Rebecca M. Kreiling Tanja N. Williamson Kenna J. Gierke James J. Duncker 20250725 spreadsheet https://doi.org/10.5066/P13V8ENL The Illinois River receives nutrients from point and non-point runoff from upstream urban and agricultural areas. These excess nutrients could be contributing to harmful algal blooms in the Illinois River and its tributaries. Successfully mitigating the blooms requires an understanding of the underlying nutrient processes occurring in the river. Phosphorus is often the nutrient that limits phytoplankton growth and is a substantial concern in aquatic ecosystems because it can be stored long-term in the streambed sediment. Streambed sediment can act as a source or sink for phosphorus, and this dynamic is influenced by site conditions, including historic phosphorus loading and current stream water phosphorus concentrations. This study quantified streambed sediment phosphorus dynamics at 10 stream sites in the Illinois River Basin during the summer and fall of 2024. These data were collected to understand how phosphorus interacts with the streambed sediment. These data will be used for an Integrated Water Availability Assessment study. 20240624 20240927 ground condition Complete None planned Illinois River -90.6592 -88.1543 42.1900 38.8910 ISO 19115 Topic Category environment inlandWaters None streambed sediment phosphorus storage eutrophication USGS Thesaurus phosphorus USGS Metadata Identifier USGS:681ca885d4be0209b5cb9c42 None Illinois River Kankakee River Fox River Des Plaines River Grand Calumet River No access constraints. Please see 'Distribution Information' for details. These data are marked with a Creative Common CC0 1.0 Universal License. These data are in the public domain and do not have any use constraints. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Rebecca M Kreiling USGS - MIDCONTINENT REGION Research Ecologist mailing and physical

Upper Midwest Env Sciences Ctr,UMESC - Laboratory/Office - #1

La Crosse WI 54603 608-781-6346 rkreiling@usgs.gov Funding was provided by the USGS Water Mission Area Next Generation Water Observing System The data set was produced with Windows 11, Microsoft Excel 365, and R version 4.4.3. File name is 2024_Illinois_River_sediment_phosphorus.csv. All contract laboratories performed quality control checks including running certified reference standards. All equipment was calibrated prior to using it for this study. All values fall within expected ranges. Data were checked for duplication and omission. Data are 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. No formal positional accuracy tests were conducted. No formal positional accuracy tests were conducted. American Public Health Association American Water Works Association Water Environment Federation 2022 24th publication American Public Health Association, Washington DC Digital and/or Hardcopy 2022 publication date APHA et al. 2022 reference A. Mehlich 1984 publication Comm Soil Sci Plant Anal 15:1409-1416 https://doi.org/10.1080/00103628409367568 Digital and/or Hardcopy 1984 publication date Mehlich 1984 reference Rebecca M. Kreiling Patrik M. Perner Kenna J. Breckner Tanja N. Williamson Lynn A. Bartsch James M. Hood Nathan F. Manning Laura T. Johnson 2023 publication Science of the Total Environment 863:16084 http://dx.doi.org/10.1016/j.scitotenv.2022.160804 Digital and/or Hardcopy 2023 publication date Kreiling et al. 2023 reference Zachary P. Simpson Richard W. McDowell Leo M. Condron Marshall D. McDaniel Helen P. Jarvie Jonathan M. Abell 2021 publication Journal of Environmental Quality 50:287-311 https://doi.org/10.1002/jeq2.20202 Digital and/or Hardcopy 2021 publication date Simpson et al. 2021 Reference Wolfgang Durner Sascha C. Iden 2021 publication Soil and Tillage Research 213:105086 https://doi.org/10.1016/j.still.2021.105086 Digital and/or Hardcopy 2021 publication date Durner and Iden 2021 Reference Streambed sediment and water were collected from 10 sites within the Illinois River Basin from June through September 2024. All sites were sampled once except the Illinois River site at Starved Rock which was sampled in June and September. The September sampling occurred during an active harmful algal bloom at the site. Water samples were collected 0.2 m below the water surface and analyzed for total phosphorus (TP) and soluble reactive phosphorus (SRP). The SRP samples were filtered on site through a 0.45-um filter and frozen until analysis. The TP samples were acidified to pH < 2 in the field for sample preservation. In the laboratory, TP samples were digested with potassium persulfate. Samples for TP and SRP were analyzed using the ascorbic acid method (APHA et al., 2022) on a discrete autoanalyzer. Method detection limits for analyses of SRP and TP was 0.001 mg P/ L. APHA et al. 2022 20240624 Rebecca Kreiling United States Geological Survey Research Ecologist mailing and physical

