Brent T. Aulenbach Joshua C. Henley Kristina G. Hopkins 20230404 tabular digital data Reston, VA U.S. Geological Survey https://doi.org/10.5066/P9G8HZTY Brent T. Aulenbach Joshua C. Henley Kristina G. Hopkins 2023 publication USGS Scientific Investigations Report 2023-5035 Reston, Virginia U.S. Geological Survey This dataset contains the percentages of impervious areas within the drainage areas of 15 watersheds in Gwinnett County, Georgia from 2000 to 2020. The dataset includes data from 16 years, 2000, 2005, 2006, and annually from 2008 to 2020. The dataset was derived from impervious area coverages provided from the Gwinnett County Department of Public Utilities. These coverages were determined from 1:1,200-scale aerial photography with a 1-meter square grid size created by digitizing polygons of impervious surfaces. Watershed imperviousness was determined for various land cover types that were provided with the impervious area coverages. These included transportation and buildings land cover types for all impervious area scenes and additionally for recreation, structures, and utilities land cover types for scenes from 2008 through 2020. Impervious areas within a 200-ft stream buffer from National Hydrography Dataset flowlines were also determined for 2019. The purpose of this dataset is to provide impervious area data used to summarize changes in imperviousness for the 15 Gwinnett County watersheds over the 2000 to 2020 period. Data were used in the U.S. Geological Survey (USGS) Scientific Investigations Report "Hydrology, water-quality, and watershed characteristics in 15 watersheds in Gwinnett County, Georgia, 2002-20". This study is part of a long-term program to monitor and analyze the hydrologic and water-quality conditions of 15 watersheds in Gwinnett County, Georgia by the USGS in cooperation with Gwinnett County Department of Water Resources. 2000 2020 publication date Complete None planned -84.2721 -83.8468 34.1514 33.7676 ISO 19115 Topic Category inlandWaters imageryBaseMapsEarthCover USGS Thesaurus land use and land cover Marine Realms Information Bank (MRIB) keywords watershed Other impervious area USGS Metadata Identifier USGS:63503d9ed34e47431c15c5a3 Geographic Names Information System Gwinnett County State of Georgia None. Please see 'Distribution Info' for details. None. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Brent T Aulenbach U.S. Geological Survey, Southeast Region Research Hydrologist mailing address

1770 Corporate Drive Suite 500

Norcross GA 30093 US 678-924-6626 678-924-6710 btaulenb@usgs.gov Funded through a cooperative agreement between Gwinnett County Department of Water Resources and the U.S. Geological Survey MacOS Big Sur, version 11.7.1; Microsoft Excel for Mac, version 16.67; 05_GwinnettCoGa_ImperviousArea.csv 19 KB Watershed impervious areas were calculated from the impervious area and attributed land cover datasets as provided from the Gwinnett County Department of Public Utilities. There were some obvious inconsistencies in the attribution of land cover types between years and we generally did not attempt to resolve these. In a few years, 2005, 2012, and 2014, we have reassigned some land cover types to improve temporal consistency. These are noted in the Notes column of the csv file. Also below. The use or modification of inconsistent attribution of land cover types between years did not substantially affect the interpretation of the long-term temporal patterns in impervious areas in the study watersheds. Temporal patterns in watershed impervious areas by land cover type were examined and values some years were not always sensical with the overall temporal patterns. This was likely due to inconsistent attribution of land cover types between years. More substantial nonsensical data is noted in the Notes column. Nonsensical data does not substantially affect the interpretation of the long-term temporal patterns in impervious areas in the study watersheds. Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. Gwinnett County Department of Public Utilities 202203 raster digital data Digital and/or Hardcopy 2000 2020 publication date Imperviousness Impervious area and land cover types, 1-meter resolution grid Impervious area was determined from detailed countywide impervious area datasets developed to support the Gwinnett County stormwater utility (Gwinnett County Department of Public Utilities, unpublished data; Imperviousness). The dataset was first created in 2000, and was updated in 2005, 2006, and 2008-20 annually and has a 1-square meter grid size. Imperviousness was determined for the 15 study watersheds using the drainage areas shapefile 01_GwinnettCoGa_Watersheds_StreamStats.shp on child page “01: Watersheds shapefile for the 15 study watersheds in Gwinnett County, Georgia.” Watershed imperviousness was categorized into the five land cover types provided in the impervious area datasets: transportation, buildings, recreation, structures, and utilities. Impervious areas were also determined within a 200-ft stream buffer of each watershed from the high resolution 1:24,000-scale National Hydrography Dataset flowlines (USGS, 2021a) for 2019 to evaluate whether this would be a more useful variable for explaining variations in watershed hydrologic metrics and water quality than overall watershed imperviousness. Temporal patterns in watershed imperviousness by land cover type were occasionally nonsensical and this was likely due to inconsistent attribution of land cover types between years. Impervious areas were generally calculated based on the data provided and some of the more substantial nonsensical data is noted in the Notes column. Some data used in previous analyses (data from 2005, 2012, and 2014) were modified to correct for some obvious inconsistent coding of land cover types during those years. Most notable is data from 2012 where transportation impervious areas were low in most watersheds due to areas with roads under construction not being assigned to the transportation land cover type. Situations where modifications were incorporated into the dataset are noted along with the reference to the published modified values used in Aulenbach and others (2017). The inclusion of nonsensical data or the use of modified values does not substantially affect the interpretation of the long-term temporal patterns in impervious areas in the study watersheds. Impervious area datasets were provided by the Gwinnett County Department of Public Utilities in August 2021 and March 2022. Aulenbach, B.T., Joiner, J.K., and Painter, J.A., 2017, Hydrology and water quality in 13 watersheds in Gwinnett County, Georgia, 2001-15: U.S. Geological Survey Scientific Investigations Report 2017-5012, 82 p., accessed July 11, 2020, at https://doi.org/10.3133/sir20175012. Imperviousness 202203 05_GwinnettCoGa_ImperviousArea.csv Comma Separated Value (CSV) file containing watershed imperviousness for various years, land cover types, and within 200-foot stream buffers. Producer Defined Watershed Watershed names used in the associated U.S. Geological Survey Scientific Investigations Report. Watershed drainage area defined by site specified in value definition shown in parentheses Producer Defined Wildcat Creek Wildcat Creek near Lawrenceville, Ga. (USGS site number 02205000) Producer defined Sweetwater Creek Sweetwater Creek at Club Drive near Lilburn, Ga. (USGS site number 02205865) Producer defined Yellow River near Snellville Yellow River near Snellville, Ga. (USGS site number 02206500) Producer defined Yellow River near Lithonia Yellow River at Ga 124, near Lithonia, Ga. (USGS site number 02207120) Producer defined No Business Creek No Business Creek at Lee Road, below Snellville, Ga. (USGS site number 02207185) Producer defined Big Haynes Creek Big Haynes Creek at Lenora Road, near Snellville, Ga. (USGS site number 02207385) Producer defined Brushy Fork Creek Brushy Fork Creek at Beaver Road, nr Loganville, Ga. (USGS site number 02207400) Producer defined Alcovy River Alcovy River at New Hope Road, near Grayson, Ga. (USGS site number 02208150) Producer defined Wheeler Creek Wheeler Creek at Bill Cheek Road, near Auburn, Ga. (USGS site number 02217274) Producer defined Apalachee River Apalachee River at Fence Road, near Dacula, Ga. (USGS site number 02218565) Producer defined Richland Creek Richland Creek at Suwanee Dam Road, near Buford, Ga. (USGS site number 02334480) Producer defined Level Creek Level Creek at Suwanee Dam Road, near Suwanee, Ga. (USGS site number 02334578) Producer defined Suwanee Creek Suwanee Creek at Suwanee, Ga. (USGS site number 02334885) Producer defined Crooked Creek Crooked Creek near Norcross, Ga. (USGS site number 02335350) Producer defined North Fork Peachtree Creek North Fork Peachtree Creek at Graves Rd, near Doraville, Ga. (USGS site number 02336030) Producer defined Study area Watersheds study area Producer defined DrainArea Watershed drainage area within