00||41.00||47.00||mid|
|Total sulfate (mg/L as SO4)||15||140||7.66||10.60||11.70||12.31||14.00||mid-lo|
|fecal coliform (MF M-FC broth 44.5° C)||10||79||1.00||1.00||6.00||80.00||750.00||mid-hi|
|Trichromatic uncorrected chlorophyll-a (µg/L)||15||67||0.01||8.94||10.90||13.42||44.90||mid-lo|
|Hardness (mg/L Ca+Mg)||15||138||27.00||30.00||31.33||33.00||798.00||low|
|Total filtrable residue (mg/L dried at 180° C)||15||127||42.00||101.00||108.00||116.00||203.00||low|
|Lab turbidity (NTU)||15||141||1.00||2.00||2.40||2.90||7.10||low|
|Sample site depth (meters)||15||140||1.00||6.20||6.60||7.00||7.70||high|