SEASONAL SUBSTRATE TEMPERATURE ANOMALIES AT SAND CREEK, AMAN PARK, OTTAWA COUNTY, MICHIGAN

Substrate and stream temperature data were collected on Sand Creek, a small, sand-dominated stream in West Michigan. Data collected in February, May, August, and October of 2008 (171, 204, 181, and 215 data points respectively) showed pronounced substrate temperature anomalies within a 40 meter reach of the stream. During February and October anomalous areas were warmer than the average substrate and stream temperatures, whereas during May and August anomalous areas were cooler than the average substrate and stream temperatures. February average substrate and stream temperatures were 3.6°C and 0.7°C, respectively, while anomalous areas showed temperatures in excess of 10°C. In August, average substrate and stream temperatures were 15.1°C and 19.4°C, respectively, while anomalous areas had temperatures as low as 10.4°C. Fixed temperature probes placed in shallow wells on the flood plain of the Creek, and in the stream, had thermographs consistent with a combination of surface water, groundwater, and hyporheic water. Diurnal temperature variations in some some wells suggest that hyporheic water does exist on the flood plain of Sand Creek and may be contributing to substrate temperature anomalies within the stream channel. Observed substrate anomalies are likely the result of a combination of groundwater and hyporheic water traveling through preferential flow paths in abandoned stream channels which intersect the modern stream channel.