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Numerous water quality studies have been conducted throughout the Johnson Creek watershed. Unfortunately, many were conducted with objectives other than characterizing the entire Johnson Creek watershed. Other sampling programs were designed to provide site-specific water quality data related to a capital improvement project or were of limited duration. As a result, there is no recent summary characterizing the water quality throughout the entire watershed. A brief summary is provided from recent data collected by local jurisdictions as well as efforts related to DEQ’s development of the Total Maximum Daily Load (TMDL) and recent data collected by the USGS.
DEQ rates Johnson Creek water quality as poor. DEQ utilizes the Oregon Water Quality Index (OWQI) to analyze a set of water quality parameters to produce a score describing general water quality. Water quality parameters used in this index include temperature, dissolved oxygen (percent saturation and concentration), biochemical oxygen demand, pH, total solids, ammonia and nitrate nitrogen, total phosphorus, and fecal coliform bacteria. OWQI scores range from 10 (worst case) to 100 (ideal water quality). Table 6 summarizes the seasonal average OWQI results for the Lower Willamette Basin during the 1986 –1995 Water Years.
Table 6. Seasonal Average Oregon Water Quality Index (OWQI) Results for the Lower Willamette Basin (WY 1986-1995)
| Site |
River Mile |
Summer Average |
FWS |
Minimum Seasonal |
| Tualatin River @ Rood Bridge |
39 |
78 |
66 |
66 |
| Tualatin River @ Hwy. 210 (Scholls) |
26.9 |
50 |
48 |
48 |
| Tualatin River @ Elsner Road |
16.2 |
53 |
57 |
53 |
| Tualatin River @ Boones Ferry Road |
8.6 |
37 |
40 |
37 |
| Beaverton Creek @ 216th Ave. (Orenco) |
0.3 |
36 |
59 |
36 |
| Fanno Creek @ Bonita Road (Tigard) |
2.3 |
55 |
55 |
55 |
| Clackamas River @ High Rocks |
1.2 |
87 |
88 |
87 |
| Johnson Creek @ SE 17th Avenue |
0.2 |
26 |
30 |
26 |
| Columbia Slough @ Landfill Road |
2.6 |
30 |
22 |
22 |
| Willamette River @ Hawthorne Bridge |
13.2 |
79 |
74 |
74 |
| Willamette River @ SP&S RR Bridge |
7.0 |
74 |
75 |
74 |
| Swan Island Channel (Willamette River) |
0.5 |
63 |
77 |
63 |
WY = Water Year (October-September)
Summer = June –September
FWS = (Fall, Winter, & Spring)
Scores = Very Poor 0-59, Poor 60-79, Fair 80-84, Good 85-89, Excellent 90-100
DEQ has been monitoring Johnson Creek at SE 17th Avenue since 1990. OWQI scores listed in Table 6 reveal that this site scored greater than 30 only twelve percent of the time. All results were in the “very poor” range of OWQI scores. Johnson Creek is impacted by very high concentrations of nitrate-nitrogen and high concentrations of total phosphates, fecal coliform bacteria, total solids, and biochemical oxygen demand also impair water quality at this location. These conditions occur throughout the year. On average, OWQI scores for Johnson Creek are very poor as indicated in the above table. Of all of the DEQ-monitored sites in the Willamette Basin, only the Columbia Slough scores are worse than Johnson Creek in terms of minimum seasonal averages (see DEQ web site at http://www.deq.state.or.us/lab/wqm/wqimain.htm).
The City of Portland has been monitoring Johnson Creek in response to a number of programs and projects. Portland monitored ambient conditions within Johnson Creek at five main stem locations and two tributaries (Crystal Springs and Kelley Creek) during 1996-2000. Generally, the monthly grab samples revealed fair dissolved oxygen concentrations, and high temperatures and E. coli bacteria levels, as referenced above. Selected water quality results during the past five years during the summer season (July through October) are presented in a table in the Action Plan in Appendix C.
Most pollutants are washed off land surfaces and discharged to waterbodies during storm runoff events. Storm event monitoring can provide opportunities to identify nonpoint pollution sources and loadings. The City of Gresham has conducted water quality sampling programs at various locations in Johnson Creek since the early 1990’s. During Permit Year 6 of their NPDES Permit, Gresham sampled four locations within Johnson Creek during 2000–2001 at the upstream and approximate downstream jurisdictional boundaries and two intermediate locations near Main City Park. Both routine monthly and storm event monitoring were conducted. Table 7 summarizes results from monitoring Johnson Creek at Palmblad Road (upstream jurisdictional boundary) during four storm events in 2000-2001.
