Several sites around Itasca State Park that are potentially representative of input sources to Deming Lake were sampled in August 2023. Water from a bog on the southeast margin of Deming Lake represent surface inputs, and water from springs along Nicollet Creek, and from Elk Spring on the margins of Elk Lake represent regional groundwaters. These were sampled with syringes fit 0.22 μm syringe filters, waters were acidified at the University of Minnesota Itasca Biological Station. Water elemental compositions were determined using a Thermo Fisher iCAP-Q inductively coupled plasma mass spectrometer (ICP-MS) at the WHOI Plasma Facility following 200 dilution of a 10 μL aliquot in 2 % HNO3. Indium (In) was added to samples at a concentration of 1 ng/g prior to analyses to monitor and correct for instrument drift by normalizing to In intensities. Concentrations were calculated using a five-point calibration curve obtained by fitting of ion beam intensities measured for serial dilutions of a gravimetrically prepared multi-element standard. The relative standard deviation (RSD) for five measurements of each sample was ~10% on the iCAP-Q. The accuracy and precision of similar concentration measurements on iCAP-Q at WHOI have previously been determined to be ± 5-10 % (1SD) based on comparison with USGS reference materials AGV-1, AGV-2, BHVO-1, BHVO-2, BIR-1, and BCR-2 prepared and analyzed as unknowns during earlier runs (Jochum et al., 2016; Shu et al., 2017).