Dutch Bill Creek Water Quality Study
Turbidity, Nutrients and Bacteria
Table of Contents
Introduction to CCWI
Community Clean Water Institute (CCWI) is a 501(c)(3) non-profit organization dedicated to promoting and protecting clean water and public health by identifying water pollution, advocating for sound water policies, and providing information/education to the public. CCWI coordinates a Citizen Water Quality Monitoring Program in over 20 rivers and streams in Sonoma County including the Russian River and its many tributaries and coastal streams such as Salmon Creek and Cheney Gulch. CCWI works with a variety of citizen, neighborhood and watershed groups
The primary objective of CCWI’s Dutch Bill Creek Water Quality Study, Turbidity, Nutrients and Bacteria was to collect water quality samples on Dutch Bill Creek over the 2007 / 2008 and the 2008 / 2009 winters in order to document and analyze the water quality of Dutch Bill Creek during storm events. Water quality parameters analyzed were turbidity, nitrates, phosphates, conductivity, pH, dissolved oxygen, temperature, and bacteria concentrations. A secondary objective was to train interns and interested citizens in the study and to show them how to process and also to present the information to the public.
The study was a success in that over 200 samples were collected and analyzed, existing water quality conditions during storm events have been documented, three student interns have been trained in water quality science and study techniques, all data has or will be made public, and decisions in regards to best management techniques, restoration, and future monitoring of the Dutch Bill Creek Watershed can be better discussed in light of data collected.
Dutch Bill Creek is a third order stream within the Russian River Watershed. It has historically been a habitat for both Steelhead Trout and Coho Salmon. There is no longer a wild Coho run however, the Coho Recovery Program is attempting to reintroduce Coho to Dutch Bill Creek. Dutch Bill Creek, as part of the Russian River Watershed, is listed on the 303(d) list of impaired waters for sedimentation/siltation and temperature, under the federal Clean Water Act 2006.
Baseline data collected through CCWI’s volunteer monitoring program indicates that water temperature is potentially impaired in several specific locations along the main stem of Dutch Bill Creek during the summer months. Data presented in the 2000 California Department of Fish and Game (CDFG) Stream Inventory Report of Dutch Bill Creek reported temperatures in the main stem to be within limits for salmonid species, however temperature conditions in tributaries leading into Dutch Bill Creek, including Lancel and Grub creeks were above the threshold stress level of 18ºC (65º F) for salmonids. Data collected by CCWI indicates that water temperature does not exceed threshold stress levels during the rainy season.
Data collected by CCWI supports the listing of Dutch Bill Creek as impaired for sediment. Turbidity values commonly surpass turbidity and suspended material objectives set by the North Coast Water Quality Control Board (NCRWQCB). CDFG Stream inventory report also documents embeddedness and substrate conditions outside of the desired norms defined by the NCRWQCB. Desired conditions for sediment related indices are briefly summarized below, however for a complete discussion of desired sediment conditions refer to the 2006 NCRWQCB report titled Desired Salmonid Freshwater Habitat Conditions for Sediment-Related Indices.
The NCRWQCB objectives for sediment related indices details desired conditions for embeddedness and substrate composition along with various in stream habitat indices and turbidity levels. The objective for turbidity states that turbidity shall not be increased more than 20 percent above naturally occurring background levels. Describing what “naturally occurring background levels” are for Dutch Bill Creek is a difficult task, however the data collected indicates that turbidity levels regularly exceed background levels, especially during smaller and early season storm events.
Data indicates that chronic turbidity is unlikely a problem in Dutch Bill Creek. Chronic turbidity is defined as elevated turbidity levels persisting for long periods of time such as multiple days or even weeks. However, peak turbidity levels increased dramatically with high intensity precipitation events and the levels often exceeded natural background levels.
