The South New River Canal (C-11) basin between water-control structures S-9 and S-13 is an area that is primarily undeveloped and the system of waterways within the basin is highly controlled for water-management purposes. Most of the recharge to the canals is by induced ground-water inflow and seepage. The chemical character of the surface and ground waters in inundated areas is mixed calcium-bicarbonate and sodium-chloride type. Inorganic nitrogen concentrations in surface waters are slightly higher in developed areas than in undeveloped areas. Concentrations of inorganic nitrogen in ground water in drained areas are 2-4 times greater than in undeveloped inundated areas. Average orthophosphate concentrations are uniformly low (0.01 to 0.03 milligrams per liter) throughout the basin. Total residue concentrations are fairly uniform throughout the basin and fluctuate primarily in response to hydrologic conditions. Runoff and load-discharge indices indicated that the loads of inorganic nitrogen, total residue, and phosphorus, and the discharge per unit of land drained were uniform throughout most of the basin. (Woodard-USGS)