Characterization of urban runoff treatment ponds
within San Dieguito River Park
Final Report:
June, 2013
Elayna Flanders
California State University San Marcos
May 2012 – December 2012
Advisors
George Vourlitis & William Kristan
Department of Biological Sciences
California State University San Marcos
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TABLE OF CONTENTS
Executive Summary…………………………...…………………………………………..4
Project Objectives………………………………………………………………………... 5
Project Approach………………………………………………………………………….6
Project Outcomes………………………………………………………………………….9
Conclusions………………………………………………………………………............14
Appendices……………………………………………………………………………….15
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ACKNOWLEDGEMENTS
Agriculture and Food Research Initiative Competitive Grant no. 2011-38422-31204
from the USDA National Institute of Food and Agriculture supported this project. The
help and guidance from Dr. George Vourlitis, Dr. William Kristan and the San Diego
River Park is greatly appreciated. Thank you to San Diego Coast Keeper for training us
and allowing us to use their equipment. Donations made by CSUSM staff were also a
huge help in this project. Also a huge thank you to the Water Resource Institute for
developing a great internship program and letting us be a part of it.
Funding for this project provided by the U.S. Bureau of Reclamation, Southern
California Area Office; California Urban Water Agencies; and California Urban
Water Conservation Council
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EXECUTIVE SUMMARY
The San Dieguito River Park (SDRP) has an existing water treatment system
comprised of four treatment ponds. These freshwater ponds are designed to naturally
filter local urban runoff before entering the salt marsh habitat of the lagoon. There is
currently little quantitative data collected, and none has been analyzed to determine the
ponds overall efficiency. Due to the magnitude of this study Shelley Lawrence and
Elayna Flanders completed a combined research project in which a series of samples
were taken and analyzed to quantitatively evaluate if the original ecological goals of the
system are being met. The primary USDA discipline related to this project is water
quality/water resources.
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PROJECT OBJECTIVES
This research project directly focuses on urban and agricultural run off and it’s
affect on water quality involving the San Dieguito River Park’s watershed region.
Volunteering for the River Park over the past few years has allowed me to truly
understand the importance of preserving, restoring and maintaining good water quality of
this natural resource. This internship has allowed me to take my understanding and
passion for wildlife biology to the next level. It has given me the opportunity to apply
my knowledge and skills learned at the graduate level toward creating and implementing
a research project regarding water quality at the River Park.
The real life experience gained from this research project is invaluable and will
transfer over into a career once graduating with my Masters in Biological Science at
California State University San Marcos. This research has confirmed my passion for
field ecology, research, and wildlife biology. It has given me the opportunity to learn
more about USDA job opportunities and made me realize this is truly my passion in life.
I plan on continuing a relationship with WRI and SDRP in hopes to apply for potential
career opportunities with USDA soon into the future.
The initial goal of this internship research was to assess the four treatment ponds
based on soil, water and plant pollution levels to determine if the treatment ponds were
efficiently filtering the urban runoff. Once researching further into the project we
realized the scope of the project was larger than anticipated. The project was scaled
down to a manageable size by first focusing on soil and water characterization in pond
one and four. We felt it sufficient to look at the two ponds thought to have the most
significant difference in the amount of pollutants found within them. Pond one having
highest pollutants found and four with hopefully minimal amounts of pollutants after
being filtered three times through the natural pond filtrations systems. Comparing
treatment pond one to four will allow us to compare changes in water and soil pollution
from the time it enters the system to it’s last filtration before entering the salt water marsh
habitat. This will determine water and soil quality of the ponds during both dry summer
months and rainy winter season.
Additional adjustments to our initial research include eliminating measurement of
water flow. Even during winter rainy season we could not obtain a flow reading in pond
one to compare to our flow reading in pond four. It was also determined that soil samples
only needed to be collected and analyzed two days during the dry season and two days
during the rainy season. We partnered with Coast Keeper to collect our water samples
and completed their rigorous training program. We learned various techniques and
proper ways to collect samples and avoid any contamination. Lastly preparing and
analyzing the samples was much more time consuming than we had originally planned
for. Our advisor Dr. Vourlitis trained us in the lab. He demonstrated how to run samples
in the carbon and nitrogen auto analyzer. This is a very detailed process where we spent
days grounding, weighing, and loading our samples to be analyzed for total Carbon and
Nitrogen content. Finally, the data analysis and final report tasks were underway and all
necessary tasks were complete.