Samples were analyzed for nitrogen and phosphorous concentrations in order to document existing conditions and to better understand this complex system. Collected data indicates that nitrate and phosphate fluxes are elevated above background levels in areas of higher population density located in the headwaters of Dutch Bill Creek, near the communities of Camp Meeker and Occidental. Data does not indicate that nutrient concentrations are a problem in Dutch Bill Creek during the rainy season. Nutrient concentrations may be a useful surrogate to waste discharge and a valuable tool to estimate anthropogenic influence.
Limited samples were analyzed for Total Coliform and E-coli concentrations. Data collected is consistent with past studies conducted by CCWI that record higher pathogen concentrations in the upper watershed near the communities of Camp Meeker and Occidental. Data indicates that the highest pathogen concentrations are found upstream of Camp Meeker and down stream of Occidental. Occidental’s sewer systems were recently upgraded however so additional testing may be necessary to determine whether or not those upgrades have reduced pathogen populations. The need for septic system inspections and upgrades in Camp Meeker were also highlighted by the results of this study under the rules of Assembly Bill 885 which requires the inspection of septic systems and the upgrade of systems that are not up to code.
Dutch Bill Creek is a third order stream with a total catchment area 10.7 square miles. The Coho Recovery Program has been working since 2006 to reintroduce Coho to Dutch Bill Creek as it is historically habitat to both Steelhead Trout and Coho Salmon. There continues to be a wild Steelhead population resident to Dutch Bill Creek. Major tributaries to Dutch Bill Creek include Tyrone Gulch, Crawford Gulch, Duvoul Creek, Grub Creek, Alder Creek, Baumert Springs and Lancel Creek.
Figure 1: CCWI monitoring sites within the Dutch Bill Creek (DBC) watershed. Dutch Bill Creek begins near Occidental (DBC 060) and flows northwest to the Russian River (RUS 040). Sub-watersheds are delineated.
The geology of Dutch Bill Creek watershed comprises Franciscan assemblage sandstones, siltstones, and serpentinites. It also includes smaller deposits of Tertiary aged Wilson Grove Formation sandstone. Wilson Grove sandstone outcrops are found on hilltop terraces at the crests of the Dutch Bill Creek watershed, predominantly within in the Lancel and Grub Creek sub-watersheds. This is noted because differences in sediment load and water chemistry may be significant with the differing geology and topography of these watersheds. Significant Road networks and land use are also significant factors affecting the composition of Dutch Bill Creek and its surrounding watershed. It is difficult to attribute differences in water quality to natural geologic and topographic variation or to anthropogenic causes; however some effort will be made in this regard.
Dutch Bill Creek Watershed is privately owned and relatively undeveloped. The bulk of development within the watershed is concentrated in the communities of Camp Meeker and Occidental. Other communities include development in the Tyrone Gulch area, Westminster Woods and Alliance Redwoods Conference Grounds along with scattered individual residences. The bulk of the watershed is second growth conifer forest with lesser areas of oak woodland and agricultural areas. Agriculture uses include rangeland, vineyards and orchards. Agricultural areas are concentrated in the upper watershed near occidental and Lancel Creek and Grub Creek sub-watersheds.
The dominant substrate in the main stem of Dutch Bill Creek includes gravel, sand, cobblestones and bedrock. The substrate is generally boulders and bedrock in the upper reaches and sands, gravels and cobblestones in the lower reaches. The 2000 Stream Inventory Report of Dutch Bill Creek by CDFG reported levels of embeddedness that were above desired conditions in much of Dutch Bill Creek. Embeddedness is the degree to which larger particles such as gravels and cobbles are surrounded or covered by fine sediment such as silt or sand. The greatest problem attributed to embeddedness is that the deposited gravels contain high levels of fine materials, which reduces permeability in reds potentially slowing their growth. At higher levels these silts may even be lethal.
Desired conditions set by the NCRWQCB call for an embeddedness of 25% or less in pool tail outs. Of the 163 pool tail-outs measured by the CDFG in Dutch Bill Creek, only 21% had a value within the acceptable range.
