Yaquina Estuary is to prevent future degradation of estuarine water quality and accompanying 
loss of beneficial uses from the system. 
1.3 Designated Uses of Yaquina River and Estuary, Impairments and Assessments 
The Yaquina River and Estuary have many designated uses, including aquatic life 
harvesting (shellfish growing and fishing), agricultural (livestock watering), municipal (public 
water supply), recreation (water contact recreation), ecological (resident fish and aquatic life, 
salmonid spawning and rearing, anadromous fish passage) and aesthetics (Table 1.1). Causes for 
impairment listings in the Yaquina Estuary and River include pathogens, thermal modifications, 
diminished biologic integrity, and organic enrichment/low dissolved oxygen (Table 1.1). Most 
of the impairments occur in the Yaquina River, with the exception of fecal coliform impairment 
which occurs in the lower portion of the estuary. 
The Oregon Department of Environmental Quality (ODEQ) assessed the water quality in 
the Oregon Mid Coast Basin, which includes the Yaquina River during 1986-1995 (Cude, 1995). 
The following is an excerpt from this assessment. 
Nitrate nitrogen is the primary limiting factor on water quality throughout the Mid Coast 
basin. High levels of nitrates accompanied by increases in total phosphates, total solids, 
and biochemical oxygen demand, appear during periods of heavy precipitation. 
Nutrient-rich erosion products deposited during storm events place a high demand on 
available dissolved oxygen in the water. These products may be naturally occurring, but 
are more likely the result of non-point source pollution. 
As part of this ODEQ study, an Oregon Water Quality Index (OWQI) that incorporates 
temperature, dissolved oxygen, biochemical oxygen demand, pH, total solids, ammonia and 
nitrate nitrogen, total phosphorous and fecal coliforms was developed. Based on this index, 
water quality for the Yaquina River (at Rivermile 24.9) was categorized as poor during the fall, 
winter, and spring, and good during the summer. The water quality in the Yaquina estuary was 
reassessed in 2006 using data from water years 1996-2005 (Mrazik, 2006). In this more recent 
assessment, the Yaquina River was assessed as having good condition throughout the year. 
In the National Estuarine Eutrophication Assessment (Bricker et al., 1999), the Yaquina 
Estuary was placed in the low category of eutrophication status based on a qualitative assessment 
that it exhibited few symptoms of eutrophication. However, conditions were expected to worsen 
2 
