Oregon Water Quality Index Report for Umpqua Basin

Water Years 1986-1995

The Umpqua Basin consists of three distinct subbasins: South Umpqua, North Umpqua, and Mainstem Umpqua. The South Umpqua subbasin is the most populated and most challenged with respect to water quality. However, trend analysis shows an increase in water quality in the most populated stretch of the South Umpqua River. The North Umpqua subbasin has less pressure from population growth and has the best general water quality of the subbasins. However, a closer look at water quality trends in the subbasin is warranted. The Mainstem Umpqua subbasin receives drainage from the other two subbasins as well as from other tributaries. Water quality trends in the mainstem subbasin are mixed. Comparing minimum seasonal Oregon Water Quality Index (OWQI) values (Table 1), water quality in the Umpqua basin ranges from good (North Umpqua River site) to very poor (Deer Creek site). Water quality data were routinely collected by the DEQ Laboratory in 1986-1995.

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 the Umpqua 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

South Umpqua Subbasin

The South Umpqua subbasin is the most populated of the Umpqua Basin. Water quality impacts are due mainly to municipal point sources and partly to non-point sources of pollution.

The most upstream monitoring site in the Umpqua basin is the South Umpqua River at Days Creek Cutoff Road. This site is upstream of all major point sources. Water quality at this point is the best of the monitored sites in the South Umpqua subbasin. Temperature and pH limit water quality during the summer months at this site and at the Cow Creek site. The Cow Creek site differs in that it is directly downstream from mining sites at Nickel Mountain and from the wastewater treatment facility at Riddle. pH is typically higher at the Cow Creek site than at the uppermost South Umpqua River site. Supersaturation of dissolved oxygen also limits water quality at Cow Creek. This indicates that some eutrophication is occurring at the uppermost sites in the basin. Water quality at the South Umpqua River at Days Creek Cutoff Road ranges from fair in the summer to excellent during the fall, winter, and spring. Water quality at Cow Creek ranges from poor in the summer to good during the rest of the year (Table 1).

By the time the South Umpqua River reaches the next monitoring site at Winston, the effects of human activity become noticeable. Water quality is impacted by the cumulative effects of STP's at Canyonville and Myrtle Creek, by drainage from Cow Creek, and by rural and industrial non-point source pollution. High concentrations of fecal coliform and total solids and high biochemical oxygen demand indicate the introduction of human or animal waste and other organic materials to the water throughout the year. High water temperatures, low flows, and the addition of organic materials cause problems with eutrophication, resulting in occasionally high pH. Water quality has decreased compared to the monitoring site upstream (Table 1).

Deer Creek, near its mouth in Roseburg, displays the worst water quality among the monitored sites in the Umpqua basin. Significant amounts of fecal coliform, total solids, total phosphates, and biochemical oxygen demand impact water quality throughout the year. OWQI values range from very poor in the summer to poor in the fall, winter, and spring (Table 1). The source of this pollution is not readily identifiable. Fortunately, as the Deer Creek drainage is relatively small, impacts on the South Umpqua River from Deer Creek are expected to be small, especially during summer low flow conditions.

The South Umpqua River at Stewart Park Road is located in west-central Roseburg. Water quality during the summer is similar to the site in Winston, while water quality during the fall, winter, and spring has worsened in comparison (Table 1). Besides effects from Deer Creek, the Winston-Green STP may contribute to pollution with occasional overflows during storm events. Urban nonpoint source pollution in the form of runoff from paved surfaces may contribute to pollution at this site. Episodic high levels of fecal coliform, accompanied by high total solids, phosphates and biochemical oxygen demand during the winter, indicate the introduction of organic waste to the river.

The most downstream site on the South Umpqua River is at Melrose Road. This stretch of river is the recipient of all accumulated upstream sources not removed by natural self-purification. It is also directly impacted by a major wastewater treatment facility at the downstream end of Roseburg. Historically, high levels of fecal coliforms, total phosphates, and biochemical oxygen demand have hampered water quality. When these conditions are coupled with high water temperatures, eutrophication (especially heavy at this site) ensues. This brings high pH values and high dissolved oxygen levels which further degrade water quality. On the average, water quality is poor throughout the year (Table 1). However, during this time improvements have been made to regional wastewater treatment facilities, including the Roseburg plant, and results of trend analysis show a significant improvement in water quality from 1986 to 1995 (Figure 1).