Table 7. Storm Event Sampling Results in Johnson Creek at Palmblad Road (Gresham)
| Water Quality Parameter |
Maximum value |
Mean value (four storms) |
| Turbidity |
544 ntu |
399 ntu |
| Total Suspended Solids |
491 mg/L |
199 mg/L |
| Total Phosphorus |
930 ug/L |
492 ug/L |
| E.coli bacteria |
5,900 cfu/100mL |
2,525 cfu/100mL |
ntu = nephelometric turbidity unit
ug/L = micrograms per liter
mg/L = milligrams per liter
cfu = colony forming unit
Results from the above storm events reveal extremely poor water quality conditions as compared to “natural” conditions and state and federal standards and recommended guidelines. In fact, the mean values in Table 7 exceed state water quality standards or EPA guidelines ranging from 2.4 to 6.2 times more (EPA, 1999, and 1986; OAR, 1992). The maximum value for E.coli bacteria listed in Table 7 (5,900 cfu/100mL) is more than 14 times the state water quality standard of 406. Also, the desired phosphorus goal for the prevention of plant nuisances in streams is 100 µg/L (EPA, 1986). Finally, in a study downstream from the discharge of a rock quarry where inert suspended solids were increased to 80 mg/L, the density of macroinvertebrates decreased by 60 percent while in areas of sediment accumulation, benthic macroinvertebrate populations also decreased by 60 percent regardless of the suspended solids concentration (Gammon, 1970).
While some studies reveal that oxygen levels in Johnson Creek do not generally fall below water quality standards, levels do decrease in the middle, flat section of the creek, possibly a result of the addition of oxygen depleted groundwater into the area. The City of Portland’s Ambient Monitoring Program sampling during July though October, 1998-2002, revealed minimum DO values ranging from 5.5 to 9.8 mg/L with a mean value of 7.84 mg/L. A number of these values do not meet the state standard of 11.0 mg/l for spawning periods and 8.0 mg/L all the rest of the time. (See City of Portland Ambient Monitoring Results summary and DEQ Dissolved Oxygen and Intergravel D.O. Criteria DEQ Table 21 in Appendix C (PDF, 10 KB).)
A number of studies of nutrient levels in Johnson Creek show high levels of phosphorus (P) and nitrogen (N) at various locations. Nitrate levels were found to increase downstream and particularly where there is low flow. Nitrate levels are also high in Crystal Springs, likely a result of leaching from septic tanks and input from the duck pond in Westmoreland Park (McConnaha 2002).
A 2002 study of the sources and hydrologic pathways of nutrients
in an urbanizing landscape and their relative nutrient contributions to Johnson
Creek revealed that Total Phosphorus (TP) concentrations did not vary significantly
between urban and non-urban areas for the entire study period or during the
wet season. This is thought to be the result of the continuous input of particulate
P that is an unreactive form and transported by surface runoff from both urban
and agricultural areas within the watershed (Heathwaite and Johnes, 1996). Other
sampling results of this study found that surface and near-stream shallow groundwater
have significantly higher phosphorus concentrations within urban areas, while
stream water and near-stream groundwater nitrogen concentrations were higher
in non-urban areas. Johnson Creek surface water had almost twice as much N than
near-stream groundwater. These results indicate that Johnson Creek receives
significant input of N to the stream from surface sources. Significantly higher
stream water N levels were correlated with non-urban landuse areas, while elevated
levels of P were highly correlated with urban land use.
Turbidity has been monitored during both high and low flow conditions in Johnson Creek. Relatively high turbidity levels were measured during both high and low flow conditions, and are most likely a result of bank erosion, roadside ditch erosion, runoff from construction activities, and runoff from agricultural and nursery operations. Turbidity levels are high in the upper portions of the watershed indicating that sedimentation begins and sources are most likely originating in the upper watershed. See stormwater discussion below for more details on high turbidity and total suspended solids data in the upper Johnson Creek watershed area.
Johnson Creek has elevated levels of many metals and is classified as a “waterbody of concern” by the Oregon Department of Environmental Quality due to elevated levels of copper, chromium and nickel in water and sediments. Higher levels of copper and zinc are found when flows are high, most likely a result of runoff into the creek. Generally, metal concentrations increase downstream. When flows are high Johnson Creek may also be a source for chromium, copper, mercury and zinc in the Willamette River (McConnaha 2002).
In general, water quality in Johnson Creek is considered poor. During 1998, Johnson Creek was placed on the 303(d) list by DEQ for summer temperature, bacteria, and toxics (DDT and Dieldrin). Temperature was listed, although data collected was obtained during a drought year. Temperature was de-listed during 2002, however, due to numerous data results showing temperature problems throughout the watershed, DEQ is currently moving forward with development of a Total Maximum Daily Load (TMDL) for temperature (Geist, 2003). In addition, DEQ added PCBs, and PAHs to the 2002 303(d) list. The 303 (d) listing includes the entire stream, from the mouth to headwaters.
