In puan area the environmental surveys were carried out at two farms of hard clam, Meretrix lusoria from April 1987 to November 1978 in order to know heather the farm environments could be rehabilitated for the cultivation of hard clam or not. The range of temperature of surface seawater was $10.7{~}27.4^{circ}C$, pH $7.6{~}8.2$, salinity $22.3{~}30.3$ ppt, COD $0.20{~}4.71;mg/{ell}$, sulfide $0.04{~}0.22;{mu}g-at./{ell}$, suspended solid $34.8{~}199.3;mg/{ell}$ chlorophyll a $3.71{~}49.02;mg/m^3$, TIN $2.01{~}24.47;{mu}g-a5./{ell}$, phosphate $0.60{~}11.03;{mu}g-at./{ell}$ and silicate $4.04{~}476.36;{mu}g-at./{ell}$. The range of temperature of substratum (bottom soil) was $14.2{~}29.7^{circ}C$, pH $8.3{~}9.5$, water content of substratum was $0.28{~}0.49;mg/g$ dried mud, COD $2.80{~}50.94;mg/g$ dried mud, total organic matter $1.05{~}1.97\%$ concentration of total Kjedhal nitrogen $31.9{~}194.9;{mu}g./{ell}$ dried mud, and sulfide $0.032{~}0.133;mg/g$ dried mud. Fine sand was dominant ranging over $92{~}95\%$ and silt and clay was $2.8{~}8.1\%$ of the composition of substratum. Some residual agricultural chemicals, ${alpha},;{eta},;{gamma}$-BHC, heptachlor, heptachlor-epoxide, aldrin, DDE, DDT and dieldrin were detected in hard clams collected from Puan areas. Especialy, more chemical were detected during the period of rainfalls. From above results, it is considered that the hard clam frams were not yet recovered from deteriorated conditions for aquaculture.