Figure 1. Trend Analysis Results for the South Umpqua River at Melrose Road

North Umpqua Subbasin

The North Umpqua subbasin is less populated, with most of the population situated in the Sutherlin Creek drainage. Sutherlin Creek enters the North Umpqua River approximately three miles upstream from the monitoring site on the North Umpqua River at Garden Valley Road. The North Umpqua River generally exhibits the best water quality in the Umpqua basin, both in terms of instantaneous results and consistency over time (Table 1). However, the river experiences periodically high levels of fecal coliform, total phosphates, and biochemical oxygen demand during heavy precipitation. Wet weather events represent a combination of point and non-point source impacts. The North Umpqua River experiences relatively high summer water temperatures influenced by non-point source impacts. Increasing severity of these impacts has led to a significant decrease in water quality (Figure 2) during the same time as quality was increasing in the South Umpqua River (Figure 1). Water quality remains good in the North Umpqua basin, but a closer look at non-point source impacts may be warranted to reverse the decreasing trend.

Figure 2. Trend Analysis Results for the North Umpqua River at Garden Valley Road

Mainstem Umpqua Subbasin

Calapooya Creek enters the mainstem Umpqua River approximately eight miles downstream of the convergence of North and South Umpqua Rivers. The monitoring site on Garden Valley Road at the town of Umpqua represents influences from agricultural lands dominating that portion of the drainage. STP's at Oakland and Sutherlin discharge to Calapooya Creek. High levels of fecal coliform, total phosphates, total solids, and biochemical oxygen demand load the creek during all flow conditions. This indicates the presence of untreated animal wastes and other organic matter in the creek throughout the year. Heavy precipitation can result in overflow conditions at the STP's. During the low flow summer months, high water temperatures intensify water pollution. On the average, water quality is poor during the summer and fair during the fall, winter, and spring in Calapooya Creek (Table 1). Seasonal trend analysis indicates a significantly decreasing trend in water quality at this site (Figure 3). Point and non-point source impacts will need to be examined if an effort to improve water quality in Calapooya Creek is to be successful.

Figure 3. Trend Analysis Results for Calapooya Creek at Umpqua

The confluence of the North with the South Umpqua River dilutes the poor water quality seen at the mouth of the South Umpqua River. When we move downstream eight miles to the town of Umpqua, we see that the river's buffering capacity (its ability to resist impacts on water quality) has been largely restored. The monitoring site on the Umpqua River at the town of Umpqua is immediately downstream of the confluence of Calapooya Creek. Loading of the Umpqua River with fecal coliform, total phosphates, and biochemical oxygen demand correspond to loading of Calapooya Creek on the same date. Other than impacts from Calapooya Creek, water quality in the Umpqua River at Umpqua is generally good throughout the year (Table 1). In 1993 the mainstem Umpqua River monitoring location was moved downstream to the city of Elkton. We see that water quality averages have slightly improved (Table 1), possibly because of the distance from the nearest source of poor quality water (Calapooya Creek). The river is still impacted by biochemical oxygen demand in the wet seasons and by high temperature in the summer, so the effects of non-point source pollution are more evident.

Elk Creek enters the Umpqua River just downstream of the monitoring site in Elkton. Elk Creek was originally monitored at Hayhurst Road in Drain, just downstream of Drain's wastewater treatment facility. Water quality in Elk Creek was impacted by high levels of fecal coliform, total phosphates, total solids, and biochemical oxygen demand. Occasionally high temperatures also influence water quality in Elk Creek. OWQI scores for Elk Creek at Drain were generally poor throughout the year (Table 1). Fortunately, over time the frequency and severity of these impacts lessened, leading to a significant increase in water quality from 1986 to 1993 (Figure 4). In 1993 the Elk Creek monitoring location was moved downstream to the city of Elkton. After flowing through Drain, Elk Creek meanders through Putnam Valley before dropping through the forested hills above Elkton and into the Umpqua River. This steep gradient change assists the creek in purification and we can see that OWQI scores have improved to generally good quality throughout the year (Table 1). The river is still impacted by high fecal coliform, total phosphates, total solids, and biochemical oxygen demand in the wet seasons and by high pH, total solids, and temperature in the summer, so the effects of non-point source pollution are more evident.

Figure 4. Trend Analysis Results for Elk Creek at Drain

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

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