Oregon Water Quality Index Report for the Umatilla Basin 

Water Years 1986-1995

The Umatilla River and its tributaries drain Oregon's northwestern corner of the Blue Mountains. The upper parts of the basin historically supported great runs of anandromous fish, but activities in the lower parts of the basin have dwindled those populations. While the upper parts of the basin are primarily used for logging, the majority of the basin primarily supports grazing, confined animal feeding operations (CAFOs) and irrigated and non-irrigated agriculture. Naturally dry, the lower Umatilla Basin was developed by the United States Bureau of Reclamation (USBR) in the early part of the century. Now, the McKay Reservoir and dam on McKay Creek are used to augment flow in the Umatilla River. Flow is depleted by diversion into various irrigation canals. Most of the flow in the lower parts of the Umatilla River is due to irrigation returns and groundwater recharge. The Oregon Department of Environmental Quality is working with the Umatilla Basin Watershed Council, the Confederated Tribes of the Umatilla Indian Reservation, and other agencies to develop a Total Maximum Daily Load for the river. The Umatilla River is listed as water quality limited for algae, fecal coliform, flow modification, pH, nutrients, and temperature. Water quality data were routinely collected by the DEQ Laboratory in water years 1986-1995 and intensive monitoring was conducted in the summer of 1993. Additional intensive monitoring was performed in 1996, however that data is not included in this report. On the average, Oregon Water Quality Index (OWQI) values at monitored sites in the basin are poor throughout the year, and water quality is worse in the summer than during the rest of the year. Results indicate that general water quality was best in the Umatilla River at
Oregon Highway 11 in Pendleton and worst in the Umatilla River at Westland Road in Hermiston (Table 1). Trend analyses performed on OWQI data for the Umatilla Basin indicate a significant improvement in general water quality in the Umatilla River at Yoakum.

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 Umatilla 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

Umatilla Subbasin

Although the Umatilla Basin contains several subbasins, including the Willow and Walla Walla Subbasins, DEQ Laboratory concentrates water quality monitoring efforts on the Umatilla Subbasin. The Umatilla River begins at the convergence of the North and South Forks of the Umatilla River, which drain portions of the Umatilla National Forest in the Blue Mountains. As the Umatilla River leaves the mountains and enters the dry climate of the Umatilla-Deschutes basalt flow, it passes through the Umatilla Indian Reservation and receives drainage from tributaries such as Meacham Creek. It then enters the city limits of Pendleton and reaches the most upstream DEQ Laboratory monitoring site on the Umatilla River at Highway 11.

Results from monitoring the Umatilla River at this site reflect water quality impacts from non-point source activities, such as logging, grazing, and agricultural activities. The greatest impacts to water quality at this monitoring site occur during the summer, when flow is at its lowest. Water temperature at this site tends to be warmer than at the other monitored sites, although this site is typically monitored later in the day than the other sites. Eutrophication is evidenced by high pH, high dissolved oxygen supersaturation, and high biochemical oxygen demand. On the average, OWQI scores for the Umatilla River at Highway 11 in Pendleton are poor in the summer and good during the fall, winter, and spring (Table 1). This represents background conditions in the Umatilla River, which can be compared to results from monitoring at downstream sites.

A short distance downstream from the monitoring site at Highway 11, the Umatilla River receives drainage from Wildhorse Creek. Wildhorse Creek drains Wildhorse Mountain and Reed & Hawley Mountain and passes through the cities of Athena and Adams before converging with the Umatilla River. The Athena Wastewater Treatment Plant (WWTP) is permitted to discharge treated wastewater to Wildhorse Creek between November and April. After converging with Wildhorse Creek, the Umatilla River flows through Pendleton, receiving drainage from McKay Creek at the western city limit. Pendleton WWTP discharges to McKay Creek near its mouth.

McKay Creek headwaters are in the Blue Mountains. Its waters are impounded at the McKay Reservoir. The reservoir and land immediately surrounding it are designated as the McKay Creek National Wildlife Refuge. The USBR regulates flow from McKay Reservoir with McKay Dam. Flow from McKay Creek is used to augment flow in the Umatilla River during the growing season, when water is diverted from the river for agricultural use. Uses of lands in the upper McKay Creek watershed include logging, grazing, and agriculture. DEQ Laboratory monitored water quality in McKay Creek one mile downstream from the McKay Dam from 1986 to 1993. High concentrations of nitrate nitrogen, total phosphates, fecal coliform, total solids, and biochemical oxygen demand were detected throughout the year. Sources of nutrients and fecal coliform include fertilizer application and grazing cattle. High concentrations of total solids indicate soil erosion. 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 of McKay Creek is evidenced by high pH and high dissolved oxygen supersaturation detected during water quality monitoring. On the average, OWQI scores at this site were poor throughout the year, with summer scores being slightly better than fall, winter, and spring scores (Table 1).