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PROJECT APPROACH
Planning
In determining the layout and methods for this research plan many preliminary
steps were taken before data collection was conducted. We first met with SDRP’s
environmental planner Shawna Anderson, the Directors of the park, Susan Carter and
Dick Bobertz, and also the Ranger staff at the Park. It was extremely important for us to
meet with all involved staff at the River Park in order to make connections and gain any
and all information pertaining to our research area. They supplied us with all of the Parks
plans and reports regarding the pond construction and background information. This
information indicated elevation levels, and how flow was directed through each pond.
This helped us determine transect line placement and sampling techniques.
To further advance our knowledge of treatment pond filtration systems we did
extensive research looking into other similar filtrations systems that have already been
studied. We researched published journal articles pertaining to our study and realized
there are not too many publications involving natural treatment pond efficiency. Once all
resources and information were gathered we met with our advisors, Dr. Gorge Vourlitis
and Dr. William Kristan at California State University San Marcos to formulate a
research plan. Their combined knowledge of statistics, and ecology aided in setting up
our experimental design. We used them as reference to make sure our research would be
accurate and express a well-balanced design that is not bias in any way.
Methods
Figure one below represents a diagram of the four treatment ponds located at SDRP.
Figure 1. Letter A represents where the urban runoff enters into the treatment
pond one. It is then diverted under a constructed berm by a culvert to direct flow
into treatment pond two. It is then filtered through and underneath the trail
through a culvert into treatment pond three, where it filters through again and
under a berm through a culvert into treatment pond four where it is filtered for a
fourth time before being released into the salt water marsh, letter B.
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Sample Collection
It is determined that six soil samples will be collected from treatment pond one
and four in both summer and winter. At each pond one 100m Transect line is set up
following the gradient flow of water (Figure 2.). During summer when water was not
flowing the lowest points of elevation showed where the water would naturally flow.
Figure two indicates transect lines and areas where samples were collected. Along the
100m transect a coin toss determined direction from the base line to collect the soil
sample. Then a random number generator indicated how far out from the base line to
collect each sample. Samples were collected using a soil core sampler (Figure 3). Each
sample was placed into a labeled 50mL falcon tube. Samples were taken to the lab, dried
for 24 hours in a drying oven and then finely ground for analysis.
Figure 2. Random sampling technique layout
Figure 3. Soil Core Sampler
Vegetation samples were collected in ponds one and four. Native cattails mostly
dominated pond one, where pond four was filled with woody shrubs. Although the
vegetation was much different between the ponds we collected plant samples along our
transect lines in hopes of using it in our analysis. Upon analysis, we found this data was
inconsistent and could not be used to measure pollution levels.
Water samples were carefully taken each month with the help of the San Diego
Coast Keeper. We completed rigorous training and techniques including methods of
collecting water samples without contamination, which are listed in appendix pages 1423 along with all equipment used. Samples were collected from May 2012 through May
2013 to characterize the water quality during the dry summer months, and rainy winter
season. Water was then assessed for nitrogen and carbon levels, conductivity, temperature,
pH, and dissolved oxygen (Figure 4).
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Figure 4. Treatment pond one water collection and filtration technique
Once all samples were collected they were brought to the lab for analysis. Dr.
George Vourlitis trained us on correct techniques for the Carbon and Nitrogen analyzer.
Accuracy is key with this machine and we made sure to spend time running trial samples
before assessing our own data. While learning the machinery the soil and vegetation samples
were set to dry for one week at 70°C. Then these samples were ground into a fine powder.
Samples were then prepared for analysis by weighing out 5-10mg of the sample into a small
aluminum tin. The top to each tin was carefully folded over using tweezers insuring the
sample was fully enclosed into the tin. Additionally four standards were prepared the same
way and run in order to calibrate the readings. After calibration the samples were run
through the analyzer giving output values for the total carbon and nitrogen. These samples
along with vegetation samples were run through the Carbon and Nitrogen analyzer (Figure
5). Due to extensive costs for water sample analysis this was done through the San Diego
Coast Keeper and results were sent to s for statistical analysis.
