This will cause suspended sediment and turbidity to rise. Since the Umptanum area is undeveloped, no soil tillage is taking place. The valley that the Umptanum Creek lies in is mostly sagebrush. On the other hand, the Wenas Valley is mostly fields and farming is widespread. As Wenas Creek continues toward the Yakima River, it flows through miles of residentially developed area.
Residential development can have many effects on water quality.
Issues here include road runoff, septic systems, pesticide and fertilizer use, and disruption of the soil for construction. There is no residential development on Umptanum Creek. Wherever there is development, there are going to be roads, and along with roads come road runoff. Runoff is what happens when it rains and washes road tar, tire rubber, and oil off of the road and into roadside ditches which eventually drain into nearby streams. The substances washed off the road can add to nitrate and turbidity levels in the stream.