The mainstem of Ames Lake Creek (also referred to simply as Ames Creek) is horseshoe shaped, draining primarily rural residential uplands before traversing the APD across the floodplain of the Snoqualmie River. The upper reach is fairly steep as it roughly follows Union Hill Rd. before entering Ames Lake. Ames Lake measures 76 acres and is ringed with homes on over 100 lots that range in size from roughly ¿ acre to some that are greater than 1 acre in size. The creek continues northward from the lake outlet as it descends to the valley floor.

Like many other tributaries in the APD, the floodplain portions of Ames Creek and its tributaries have been deepened and straightened over the years to benefit agriculture along the valley floor. While numerous small tributaries and drainage channels enter Ames Creek throughout its course, Sikes Lake Creek is a key tributary that drains the northeast portion of the basin and Sikes Lake before joining the mainstem in the floodplain a short distance upstream from the creek mouth. As described below, water quality in the Sikes Lake Creek drainage differs from the mainstem for some parameters.

Chinook salmon, coho salmon and steelhead are known to utilize Ames Creek to different degrees. Chinook juveniles rear in the floodplain portions of the creek, while coho are known to ascend up to Ames lake and beyond for spawning and rearing. Steelhead use is believed to be less extensive than coho salmon in this basin, but more extensive than Chinook.

The Ames Creek floodplain is low-lying and thus prone to flooding when the Snoqualmie River is running high. Even when the Snoqualmie River has not overtopped its banks, the water level in the river can be high enough to flood Ames Creek, beginning at the creek mouth and flooding back into the valley. The photograph above (Figure 5, photo by K. Higgins) shows floodwaters spilling across NE 100th Street from north to south (right to left), while the creek itself flows from south to north (left to right). The majority of the APD within the Ames Creek basin is within the 100-year floodplain of the Snoqualmie River.

The Snohomish River Basin Salmon Conservation Plan highlights the need to protect and restore hydrologic and sediment processes in the Ames Creek sub-basin, neighboring Patterson Creek and other similar areas. The riparian corridor has been heavily altered in floodplain areas in particular, but upland areas also feature substantial encroachment of residential and agricultural development into riparian areas, loss of functional wetlands and mature forest cover. These types of changes tend to contribute to water quality degradation by increasing stream temperature as well as the input of pollutants and sediment. The loss of wetlands to filling can exacerbate flood flows in the stream while decreasing summer low flows.