Sampling sites for Turbidity and Nutrient were distinguished from sampling sites for Bacteria.
CCWI chose turbidity and nutrient monitoring sites in order to best characterize turbidity levels and water chemistry in the upper, middle and lower reaches of Dutch Bill Creek as well as significant tributaries of Lancel and Duvoul Creek.
DBC 007: Located below the bridge where Bohemian Highway crosses Dutch Bill Creek just downstream of the confluence of Tyrone Gulch with Dutch Bill Creek. Drainage area to site is 10.6 Sq. Miles. The site is located within a low gradient pool-riffle reach with a gravel and cobble substrate. The staff plate (water level gauge) and pressure transducer installed by the Coho Recovery Program are located at this site.
DBC 030: Located just upstream of the former Camp Meeker Dam in Camp Meeker. Drainage area to the site is 3.1 Sq. miles. The site is located within a low gradient glide with a sand and gravel substrate. The site has historically had high sedimentation levels because it acts like a sediment trap because debris are sucked into the backwater behind Camp Meeker Dam.
DBC 050: Located 75 yards downstream from the sewer pump station, where primary sewage is collected and pumped up hill for treatment. Drainage area to the site is 0.73 Sq. miles. The site is located within mid-gradient step-pool reach with bedrock, boulders, cobbles and gravel form the substrate.
DUV 010: Located just upstream of the crossing of Bohemian Highway and Duvoul Creek. Drainage area to the site is 1.35 Sq. miles. The site is located within mid-gradient step-pool reach with bedrock, boulders, and cobble substrate.
LAN 010: Located just upstream of the crossing of Old Bohemian Highway and Lancel Creek. Drainage area to the site is 1.61 Sq. miles. The site is located within mid-gradient step-pool reach with a substrate composed of bedrock, boulders, and cobbles.
Sampling sites for Bacteria were distinguished from sampling sites for Turbidity and Nutrients.
CCWI chose bacteria monitoring sites in order to bracket suspected pathogen sources including Camp Meeker and Occidental. Locations of the bacteria monitoring sites are annotated on Figure 1 above.
DBC 007: This site is located below the bridge where Bohemian Highway crosses Dutch Bill Creek just downstream of the confluence of Tyrone Gulch with Dutch Bill Creek. Drainage area to site is 10.6 Sq. Miles. The site is located within a low gradient pool-riffle reach with a gravel and cobble substrate. The staff plate (water level gauge) and pressure transducer installed by the Coho Recovery Program is located at this site.
DBC 020: This site is located on Westminster Woods property just downstream from the confluence of Grub Creek with Dutch Bill Creek. Drainage area to site is 5.7 Sq. Miles. The site is located within a low gradient glide with a cobble, gravel and sand substrate.
DBC 025: This site is located just downstream from Camp Meeker. Drainage area of this site is 3.7 Sq. Miles. It is located within a mid-gradient step-pool reach with a boulder and cobble substrate.
DBC 040: This site is located just downstream from the confluence of Lancel Creek and Dutch Bill Creek. Drainage area to site is 2.7 Sq. Miles. The site is located within a low to mid-gradient step-pool reach with a boulder, cobble and gravel substrate.
DBC 050: This site is located 75 yards downstream from the sewer pump station, where primary sewage is collected and pumped up hill for treatment. Drainage area to the site is 0.73 Sq. miles. The site is located within a mid-gradient step-pool reach with bedrock, boulders, cobblestones and gravel substrate.
Water samples were collected from sampling sites during the beginning, peak and end of each storm during the 2007/2008 and the 2008/2009 winters. Water samples were collected by hand following CCWI’s Standard Operating Procedures (SOP) for grab sampling. (http://www.ccwi.org/issues/SOP.htm). Every effort was made to collect samples during the rising limb, peak and falling limb of the hydrograph. In practice this level of sampling proved to be quite difficult and laborious. These difficulties led use to pursue an automated sampling unit to aid us in our data collection.