2630 Fanta Reed Rd.

La Crosse WI 54603 USA 608-781-6346 rkreiling@usgs.gov The top 5-10 cm of sediment was collected with a shovel at each site. The sediment was placed on ice and transported to the laboratory. Equilibrium P concentration (EPC0) analysis and extraction of exchangeable P occurred within 24 hours of sample collection. Sediment measurements included volatile solids, sediment bulk density, particle-size analysis, MgCl2-exchangeable SRP (exSRP), % total carbon (% C), % total N (% N), and sediment TP. The Mehlich-3 method was used to extract aluminum (Al), calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), P, and zinc (Zn) from the sediment (Mehlich, 1984). Limits of detection for Mehlich-3 analyses were Al: 0.46 mg/kg, Ca: 1.21 mg/kg, Cu: 0.01 mg/kg, Fe: 0.02 mg/kg, K: 0.63 mg/kg, Mg: 0.07 mg/kg, Mn: 0.03 mg/kg, Na: 0.09 mg/kg, P: 0.38 mg/kg, and Zn: 0.03 mg/kg. The P saturation ratio (PSR) of sediment was calculated using molar concentrations of Mehlich3-P, Al, and Fe: PSR = (P)/(Fe+Al). EPC0 was measured by following Kreiling et al. (2023). The phosphate exchange potential (PEP), which is a measure of the relative difference between EPC0 and SRP, was obtained following Simpson et al. (2021). The potential for the sediment to remove P from the water column is indicated by negative PEP values, whereas positive values indicate a potential for the sediment to release P. Equilibrium between the water column and sediment is indicated by values close to zero. The PEP values allow for comparison of potential sediment uptake and release across streams with vastly different SRP concentrations by accounting for differences in scale through log-transformation while maintaining the direction of P movement (Simpson et al., 2021). PEP = log10 (EPC0) - log10 (SRP). Particle size distribution was measured with PARIO particle size analyzers utilizing the integral suspension pressure method (Durner and Iden, 2021). Particle classes included coarse sand (630—2,000 µm), medium sand (200—<630 µm), fine sand (63—<200 µm), coarse silt (20—<63 µm), medium silt (6.3—<20 µm), fine silt (2.0—<6.3 µm) and clay (<2.0 µm). The particle size categories were also grouped into sand (63—2,000 µm) and silt (2.0—<63 µm). exSRP was extracted from the sediment and analyzed using the ascorbic acid method (APHA et al., 2022). Dried sediment samples were analyzed for % N and % C and ashed samples were analyzed for % inorganic C on a Variomax® CN analyzer. % Total organic carbon (% TOC) was calculated as the difference between % C and % inorganic C. Sediment TP was determined by inductively coupled plasma mass spectrometry using EPA Method 6010B. Mehlich 1984 Kreiling et al. 2023 Simpson et al. 2021 Durner and Iden 2021 APHA et al. 2022 20240625 Rebecca Kreiling United States Geological Survey Research Ecologist mailing and physical

