We had a landscaping company till in compost, install irrigation and hydroseed last October. The rains we had in the Puget Sound area washed a fair percentage of it away. They came back a couple of weeks ago, cleaned up the mess, installed some drains and hydroseeded the washed out areas. The weed whose pictures I have attached was growing sparsely in one are but in the past 2 or 3 weeks has gotten much thicker in that area and is appearing all over the lawn. Any help in eradicating this weed would be greatly appreciated as I have 29,000 square feet of lawn and I don't want it spreading over the whole area. The lighter area extending to the left from the umbrella is the concentration of this weed.