T. R. Bayles, "Early Mills, Roads, and Industries in Brookhaven Town," 1976:
"The South Haven mill, located just north of the 'goin over' of the Montauk highway, and was in operation in 1745, and contained the large mill stones between which the grain was ground, until it was torn down by the extension of the Sunrise highway in 1958. Water still poured through the mill race as it did before the Revolution, but the mill wheels had long been silent. As with the Yaphank mills this was a grist and saw mill. Sam Carman conducted a tavern and general store just to the west of the mill, and with the meeting house across the road built in 1740 [Br09A, SH03], this was the center of life in this part of Brookhaven town in those years."
Eugene L. Armbruster, "Landmarks on the Montauk Highway," 1925. p. 11:
"THE CARMAN HOUSE shingled and painted white, was kept as a tavern in the stage-coach days. Along this house runs a lane northeast from the road to CARMAN'S GRIST MILL. The latter is almost completely hidden by the house. This mill, a shingled, unpainted structure, standing on Carman's River, was purchased by one Havens in 1745 and was later owned by the Carman Family."
At the dam, there were at least two "mills" both of which were powered from the same turbine. The larger (more easterly building) contained the grist mill. A smaller building on the west side of the raceway contained a saw and planning mill. About 1875, the saw/planning mill appears to have been torn down as part of an agreement between the Suffolk Club and Henry W. Carman on Henry's sale of the dam and upstream property to the Club. See photo section. The grist mill and dam were removed in 1958 on construction of Sunrise Highway. A new dam structure was constructed, essentially incorporating the highway crossings, which were slightly north of the original dam.
"The Carmans River flows south through a gap in the Ronkonkoma moraine from its headwaters located in the area of Artist Lake in Middle Island. (see Figure 4-2). It reaches the dividing line between Hydrogeologic Zones III and VI at Yaphank, about six miles from its headwaters, with flows measured at the USGS gauging station ranging from 8.3 mgd (1967) to 24.3 mgd (1979), and a long-term (1942-92) average of 15.6 mgd. (Spinello et al., 1993). Farther south, the rate of discharge of groundwater to the river increases as it traverses the outwash plain, and by the time the river reaches the boundary of the CPB at Route 27, some 12 miles south of its starting point, the average flow rate has increased to about 35 mgd. The southernmost 3 miles of the river are tidal, where it gains an estimated additional 11.5 mgd of groundwater, bringing the total freshwater discharge into Bellport Bay at the mouth of the river to 46.5 mgd. (Warren et al., 1968)." [http://pb.state.ny.us/cpb_plan_vol2/vol2_chapter04.htm]
Long Island sources: Reports, resolutions, authorizations, surveys and designs showing sources and manner of obtaining from Suffolk County, Long Island, an additional supply of water for the city of New York ... (Google eBook. New York (N.Y.). Board of Water Supply, Charles Strauss, Jonas Waldo Smith. 1912. p. 562:
"Grist-mill And Sawmill At South Haven
"This mill is situated at the outlet of the pond on the Carman's river, just above the South Country road, and belongs with the surrounding land, and the pond above, to the Suffolk club. The sawmill has an under-shot wheel 2 feet by 10 feet rated at 25 H.P. which is said to do about $750 of business annually. The grist-mill has two turbines 24 and 16 H.P. respectively, and one old 12-H.P. tub wheel. This mill does about the same amount of business as the sawmill."