Oregon Water Quality Index Report for the Grand Ronde Basin

Water Years 1986-1995

The Grande Ronde River and its tributaries drain the Blue and Wallowa Mountains and empty to the Snake River. The Grande Ronde Basin contains a number of wilderness areas including Eagle Cap, Wenaha-Tucannon, and Hells Canyon. The Grande Ronde Valley, in the upper subbasin, is the most heavily populated and most intensely cultivated area in the basin. Land uses in the basin include logging, irrigated and non-irrigated agriculture, urban/municipal uses, recreation, and mining. The Oregon Department of Environmental Quality is working with local watershed councils, water users groups, and agencies to develop a Total Maximum Daily Load for the Grande Ronde River. Water quality data were routinely collected by the DEQ Laboratory in water years 1986-1995. Additional biology, habitat, and water chemistry monitoring have been performed in the upper parts of the basin since 1991. On the average, Oregon Water Quality Index (OWQI) values at monitored sites in the basin range from fair (Grande Ronde River at Peach Lane) to excellent (Minam River) (Table 1). Water quality is commonly impacted by the introduction of organic matter to streams. The presence of organic matter increases biochemical oxygen demand, which means less dissolved oxygen is available for aquatic life. The introduction of untreated animal or human waste increases the possibility of bacterial contamination of water, increasing the risk of infection to swimmers. Eutrophication is the process of enrichment of water with nutrients, mainly nitrogen and phosphorous compounds, which results in excessive growth of algae and nuisance aquatic plants. It increases the amount of organic matter in the water and also increases pollution as this matter grows and then decays. Employing the process of photosynthesis for growth, algae and aquatic plants consume carbon dioxide (thus raising pH) and produce an overabundance of oxygen. At night the algae and plants respire, depleting available dissolved oxygen. This results in large variations in water quality conditions that can be harmful to other aquatic life. While natural sources of nutrients can influence eutrophication, the introduction of nutrients strengthens the process. Sources of nutrients include wastewater treatment facility discharge and faulty septic systems, runoff from animal husbandry, fertilizer application, urban sources, and erosion. High water temperatures compound the decline in water quality by causing more oxygen to leave the water and by increasing the rate of eutrophication. Removal of streamside vegetation, among other factors, influences high stream temperature and, via erosion, increases sedimentation of streams.

Table 1. Seasonal Average OWQI Results for Grande Ronde Basin (WY 1986 - 1995)

Summer: June - September; FWS ( Fall, Winter, & Spring): October - May
Scores - Very Poor: 0-59, Poor: 60-79, Fair: 80-84, Good: 85-89, Excellent: 90-100

Upper Grande Ronde Subbasin

The headwaters of the Grande Ronde River arise from the Blue Mountains in southwest Union County. The Upper Grande Ronde Subbasin is the most heavily populated and most intensely cultivated area in the basin. Since 1991, DEQ Laboratory has studied the effects of point and non-point source pollution in the subbasin. DEQ Laboratory has also studied the effectiveness of remediation activities, specifically the improvement of stream conditions in tributaries that had previously been channelized and/or grazed. Major tributaries to the upper Grande Ronde River, as it descends from the Blue Mountains, include Sheep, Meadow, and Beaver Creeks. The uppermost reaches of Beaver Creek are protected and serve as the City of La Grande's Watershed, the city's source of drinking water.

The uppermost site routinely monitored by DEQ Laboratory is on the Grande Ronde River at Hilgard State Park. This monitoring site is downstream of logging and grazing activities. The greatest impacts to water quality at this monitoring site occur during the summer, when flow is low and water temperature is warm. Eutrophication is evidenced by high pH, high dissolved oxygen supersaturation, and high biochemical oxygen demand. The high levels of biochemical oxygen demand are also seen in conjunction with high levels of total phosphates and fecal coliform during periods of heavy precipitation. This indicates the introduction of fecal and other organic materials to streams as a result of field runoff and erosion. On the average, OWQI scores for the Grande Ronde River at Hilgard State Park are good in the summer and excellent during the fall, winter, and spring (Table 1).

Eight miles downstream of Hilgard State Park, the Grande Ronde River enters La Grande and the Grande Ronde Valley. Water is diverted from the Grande Ronde River into irrigation canals at several points in the valley. The La Grande Wastewater Treatment Plant (WWTP) is permitted to discharge treated wastewater to the Grande Ronde River at Pierce Road, downstream of Island City. Further downstream, DEQ Laboratory monitors water quality in the Grande Ronde River at Peach Lane, at the center of the Grande Ronde Valley. High concentrations of total phosphates, fecal coliform, and biochemical oxygen demand were detected in the Grande Ronde River at Peach Lane during all seasons. Sources of phosphates and fecal coliform include fertilizer application, grazing cattle, WWTP overflow conditions, and leaky septic systems. High concentrations of biochemical oxygen demand indicate the introduction of organic materials to the creek, either from erosive forces or from decay of algae when eutrophication is active. Active eutrophication was evidenced by the high pH and high dissolved oxygen supersaturation detected during the summer, when flow is low and water temperature is warm. On the average, OWQI scores at this site were fair throughout the year (Table 1).