Figure 5. Farthest left shows samples wrapped in small tins for analysis. Each row includes samples from
treatment pond one and two including soil, plant, and blanks. The center picture shows how samples are
loaded into the machine. On the right Shelley is loading them into place to be analyzed.
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Statistical Analysis
Vegetation was dropped from statistical analysis due to the difference in vegetation
type. Because we could not sample the same vegetation from each pond we were unable to
compare results to determine different levels of pollutants held within the plants. Our
analysis compared nitrogen, dissolved oxygen, conductivity, and pH in both soil and water
between treatment ponds one and four. Statistical t-test was preformed to determine if there
was a significant decrease in each of these variables between the two ponds.
Presentations & Announcements
Our research was first announced in the SDRP monthly Riverscape (appendix p. 26).
Once our research plan was in place it was presented at the Citizens Advisory Committee
(appendix p. 27). Our results were then presented at the CSUSM Poster Showcase (appendix
p. 28). The next phase of the project was announced again the SDRP Riverscape (appendix
p. 29). Lastly our final results will be presented at The 5th Annual Water Resources and
Policy Initiatives Conference.
PROJECT OUTCOMES
Results show that the treatment ponds significantly filter pollutant levels in water
and soil between treatment pond one and four. This indicates that they are effectively
filtering pollutants before entering into the SDRP lagoon. Water quality shows a
significant difference in pH, ammonia, dissolved oxygen, and nitrate (p< 0.05) but no
significant difference of phosphorus or conductivity means (p>0.05) between ponds one
and four (Figure 6 & 7). Soil samples showed a significant reduction in soil carbon
(p<0.05) and no significant difference in nitrogen levels (p>0.05) between treatment ponds
one and four in the summer (Figure 8). However in the winter no significant difference in
carbon and nitrogen levels were indicated (p>0.05, Figure 9). When comparing winter
and summer nitrogen levels summer showed a significantly higher nitrogen content in soil
than wet winter months (p<0.05, Figure 10). There was no significant difference in
carbon levels found when comparing winter and summer data (p>0.05, Figure 11).
There was no significant difference in conductivity between the two ponds and
levels are higher than the EPA range for conductivity levels (Figure 12). According to
EPA standards dissolved oxygen levels (appendix p. 28) in treatment pond one are not at
an acceptable range but they are once measured in treatment pond four (Figure 13). There
is significantly lower dissolved oxygen found in the ponds during dry summer months
(p=0.05).
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Figure 6. Mean levels of ammonia, nitrate, and phosphorus in treatment
ponds one and four. Error bars show standard deviations. Phosphorous
showed no significant difference between ponds one and four (p=
0.060). Nitrate showed a significant difference between ponds one and
four (p= 0.009). Ammonia showed a significant difference between
ponds one and four (p= 0.036).
Figure 7. Mean levels of ammonia, nitrate, and phosphorus in treatment
ponds one and four. Error bars show standard deviations. Phosphorous
showed no significant difference between ponds one and four (p=
0.068). Nitrate showed no significant difference between ponds one and
four (p= 0.563). Ammonia showed a significant difference between
ponds one and four (p= 0.038).
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Figure 8. Mean percent carbon and nitrogen in treatment ponds one and
four. Error bars show standard deviations. Significantly higher carbon
content found in treatment pond one over pond four (p= 0.0389). No
significant difference in nitrogen levels found between ponds one and
four (p= 0.067).
Figure 9. Mean percent carbon and nitrogen in treatment ponds one and
four. Error bars show standard deviations. No significant difference in
carbon (p= 0.119) and nitrogen (p= 0.246) levels found between ponds
one and four.
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Figure 10. Mean percent nitrogen in treatment ponds one and four. Error
bars show standard deviations. There is a significant difference in
nitrogen levels found in pond one during the summer and winter data
collection (p= 0.029).
Figure 11. Mean percent carbon in treatment ponds one and four. Error
bars show standard deviations. No significant difference indicated (p=
0.067).
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Figure 12. Mean comparison of measured conductivity levels in ponds
one and four compared between summer and winter. Error bars show
standard deviations. No significant difference indicated winter (p= 0.45),
summer (p= 0.80).
