In Pacific Northwest lakes, phosphorus is usually the limiting nutrient, but in general, higher nitrogen concentrations are also associated with more productive lakes. Lakes with good water quality and low productivity like Angle, Geneva, Lucerne, Pine, Pipe, Star and Steel tended to have lower nitrogen concentrations than lakes like Allen, Cottage, Dolloff, Fivemile, Leota, Spring, Trout, and Wilderness which have medium to high productivity. Many of the higher productivity lakes are linked to wetlands which may contribute to the higher nitrogen levels. Pet and livestock wastes have a high nitrogen content, so dispose of them properly before they leach into surface runoff or ground water. Finally, use native plants to help prevent erosion of topsoil and lake and stream banks.
Spring Lake is different than the rest because about a quarter of the shoreline is wetland.
Also, a large portion of the Spring Lake watershed is in King County Open Space, protecting it from future development. Even with these vast natural resources, Spring Lake has some challenges ahead. Residents completed a noxious weed survey of the lake in the summer of 98 and were dismayed at the extent of Eurasian watermilfoil throughout the lake. Earlier surveys had also shown developing areas of purple loosestrife along the shore. Some of those purple loosestrife infested areas are decreasing as cutting and other measures are being adopted.