Abstract

2021 Grand River Water Quality Sampling

The goals of this research project were to collect repeat samples at designated reaches and under different flow conditions along the Grand River, sample the entire Grand River over a short period of time, collaborate with wastewater treatment plant labs and technicians to analyze water samples, and to calculate a Water Quality Index (WQI) for samples collected.

Seven different reaches were sampled and over 120 samples were collected between May 7th and August 12th of 2021. Water samples were collected and analyzed for nitrate, total phosphate, ammonium, chloride, dissolved oxygen, biological oxygen demand , total suspended solids, E. coli, and total coliform. Additional parameters were measured in the field using an In-situ Aqua TROLL 500 Multiparameter Sonde: water conductivity, specific conductivity, turbidity, oxidation reduction potential, resistivity, salinity, and total dissolved salts.

Water samples from the Grand River were collected from bridges and roads, and from kayaks. The samples collected were analyzed at the Allendale Wastewater Treatment Plant or in the GVSU Honors College Lab. Sample collection took place in the morning with lab analysis taking place midafternoon of the same day minimizing sample storage time. Lab methods included: 1) HACH spectrometer analysis; 2) Total Suspended Solids Filtration; 3) dissolved oxygen and biological oxygen demand (BOD); and 4) IDEXX Colilert 2000 Quanti-Tray method. As the flow increases in a given reach, the nutrient levels also increase due to run-off. The only exception was chloride generally decreased with increasing flow, which could be attributed to dilution from rain water low in chloride. Reach-scale E. coli most probable numbers (MPN) showed more variability than other measured parameters. Water Quality Index (WQI) values for the Grand River on August 4 and 5 were relatively consistent and above 70 (good) for the entire river.