By Herb Garn
Bob Brod and Herb Garn, members of the Friends’ Watershed Committee, recently made new measurements of the flow of Frederick Springs and the smaller western springs, showing the quick response of the springs to the wet year we had in 2024.
Total precipitation for 2024 was 48.47 inches, 30 percent greater than the annual long-term average of 37.13. The flow of Frederick Springs was measured as 3.13 cubic feet/sec (1,400 gallons/minute), while the average flow of the spring (2009-2025) is 2.51 cubic feet/sec (1,130 gallons/minute). This flow is the fourth-highest flow measured since 2009 (Fig. 1), indicating that part of 2024 precipitation apparently recharged the aquifers contributing to the flow of the springs.
The smaller springs west of Frederick Springs, originating in the Acker Tributary south of the main trail (we could call them Acker Springs), where the stream becomes perennial and flows into the marsh (Fig. 2), are less well-known and haven’t been measured as often, but also have a significant contribution to the marsh. Flow of these springs was measured at 1.85 cubic feet/sec (830 gallons/min), while the average flow is 1.47 cubic feet/sec (660 gallons/min).
The two sets of springs have flows that are fairly closely related to one another (Fig. 3) since they are fed by the same aquifers, with the smaller springs having somewhat less contribution from the lowermost sandstone aquifer.
All together, the groundwater contributions to the marsh are significant, making the Pheasant Branch marsh the gem that it is.
About our author: Herb Garn is the Co-Chair of the Friends of Pheasant Branch Conservancy Watershed Committee and professional Hydrologist, retired from the US Geological Survey where he was Assistant Director for Surface Water Monitoring and Lake Studies with the Wisconsin Water Science Center.