Based on the consistency of the dirt around the outlet pipes, it appears the pond walls (basin) has some leakage issues that are masked by the spring water inflow of 75+gpm. Whenever you decide to drain, try to rework the basin by adding depth and compacting all of the bottom clay and sides with a sheepsfoot roller around upper areas. The best compactor is the vibratory sheepsfoot which is what I would insist be used.
You current depth appears pretty good at 10 to 14ft. For WI better would be 12 to 18 or 20ft. With current depth and condition you may not need to rework the basin for another 10-20 yrs assuming the springs maintain the current flow rate. Spring water is likely minimizing winter kill issues.
Your current fix is repairing the outlet pipe integrity. It may be as simple as a partial draining and excavating out dirt around the pipes and backfilling with one or two loads of clay that is well compacted around the outlet pipe area. Then consider using some broken riprap over the new dirt work to stabilize it from weathering and erosion.
Last edited by Bill Cody; 03/26/15 04:14 PM.
