Background

In 1998, the Northwest Florida Water Management District (NWFWMD), St. Johns River Water Management District (SJRWMD), South Florida Water Management District (SFWMD), Southwest Florida Water Management District (SWFWMD), and Suwannee River Water Management District (SRWMD) were tasked with preparing a detailed regional water-supply plan for areas or counties within their jurisdictions to determine whether existing sources of water were adequate for current and future water needs and supplies (Florida Department of Environmental Protection, 2013). Water needs and supplies were categorized as public supply, domestic self-supplied/small public supply, commercial/industrial/mining/institutional self-supplied, power generation, agricultural irrigation, and recreational irrigation (including golf courses). The primary objective of these water-supply plans was to project future water demands by water-use category and develop alternative water supplies to help meet the projected demands.

In 2012, the Florida Legislature mandated that the FDACS, Office of Agricultural Water Policy (OAWP), promote an agricultural water-conservation program that would include a cost-share program and best management practices and that would aid the WMDs in the development of consistent agricultural water-supply planning (Florida Senate, 2012). This OAWP program included assisting the WMDs in projecting future agricultural water needs by promoting consistency among the WMDs through development of improved and validated estimates of acreage of irrigated agricultural land and irrigation application rates. Under the direction of the OAWP, The Balmoral Group (https://www.balmoralgroup.us/) created a methodology and developed data sources which were used to produce a crop-specific and spatially distributed irrigation water-demand model to determine current and future water needs (The Balmoral Group, 2015).

Beginning in 2013, the FDACS created a series of agriculture and irrigated land-use maps for all Florida counties for the purpose of estimating current and forecasting future water demands. These maps, produced and updated periodically by The Balmoral Group, started with baseline data from 2010 (The Balmoral Group, 2015). The Balmoral Group used a combination of satellite images and current WMD land-use layers to create a statewide agriculture and irrigated land-use database, which includes the locations of irrigated fields and acreage totals by crop type.

Purpose and Scope

The purpose of this multiyear cooperative study between the U.S. Geological Survey (USGS) and the FDACS, OAWP, is to provide detailed geospatial data (ArcGIS shapefiles) and associated summary tables of irrigated agricultural field location and size, crop type, and irrigation information for agricultural fields for 55 selected counties. Data were field verified at various times for each county within Florida between October 2013 and August 2021. The maps and summary tables produced by this study can be used to validate the acreage totals reported in the Florida Statewide Agricultural Irrigation Demand (FSAID) Irrigated Lands Geodatabase (ILG) (https://www.fdacs.gov/Agriculture-Industry/Water/Agricultural-Water-Supply-Planning) produced by The Balmoral Group (The Balmoral Group, 2021). Fields identified as irrigated on the FSAID maps were verified by the USGS through either a field visit (or multiple visits) or through a review of the information provided within the WMD’s consumptive water-use permit (CUP). Such verification provides the FDACS an improved level of accuracy for estimating irrigated crop acreage and subsequent calculations of water demands. From the results of the USGS-verified maps, adjustments to the ILG will be made by The Balmoral Group for each county to assist the FDACS with updates to the next set of water-demand projections. This study focuses on verifying irrigated acreage by crop type and field location and does not quantify water-application rates or provide estimates of water use.

This report describes the methods and data sources used by the USGS to map, verify, and tabulate irrigated agricultural land acreage in selected counties within Florida between October 2013 and August 2021 (table 1; fig. 2). Osceola County (Marella and Dixon, 2014) was the first county to be verified and mapped through this cooperative study which detailed the crops irrigated within the county between October 2013 and April 2014. This was followed by field mapping and verification for 54 other counties (Marella and Dixon, 2015; Marella, Dixon, and Berry, 2016, 2017; Marella, Berry, and Dixon, 2017a, 2017b; Marella, Dixon, and Reich, 2018a, 2018b, 2018c, 2018d, 2018e, 2018f, 2019a, 2019b, 2019c, 2019d, 2019e, 2019f, 2019g; Marella, Dixon, and Christesson, 2020a, 2020b, 2021, 2022; Dixon and Christesson, 2022; Marella, Dixon, Christesson, and Pazmiño-Hernandez, 2022). In addition, all of Brevard, Clay, Duval, Flagler, Indian River, Nassau, Putnam, St. Johns, Seminole, and Volusia Counties and parts of Alachua, Baker, Lake, Marion, Okeechobee, Orange, and Osceola Counties were mapped and verified by the SJRWMD in 2015 ([2015 Agricultural Crop and Irrigation Survey], SJRWMD, unpublished data, 2016). At the time of publication, data were available by request from SJRWMD. Agricultural irrigation land use in all or parts of 65 of the 67 counties in Florida have been mapped and verified by either USGS or SJRWMD between 2013 and 2021 (fig. 2; table 1) with several of the counties being mapped and verified twice during this period. Only Monroe and Pinellas Counties were not verified during this 8-year period.

