In 2013, DEQ laboratory staff collected seasonal (April, September and November) water samples at 18 locations across the Mid Coast Basin. The sampling locations represented a range of watershed sizes and land uses as well as both freshwater and estuarine environments. Samples collected at the sampling location farthest upstream in the Siuslaw River watershed at Siuslaw Falls contained the greatest number of unique chemicals. The laboratory analyzed samples collected in the Mid Coast Basin for more than 500 unique chemicals. Of these, 49 chemicals were detected at least once.

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To capture seasonal use patterns and hydrologic differences, collection of water samples took place three times during the year. In general, spring and summer samples contained the greatest number of unique chemicals.

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In general, based on the sampling conducted in this study flame retardants, legacy pesticides and thallium are a concern in the upper Siuslaw River watershed. Additionally, the consistent detection of BHC compounds along the coast as well as coastal ammonia exceedances is also of concern and may warrant additional investigation. 

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Priority metals

This group includes all metals for which Oregon has existing water quality criteria. These metals occur naturally and may also be enriched by human activities. Because of this, detections of these metals are common in water. Water samples contained nine different metals with the greatest number, six, found at the Cummins Creek site. Iron exceeded the DEQ aquatic life criterion (1000 μg/L) at two sampling locations, Lake Creek at Sumich Rd during summer sampling and Siuslaw River at Siuslaw Falls during the summer and fall sampling events. The inorganic arsenic level at the Alsea River Port Docks site exceeded water quality criterion (1.0 μg/L) for the protection of human health for saltwater during summer sampling. No freshwater locations exceeded the inorganic arsenic criterion. Thallium, a rarely detected compound across the state, exceeded the applicable water quality criterion (0.043 μg/L) at the Siuslaw River sampling location at Siuslaw Falls Park during spring sampling.

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Current use pesticides

Four current use pesticides, all herbicides, were detected in the basin. No site had detections of more than one herbicide. Diuron, a commonly used commercial and agricultural herbicide, was the most common with detections at three sites, Schooner Creek, Yaquina River at Trapp Rd and Marker #47. All 27 diuron detections occurred during summer sampling. Atrazine was detected at the Wolf Creek site during spring sampling. Fluridone, an herbicide used for aquatic weed control, occurred in the spring sample at the Panther Creek site and trifluralin was detected during the spring at the Suislaw River at Siuslaw Falls site. The levels of these herbicides did not exceed any applicable EPA benchmark or DEQ criteria for the protection of aquatic life.

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Legacy pesticides

Detections of legacy pesticides occurred at four sites in the Mid-Coast Basin. The Siuslaw River at Siuslaw Falls had the greatest number of unique chemicals in this group, eight. Of which, five (aldrin, dieldrin, heptachlor, heptachlor epoxide and hexachlorobenzene) exceeded their applicable Oregon DEQ criteria for the protection human health. All detections at the Siuslaw River at Siuslaw Falls site occurred during the spring with the exception of endosulfan sulfate, which occurred during the summer and fall. Detections of BHC-alpha occurred at one freshwater site, Siletz River at Moonshine Park, during summer sampling. Samples from the two estuary sites, Alsea River at Port Docks and Siuslaw River at Florence, contained detectable levels of BHC-alpha and beta. These compounds also were found in other estuaries along the Oregon coast and may be transported via the air. Because of their chemical nature, legacy pesticides tend to persist in sediments and bio-accumulate in the food chain making them a concern in the environment.

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Combustion by-products (including dioxins and furans)

Detections of combustion by-products occurred at three sites in the Mid Coast Basin. These detections occurred during the summer and fall. Combustion by-products are associated with incomplete combustion of organic matter from automobiles, fossil fuels burning, woodstoves and cigarette smoke. They may also be the result of stormwater run-off. All six compounds detected in the basin occurred in 28 samples from the Yaquina River at Trapp Rd site. Of the six compounds detected at this site, all six were present during the summer sampling, but only two, phenanthrene and fluoranthene, were present during fall. Two compounds, benzo(b)fluoranthene and chrysene, exceeded Oregon DEQ Table 40 water quality criteria at the Yaquina River site, both during the summer sampling. The only detection of anthracene, statewide, occurred at the Yaquina River site below the applicable water quality criterion. Three combustion by-products were detected in the estuarine site, Alsea River at Port Docks. One compound, benzo(b)fluoranthene, exceeded its applicable water quality criterion at this site during the fall sampling. No detectable concentrations of dioxins and furans occurred in any samples in the Mid-Coast Basin.