With some assistance an ISCO automated pumping sampler was also deployed at sampling site DBC007 during limited storm events. The ISCO was programmed to pump a water sample every hour over the course of a day, collecting a total of 24 samples over the course of a storm event.
Samples were analyzed for Turbidity, Conductivity, Nitrates and Phosphates. Temperature, Dissolved Oxygen, pH and Bacteria concentrations were analyzed on a limited number of samples. Temperature, Dissolved Oxygen and pH must be measured in the field, thus samples collected by the ISCO or samples collected rapidly in the field and later analyzed in the CCWI lab were not analyzed for the above parameters. Instrumentation and analysis methods are detailed in CCWI’s Sampling and Analysis Methods document available at (http://www.ccwi.org/issues/analysismethodsccwi07-4.pdf).
Water level data was recorded at sampling sites DBC007 and DBC030 off of staff plates mounted along Dutch Bill Creek. The Coho Recovery Program has installed a pressure transducer at sampling site DBC007. The pressure transducer records the stage (water level) every 15 minutes. Stage data for 2007/2008 has not been made available yet, however 2008/2009 winter stage data is incorporated into this report.
Turbidity is an optical measure of the amount of suspended particles in the water column, including suspended sediment, algae, organic matter, and pollutants commonly measured in NTUs. Turbidity generally increases during storm events. Sediment sources include surface erosion, bank failures, landslides and entrainment of the stream bed during high flows. Roads, rangeland, farmland, and other impacted areas tend to increase sediment transport to waterways and elevated turbidity values are commonly observed.
Figure 4: Turbidity data collected during the 2007-2008 winter at the five turbidity and nutrient monitoring sites on Dutch Bill Creek. The average daily discharge from Austin Creek is plotted to help visualize storm events. Discharge data for the USGS station 11467200 on Austin Creek is available through the USGS Water Resources website.
2007 – 2008 turbidity data is plotted above in Figure 4. The hydrograph plotted is that of Austin Creek. Discharge data was not available for the 2008 water year for Dutch Bill Creek at the time this report was prepared. The hydrograph plotted is a visual reference; it is expected that the hydrograph of Dutch Bill Creek is similar. Our data shows that turbidity in Dutch Bill Creek changes abruptly and it tends to peak quickly as can be seen in the hydrograph. Generally, observed turbidity values tend to peak at about 150 NTUs. The highest turbidity value collected during the 2007 – 2008 winter had a value of 382 NTUs.
Data indicates that peak turbidity levels during the beginning of the storm season were higher than those recorded at the end of the storm season (refer to figures 4, 5 and 6). The highest turbidity values were recorded during the Dec 19, 2007 storm, the first significant storm of the 2007/2008 winter (Figure 5). Data collected during a storm of similar magnitude at the end of the storm season (2/24/08) records turbidity values that are significantly lower than the Dec 19, 2007 storm (Figure 6). Recorded turbidity values at DBC007 during the Feb 24, 2008 storm peak at 91 NTUs. Recorded turbidity values at DBC007 during the Dec 19, 2007 storm peak at 382 NTUs.
Samples analyzed at DBC 007 during the Feb 24, 2008 storm were collected through the use of an ISCO automated pumping sampler. A sample was pumped every hour during the course of the storm, thus we have added confidence that the recorded peak is near to the actual peak turbidity value. The difference in recorded turbidity values between the two storms is thought to be real and not a result of low sampling frequency.
For storms that were not sampled with the ISCO pumping sampler it is possible that a sample was not collected during the peak of the storm. For example during the largest storm of the 2007 – 2008 winter (1/4/2008) two trips were taken to collect samples. It is highly probable that samples were not collected during the peak of the storm, thus the recorded peak turbidity is likely below the actual peak value for this storm event.