The shapefiles and tabulated summaries of acreage presented in publications and data releases for counties listed in table 1 provide estimates of irrigated acreage by irrigation system and crop type for the year(s) they were inventoried. In addition to being used to validate irrigated acreage for the FDACS, the data compiled in this project will contribute to the USGS National Water-Use Science Project (https://www.usgs.gov/mission-areas/water-resources/science/national-water-use-science-project) for a better understanding of the accuracy of irrigated acreage published by other sources and to provide a better knowledge of the geographic distribution of irrigated acreage across counties or hydrologic basins.

Project Assumptions and Limitations

For the purpose of this study, it was assumed that if an irrigation system was visually observed on a field, the system would be in use at some point during that growing season. This assumption was necessary because only a small number of irrigation systems were observed in operation during field visits; therefore, the irrigation acreage totals tabulated may include some acreage not actually irrigated because not all irrigation systems observed may have been used during the year visited. In addition, some growers use portable irrigation systems (portable or traveling gun) or move irrigation systems (center pivots or linear move system) from one field to another. In those cases, unless the irrigation structures were visibly in use or were still connected to a pump at the time of the visit, the acres were not counted as irrigated; however, when a field was obviously irrigated (greener or taller than surrounding fields), but no irrigation system was observed, evidence of an irrigation system, such as wheel tracks through the field, was used along with the WMD CUP to count that acreage as irrigated. For Miami-Dade County, where portable high-volume irrigation guns are mounted on truck beds (fig. 3) and moved daily from field to field through the growing season, all acreage identified as a row crop was counted as irrigated.

During field-verification trips, specific attributes were noted for each irrigated field on a working base map: crop type (general and specific), irrigation system type, and water source. Water sources are groundwater, surface water, and (or) wastewater effluent (municipal or agricultural). Groundwater was assigned as the default water source for fields where a water source could not be verified through a visual observation or by the WMD CUP records. In some cases, both groundwater and surface water were used for irrigation, and these sources were identified through the WMD CUPs and labeled in the attribute table. These assumptions and other limitations were documented in the attribute tables.

Attribute data collected for each irrigated field included crop type, irrigation system type, and primary water source if the source could be confirmed in the field by observation from an adjacent road. The field verification in some counties included visits to fields during two growing seasons: spring/summer and fall/winter. If a field had a crop present during each of these two growing seasons it was considered “double cropping,” and the actual field acreage was recorded twice. Double cropping was most observed for row crops. In some cases, the second crop was a cover crop. Cover crops are typically not irrigated and therefore were not counted in the irrigated totals for these fields. All other crops that are not seasonally grown, such as citrus, blueberries, grapes, peaches, ornamentals (container nurseries and tree farms), sod, and sugarcane, were field verified throughout the calendar year.

Crop Types and Agricultural Categories

Crops and fields were assigned to one of six primary types or agricultural categories: row crops and vegetables, fruit crops (including orchards and berries), field crops (including grass, hay, and pasture), nursery and sod, all other irrigated land, and nonirrigated land. The specific crops within these six categories are detailed below and are also found in the most recent USDA Census of Agriculture (USDA, 2019) and the SJRWMD Crop Identification Field Guide (SJRWMD, 2015a):

Irrigation Systems

Irrigation systems were assigned to one of three primary categories: micro-, sprinkler, and flood-seepage irrigation. The specific irrigation systems under these three categories are detailed below and are also defined by Izuno and Haman (1987), Smajstrla and others (1991), and the SJRWMD Irrigation System Identification Field Guide (SJRWMD, 2015b):

Preliminary Map Development and Data Compilation

The first step in the process was to create a preliminary base map for each county from data layers obtained from the ILG as part of the most recent FSAID layer at the time field work was being planned. These ILG maps provided a spatial representation of the location of irrigated land (by field) and an estimate of the crop type on each field by county. These ILG maps were created by The Balmoral Group from multiple land-use coverages and images which provided the most recently available irrigation land-use layers beginning with FSAID II in 2013–14 (The Balmoral Group, 2015) to the most recent FSAID VIII for 2019–20 (The Balmoral Group, 2021).

