Sandstone=

49% to 89% less with peak runoff

26% to 83% build up―good on sandstone

20% to 49% less with moderate runoff

Basalt=

16% to 53% less with moderate runoff

20% - 42.5% build up―good on basalt

56% to 90% less with peak runoff

Alluvial soil=

50% to 60% less with peak runoff

3.4% to 26% build up―good on alluvial.

10% - 20% less with moderate runoff