Are you considering the age of (stormwater) infrastructure?
The age of the flow control or runoff facility is used to determine the levels of flow control and runoff treatment provided by existing facilities. If a facility was constructed before 1998, it is classified as providing limited treatment and/or flow control. The 1998 KCSWDM introduced the current flow duration standard for flow control. If a facility was built after 1998 it is classified as providing significant flow control and/or runoff treatment.
Looking through criteria, future conditions and zoning buildout isn’t shown. How are you aligning future buildout in the conversation?
Evaluation of a future buildout scenario is not a requirement of the NPDES Phase II watershed planning. In previous experience with detailed modeling of future buildout conditions, we have consistently seen that buildout with stormwater treatment meeting current standards is not further degrading flow and water quality conditions compared to existing. So existing conditions provide a reasonable “worst case” scenario. The plan for the selected subbasin may consider land use management actions or zoning changes to meet preservation or restoration goals.
Have we considered climate change in the modeling?
The scope of this study considered climate change in general. Existing hydrologic models of existing and future climate scenarios, developed for King County, were used to estimate increases in storm runoff (peak hourly and daily flows) for Sammamish watersheds.
Can you talk more about how you are accounting for receiving water conditions 303d listings?
The Receiving Water Assessment will include all 303d listings. Level 4 and 5 303d listings will be used as one indication of degradation within the basin.
Have you looked at how much of the undeveloped land will be developed in the future?
No, a future conditions analysis is beyond the scope of this study.
How are you addressing basins with undersized stormwater systems, such as those along the East Lake Sammamish Parkway?
One factor that may be considered as we identify Priority Basin(s) is known existing drainage issues such as undersized stormwater systems. Existing drainage issues may be considered as an indicator of degradation within the basin. Addressing existing drainage issues may also provide a future opportunity to improve flow control and/ or runoff treatment retrofit projects. However, the current study does not include the design of stormwater retrofit or infrastructure projects.
How are you being mindful of Kokanee Salmon?
Kokanee Salmon habitat is one indicator of the resource value of a receiving water and will be considered in the prioritization of basins for future retrofit projects and management actions. We are including Zackuse, George Davis (Inglewood subbasin), Ebright (Thompson subbasin), Pine Lake and Laughing Jacobs creeks as including Kokanee habitat.