In addition to the FSAID ILG layer, several additional data sources and layers were added to create the working base map. These included point and polygon shapefiles of the most current agricultural irrigation CUPs from the WMDs, including the SFWMD’s Geospatial Open Data Portal (SFWMD, 2020), the SJRWMD’s Geospatial Open Data (SJRWMD, 2020), the SWFWMD’s Geospatial Open Data Portal (SWFWMD, 2020), and the NWFWMD and SRWMD permit property-boundaries. The locations of CUPs (for wells and surface-water intakes) and the permit property boundaries associated with each withdrawal point helped identify fields that may have been missed on the original FSAID map. Another data layer added to the working base map was obtained from the FDACS Division of Plant Industry, Citrus Health Response Program (CHRP). This data layer identified abandoned citrus groves in each county where trees were either already removed or were awaiting removal. Since 2011, CHRP has maintained a statewide database of abandoned citrus groves that have been confirmed by local FDACS staff in each county (FDACS, 2020). Abandoned groves documented with this layer were labeled and removed from the working base map; however, many of these abandoned groves were still checked during the field verification in case citrus was replanted or another irrigated crop was present. Once all data sources were compiled, the working base map was ready for use in the field-verification process.

Field Verification

Field verification was conducted by using the working base map between 2013 and 2021 during various times of the year depending on the agricultural practices that typically occur in each county. In southern and central Florida, crops can be grown during winter months, and in many areas, multiple crops can be grown on the same field due to the warmer climate. In the counties within the SFWMD and the SWFWMD, field verification was primarily conducted between December and September. In northern Florida, the cooler winter temperatures shorten the primary growing season; therefore, in the counties within the SRWMD and the NWFWMD, field verification was conducted between April and December. In northern Florida, many fields still had two crops growing during the year.

Attempts were made to physically observe each field shown on the working base map as irrigated and each field with a CUP. Observations were made from a public road at least once during the field verification. In many counties, fields with row crops were visited two or three times during the calendar year because of the possibility of having multiple crops planted. Private property was only entered during field verification after receiving permission from the landowner, which was only done a few times throughout the entire multiyear project. During the initial visit to each field shown on the working base map, the field was identified as either active or inactive agriculture (fig. 7).

Active agriculture usually had the presence of a planted crop, evidence of a recent harvest, or signs of a future planting. If the field was actively in agriculture, it was then determined if it was irrigated, usually by the presence of an irrigation structure or system on the field, the presence of an irrigation pump, or record of a CUP shown on the working base map, which often confirmed that the field had the capability of being irrigated. The fields that could not be clearly identified as irrigated were labeled as “could not verify” (CNV). If the field could not be accessed or seen clearly from a public road, it was labeled as “could not access” (CNA). Once a field was determined to be active, several items were labeled on the base map for that field, including crop type (general or specific), irrigation system, and water source, if those could be determined from the road. In addition, the shape of field was compared to the one presented on the working base map, and notes about differences were made. The attribute table and shape of the polygons were adjusted when staff were back in the office.

Inactive agriculture usually included fields with no evidence of agricultural activity, such as fields that were unmaintained or overgrown with weeds, even though an irrigation system may have been present. In some cases, signs indicating that the property was for sale or was pending rezoning were present. Even though the field appeared to be inactive agriculture, the shape of the field was compared with the one on the working base map in case part of it was still active. The CUPs for most of these inactive fields were checked to see if the CUP was still active when staff returned to the office. If the CUP was still active, the field was labeled as fallow; if the CUP had expired or no evidence of permit activity was found (for example no new correspondence was seen in the permit file), the field was labeled as abandoned (fig. 7).

