IMPORTANT INFORMATION FOR DELAVAN LAKE RESIDENTS

THE COMPREHENSIVE LAKE WATER QUALITY PROGRAM

​The Delavan Lake Water Quality program, jointly financed by the Delavan Lake Sanitary District, the Town of Delavan, and the United States Geological Survey includes monthly monitoring of the lake and its watershed. It also includes the gathering of upstream "loading" data from an automated sampling station on Jackson Creek, and sampling from 8 strategically located stream crossings throughout the watershed. The purpose of the comprehensive monitoring program is to systematically gather the information which the Lake Committee and its expert advisers require to evaluate and guide its ongoing efforts to maintain and improve lake water quality.​

The 0.80 inch rainfall and the gradual snowmelt provided the perfect opportunity to conduct the first of 8 regularly scheduled sampling efforts in carefully identified locations around the lake's extensive watershed. The sampling is conducted according to strict protocols and the staff charged with the responsibility for collecting the samples has received extensive training by skilled USGS personnel. The samples, 2 from each of the 8 sites are sent to CT Laboratories in Baraboo WI for analysis. The lab is fully certified by cognizant state and federal agencies. Additionally, members of the team reviewed their capabilities. You can check them out at www.ctlaboratories.com. Five separate analyses are conducted on each sample. They include, total phosphorous, total nitrogen, and suspended solids. The resultant information is then forwarded to each of our team members for interpretation. Should one location or another indicate a particularly high concentration of nutrients or suspended solids, the team will further evaluate conditions "upstream" in an effort to identify the source of the elevated loadings, and recommend specific actions to remediate the problem area.​

An essential part of the watershed monitoring program is the automated sampling site at Jackson Creek maintained by the USGS as an integral part of the Comprehensive program. Jackson Creek accounts for an estimated 68% of all water and approximately 75% of the total phosphorus entering Delavan Lake. The station measures stream flow in real time and the chart below clearly shows the impact of the rainfall and melting over the first weekend in March.

The automated sampling system will obtain samples of the incoming stream water both routinely and at peak flow periods. The samples will be subsequently analyzed for suspended sediment, dissolved phosphorous, sediment particle size and Nitrogen. The aggregated information will yield estimates of nutrient loading which can be readily compared to historical data. The Mound Road Sedimentation Ponds, which were rebuilt in 2009, are a critical part of the Lake protection system and the data resulting from both sets of sampling will provide useful management data. The Lake Committee intends to conduct a detailed study of the rate at which sediment has been accumulating in the rebuilt sediment and nutrient control ponds this spring. The information gathered at the station will complement sampling at the route 50 bridge which will in turn provide insight into the effectiveness of the recently completed Inlet dredging project.​

The In-Lake element of the program is already underway. The first sampling was conducted by USGS staff in February (yes, through the ice). The second sampling will take place as soon as practicable after the ice leaves the Lake. The samples will be analyzed along distinct and meaningful parameters. The results, as was the case last year, will be reported as they become available on the Towns website under the Lake Information tab. We are actively working with others to reliably summarize this data in a simple set of “dashboard measures”. The task has proved to be more complex that we anticipated. Nevertheless, we hope to have that “dashboard” in place by early summer.​

Dale M. Robertson – USGS Wisconsin Water Science Center