Sources of Excess Phosphate Leading to Cyanobacteria

Home , Lake Temescal, Sag pond

SOURCES OF EXCESS PHOSPHATE LEADING TO

CYANOBACTERIA BLOOMS AT LAKE TEMESCAL, OAKLAND, CA.

A University Thesis Presented to the Faculty

California State University, East Bay

In Partial Fulfillment

of the Requirements for the Degree

Master of Science in Geology

Faithe Lovelace

March, 2017

Acknowledgements

I would like to thank Dr. Jean Moran for the countless hours she put into this project, without your insight this project would not be possible. Thank you, Dr. Michael

Massey, for your help and data. Thank you, Pamela, Beitz and all East Bay Regional Park

District for presenting the project and the continuous support, suggestions, and funding for the project. Thank you, Glenn, Carr for your help in the field and all the support your provided. I would like also like to thank my parents Michael and Mary Catherine for their unwavering belief and support.

Abstract

Lake Temescal is a dammed sag pond formed as a result of long-term creep along the

Hayward Fault. It is a popular swimming, hiking, and fishing spot within the East Bay

Regional Parks District (EBRPD). Over the past decade, the lake has experienced numerous cyanobacteria (commonly known as “blue green algae”) blooms and high

3- phosphate (PO4 ) concentrations have been implicated in the blooms, as phosphate is a typically a limiting nutrient. Further water quality, and water chemistry testing, collected over 16 months (November, 2015 – March, 2016), provided insight into sources and cycling of phosphate in the lake and its watershed. Advanced analyses such as the ratio of total nitrogen to total phosphorous (TN:TP), X-ray absorption spectra

(XAS) of lake bottom sediments, and 18O of phosphate were applied as tracers of phosphate source and cycling.

In general, phosphate concentrations in Temescal watershed creeks and in the lake are well above typical background levels and well above concentrations implicated in blooms. Water quality and chemistry results demonstrate water column stratification and seasonal cycling of the lake, including establishment and breakdown of a thermocline and a persistent redoxcline. Because of rapid sedimentation in recent decades, the lake is only x m deep, and the entire water column is warm by the end of summer. Low dissolved oxygen and high temperatures correlate with higher phosphate concentrations. Samples from late fall show a decrease in phosphate, suggesting that the cycle switches from the internal cycling of phosphorus within the lake system, to

iii receiving external phosphate from the watershed. In June, an external source of phosphate affects the surface of the lake as evidenced by low TN:TP values and an increase in phosphate concentrations.

In March and June 18O of phosphate samples were collected at various depths.

Expected values for 18O of P were calculated from an empirical formula using parameters collected in the field and then compared to the results; the actual values.

The lake would be in equilibrium with the ecosystem if the expected and actual values were the same. The March shallow depth results were closer to the expected values, but the deep samples were extremely far from the expected. External source nutrients are leading to disequilibrium resulting in high 18O of P at the bottom of the lake.

Groundwater is a plausible source of phosphate due to the deeper portion being more out of equilibrium and the shallow portion is closer to equilibrium as the groundwater is being diluted. The 18O of P values are also suggesting a more natural phosphate. Lake

Temescal is experiencing more natural conditions in the winter when the temperature is low, phosphate is low and TN:TP is high. All June 18O of P values were extremely out of balance with the ecosystem, but most out of equilibrium at the surface. In June, an external source of phosphate is affecting the surface of the lake leading to extreme disequilibrium. The external source is then confirmed by the low TN:TP values

(indicative of a non-natural source) and an increase in phosphate concentrations. The

June values at deep depth suggest anthropogenic sources and the shallow portion are not in the literature.

Some of the 18O of phosphate results found in the waters of Lake Temescal have previously not been reported in the literature. High temperatures, low dissolved oxygen, high phosphate concentration, and low TN:TP were found to be contributing factors on the equilibrium of the 18O of phosphate results. The sources of natural and anthropogenic phosphate can be a result of lake stratification, phosphate movement in the sediment and groundwater or inflow from the surrounding watershed.