In 1993, DEQ Laboratory relocated monitoring efforts on McKay Creek downstream to Kirk Street in Pendleton. This shift was made to monitor the influence of non-point source pollution from the residential areas along the creek, rather than merely monitor conditions in the reservoir. This monitoring site is located in a suburban area, so the results of monitoring reflect local non-point pollution, such as runoff from paved surfaces entering the creek via storm drains, as well as the cumulative affects of non-point source pollution from upstream sources. High levels of nitrate nitrogen, biochemical oxygen demand, and pH persist at this location. Moderately high levels of total phosphates and dissolved oxygen supersaturation are occasionally detected. On the average, OWQI scores at this site were good in the summer and poor in fall, winter, and spring (Table 1).

After converging with McKay Creek, the Umatilla River continues west. It flows through the industrial district and log yard at Rieth before receiving drainage from Birch Creek. Like McKay Creek, Birch Creek drains a portion of the Blue Mountains and flows north toward the Umatilla River. Birch Creek passes through the city of Pilot Rock, alongside industrial waste ponds, and over two minor impoundments before reaching the Umatilla River. Lands in the Birch Creek drainage are used for logging, agriculture, grazing, dairy, and CAFOs.

After leaving Rieth and converging with Birch Creek, the Umatilla River continues west through lands used for agriculture and grazing. DEQ Laboratory monitors the Umatilla River at Yoakum, upstream of all USBR diversions. Eutrophication is active during the low-flow summer months when water temperatures are high, as indicated by high levels of pH and dissolved oxygen supersaturation. High concentrations of biochemical oxygen demand during the summer indicate the presence of algae and other organic material. Eutrophication in this stretch of the river is fueled by high concentrations of total phosphates. Total phosphate concentrations of the magnitude present at this site are not present upstream at the monitoring site on the Umatilla River at Highway 11. Sources of phosphates and the resulting eutrophication include Wildhorse Creek, Pendleton WWTP, McKay Creek, and Birch Creek. Moderately high concentrations of nitrate nitrogen were also detected at this site, which can be attributed to sources including McKay Creek. On the average, OWQI scores at this site were poor throughout the year, with summer scores being slightly worse than fall, winter, and spring scores (Table 1). Trend analysis shows that water quality conditions have significantly improved over the last ten years (Figure 1). Interestingly, the majority of improvement occurred during the late summer months.

Figure 1. Trend Analysis Results for the Umatilla River at Yoakum

The lands of the lower Umatilla Subbasin are heavily irrigated and used intensively for agriculture, grazing, and CAFOs. Other uses include industrial operations, food processing operations, and residential/municipal uses. Sources of irrigation include the Umatilla River, Cold Springs Reservoir, and the Columbia River. The lower Umatilla Basin has been designated as a groundwater management area, as excessive levels of nitrate nitrogen and other constituents are present in the water table. The primary sources of groundwater contamination appears to be irrigated agriculture, food processing land-application operations, large-scale CAFOs, and the Umatilla Army Depot washout lagoon. Residential septic systems have also contributed to this contamination. Local interests are currently developing an action plan to address the groundwater contamination problems in the lower Umatilla Basin. During summer when flow in the Umatilla is lowest, most of the flow in the river is either from irrigation returns or from groundwater discharge. Summarily, water quality in the lower Umatilla River is severely limited. Butter Creek is the largest natural tributary to the lower Umatilla River and drains areas used for agriculture and nurseries. WWTPs at Echo, Stanfield, and Hermiston, are permitted to discharge treated wastewater to the Umatilla River or nearby irrigation returns between November and April.

Upstream of the Hermiston WWTP, the DEQ Laboratory monitors water quality in the Umatilla River near the junction of Westland and Highland Roads west of Hermiston. Nitrate nitrogen is the biggest impact on water quality at this site, followed by high dissolved oxygen supersaturation, which is due to eutrophication. An overly abundant supply of nitrogen and a sufficient supply of phosphates is available to fuel eutrophication. Moderately high pH and biochemical oxygen demand values detected at this site also reflect the effects of eutrophication. Moderately high levels of total solids detected result mainly from erosion and are most likely returned to the river from irrigation canals. High levels of fecal coliforms were occasionally detected, and sources for this contamination include CAFOs and leaky septic systems. Finally, low flows combined with high solar radiation (due to lack of adequate shading of stream surfaces) during the summer led to warm stream temperature. Average OWQI values for the Umatilla River at Westland Road are very poor throughout the year, with most impairment during the summer (Table 1).

Acknowledgment: Software used for trend analysis was the WQHydro package developed by Eric Aroner of WQHydro Consulting.

References

Johnson, D. M., et al., 1985. Atlas of Oregon Lakes. Oregon State University Press, Corvallis, Oregon.

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