2630 Fanta Reed Rd.

La Crosse Wisconsin 54603 USA 608-781-6346 rkreiling@usgs.gov 2024_Illinois_River_sediment_phosphorus.csv Comma Separated Value (CSV) file containing data. Producer Defined Site Name Site name assigned to each sampling location Producer Defined Site name assigned to each site USGS Station ID USGS station identification number for the USGS gaging station where the sediment and water quality samples were collected Producer Defined USGS gaging station identification number Sample Date Date that samples were collected from the site (MM/DD/YYYY) Producer Defined 6/24/2024 9/27/2024 Equilibrium Phosphorus Concentration (mg P/L) The concentration of soluble reactive phosphorus in the stream water at which there is no streambed sediment uptake or release Producer Defined 0.0238 0.5536 milligrams phosphorus per liter Phosphate Exchange Potential Magnitude of difference between EPC0 and SRP. Simpson, Z.P., R.W. McDowell, L.M. Condron, M.D. McDaniel, H.P. Jarvie, and J.M. Abell (2021). Sediment phosphorus buffering in streams at baseflow: a meta-analysis. Journal of Environmental Quality 50:287-311. Producer Defined -0.7393 1.1186 unitless Sediment Total Phosphorus (mg P/kg dry sediment) Total phosphorus concentration in the streambed sediment Producer Defined 258.18 997.97 milligrams phosphorus per kilogram dried sediment MgCl2-exchangeable SRP (mg P/kg dry sediment) The amount of soluble reactive phosphorus that is extracted from the streambed sediment using a magnesium chloride solution Producer Defined 1.25 26.42 milligrams phosphorus per kilogram dried sediment Carbon in Sediment (%) Amount of total carbon present in the streambed sediment Producer Defined 1.4 11.23 percent Nitrogen in Sediment (%) Amount of total nitrogen present in the streambed sediment Producer Defined 0.023 0.208 percent Total Organic Carbon in Sediment (%) Amount of total organic carbon present in the streambed sediment Producer Defined 0.26 3.46 percent Molar Ratio of Carbon to Nitrogen The molar ratio of carbon to nitrogen present in the streambed sediment Producer Defined 26.21 223.32 Mehlich-3 Extracted Aluminum (mg Al/kg dry sediment) The amount of aluminum that is extracted from the streambed sediment using a Mehlich-3 acid digestion Producer Defined <0.46 322.77 mg aluminum per kilogram dried sediment Mehlich-3 Extracted Calcium (mg Ca/kg dry sediment) The amount of calcium that is extracted from the streambed sediment using a Mehlich-3 acid digestion Producer Defined 2065.9 8252.1 milligrams calcium per kilogram dried sediment Mehlich-3 Extracted Copper (mg Cu/kg dry sediment) The amount of copper that is extracted from the streambed sediment using a Mehlich-3 acid digestion Producer Defined 0.23 3.55 milligrams copper per kilogram dried sediment Mehlich-3 Extracted Iron (mg Fe/kg dry sediment) The amount of iron that is extracted from the streambed sediment using a Mehlich-3 acid digestion Producer Defined 160.5 617.74 milligrams iron per kilogram dried sediment Mehlich-3 Extracted Potassium (mg K/kg dry sediment) The amount of potassium that is extracted from the streambed sediment using a Mehlich-3 acid digestion Producer Defined 14.54 97.04 milligrams potassium per kilogram dried sediment Mehlich-3 Extracted Magnesium (mg Mg/kg dry sediment) The amount of magnesium that is extracted from the streambed sediment using a Mehlich-3 acid digestion Producer Defined 112.32 601.35 milligrams magnesium per kilogram dried sediment Mehlich-3 Extracted Manganese (mg Mn/kg dry sediment) The amount of manganese that is extracted from the streambed sediment using a Mehlich-3 acid digestion Producer Defined 30.58 268.56 milligrams manganese per kilogram dried sediment Mehlich-3 Extracted Sodium (mg Na/kg dry sediment) The amount of sodium that is extracted from the streambed sediment using a Mehlich-3 acid digestion Producer Defined 10.96 142.1 milligrams sodium per kilogram dried sediment Mehlich-3 Extracted Phosphorus (mg P/kg dry sediment) The amount of phosphorus that is extracted from the streambed sediment using a Mehlich-3 acid digestion Producer Defined 7.91 139.88 milligrams phosphorus per kilogram dried sediment Mehlich-3 Extracted Zinc (mg Zn/kg dry sediment) The amount of zinc that is extracted from the streambed sediment using a Mehlich-3 acid digestion Producer Defined 2.33 37.58 milligrams zinc per kilogram dried sediment Phosphorus Saturation Ratio The portion of the streambed sediment that is saturated with phosphorus Producer Defined 0.034 0.347 unitless Water content (%) The amount of water in the sediment Producer Defined 15.14 48.95 percent %Volatile Sediment (% volatile solids/g dry sediment) Percent of mass of sediment that is lost upon being dried in a muffle furnace at 450 degrees Celsius Producer Defined 0.06 10.73 percent volatile solids per gram dried sediment Sediment Bulk Density (g/cm3) The weight of streambed sediment in a given volume Producer Defined 0.8 1.97 grams per cubic centimeter Total Porosity (%) The fraction of the bulk sediment volume that is not occupied by solid matter Producer Defined 25.53 69.66 percent Water-filled Pore Space (%) The percent of streambed sediment pore space filled with water Producer Defined 56.49 100.0 percent Stream Water Total Phosphorus (mg P/L) Total phosphorus concentration in stream water Producer Defined 0.040 0.495 milligrams phosphorus per liter Stream Water Soluble Reactive Phosphorus (mg P/L) Soluble reactive phosphorus concentration in stream water Producer Defined 0.007 0.380 milligrams phosphorus per liter Sand (%) The amount of sediment that is composed of sand particles (63—2,000 µm) Producer Defined 34.33 99.01 percent Silt (%) The amount of sediment that is composed of silt particles (2.0—<63 µm) Producer Defined <0.01 53.53 percent Clay (%) The amount of sediment that is composed of clay particles (<2.0 µm) Producer Defined 0.97 18.06 percent Fine Sand (%) The amount of sediment that is composed of fine sand particles (63—<200 µm). This particle size category is a subset of the sand category. Producer Defined 3.48 57.91 percent Medium Sand (%) The amount of sediment that is composed of medium sand particles (200—<630 µm). This particle size category is a subset of the sand category. Producer Defined 1.56 78.45 percent Coarse Sand (%) The amount of sediment that is composed of coarse sand particles (630—2,000 µm). This particle size category is a subset of the sand category. Producer Defined <0.01 48.62 percent Fine Silt (%) The amount of sediment that is composed of fine silt particles (2.0—<6.3 µm). This particle size category is a subset of the silt category. Producer Defined <0.01 6.13 percent Medium Silt (%) The amount of sediment that is composed of medium silt particles (6.3—<20 µm). This particle size category is a subset of the silt category. Producer Defined <0.01 9.47 percent Coarse Silt (%) The amount of the sediment that is composed of coarse silt particles (20—<63 µm). This particle size category is a subset of the silt category. Producer Defined <0.01 40.4 percent Notes Notes about the site including where the sediment was collected. Producer Defined << empty cell >> No Data Producer defined Notes about the site including where the sediment was collected. U.S. Geological Survey - ScienceBase mailing address

Denver Federal Center

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Denver CO 80225 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 for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Digital Data https://doi.org/10.5066/P13V8ENL None 20250725 Rebecca M Kreiling USGS - MIDCONTINENT REGION Research Ecologist mailing and physical

Upper Midwest Env Sciences Ctr,UMESC - Laboratory/Office - #1

La Crosse WI 54603 608-781-6346 rkreiling@usgs.gov FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata FGDC-STD-001.1-1999