SOURCES OF EXCESS PHOSPHATE LEADING TO

CYANOBACTERIA BLOOMS AT LAKE TEMESCAL, OAKLAND, CA.

Faithe Lovelace

Approved: Date: Table of Contents

Acknowledgements ...... ii

Abstract ...... iii

List of Figures ...... ix

List of Tables ...... xi

List of Equations ...... xii

Introduction ...... 1

Background ...... 5

Cyanobacteria ...... 5

Phosphate Cycle...... 7

External phosphate inputs to the Lake Temescal Watershed ...... 9

Internal phosphate cycle at Lake Temescal ...... 12

Local Geology ...... 13

Water Quality and Chemistry ...... 18

Nitrogen and Phosphate Relationship ...... 19

18 3- O of PO4 as a Source Indicator ...... 20

Phosphate tracing with Spectroscopy ...... 23

Methods ...... 25

Results and Discussion...... 33

vii

Hydrology and Hydrogeology ...... 33

Water Quality and Water Chemistry ...... 40

Nitrogen and Phosphate Relationship ...... 51

Stable Isotopes of the Water Molecule ...... 53

Source Indication from 18O of P ...... 58

Conclusion ...... 67

References Cited ...... 71

Appendix ...... 79

viii

List of Figures

Figure 1 Topographic Map of Lake Temescal and the surrounding watershed ...... 4

Figure 2 Map of California showing reported cyanobacteria sightings and toxins in

California...... 5

Figure 3 The Phosphate Cycle...... 11

Figure 4 Geological Map of Lake Temescal and the Lake Temescal Watershed...... 17

Figure 5 Select subtances from the Young et al. (2009) ...... 23

Figure 6 X-ray absorption edges shown on a log-log plot...... 25

Figure 7 Map of Temescal and the watershed ...... 28

Figure 8 2015-2016 rating curve for Temescal Creek...... 31

Figure 9 Precipitation hyetograph ...... 35

Figure 10 Watershed map of Lake Temescal...... 37

Figure 11 Temperature profile of North Dock...... 41

Figure 12 Dissolved Oxygen profile...... 42

Figure 13 XAS results showing an iron associated phosphate ...... 43

Figure 14 Temperature profile for the North Dock...... 44

Figure 15 Dissolved Oxygen Profile for the North Dock...... 44

Figure 16 Phosphate concentration at select surface locations ...... 45

Figure 17 Total Nitrogen concentration at select surface locations...... 46

Figure 18 Nitrogen vs Phosphate...... 46

Figure 19 Phosphate graphed against precipitation...... 48

Figure 20 Total Nitrogen and phosphate versus temperature ...... 48 ix

Figure 21 Phosphate plotted against Dissolved Oxygen...... 49

Figure 22 Phosphate concentrations for four depth profiles...... 49

Figure 23 Water Chemistry and Quality results plotted against Sulfate...... 51

Figure 24 Select locations for TN:TP changes for data collection period...... 52

Figure 25 Stable Isotopes for all samples...... 56

Figure 26 Stable Isotopes results separated by location...... 57

Figure 27 Stable Isotopes broken into seasonal grouping...... 58

Figure 28 Actual results for the sampling events plotted against depth...... 59

Figure 29 Expected results for the two sampling events plotted against depth...... 60

Figure 30 Actual and expected results for June...... 62

Figure 31 Actual and expected values for March...... 62

Figure 32 Actual values subtracted from expected values...... 65

Figure 33 Actual values subtracted from expected values ...... 65

Figure 34 Actual values subtracted from expected values...... 66

Figure 35 Actual values subtracted from expected values...... 66

Figure 36 18O of P for select substances and Lake Temescal results...... 67

List of Tables

Table 1 Radon sample results ...... 35

Table 2 TN:TP data for various sources ...... 53

List of Equations

18 Equation 1 Formula to calculate the expected values of OP ...... 21

Equation 2 The term can be solved using this equation ...... 21

xii

Introduction

Lake Temescal is a sag pond formed as a result of long-term creep along the

Hayward Fault, and is now dammed (Figure 1). Today, Lake Temescal is a popular swimming, hiking, and fishing spot within the East Bay Regional Parks District (EBRPD).