Figure 13. Mean comparison of measured dissolved oxygen and EPA
standards, based on water temperature, for each pond one and pond four. Error
bars show standard deviations. Pond one (p= 0.004) and pond four (p= 0.004)
dissolved oxygen levels show significant differences between levels found in
ponds one and four.
When analyzing these results they were compared to EPA standards. These standards
indicate optimal brackish water pH to range between 7.5-8.5. The treatment ponds are a fresh
water filtration system that filters into a salt-water marsh habitat, although it starts fresh by the
time it hits treatment pond four, water becomes brackish. It is important to maintain this
optimal pH level to remain a healthy lagoon for all organisms. Both ponds pH level fell
within a healthy range showing a significant increase in pH between pond one and four in both
winter (p=0.002) and summer (p=0.005).
Phosphate, nitrate and ammonia levels must also be kept within a specific range to
maintain a healthy ecosystem. Fluctuations in any of these levels can result in algal blooms.
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This may indicate low levels of dissolved oxygen making it hard for organisms to survive.
The treatment ponds both showed low levels of nitrate, ammonia and phosphorous. Realizing
that they are not directly affected by any large agricultural runoff leads us to believe that is
why levels are lower than one might expect. Because dissolved oxygen can be dependent on
temperature the data was analyzed according to specific requirements (appendix p. 29).
Results show significant improvement in dissolved oxygen between pond one and four.
Comparing values showed pond one did not fall within a safe range where pond four did. No
significant difference in conductivity was found between the two ponds. Conductivity
indicates how well water can pass electrical current through it. It is affected by the amount of
anions and cations found in the water. Although results showed improved conductivity in
pond four neither of the ponds fall within the safe range of 150-500µmhos/cm.
Ponds showed effective filtering of pollutants in both dry summer months and also
wet winter months. Soil data indicated a higher level of nitrogen found in summer months
compared to winter months. It is concluded that sediments have more time to settle into the
soil and accumulate during the summer season. Both summer and winter seasons showed a
decrease in the amount of carbon and nitrogen levels between ponds one and two, however
they were not always significantly lower. Dissolved oxygen showed significantly higher
levels in treatment pond four and also during the winter season. This reiterates the
effectiveness of the ponds function. Increased dissolved oxygen promotes healthy ecosystem
for aquatic organisms. It is not surprising that dissolved oxygen is lower in hot summer
seasons because high temperatures can cause low oxygen levels. These results do not show
significant decreases in all pollutant levels between the two treatment ponds. However
overall results indicate improved water and soil quality between treatment pond one and
treatment pond four.
CONCLUSIONS
This research concluded that the treatment ponds effectively filter pollutants before
entering into the lagoon habitat. This research has provided the park with a better
understanding of the treatment ponds effectiveness and will also provide vital information to
other organizations looking for ways to naturally filter pollutants. SDRP is an extremely large
natural resource and currently they do not have much documented research available. We
hope that our project not only offers them information on the efficiency of their work at the
lagoon but also serves as a start to many more research projects to come. Our detailed design
and statistical set up and analysis will hopefully guide them to conduct well-balanced designs
of future projects.
The skills I have learned from this experience are invaluable and will be used toward
future research projects in various career paths. This internship taught me how to design and
implement a large-scale field research project. I now feel confident in setting up statistically
accurate non-bias monitoring and management plans for ecological reserves. This is a vital
skill to have when working as a wildlife biologist for larger agencies such as USDA. I have
also learned realistic goals for time management and also enhanced my laboratory techniques.
It allowed me to professionally interact with different project managers and environmental
planners while collaborating with my college. It enhanced my relationship with SDRP and
also CSUSM professors. This also gave me the opportunity to gain experience presenting our
project to the Citizens Advisory Committee and also the CSUSM poster showcase.
Overall this internship has given me hands on experience enhancing my skills for
future career opportunities. I have to thank CSU San Bernardino and the Water Research
Institute for supporting me through this process. This has been an incredible experience and I
look forward to presenting future research and working with these organizations in the future.
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APPENDICES
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SDRP Riverscape Announcement of Project
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Citizens Advisory Committee Presentation Agenda
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CSUSM Treatment Pond Poster Presentation
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Dissolved oxygen temperature chart
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