During the spring, summer and fall of 2011 the Macatawa Watershed Project will be working in conjunction with our partners (Hope College and the Outdoor Discovery Center Macatawa Greenway) to collect samples of suspended sediment at 43 locations throughout the watershed. The intensive monitoring project is funded in part by the Michigan Department of Environmental Quality and has allowed us to construct our own sampling equipment (pictured at right). Sediment enters our local waterways via stream bank erosion and surface runoff during rain events. It is important to learn more about sediment because phosphorus is often attached to sediment and Lake Macatawa suffers from excessive levels of phosphorus. The monitoring will allow us to measure how much sediment is coming from different parts of the watershed so we will be able to better target remediation activities. The data collected was used to rank the subwatersheds from worst to best in terms of how much sediment was collected in each tributary. In the map below, the 8 major subwatersheds are numbered 1-8, 1 indicating the most amount of sediment and 8 indicating the least. The pink dots represent the relative amount of sediment collected based on the amount of contributing area.
Sediment Sampling Field Crew:
Click here to Enter Sediment Collection Data
Click here to Enter Sediment Weight Analysis
Volunteer Secchi Disk Monitoring
Volunteers collect water transparency data using an 8-inch, circular, black and white metal plate attached to a calibrated rope. This tool is called a Secchi disk. Volunteers take secchi readings for a designated spot in Lake Macatawa about once a week during open water season. The volunteer lowers the disk into the water until it is no longer visible and notes that depth from the markings on the rope. The disk is then lowered a little further and then raised back up until it is just visible. This second depth reading is averaged with the first, and the final number is recorded on a data sheet.
This measure estimates the clarity of the water. Water transparency is a quick and easy measurement that tells scientists a lot about a lake’s water quality. First it indicates the amount of light penetration into a lake. Second, Secchi transparency provides an indirect measure of the amount of suspended material in the water. Changes in transparency over time can be an important red flag that a change in water quality is occurring.
Secchi disk measurements provide objective means to evaluate water clarity versus subjective statements such as “It is clear,” or “It is muddy.” One person’s clear water may be another person’s muddy water.
We’d like to have additional help! Contact the MACC to learn more about becoming a part of the volunteer monitoring program.
Click here to see the MACC’s Secchi data through 2013 that is collected at 4 locations weekly throughout the spring and summer months by our local volunteers.
The graph below summarizes the annual average Secchi depth from 2002 to the present at 4 locations in Lake Macatawa. The overall trend seems to indicate that the Secchi depth is decreasing, meaning that the clarity of the lake is decreasing. Increasing Secchi depth would indicate improved water clarity.