509 e e e e e e @ e s e e ° e e e e e ° ° e e ° ° . * e ° e * ° ® e e e e e e ° a e e ° ‘ e e e e ° e e _ SCALE 012345 MILES (a) @e RECORDING RAIN GAUGES N f KASKASKIA ng BONEYARD (oe e jo / ° ene o e ‘ { \ eo! (o e) e NONRECORDING RAIN GAUGE o RECORDING RAIN GAUGE SCALE 7 NETWORK BOUNDARY 4 1 5 3 4 (b) enenthareerereenceey MILES Fig. 1—Sampling networks in 1962. (a) East Central [linois network and (b) Kaskaskia and Boneyard networks. diameter orifices. The galvanized buckets were coated with a plastic paint to reduce possible contamination. The buckets were washed with water from a pressure sprayer twice weekly on a routine basis and, occasionally, more frequently during periods of sample collection. On the Kaskaskia and the Boneyard networks, polyethylene containers with a catch area of approximately 300 sqin. were placed by each rain gauge to collect rainwater Samples since the rain gauges had 8-in. instead of 12.6-in. orifices. On these small networks the rainwater samplers were thoroughly cleaned shortly before each storm. The 1963 sampling networks are shown in Fig. 2. The outer border encompasses an area of 6000 square miles containing 16 auto-

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