DEVELOPING A MANAGEMENT PLAN FOR A SMALL, RURAL WATERSHED IN SOUTH-CENTRAL MICHIGAN THROUGH MONITORING OF STREAM FLOW, TURBIDITY, AND TEMPERATURE

In Summer 2002, we monitored stream flow and water quality of Rice Creek, a 4th order tributary of the Kalamazoo River in south central Michigan. The stream is managed as an agricultural drain and is on EPA’s non-attainment list for suspended solids. Rice Creek includes three distinct segments: the 12 km stem, the 21 km North Branch with multiple in-stream lakes, and the 24 km South Branch. Our study is part of a multi-year undergraduate interdisciplinary monitoring project, funded by an EPA Section 319 watershed-planning grant.

We generated rating curves for 10 gauging stations by comparing discharge and stage measurements (mean R2 of 0.88). Hydrographs, prepared using rating curves and continuously logging pressure transducers, show a 43-74% summer decline in discharge due to lack of rain. Spikes in discharge following isolated rain events were short-lived. Superimposed on the decline are regular daily cycles in stage of ~0.1 ft with crests at 2-6 pm and troughs at 12-4 am.

Daytime measurements of total suspended solid (TSS) concentrations and turbidity did not vary consistently with date or discharge. TSS concentrations ranged from 0.5-22 mg/L, with calculated loads as high as 1567 kg/day. TSS concentrations and turbidity tended to be highest in the South Branch and lowest in the North Branch sites downstream from lakes. However, continuous monitoring of turbidity shows cyclical daily variations throughout the watershed, with nighttime levels 3-4 times higher than daytime levels.

Temperature, logged continuously at 6 stations, also showed a daily cycle that varied in magnitude in different stream segments. Upstream sites show 6-9C daily range; variation at the most downstream sites was 3C. Waters in the North Branch between lakes were always 5-9C warmer than in other parts of the stream.

Stream management initiatives should address the flashiness of the stream, high and variable water temperatures, and site-specific sources of turbidity.