Temperature
The numerous investigations of temperature in Johnson Creek over the years have consistently indicated that elevated temperatures are a problem throughout the watershed. Elevated temperatures, with some potential contribution from elevated nutrients, result in dissolved oxygen concentrations that frequently drop below guidelines in the summer.
While there is not a long-term temperature record for Johnson Creek the USGS has collected temperature records from 6 stations since 1998 (3 along mainstem, 2 in Crystal Springs and 1 in Kelley Creek). The existing data provides a good understanding of seasonal temperature patterns and dynamics. From an analysis of one year of data it appears that there are more total days with maximum temperature above 20 degrees when moving downstream. Kelley Creek had the fewest days above 20 degrees C (McConnaha 2002).
The City of Portland’s Ambient Monitoring Program found that over a 4-year period, mean maximum summertime temperatures in Johnson Creek exceeded state standards (See City of Portland Ambient Monitoring Results summary table in the Action Plan in Appendix C (PDF, 10 KB).) For the Willamette Basin for which salmonid fish rearing is a designated beneficial use this standard is 17.8 degrees C. Data collected by BES as well as DEQ indicate that water temperatures in Johnson Creek peak between River Miles 5 and 6.5 – approximately 60th Avenue upstream to I-205 (Geist, 2003). (See City of Portland Ambient Monitoring Results summary table in the Action Plan in Appendix C (PDF, 10 KB).)
Although it is fed by cool groundwater springs, Crystal Springs Creek has warmer summer and wintertime temperatures than Johnson Creek and may present a source of high summer water temperatures in lower Johnson Creek. This may be attributed to solar warming in ponds along the creek located at Reed College, the Rhododendron Gardens, Eastmoreland Golf Course and Westmoreland Park (McConnaha 2002).
Bacteria
Several studies found that bacteria concentrations in Johnson Creek exceed state water quality criteria. Concentrations are highest during high flows, most likely a result of stormwater outfalls discharging surface runoff from areas with leaking septic tanks or cesspools or areas with high concentrations of animal wastes.
Routine monitoring by both Portland and Gresham reveal high bacteria levels throughout the Johnson Creek watershed. Data suggest that the bacteria levels exceed state water quality standards for E. coli bacteria. These standards include a 30-day log mean of 126 E. coli organisms per 100 mL, based on a minimum of five samples, and no single sample shall exceed 406 E. coli organisms per 100 mL. The City of Portland’s Ambient Monitoring Program conducted monthly sampling revealed geometric mean values for E. coli bacteria ranged from a low of 44 to a high of 1,894 colonies/100mL with a mean of 553 colonies/100mL (See City of Portland Ambient Monitoring Results summary table in the Action Plan in Appendix C (PDF, 10 KB).) These exceedances occur both during winter storm events as well as during the dry summer periods.
From 1998 through 2001, Clackamas County Water Environment Services (WES) collected bacteria samples at three locations between 92nd and 45th Avenue in Johnson Creek. Results reveal relatively high E. coli values. Geometric means ranged between 321 and 1,423 and fecal coliform bacteria geometric mean values ranged between 741 to 1,093 organisms/100mL.
Figure 7 (PDF, 87 KB) summarizes E. coli bacteria data throughout the Johnson Creek watershed. Results reveal exceedances of state standards throughout the drainage basin.
Toxics
DDT was identified as a problem based on the results of a USGS investigation (Edwards 1994), which found high instream concentrations. In addition, the USGS is working on a toxics monitoring report from data collected during 2002. Additional investigations of DDT are planned to determine whether DDT concentrations have changed over time, and to provide further evaluation of the nature and sources of DDT concentrations throughout the watershed.
During May 2000, and August 2001, the City of Gresham obtained sediment samples within Johnson Creek. Table 8 summarizes selected toxics results from these sampling sessions.