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Flame retardants

The most common group of chemicals detected in the basin was flame retardants with 14 compounds detected. Two sites in the Siuslaw River, at Siuslaw Falls Park (10 compounds) and at the Florence Boat Docks (9 compounds), accounted for a majority of these detections. Additional compounds were detected at Yachats River at RM 0.9 (1 compound), Wolf Creek at mouth (1 compound) and Alsea River at Mill Creek (2 compounds). Due to laboratory capacity, analysis for this group of chemicals only took place once, therefore, seasonality of these compounds cannot be discussed. There are no federal or state criteria developed for this chemical group, however, concern over these chemicals in humans and the environment prompted a ban on their manufacture and use. Similar to PCBs in structure, these chemicals tend to bio-accumulate in the food chain and are most often associated with sediments in the aquatic environment.

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Plant and animal sterols

The laboratory measured four plant and animal sterols in the Mid-Coast Basin. All four of these sterols occur naturally in the environment but may also be enriched by humans and human activities. None of the 29 sterols detected currently have a screening value. The predominant source of the two plant sterols analyzed, beta-sitosterol and stigmastanol, is terrestrial plants. Other sources of these sterols may be industrial processes (wood pulping, food oils) and modern pharmaceutical supplements. Beta-sitosterol and stigmastanol were detected at all locations in the Mid Coast Basin. Levels varied across the basin with the lowest values detected at the Alsea River at Port Docks (beta-sitosterol) and Siletz River at Moonshine Park (stigmastanol) sites and the highest values detected at the Alsea River at Mill Creek (beta-sitosterol) and Yachats River (stigmastanol) sites. The laboratory also measured two animal sterols, cholesterol and coprostanol (both 100 percent detection). Measured levels varied across the basin with the lowest levels detected at the Cummins Creek (cholesterol) and Siletz River at Moonshine Park (coprostanol) sites and the highest levels detected at the Lake Creek at Deaddog Hole (cholesterol) and Schooner Creek (coprostanol) sites. Coprostanol is specific to fecal matter from humans and higher mammals (i.e., cattle and birds) as it is formed during digestion from cholesterol. The ratio of coprostanol to cholesterol may be used to evaluate contamination by human sewage. A ratio less than one indicates a biogenic source (i.e., livestock, higher animals) and greater than one a sewage or human source. Ratios measured at all sites in this study were less than one, potentially indicating a biogenic source of coprostanol.

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Consumer product constituents including pharmaceuticals

The lab analyzed water samples for 28 consumer product constituents including pharmaceuticals. Five compounds in this group were detected across three sites. Three pharmaceuticals, carbamazapine (anti-convulsant), sulfamethoxazole (antihistamine) and venlafaxine (mood enhancer), were detected in Schooner Creek. Carbamazapine and venlafaxine were detected during the summer sampling while sulfamethoxazole was detected during all three sampling events. This location receives discharge from a major wastewater facility. The insect repellant, DEET, was detected at one site, Siletz River at Moonshine Park, during the summer sampling. In addition, the plasticizer, bis(2-ethylhexyl)adipate, was detected in Wolf Creek during the spring sampling. This compound is used in common personal care products such as nail polish and cosmetics as well as in aircraft hydraulic fluids. Water quality criteria or benchmarks do not exist for these compounds.

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Industrial chemicals, ammonia and PCBs

Ammonia is a naturally occurring compound commonly found in waste products. It is included as an industrial compound because of its use in fertilizers and dyes. It may be extremely toxic to aquatic organisms. Detectable levels of ammonia occurred in samples from 14 of 18 sites. Most of these detections were measured during the summer with occasional detections in the spring and fall. No samples exceeded current aquatic life water quality criteria. No samples contained detectable levels of any other industrial chemicals or PCBs.