Figure 5 (below): Turbidity data collected during the first significant storm of the 2007-2008 winter at the five turbidity and nutrient monitoring sites on Dutch Bill Creek. The average daily discharge from Austin Creek is plotted to help visualize storm events. Discharge data for the USGS station 11467200 on Austin Creek has been downloaded from the USGS Water Resources website.
Figure 6: Turbidity data collected during a storm at the end of the 2007/2008 winter at the five turbidity and nutrient monitoring sites on Dutch Bill Creek. The average daily discharge from Austin Creek is plotted to help visualize storm events. Discharge data for the USGS station 11467200 on Austin Creek, downloaded from the USGS Water Resources website.
Two conspicuous peaks are apparent in the turbidigraph portrayed in Figure 6 for site DBC 007. It is expected that the peaks in turbidity correspond to real peaks in the hydrograph that have been flattened in the creation of average daily discharge. The hydrograph for Dutch Bill Creek is expected to mimic the form of the turbidity values.
Figure 7: Turbidity data collected during a storm at the end of the 2008-2009 winter at the five turbidity and nutrient monitoring sites on Dutch Bill Creek. Please note that the scale of turbidity axis is logarithmic not linear. Stage data was recorded every 15 minutes at DBC007.
Turbidity data for the 2008 /2009 winter record similar results to those recorded in the 2007/2008 winter. Observed turbidity values tend to peak at about 100 NTUs. The highest turbidity value recorded during the 2008/2009 winter had a value of 884 NTUs. It was recorded during the first significant storm event (Nov 1, 2008) of the 2007/2008 winter at DBC050. The peak turbidity value recorded at DBC007 for the Nov 1, 2008 storm was 30.3 NTUs. The peak stage value during Nov 1, 2008 was 1.13 ft. During the storm event of Feb 16, 2008 the peak turbidity at DBC007 was 43.7 NTUs and the peak turbidity at DBC050 was 50.1; the peak stage value was 2.91 ft. The peak stage during the Feb 16, 2008 storm was more than twice that of the Nov 1, 2008 storm yet turbidities have similar values. It should be noted that a relationship between stage and discharge has not been developed for Dutch Bill Creek. It is expected based on Austin Creek discharge data that the discharge associated with a stage of 2.91 ft is 5 to 15 times that of the discharge associated with a stage of 1.13 ft.
Data collected by CCWI supports the listing of Dutch Bill Creek as impaired for sediment.
The NCRWQCB objectives for sediment related indices details desired conditions for turbidity. The objective for turbidity states that turbidity shall not be increased more than 20 percent above naturally occurring background levels. CCWI interprets this objective to mean that peak turbidities should not be increased 20% above naturally occurring peak levels during individual storm events. Collected data show that for similar magnitude storm events (storm events with similar peak stage or discharge levels), early season storm events record turbidity levels that are significantly higher during early season storms than late season storms. Increases in turbidity in the range of 100 to 400% have been recorded.
Higher turbidity values recorded in early season than late season storms are thought to be primarily attributed to road runoff. Dust and fine particles that accumulate on unpaved road surfaces over the dry season are washed into waterways during the first few significant storm events. Other contributors may be erosion of freshly graded surfaces and other impacted areas that may be associated with agriculture.
A potential natural source of fine sediment in early season storm events is the entrainment of fine sediment that has moved into the channel network through soil creep and dry ravel processes during the dry season. Soil creep and dry ravel processes involve the down slope movement of particles due to bioturbation, natural expansion and contraction of the soil and fire. It is expected that soil creep and dry ravel are secondary sources as compared to road surface erosion.
It is unknown if peak turbidity levels during large storm events are elevated above natural levels in Dutch Bill Creek. A parallel watershed study would be necessary to make any conclusions in this regard. It also should be noted that water year 2008 and 2009 were low rainfall years.
