Environmental Impact


The Sammamish Valley ecosystem includes the entire broad valley trough, steep bluff hillsides, and upland plateaus created as glacial ice cut into deposits from earlier glacial advances.  When the valley was carved out, the ice created the steep sided bluffs of the valley and uplands, now known as English Hill and Hollywood Hill on the eastern side of the valley.  The surface of the uplands generally lie between 300 and 500 feet above the valley floor and are bordered by the steep sided bluffs. The floor of the Sammamish Valley is relatively flat with low valley bottom gradients.

Proposed urban use development in the Ordinance lies directly on top of the King County Special District Overlay 120 (SO-120). The purpose of SO-120 is to provide a Rural Area Buffer on the steep side slopes of the Valley between valley floor agriculture and upslope residential land uses, and does so by strictly limiting impervious surfaces in the Overlay. Placing commercial, urban use development directly in the specially designated steep sloped rural buffer to the agricultural lands and Sammamish River has significant negative impacts.

The Rural Area Buffer includes some environmentally sensitive sections including areas of steep slope, erosion, landslide, and seismic hazards.  In addition, drainage from the upland plateaus has created eleven mapped, perennial small creeks cutting down the valley slopes. These creeks and other seeps all drain into the valley and converge with the Sammamish River.  Several, including Gold and Derby Creeks, support fish populations.  All water discharges from the uplands and from the Rural Area Buffer eventually flow downward to the Sammamish Valley floor. The Rural Area Buffer is necessary to protect the valley floor from the erosion and deposition of sediments from the valley bluffs and from changes in the surface and groundwater hydrology flowing to the Sammamish River.

Sammamish Valley Farmland

Sammamish Valley farmers produce fresh, high quality, local produce on the incredibly fertile soils. The Valley is considered to be one of the most fertile agricultural valleys in the country, with the capacity to feed 80,000 people fresh vegetables using intensive organic growing methods.

Farm yields for 2012 were a little over 100 tons of high quality produce grown on 10 acres for one farmer, which is approximately 3 times the USDA average. The unique soils of the Sammamish Valley are capable of such high yields because of the 2 feet of top soil underlain by 4 inches of volcanic ash and a layer of preserved leaves. The Valley can supply sustainable high yields for the future as climate change decreases yields in the Midwest and California. If farmed to its full potential, the Valley could annually produce more than $54 million worth of fresh, local organic vegetables.

Surface Flow and Groundwater Contamination

The Ordinance allows for large parking lots and impervious surface areas in Rural Areas, including on the steep slopes of the SO-120 rural buffer to the Sammamish Valley APD. The current violators have no stormwater or surface water catchment systems or sewers, and thus are contaminating multiple water bodies. Rainfall from the upland slopes races down the structures’ roofs, hard surfaces and asphalt parking lots, heating the water and washing toxics and trash directly across the farmland and into the Sammamish River. Farmers struggle with waterlogged soils and toxicity. Both the speed and intensity of the water once it reaches the Valley floor increases sedimentation in the Sammamish River. Any increases in impervious surfaces in the Rural Area Buffer has an immediate and detrimental effect on the farmland and river in the Valley bottom.

Of particular concern, in regard to groundwater contamination, is the overuse of the septic systems in old single family homes which have been illegally converted to bars and entertainment centers. Several of the violators must pump the inadequate household septic systems far too often. These potentially failing systems may leach excess or inadequately treated waste water into the groundwater, causing potential contamination of the Valley groundwater, which can spread into the Sammamish River.

Habitat Loss

The Ordinance affects the whole Sammamish Valley ecosystem, which includes the sloped Rural Area Buffer, the Agricultural valley floor, and the Sammamish River watershed. Currently the Rural Area Buffer is a wildlife habitat hosting numerous species. The 2016-17 Audubon Society field survey found over 100 bird species in the Rural Area Buffer and along the Sammamish River. These species include hawks, owls, great blue herons, osprey, and bald eagles. The Valley also serves as a resting site for birds migrating on the Pacific Flyway. In addition, many mammalian species (including deer, rabbits, bats and beavers), insect and reptilian species, also flourish in the Rural Area Buffer. All would be displaced by noisy, lighted bars and event centers.

Harm to Threatened Salmon Runs

Eliminating protection from the Rural Area Buffer threatens fish runs with stream-side development. The Sammamish Valley is home to the Sammamish River, a major migratory route for multiple salmon runs, including those from the Issaquah Hatchery, and numerous contributing watersheds in WRIA 8. Over $80,000 has been spent for salmon habitat and recovery in the watershed. The water must be kept clean and cool to sustain these fishery resources both for citizens and wildlife.

Commercialization of the Rural Area Buffer harms multiple surface water features including 11 small tributary creeks (among them Derby Creek, Gold Creek, and Tributary 0095 which all have fish habitat enhancement projects built or in final planning). These tributaries provide a source of cool, clean water for Salmonid species, and with restoration, spawning and rearing habitats. 

Chinook Salmon and Steelhead Trout, both listed as threaten under the Endangered Species Act are known to be present in the Sammamish River. In addition, Coho Salmon, Sockeye, Kokanee, and Cutthroat Trout are also located in the Sammamish River, along with numerous other native freshwater species. The species include those traveling to/from spawning and rearing habitats which use the Sammamish River as a major migratory route.

The Ordinance directly harms the fishery resources by increasing warm, impervious surfaces leading to increased hot, toxic runoff and sedimentation. Several bars and event centers have parking lots within five feet of Derby Creek and other direct tributaries to the Sammamish River with no stormwater pollution prevention controls. All water contamination threatens the salmon, and other fish, aquatic and avian species frequenting the area.

Harm to Farm Ecosystem

A healthy farm ecosystem has to maintain a certain size in order to function. Any change in density of rural lands surrounding farmlands has an immediate and detrimental effect on farming production, which is why SO-120 (discussed above) is so important to sustaining the Sammamish Valley APD.

Specifically, water management can make or break farms and agricultural-related businesses. Rural areas do not have storm sewers, so storm water runoff from roads and uphill properties pollutes farmland and makes it too wet to farm. Farmers often are unable to build diversion ditches for polluted runoff. Farms in the APD have already lost land to farming due to runoff issues from recent development. Since some of this land is in the Farmland Preservation Program, this loss is not only the farmer’s loss, but a loss to all the citizens of King County who voted to tax themselves so that food could be produced here.

Both land price speculation and water management issues have a direct and immediate impact on farms in the APD. Bringing urban activities onto Rural Area Buffer lands to the APD will harm the viability of the APD.

Ill-conceived urban use development within the Sammamish Valley ecosystem has a direct negative impact on farming, the watershed, fish and wildlife, and on all citizens, who rely on these resources now and into the future.

KC Special Overlay SO-120.jpg