Table 8. Sediment sample results in Johnson Creek
| Sample Date |
Sample Site |
4,4’ DDD |
4,4’ DDE |
4,4’ DDT |
Alpha-Chlordane |
Chlor-dane |
PCB 1016 |
PCB 1221 |
PCB 1232 |
PBB 1242 |
PCB 1248 |
PCB 1254 |
PCB 1260 |
Dieldrin |
Toxaphene |
| Detection Limit |
13.4 |
13.4 |
13.4 |
13.4 |
300 |
67 |
67 |
67 |
67 |
67 |
67 |
67 |
13.4 |
400 |
|
| 05/30/00 |
JCI1 |
13.4 |
13.4 |
22.1 |
13.4 |
300 |
67 |
67 |
67 |
67 |
67 |
67 |
67 |
13.4 |
400 |
| 05/30/00 |
JCI2 |
14.8 |
29.7 |
15.4 |
13.4 |
300 |
67 |
67 |
67 |
67 |
67 |
67 |
67 |
13.4 |
400 |
| 08/28/01 |
JCI1 |
33.5 |
33.5 |
33.5 |
33.5 |
750 |
67 |
134 |
67 |
67 |
67 |
67 |
67 |
33.5 |
1000 |
| 08/28/01 |
JC12 |
89.4 |
60.7 |
89.4 |
89.4 |
2000 |
179 |
358 |
179 |
179 |
179 |
179 |
179 |
89.4 |
2670 |
Note: units are ug/Kg
JCI1 = Johnson Creek at 174th (downstream jurisdictional boundary)
JCI2 = Johnson Creek at Palmblad Road (upstream jurisdictional boundary)
Oregon does not currently have freshwater sediment standards. DEQ utilizes guidelines contained in the November 1998 Dredged Material Evaluation Framework-Lower Columbia River Management Area for evaluating freshwater sediments. This document uses a tiered evaluation process in a sequential manner for evaluating the suitability of dredged material for unconfined aquatic disposal. Table 9 presents dry weight interpretive guidelines for selected chemicals including a screening level, bioaccumulation level, and maximum level. A screening level (SL) value is listed that identifies chemical concentrations at or below which there is no reason-to-believe that dredged material disposal would result in unacceptable adverse effects due to toxicity measured by sediment bioassays. These screening values were developed for the marine environment. Freshwater values are under development. A second, higher Maximum Level (ML) is identified for each chemical above which there is reason-to-believe that the material would likely fail the standard suite of biological tests and thus be unacceptable for unconfined aquatic disposal. A third chemical screen, the bioaccumulation trigger (BT) has been determined for some chemicals of concern. This may be an important factor in determining sediment suitability for sediments at or above the ML. Bioaccumulation is defined as the accumulation of contaminants in the tissues of organisms through any route, including respiration, ingestion, or direct contact with contaminated water, sediment, or dredged material. Although not directly applicable to Johnson Creek sediments, it provides a comparative summary for the relative concentrations of sediment results obtained in Table 8.
Table 9. Sediment guidelines – Dredged Material Evaluation Framework
| Pesticides |
Screening Level |
Bioaccumulation Level |
Maximum Level |
| Total DDT (sum of 4,4’ – DDD, 4,4’-DDE, and 4,4’ – DDT) |
6.9* |
50 |
69 |
| alpha-Chlordane |
10 |
37 |
--- |
| Dieldrin |
10 |
37 |
--- |
| Total PCBs |
130 |
38** |
3,100 |
* Concentrations are ug/kg
** This value is normalized to total organic carbon, and is expressed in mg/kg (TOC normalized).
City of Gresham sediment sampling results from May 2000 and August 2001 in Johnson Creek at Palmblad Road reveals that sediment samples for Dieldrin, alpha-Chlordane, and PCBs exceed both the screening and bioaccumulation levels. DDT also exceeds the maximum level guideline at this location. Additional sediment samples should be obtained to confirm these results and to isolate source areas.
In addition, water column samples obtained in Johnson Creek for the following priority pollutants: DDT, Dieldrin, PAH, PCB and Chlordane. Water quality standards for selected priority pollutants are shown in Table 10 below and were obtained from Table 20 in –Water Quality Criteria Summary in Oregon Administrative Rules (OAR) Chapter 340, Division 41 – DEQ.
Table 10. Priority Pollutants and 303(d) listings in Johnson Creek
| Compound Name or Class |
Priority Pollutant |
Carcinogen |
303(d) List Date |
|
Fresh |
Fresh |
| DDT |
Yes |
Yes |
1998 |
.001 ug/L – 0.1 ug/L |
1.1 |
0.001 |
| Dieldrin |
Yes |
Yes |
1998 |
0.007 ug/L – 0.021 ug/L |
2.5 |
0.0019 |
| PAH |
Yes |
Yes |
2002 |
0.0432 ug/L |
||
| PCB |
Yes |
Yes |
2002 |
.02002 ug/L |
2.0 |
0.014 |
| Chlordane |
Yes |
Yes |
Not listed |
.0016 ug/L |
2.4 |
0.0043 |
ug = micrograms or one millionth of a gram (10-6)
* For protection of Aquatic Life
The above priority pollutants and associated supporting data results obtained by the USGS, DEQ, and other public agencies reveals that DDT, Dieldrin, and PCBs are exceeding state standards for chronic toxicity in Johnson Creek. Additional monitoring will be required to identify and control sources of toxic contamination in the watershed.