As stated above, data collected supports the listing of Dutch Bill Creek as impaired for turbidity, however data does not indicate that chronic turbidity is a problem within Dutch Bill Creek. Chronic turbidity is characterized as elevated turbidity levels persisting for long periods of time such as multiple days or even weeks. Turbid water is defined as water with a turbidity of 27 NTUs or greater. Water with 27 mg/L (roughly 27 NTUs) of suspended sediment is considered “not drinkable,” and it results in a fifty percent drop in the catch of fish, and a less than a ten percent drop in fish production (Anderson 1975). Data indicates that turbidity levels in Dutch Bill Creek drop below 27 NTUs rapidly at the end of each storm therefore; detrimental water quality conditions are short lived.
However, Dutch Bill Creek may potentially be contributing to chronic turbidity in the lower reaches of the Russian River. Because Dutch Bill Creek has high turbidity levels even during small storm events the Russian River receives frequent pulses of turbid water. Under natural conditions Dutch Bill Creek would only convey turbid water to the Russian River during large storm events. Because the Russian River is relatively large, it takes days as opposed to hours to move water from the upper most reaches to the mouth. Pulses of turbid water moving into the main stem from various sub-watersheds may lead to prolonged durations of turbidity in the main stem. Thus, Dutch Bill Creek may be contributing to chronic turbidity in the Russian River.
Nitrate is the form of nitrogen commonly found in soil and groundwater. Nitrogen (N) cycles through the environment, moving from organic matter to ammonium (NH4+) to nitrite (NO2-) to nitrate (NO3-) as it is broken down by bacteria. We measure the amount of nitrogen (N) in nitrate (NO3-). Nitrate sources include natural decay of organic matter, fertilizers (from lawn, garden, crops, parks), sewage disposal systems (on-site septic systems and wastewater treatment plants), livestock facilities (animal manure storage), and industrial discharges.
Nitrate data collected during the 2007/2008 winter at 3 turbidity and nutrient monitoring sites within the Dutch Bill Creek watershed. Data for all monitoring sites is not included for clarity. Note that nitrate concentrations at DBC050 are consistently higher than found at DUV010 or LAN010.
Nitrate data collected during storms of the 2008/2009 winter at 3 turbidity and nutrient monitoring sites within the Dutch Bill Creek watershed. Note that nitrate concentrations at DBC050 are consistently higher than found at DUV010 or LAN010
Phosphate (PO4) is the form of phosphorus present in soil and groundwater and is necessary for the growth of plants and animals. Phosphate stimulates growth of plankton and aquatic plants, which provide food for larger organisms, including zooplankton, fish, and mammals. Phosphate sources include natural decomposition of rocks and minerals, partially treated and untreated sewage, runoff from agricultural sites, application of some lawn fertilizers (storm runoff),
detergents, and commercial cleaning fluids.
Phosphate data collected during storms of the 2007/2008 winter at 3 turbidity and nutrient monitoring sites within the Dutch Bill Creek watershed. Note that phosphate concentrations at DBC050 are generally higher than found at DUV010 or LAN010 especially in early season storm events.
Phosphate data collected during storms of the 2007/2008 winter at 3 turbidity and nutrient monitoring sites within the Dutch Bill Creek watershed. Note that phosphate concentrations at DBC050 are generally higher than found at DUV010 or LAN010 especially in early season storm events.
The State Water Quality Control Board (SWRCB) has not yet, but is in the process of developing, numeric thresholds for maximum nutrient concentrations. The primary goal of the thresholds will be to maintain nutrient levels that support the health of aquatic systems. The secondary goals aim to prevent potentially harmful algal blooms leading to oxygen declines, imbalances of aquatic species, and a general decline in water resources. According to the United States Environmental Protection Agency (USEPA) natural levels of nitrates in surface water should be low (less than 1 mg/L) and the Maximum Contaminant Level (MCL) for drinking water is 45 mg/L. The USEPA recommends phosphates to be under 0.1 mg/l in Lakes and streams.
