21. In hydrology, "'snowmelt "'is surface runoff produced from melting snow. 22. Nitrate is highly soluble, and propagates through the soil into ground water and surface runoff . 23. Trees and other plants help to control surface runoff . 24. Shallow drainage work mainly intercepts surface runoff and keeps it away from potentially unstable areas. 25. Surface runoff in hydrologic systems is generally conceptualized as occurring from pervious and impervious areas.26. Lake Kampeska briefly experienced problems with pollution from fertilizer and surface runoff until the 1990s. 27. Lake Minnetonka had problems with pollution from sewage, fertilizer, and surface runoff until the 1970s. 28. The headwaters of North Mahanoy Creek are in unpolluted springs and surface runoff near Locust Mountain. 29. Seventy percent of surface runoff is collected from rain, and 30 percent from rain on snow. 30. The amount of hydroelectric power generated is strongly affected by changes in precipitation and surface runoff .
