In the construction of artificial lakes on intermittent streams, for which funds are appropriated by the general assembly, the commission shall not proceed with actual construction work unless and until soil conservation practices are in effect on at least seventy-five percent of the land comprising the watershed of the proposed impoundment, or a willingness to carry on such practices has been shown by the owners or operators of seventy-five percent of the land by signing of a soil conservation farm plan and cooperative agreements with the local soil and water conservation district governing body.