When the lake was originally dammed, in the late 1860’s, it had a depth of 24 meters

(EPA, 1980). Over time, due to sedimentation, the lake depth has gradually decreased and now the maximum depth is only about 7 meters. Since the completion of the dam, the Lake Temescal watershed has experienced the development of innumerable urban features such as housing, tunnels, freeways, and subsurface infrastructure. More recently, the lake has experienced numerous cyanobacteria (a group of bacteria commonly known as “blue green algae”) blooms, primarily during the warm months of late summer and early fall. East Bay Regional Park District became concerned about the health and aesthetic conditions of the lake and was highly motivated to discover why the lake is a “hot spot” for cyanobacteria growth.

Several studies have been conducted on the factors contributing to growth of cyanobacteria. Carr et al. (1997) and Paerl et al. (2001) found phosphate and nitrogen to be two of the biggest factors controlling the growth and production of cyanobacteria, as they are often the limiting nutrients in freshwater ecosystem such as Lake Temescal.

Once a body of water has excess nutrients, for example through agricultural runoff where fertilizer has been added to the system, the water body can become eutrophic.

Cyanobacteria flourish when the water column is stratified and slow moving. 2

Stratification promotes a hypoxia or anoxia, a lack or absence of oxygen, in the environment below the air/water interface. Under these low oxygen conditions, sediments can release phosphate and trace elements. An ideal setting for cyanobacteria is one with high enough water velocity to distribute various nutrients, but where the water velocity is not so fast that cells are broken from currents. Global warming has greatly benefited cyanobacteria, as well. The rise in temperature has led to water being more frequently and more strongly stratified (Paerl et al., 2001). Multiple variables can therefore cause cyanobacteria to “bloom” or to exponentially grow. This thesis focuses on sources, fate and transport of one important, often limiting, nutrient: phosphorus.

The blooms are problematic for recreation, as it causes fish death, and the toxins in the water results in unsafe water conditions for humans, whether exposed by water contact or water consumption. Since 2011, California has had over a thousand reported cases of water bodies (lakes, rivers, and the delta) showing some level of toxins from cyanobacteria blooms (Baer, 2016) (Figure 2). EBRPD was been proactive with weekly monitoring of lakes in the district; other parks let nature run its course (e.g., Clear Lake,

CA). Logistical issues for water bodies such as rivers and the delta make treating the blooms difficult (BGA Lake County, 2016). Cancer, liver disease and several human deaths have been attributed to the toxic water of cyanobacteria blooms (Paerl et al.,

2001, and Albay et al., 2003).

Cyanobacteria blooms are a worldwide problem. European authorities, particularly in Netherlands, have been very proactive in their efforts to deal with algal blooms. For example, the Netherlands reduces eutrophication and phosphate inputs by

flushing and mixing lakes, dredging lake bottoms and the use of algaecides (Waajen et al., 2015). They reduce the external phosphate input and then can address the internal sediment phosphate release. The internal release is usually mitigated by the use of an application that stops release or binds phosphate. Cyanobacteria’s ability to survive in a vast array of suitable climates and environments demonstrates how adaptive the bacteria are and why they are of increasing concern not only to the scientific community, but to the general public.

Phosphorus often exists in the environment bonded to oxygen in the form of

3- phosphate (PO4 ). Phosphate can be either organic (an ester of phosphoric acid) or inorganic, referred to as “orthophosphate”, which is typically considered to be the bioavailable form of P (Murphy, 2007). Throughout this thesis inorganic phosphorus will

3- be referred to as phosphate. High phosphate (PO4 ) concentrations have been implicated in Lake Temescal blooms, through previous testing carried out by the EBRPD.