For citrus, most groves could be observed from public roads; however, it was not always clear if the grove was active or inactive at the time of the visit. Many of the reported pushed (the citrus trees have been removed from the ground) or vacant groves from the CHRP database had evidence of replanting or still had drip lines visible on the barren ground (usually an indication that the field was in the process of being replanted), and these groves were labeled as active citrus (fig. 8). In addition, if a mature grove looked like it was possibly inactive, but new trees had been planted within the grove, the grove was also labeled as active citrus. As a general rule, three factors were used to determine if a grove was active or inactive: (1) poor or no maintenance within the grove, including bark peeling off the tree trunks, no fruit on the trees, or no evidence of the grove being mowed, (2) livestock present within the grove, and (or) (3) the presence of a “for sale” or a “re-zoning” sign along the frontage of the grove (fig. 9). If a grove could not be determined as active or inactive during the site visit, the grove was labeled as CNV.

Crop, Irrigation System, and Water Source Delineation

Crops were generalized and assigned to one of the following major categories: row crops and vegetables, fruit crops (including orchards and berries), field crops (including grass, hay, and pasture), nursery and sod, all other irrigated land, or nonirrigated land. In many cases the crop type was obvious (citrus and other fruit orchards, corn, nursery, sod, and sugarcane), but in some cases the crop could not be specifically identified at the time of the field visit. This was especially true for many row or field crops that were recently planted or harvested; these crops could not be seen clearly from the road because not enough of the vegetation was visible. Also, if the view of the field was obstructed by vegetation along the field edges or by ditches along the road, the specific crop type could not be clearly determined. In these cases, the fields were identified and labeled as a row or field crop, with no specific crop assigned; however, if a specific crop could be positively identified by using the SJRWMD field guide (SJRWMD, 2015a) or by other means, it would be labeled as such under the general listing of a vegetable. In several cases, a vegetable field may have been harvested by the time it was visited; however, evidence of field plastics, drip lines, portable hoses, or unpicked crops that were still present in or along the field edges helped determine that the field was actively irrigated during the current growing season, and in some cases, the specific crop could be identified.

The irrigation status of fields of grasses, including hay, pasture, and forage, was often the most difficult to determine. Hay, which includes grass grown for the purpose of cutting and bailing, would typically have a center pivot, linear move, or traveling gun present in the field or along the field’s edge if the field was irrigated. Pasture, which is defined as grass that is routinely maintained (mowed and relatively weed free), often had livestock on the fields, with no evidence of bailed or stored hay nearby. Usually, no evidence of an irrigation system was visible (especially if it was seepage irrigation), and in these cases, the WMD CUPs were used to confirm if irrigation occurred during the year of the field visit. In most cases, the permit holder had to submit records of water withdrawn on these fields, and in some cases, the fields had greener grass than that of neighboring fields, indicating possible irrigation. Forage grass was most often unmaintained (usually not mowed, often with weeds, or with multiple bare areas) or was recently planted as a cover crop after a field or vegetable crop was harvested. Many forage grass fields had livestock present or were used to receive dairy wastewater effluent through a center pivot, traveling, or permanent gun. In these cases, the fields were often located on a dairy farm, usually near a wastewater pond. If a grass field could not be accessed or if a crop could not be properly identified, the field was labeled as either CNA or CNV.

Once a field was determined as active and a crop was identified, an irrigation category was assigned for that field. The three categories are micro-, sprinkler, and flood-seepage irrigation; however, in most cases, a specific irrigation system was also assigned to the field in the attribute table. In addition, a small percentage of fields in several counties may have used a portable irrigation system such as a traveling gun (fig. 6B) or may have moved center pivots from one field to another. In these cases, when evidence of irrigation was seen (center pivot tire tracks or portable piping piled on the edge of a field), but no irrigation system was visible, the CUP associated with that field was checked. If pumpage was reported in the CUP, that field was labeled as irrigated. For Miami-Dade County, all planted row and field crops were assumed to be irrigated, either from a microirrigation system if black sheeting was observed or from a traveling gun that can easily be moved from field to field daily (fig. 3).

If a diesel or electric pump or a pump house structure could be seen from the road, that field would be labeled as having a groundwater source unless the pump was adjacent to or located along a canal or pond, which would indicate a surface-water source (fig. 10); however, the water source could not be clearly identified for most irrigated fields. For these fields, the WMD CUP was checked to confirm the water sources because these details were almost always provided within the permit application or staff report. Many fields were irrigated with groundwater and surface water, and these fields were assigned according to the percentages of use reported in the CUP. Municipal wastewater effluent was sometimes used as a source of water primarily for citrus irrigation (fig. 10C). At many dairy farms, the water being used to irrigate pasture grasses was sometimes observed as brown indicating the use of dairy effluent as the water source, however, these same fields could be irrigated with fresh water from ponds or wells at times. A list of agricultural irrigation fields using reclaimed water for irrigation purposes was obtained from the Florida Department of Environmental Protection (2020).

