David Sherwood is among several property owners along a stretch of Walker Creek that the Marin Resource Conservation District will study with help from a $345,000 state grant. The assessment, focused on enhancing habitat for coho salmon and steelhead trout, will include designs for floodplain resotration projects on the critical lower three miles of the creek, through which all the anadromous fish must pass. Past projects on the creek faciliated by the R.C.D. have paid off, with a growing number of fish counted in recent years. The district believes that increasing areas of slow-moving water during strong storms will lead to successes such as those seen on Lagunitas Creek.   David Briggs