Although the problem has been identified, the source of the elevated phosphate, whether natural or anthropogenic, has not been identified. Because nutrients have multiple potential sources, distributed throughout a watershed, their sources are difficult to identify. This thesis describes the results of field and laboratory studies aimed at examining the sources, fate, and transport of phosphate in Lake Temescal and its watershed. Innovative methods are applied, including spatial and temporal examination of nutrient inputs to the lake, 18O of phosphate, and X-ray Absorption

Spectroscopy (XAS) of lakebed sediments.

➤ LakeTemescal ➤ N

1 mi

Figure 1 Topographic Map of Lake Temescal and the surrounding watershed. Contour interval is 20 feet. Created using Google Earth.

Figure 2 Map of California showing reported cyanobacteria sightings and toxins in California from 2011 -2015. Created by Stephanie Baer (2016) from data gathered from Environmental Protection Agency, Sonoma County Health Department, San Diego Regional Water Quality Control Board, California Environmental Data Exchange Network, Central Coast Regional Water Quality Control Board, and East Bay Regional Park District.

Background

Cyanobacteria

Microcystis is the most common cyanobacteria bloom-forming genus, and is almost always toxic (Pearl et al.) Their growth rate is typically controlled by the amount of available nitrogen and phosphate in an ecosystem. Once the cyanobacteria out- produce the rate of bloom consumption, a bloom occurs. Paerl et al. (2001) discusses the relationship that exists between the total molar and soluble ratios of nitrogen and phosphate. When the N to P ratio is less than 15 (indicating high P concentrations relative to N), cyanobacteria blooms are very probable, especially if the water

movement is relatively stable, the water can warm, and the water body becomes stratified.

One of the reasons blooms are problematic is that cyanobacteria can utilize atmospheric nitrogen, circumventing nitrogen-limiting conditions (Paerl et al, 2001).

This aspect is a drawback because it indicates a cyanobacteria bloom can grow when nitrogen and phosphate are readily available, but also when soluble nitrogen is a limiting nutrient. Cyanobacteria produce oxygen during photosynthesis, but then when sunlight is unavailable they use the dissolved oxygen present in the water for respiration

(BTNEP, 2015). Also, cyanobacteria die and are decomposed by other bacteria, which uses up available oxygen in the water. This creates an environment of low oxygen,

(called a “hypoxic” environment), or no oxygen, (called an “anoxic” environment).

Anoxia and hypoxia lead to the death of aerobic organisms such as fish, increasing scum and foul odors.

Lake sediment cores from North America and Europe, showed that in the past two hundred years 58% of the lakes had experienced an increase in cyanobacteria

(Taranu et al., 2015). Taranu et al. (2015) stated that intensified land use, sewage discharge and climate changes during the past two centuries favor disproportionate development of harmful algae in freshwaters. Of those lakes, only 3% had a decrease in microorganisms that may have been consuming the cyanobacteria. Recently, cyanobacteria blooms have expanded to places in the world that had not previously experienced high concentrations of cyanobacteria. Blooms occurred in three Turkish lakes that are used as water sources and other places such as New Zealand, Brazil, South

Africa, Europe, and the United States have all experienced blooms (Paerl et al., 2001;

Albay et al., 2003). Cyanobacteria are likely descendants of some of the oldest organisms, and have therefore been found in six continents, in the ocean, hot springs, and the artic regions of Canada (Paerl et al., 2001; Carr et al. 1997; Albay et al., 2003,

Flombaum et al., 2013; Sompong et al., 2014; Jungblut et al., 2012). Cyanobacteria blooms have caused numerous problems for several East Bay Regional Parks, including

Lake Anza, Lake Chabot, Shadow Cliffs, Lake Del Valle and Quarry Lakes, as well as Lake

Temescal.

Phosphate Cycle

The phosphorus cycle has two inter-related components, geologic and biologic

(Figure 3). It is a slower cycle than most other biogeochemical cycles because it does not have a gaseous component under ambient environmental conditions. One part of the geologic phosphorus cycle involves the weathering of rocks, while important parts of the biologic cycle involves plant uptake, consumption of plants by animals, excretion of phosphorus in animal waste, and microbial decomposition of wastes (Enger and

Smith, 2002). Humans have interfered in the phosphorus cycle, accelerating the cycle through mining, over-application of phosphate as a fertilizer, release of sewage and grey water (household products like soaps and detergents with phosphate present), and rapid runoff and erosion in densely urbanized areas. Speeding up the cycle creates the undesirable effect of phosphate overabundance in water bodies. Natural and altered

ecosystems do not have the resources to use all the available phosphate, leading to phosphate rich environments, ideal for opportunistic species such as cyanobacteria.

