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ATTACrL.'1ENT II A", Page 8 FLASH FLOODS San Narcos, located 33 miles South of Austin on U. S. Interstate 35 1S 630 N.S.L. ABOVE SEA LEVEL. It sits on the East edge of the Balcones Fa~lt, with the Hill Country to the West and North side, the watersheds from the Devil's Backbone draining from 180 degrees into the downtown area via the Willow Creek from the í'J est, Purgatory Creek from the North and Sink Springs and Blanco River from the East. The Coastal Plains to the East and South are higher than the downtown area of San Marcos, making the City highly susceptible to flooding, both flash and otherwise. There 1S one (1) retarding dam on Sink Springs about six (6) miles up stream (recently built) which helps some. The only drainage out of the City is by the San Marcos River which starts in the East side of the City and adds another 108.581 million gallons of water a day to the watershed. This river runs South by East to Victoria at the coast. The Blanco causes li-ttle flooding 1n itself, but causes the San Marcos River to back up in the downtown area and retards runoff. There have been two (2) bad floods in the last 10 years. One, a 98 year flood in 1971 and another 96 year flood in 1981. There are probably four or five times a year when streets are closed due to flash flooding becoming hazardous to motorists and residents in low lying areas. In 1981, we evacuated over 5,000 people and placed them in disaster centers. There was about five million dollars' worth of damage done to property; no lives were lost. We utilized our school buses and called for help from the National Guard which helped with the rescues. Our finance office and assigned personnel appraised the losses. HAZARDOUS ~ffiTERIALS The possibility of a hazardous material accident within the San l1arcos area 1S highly probable. The overhead storage of some 30,000 gallons of gasoline at two (2) different wholesale plants and over 60,000 gallons of underground storage at the municipal airport presents a great problem. The trucking of all types of hydrocarbons through our City on several major highways presents a hazard. Many tanks loaded with chemicals, turpentine, L. P. gas, liquified hydrogen and oxygen and all types of other chemicals come through our City carried by two ( 2) railroads. Nuclear components shipped by air, rail, trailer transport through and over our City. Radiological material used in testing for oil and gas is quite prevalent in our area. Liquified Petroleum Gases are stored in several areas in combined amounts of about 5,000 gallons.