Gwinnett County. If 200StrmBuf is equal to yes, then this is the drainage area within the 200-foot stream buffer Producer Defined 0.08 300.25 square miles 0.01 Year Year of impervious area Producer Defined 2000 2020 years 1 200StrmBuf Indication whether impervious areas are reported just for the 200-foot stream buffer (based on the 1:100,000-scale National Hydrography Dataset flowlines) or for the entire watershed Producer Defined no Impervious area represents entire watershed area Producer defined yes Impervious area represents watershed area within the 200-foot stream buffer Producer defined Bldg_IA Watershed impervious area with building land cover. Land cover type includes public buildings, mobile homes, barns, foundations, and parking decks. If 200StrmBuf is equal to yes, then this is the drainage area within the 200-foot stream buffer Producer Defined . No Data. Impervious area data not available for 2006 for Wildcat Creek and Yellow River near Snellville watersheds Producer defined 0.003 25.923 square miles 0.001 Rec_IA Watershed impervious area with recreation land cover. Land cover type includes pools, tennis courts, hard surface playgrounds, park shelters, bleachers, ball fields, basketball courts, and athletic tracks. If 200StrmBuf is equal to yes, then this is the drainage area within the 200-foot stream buffer Producer Defined . No Data. This land cover category was not used before 2008 Producer defined 0.000 1.602 square miles 0.001 Struc_IA Watershed impervious area with structures land cover. Land cover type includes paved areas, loading docks, and canopies. If 200StrmBuf is equal to yes, then this is the drainage area within the 200-foot stream buffer Producer Defined . No Data. This land cover category was not used before 2008 Producer defined 0.000 2.035 square miles 0.001 Trans_IA Watershed impervious area with transportation land cover. Land cover type includes paved roads, paved driveways, paved parking, public sidewalks, curbs, bridge/overpass, impervious medians, and runways. If 200StrmBuf is equal to yes, then this is the drainage area within the 200-foot stream buffer Producer Defined . No Data. Impervious area data not available for 2006 for Wildcat Creek and Yellow River near Snellville watersheds Producer defined 0.006 48.190 square miles 0.001 Util_IA Watershed impervious area with utilities land cover. Land cover type includes transmission towers, tanks, electric substation pads, and pump stations. If 200StrmBuf is equal to yes, then this is the drainage area within the 200-foot stream buffer Producer Defined . No Data. This land cover category was not used before 2008 Producer defined 0.000 0.205 square miles 0.001 Notes Notes regarding values that appear to be more substantially nonsensical based on temporal patterns or where there were some modifications to the dataset land cover types Producer Defined << empty cell >> No notes for this watershed-year combination Producer defined See column definition Impervious area was determined for the 15 Gwinnett County study watersheds from detailed countywide impervious area datasets developed by the Gwinnett County Department of Public Utilities to support the Gwinnett County stormwater utility (unpublished data). The datasets were created by digitizing polygons of impervious surfaces from aerial photography and have a 1-square meter grid size. Datasets are available for 2000, 2005, 2006, and annually for 2008 to 2020. Impervious areas were categorized into five land cover types: transportation, buildings, recreation, structures, and utilities. Impervious areas were also determined within a 200-ft stream buffer from National Hydrography Dataset flowlines (USGS, 2021) for 2019 to evaluate whether this would be a more useful variable for explaining variations in watershed hydrologic metrics and water quality than overall watershed imperviousness. U.S. Geological Survey [USGS], 2021, National Hydrography Dataset, accessed September 23, 2021, at https://www.usgs.gov/core-science-systems/ngp/national-hydrography/access-national-hydrography-products. U.S. Geological Survey GS ScienceBase mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. Digital Data https://doi.org/10.5066/P9G8HZTY None 20230404 Brent T Aulenbach U.S. Geological Survey, Southeast Region Research Hydrologist mailing address

1770 Corporate Drive Suite 500

Norcross GA 30093 US 678-924-6626 678-924-6710 btaulenb@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998