Monday Mar. 24th. Began repairing my Mill Dam—with hands from all my Quarters Carpenters Included.
In digging Earth for this purpose great Quantities of Marle or Fullers Earth appeard.
In the Evening, in a Bed that had been prepard with a mixture of Dung on Saturday last, I sowed Clo⟨ver,⟩ Lucerne, & Rye Grass Seeds in the Garden, to try their Goodness—doing it in the following Order. At the end next the Corner are two Rows of Clover Seed—in the 3d., 4, 5 & 6th. Rye Grass the last Row thinest Sowd 7th. & 8th. Barley (to see if it woud come up) the last also thinnest Sown—9, 10, 11, 12th. Lucerne—first a few seeds at every 4 Inches distance the next thicker & so on to the last wch. was very thick.
Carried the Sows I bot. of George Taylor to my Mill by Water.
The carpenters were needed to work on the spillway, which was made of timber. In addition, the dam probably had a timber foundation and may have been further strengthened by vertical planking on its upstream or downstream sides or in its center (CRAIK  description begins David Craik. The Practical American Millwright and Miller: Comprising the Elementary Principles of Mechanics, Mechanism, and Motive Power, Hydraulics, and Hydraulic Motors, Mill Dams, Saw-Mills, Grist-Mills, the Oat-Meal Mill, the Barley Mill, Wool Carding and Cloth Fulling and Dressing, Windmills, Steam Power, etc. Philadelphia, 1870. description ends , 167–70).
clover seed: Trifolium pratense, red clover. Unless he specifies another clover by name, GW is referring to this species.