Nitrate levels recorded never reached the MCL for drinking water (45 mg/L) at any DBC monitoring site. Nitrate levels at DBC050 and DBC030 exceeded 1 mg/l on multiple occasions. Phosphate concentrations greater than 0.1mg/l were also recorded at the above sites. Data from other monitoring sites did not record nutrient levels above the US EPA guidelines for rivers and lakes.
DBC050 is our closest nutrient monitoring site to Occidental and consistently recorded the greatest values for nutrients. The nutrient sources are most likely related to leaking sewage pipes, runoff from agricultural areas and confined animal sites, and discharge of treated wastewater by the Occidental Community Services District, which has a permit to release limited treated wastewater to DBC when stream flow is sufficient.
Data from tributaries to DBC, Lancel and Duvoul Creeks, recorded low nutrient levels relative to samples collected from sites along the main stem of DBC. Lancel and Duvoul creeks are largely undeveloped and are thought to represent near background conditions. The watersheds of both tributaries contain some areas of grazing land and significant areas of forest; they differ in geology and percent vineyard. Ridge tops of the Lancel Creek are capped with vineyards. Wilson Grove Formation Sandstone comprises the surficial geology on the ridge tops. Duvoul Creek watershed contains no vineyard or Wilson Grove formation sandstone, the geology comprises a mix of rock types associated with the Franciscan Formation. No significant difference in nutrient concentrations was observed between the two sub-watersheds, thus preliminary investigation indicates that neither limited vineyard development (as implemented in Lancel Creek watershed) nor geology has a significant influence phosphate or nitrate levels. Factors including agricultural use and geology can thus be considered insignificant in analysis of elevated nutrient levels recorded in the upper watershed of DBC.
This project monitored levels of E. coli and Total Coliforms in Dutch Bill Creek during the 2008/2009 winter. E. coli, or Escherichia coli, is a bacterium found in the lower intestine of warm-blooded animals and is an indicator of fecal pollution. There is a direct correlation between the ratios of E. coli to the presence of pathogens in the environment. We see that when total Coliforms go up E. coli levels rise as well and, that when E. coli increases more harmful pathogens increase. Therefore, when these indicators (total coliforms and E. coli.) are monitored they predict where we will find dangerous pathogens. For this reason the California Dept. of Health Services recommends that recreational water should have less then a most probable number (MPN) of 10,000 Coliforms and 235 E. coli. For comparison, drinking water should be absent of both types of bacteria.
The evidence collected in this study suggests significant sources of bacterial contamination to Dutch Bill Creek are coming from both Camp Meeker and Occidental. The site at Occidental, DBC060, exceeded recreational water quality standards for E. coli in 66% of samples, and the site just below Occidental influences, DBC050 exceeded standards in 100% of samples. Both of the Camp Meeker related sites exceeded standards in 66% of samples. The downstream site samples violating standards for both towns averaged greater than 20 the standard of 235 MPN E. coli. The upstream site at Occidental averaged 13 times the standard threshold, and the site upstream of Camp Meeker only 2.6 times higher than the standard. Other sites tested for E. coli in Dutch Bill Creek not near these areas of population density did not have significantly high E. coli levels in their samples, suggesting an anthropogenic influence versus wild animals.
Bacteria counts are elevated at DBC060, where potential sources include pre-treated sewer overflow, pasture animals, and storm water from a limited area of Occidental’s streets.
Site DBC050 is located just downstream of Occidental. Influences include storm drains, surface wash form Occidental and the entire sanitation district including collection system and pumping station. The collection system was upgraded to reduce inflow and infiltration in 2007.
Site DBC040 is located just downstream of the confluence of Lancel Creek and Dutch Bill Creek, above the community of Camp Meeker. Influences include storm drains, surface wash form Occidental and the entire sanitation district including collection system and pumping station, but the watershed of DBC040 (2.7 Sq Mi) is a much larger watershed than DBC050 (0.73 Sq Mi), thus it is expected that contamination from Occidental at DBC040 would be diluted relative to DBC050. Data suggests that this is true, bacteria concentrations are reduced between DBC050 and DBC040 with the addition of flow.