One mile downstream of Peach Lane, at river mile 150, the Grande Ronde River flow is diverted into the State Ditch. The State Ditch provides flood control and drainage for the central Grande Ronde Valley. The State Ditch returns to the Grande Ronde River at river mile 119. Between the diversion and the return, the original Grande Ronde River channel receives tributaries draining the western slopes of the Wallowa Mountains and Eagle Cap Wilderness. The largest of these tributaries is Catherine Creek. Catherine Creek descends from the Wallowa Mountains and flows through the city of Union, receiving treated wastewater from the Union WWTP, before entering the Grande Ronde Valley. It is also subjected to irrigation diversions and returns.

The most downstream site that DEQ Laboratory monitors on the Grande Ronde River is at HWY 82, on the eastern boundary of the city of Elgin. High concentrations of total phosphates and biochemical oxygen demand were detected throughout the year. High concentrations of fecal coliform and nitrate and ammonia nitrogen were detected during periods of precipitation, which allows contaminants into the river via erosion and field runoff. Sources of phosphates, nitrogen, and fecal coliform include fertilizer application, grazing cattle, irrigation returns and leaky septic systems. High concentrations of biochemical oxygen demand indicate the introduction of organic materials to the creek, either from erosive forces or from decay of algae when eutrophication is active. Active eutrophication was evidenced by high pH and high dissolved oxygen supersaturation detected during the summer, when flow is low and water temperature is warm. On the average, OWQI scores at this site were fair throughout the year (Table 1).

Wallowa Subbasin

The majority of drainage in the Wallowa Subbasin comes from the Wallowa Mountains and the protected Eagle Cap Wilderness. The wilderness and Wallowa Lake are popular recreational destinations. Other land uses in the subbasin include irrigated agriculture, grazing, and logging. The Wallowa River, after leaving the wilderness and the impoundment at Wallowa Lake, flows through the cities of Joseph and Enterprise, both of which are permitted to discharge treated wastewater from their respective WWTPs. The Wallowa River is subjected to irrigation diversions along this stretch. Between the cities of Enterprise and Wallowa, the Wallowa River converges with the Lostine River. The Lostine River Canyon projects an unprotected arm into the Eagle Cap Wilderness, serving to provide developed campgrounds in the interior of the wilderness. The Wallowa WWTP discharges treated wastewater to the Wallowa River downstream of the city of Wallowa and upstream of the mouth of Bear Creek, which also drains the Eagle Cap Wilderness.

DEQ Laboratory monitors the Wallowa River at the town of Minam, where the Wallowa and Minam Rivers converge. High concentrations of total phosphates, fecal coliform, and biochemical oxygen demand were detected throughout the year. Sources of phosphates and fecal coliform include fertilizer application, grazing cattle, WWTP overflow conditions, and leaky septic systems. High concentrations of biochemical oxygen demand indicate the introduction of organic materials to the creek, either from erosive forces or from decay of algae when eutrophication is active. Active eutrophication was evidenced by high pH and moderately high dissolved oxygen supersaturation detected during the summer, when flow is low and water temperature is warm. On the average, OWQI scores at this site were fair in the summer and good in fall, 7winter, and spring (Table 1).

In 1990, DEQ Laboratory resumed monitoring of the Minam River at Minam, after many years of not monitoring the river. The Minam River drains the Eagle Cap Wilderness and the entire river is protected as a wild and scenic waterway. Monitoring had been discontinued because the Minam River has very little water quality impairment. Monitoring resumed when it was realized that it is important to have pristine waters to compare with impaired waters. This most downstream stretch of the river can get relatively warm in the summer, when flow is low and solar radiation is high. Also, when flow is low there is less water available to dilute contaminants, such as the fecal coliform detected at moderate levels during one summer sample. During the winter, when precipitation is high, erosion and high river stages wash organic debris into the river, leading to moderate levels of biochemical oxygen demand. Still, average OWQI values for the Minam River at Minam are excellent throughout the year (Table 1).

References

Oregon Department of Environmental Quality, Water Quality Division, 1988. 1988 Oregon Statewide Assessment of Nonpoint Sources of Water Pollution. Portland, Oregon.

Oregon Department of Environmental Quality, Water Quality Division, 1988. Oregon's 1988 Water Quality Status Assessment Report (305(b) Report). Portland, Oregon.

Oregon Department of Environmental Quality, Water Quality Division, 1990. Oregon's 1990 Water Quality Status Assessment Report (305(b) Report). Portland, Oregon.

Oregon Department of Environmental Quality, Water Quality Division, 1992. Oregon's 1992 Water Quality Status Assessment Report (305(b) Report). Portland, Oregon.

Oregon Department of Environmental Quality, Water Quality Division, 1994. Oregon's 1994 Water Quality Status Assessment Report (305(b) Report). Portland, Oregon.

Written by Curtis Cude, Oregon Department of Environmental Quality, Laboratory Division