Digitizing and Attributing Irrigated Field Boundaries

Field boundaries were reviewed during field verification, and modifications to field boundaries were noted or delineated on working base maps. The working base maps with associated field notes were then brought back to the office to be digitized so that each observed field could be delineated, corrected, and properly labeled within an ArcGIS shapefile. Fields were also noted as not irrigated or were deleted from the irrigated layer if no irrigation was present or if the field was no longer classified as agriculture. Fields not originally shown in the ILG were added to the shapefile if irrigation was present, and the boundaries were digitized based on the most recent Google Earth images. For earlier published maps (2014, 2015, and 2016) the World Imagery base map from Esri ArcGIS online was used to aid digitizing (Esri, 2020).

In some cases, boundaries for irrigated fields obtained from the original FSAID layer were outlined or re-digitized based on maps provided to the WMDs for CUP applications or by using the most recent Google Earth images. This digitizing task often increased the field and acreage accuracy because farm structures, roads, canals, ponds, tree lines, and other nonirrigated areas were removed from the original digitized fields (fig. 11). In addition, many fields only had an active crop on a portion of the field, even though the entire field had the infrastructure to be irrigated. In these cases, the entire irrigated field was digitized and labeled as irrigated because the inactive part of the field was either recently harvested, being prepared for planting, or possibly fallow for the current growing season (fig. 12).

For each field that was identified as irrigated, fallow, or abandoned, an entry was made in the attribute table in ArcGIS. These entries include the general crop type (row, fruit, field, or nursery and sod) and the specific crop type (if available), general irrigation system type (flood-seepage, micro-, or sprinkler irrigation) and the specific type (if available), primary and secondary water sources, Florida Land Use Classification System code, (Florida Department of Transportation Surveying and Mapping Office Geographic Mapping Section, 1999), date and time of field visit, source of information (field visit, CUP, FDACS field staff, or other), and any comments added from the field visit. Fallow and abandoned fields were listed in the attribute table; however, they were labeled as not irrigated for the year they were observed.

Resolving Unidentified Fields and Missing Information

Several fields or groves that could not be viewed or were only partially observed during field visits from public roads were identified as CNA. In addition, if a crop could not be identified on an irrigated field or a citrus grove could not be determined as active or inactive, it was labeled as CNV. The acreage of fields assigned to the CNA and CNV categories in each county varied. For example, the combined acreage originally identified as CNA or CNV for Polk County in 2018 represented about 10 percent of the total acreage tabulated in the shapefile (Marella, Berry, and Dixon, 2017a). For each field labeled as CNA or CNV, two primary data sources were used to identify the status of each field, crop type, irrigation system, and water sources; if these two data sources did not provide a clear answer, the field was cross referenced with the most recent FSAID layer and if nothing was shown then it was removed from the attribute table. The first primary data source was the WMD CUP files which were accessed through each WMD’s ePermit portal (NWFWMD, 2021; SJRWMD, 2021; SFWMD, 2021; SRWMD, 2021; SWFWMD, 2021). Within each CUP, information for most fields labeled as CNA or CNV could be obtained from the individual permit applications, the permit staff report summaries, or recently submitted pumpage records. The second primary data source used to categorize or remove these fields was the local or regional FDACS field office or the IFAS county extension office; in many cases, personnel at these offices were able to answer or resolve most of the questions about unidentified fields. The data obtained from these sources were added to the attribute table for each of these fields that had been labeled as CNA or CNV if the field was active. but the field was removed from the attribute table if it was determined to be inactive. During 2013–17, these undetermined fields were labeled as CNA or CNV and were retained in the attribute table as irrigated acreage; however, beginning in 2018, these fields were labeled as fallow or abandoned and as not irrigated but remained in agriculture. Upon using these data sources for Polk County in 2018, the amount of acreage labeled as CNA and CNV was reduced from about 10 percent to about 5 percent.