Get a soil sample from around your pond in 5 or 6 spots down to about 4 inches. Combine samples in a bucket and mix together. Take sample of combined soil to your local coop. Have them send in your soil sample for analysis. When you get your results back put down appropriate amount of lime and fertilizer as well as seed you want to grow. They make liquid lime that is fast acting unlike ag lime but also more expensive. If you don’t want to wait on the soil sample, spray the liquid lime and put down erosion control blankets/mats with the seed in them around the shoreline of your pond.