Site DBC025 is downstream of Camp Meeker, potential pollution sources include those for DBC040 and influences of Cam Meeker. The data collected suggests that bacteria levels do increase significantly as we move downstream from DBC040 to DBC025. This indicates Camp Meeker’s septic systems measurably impact water quality. Potential sources of E. coli in Camp Meeker include failing household septic systems and surface storm water carrying pet waste and household detritus. Camp Meeker’s septic problem has been declared a Health Hazard and a Prohibition of Waiver Zone, prohibiting construction of any new septic systems. A 1989 study by Questa Engineering found strong evidence of septic failure, sewage in drains and streams, and generally poor conditions for use of septic systems.
These findings are supported by previous CCWI monitoring studies and the NCRWQCB, which pinpoints the area of Dutch Bill Creek just below Occidental with the highest concentration of bacteria, and with Camp Meeker also demonstrating unhealthy levels. http://www.swrcb.ca.gov/rwqcb1/programs/sampling/Sampling_data/russian_river/Special.pdf
The Community Clean Water Institute believes that the results of this study indicate that Dutch Bill Creek suffers from several impairments including turbidity, nutrients and Pathogens.
Collected data show that for similar magnitude storm events (storm events with similar peak stage or discharge levels), early season storm events record turbidity levels that are significantly higher during early season storms than late season storms. Higher turbidity values recorded in early season than late season storms are thought to be primarily attributed to road runoff. Dust and fine particles that accumulate on unpaved road surfaces over the dry season are washed into waterways during the first few significant storm events. Other contributors may be erosion of freshly graded surfaces and other impacted areas that may be associated with agriculture. Data indicate that elevated turbidity conditions are relatively short lived and that turbidity is not a chronic problem.
Further turbidity monitoring of Dutch Bill Creek is recommended especially during peak flows of early season storms to document if erosion control plans and sediment reduction programs are effective.
Turbidity monitoring during very large storms would also be valuable; however an automated monitoring system would be necessary to gather useful data. Habitat condition surveys including surveys of fine sediment and embeddedness are thought to be more cost effective and useful to document fine sediment impairment in Dutch Bill Creek.
Elevated nutrient levels are not thought to be an impairment to Dutch Bill Creek during winter storm conditions. Recorded nutrient concentrations for both nitrates and phosphates were at times above EPA guidelines for lakes and streams, however it is unexpected that Dutch Bill Creek faces any threat of eutrophication. If however the lower Russian River or near shore waters at the mouth of the Russian River were to experience algal blooms diagnostic of abnormally nutrient rich water, then elevated nutrient concentrations in Dutch Bill Creek may be considered a problem.
Further testing of nutrients in Dutch Bill is considered useful in that it appears that nutrient concentrations are closely associated with urban runoff and thus provide an inexpensive and useful indicator of the impacts of local communities on Dutch Bill Creek. It may be found that nitrate concentrations are a surrogate for pathogen concentrations and could be used to monitor pollution from leaking septic systems in Camp Meeker and sewage treatment lines in Occidental.
Data collected in this study suggests that fecal contamination may be contributing to the high levels of E. Coli recorded along Dutch Bill Creek at sites near Camp Meeker and Occidental. To confirm this additional testing for fecal Coliforms is required. It should also be noted that pathogen concentrations are elevated during storm events.
Community Clean Water Institute Recommendations:
CCWI would like to thank the Sonoma County Fish and Wildlife Commission, Rose Foundation, and Patagonia for financial support of this study. CCWI would also like to thank O’Connor Environmental Inc. for the use of their Isco automated pumping sampler and the UC Cooperative Extension - Sonoma County for sharing water level data collected at DBC007.