# # National Water Information System # 2024/11/21 # # # Date Retrieved: USGS Water Data for the Nation Help System # chan_mat_cd chan_mat_nm chan_mat_ds 4s 24s 96s silt siltmud unkn unknown UNSP Unspecified The channel bed material was not specified. SAND sand The channel bed was composed of sand. GRVL gravel The channel bed was composed of gravel. CBLS cobbles The channel bed was composed of cobbles. BLDR cobbles-boulders The channel bed was composed of cobbles and/or boulders. LDGE bedrock-ledge-artificial The channel bed was composed of bedrock, ledge or an artificial material like concrete or metal.