Phosphate reserves are shrinking rapidly turning the cycle into a one-way loop as the geological sources are rapidly being depleted due to rapid depletion and slow geologic accumulation (Elser and Bennett, 2011). Researchers estimate that phosphate reserves years will start to rapidly decline over the next 50 to 100 years. In 30 years, humans will use the peak amount of phosphate and the supply may be completely exhausted in 300 years (Vaccari, 2009). This results in areas with extremely high concentrations of phosphate, especially in lakes, where it accumulates and then is locally cycled within the system.

Plants need a relatively large amount of phosphate and for this reason it is considered a macronutrient (Busman, 2002). Phosphate helps transmit energy for ATP and plant maturity. It is a reactive element, readily binding to Fe, C, O, N and H

(Tamburini et al., 2014; Walter et al., 1996). The anions associated with phosphate, i.e.,

- 2- the orthophosphates H2PO4 and HPO4 , are not very soluble in water (Busman, 2002).

In a freshwater lake with no excess phosphate, a typical phosphate concentration is only

.03 mg/L (Osmond et al., 1995). Phosphate is found naturally in rocks, primarily in the mineral apatite, and is also found in soils as organic and inorganic P (Busman et al.,

2009). Apatite is very common in igneous and metamorphic rocks; most fertilizers are made from phosphate found in the mineral apatite (Paytan and McLaughlin, 2011). Clay and metal oxides in soils and sediments can adsorb the phosphate not taken up by

plants and phosphate anions are typically bound strongly to particles in soils and sediment.

External phosphate inputs to the Lake Temescal Watershed The heavily urbanized environments of the Temescal Creek and Caldecott Creek watersheds are a possible source of the excess phosphate, in Lake Temescal. The upper reaches of Temescal Creek are highly altered and channelized. The creek bed has been replaced with cement along some reaches, causing loss of riparian habitat and decreasing water infiltration. The channelized streams lead to physical processes and biogeochemical reactions that naturally filter and cycle pollutants and nutrients in the riparian zones to be eliminated. Fertilizer and manure sources of phosphate are soluble and available for plant use when they first enter the soil, but over time this becomes less true as plants reach the limit of phosphate intake (Busman et al., 2009). This solubility is made possible by moisture in the soil dissolving the fertilizer which then allows the phosphate to move slowly away and sorb to cations present in the soil such as iron, calcium, and magnesium (Busman et al., 2009). Runoff due to rain and irrigation can speed the movement significantly of dissolved phosphate from fertilizer or other sources (Busman et al., 2009).

The volume of runoff and pollutants in urban areas increases because of the predominance of impermeable surfaces such as roads, houses (roofs), and cement. The impermeable surfaces then further supply pollutants to the lake because physical processes and biogeochemical reactions that naturally filter and cycle pollutants and nutrients in the riparian zones are eliminated. Rain leading to runoff, and excess

anthropogenic surface water can also enhance rock erosion. Eroded sediments likely contain phosphate, as the area surrounding the upper Caldecott Creek portion of the watershed has noted phosphate nodules (Graymer, 2000). Erosion in urban areas is also accelerated by human activity, through construction, road building, off-road vehicles, decreasing slope stability through landscaping, and hiking off trail. The amount of particle-bound phosphate entering streams and lakes is thus controlled by the amount and intensity of rainfall, irrigation return flow, opportunities for uptake by the riparian plants, land cover, and mechanical erosion.

Channelized Stream Leaky Pipes Runoff of homes, lawns, slopes, and leaky pipes WWTP, and dissolved (particulate phosphate

Temescal Creek

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Figure 3 The Phosphate Cycle. Phosphate can enter a lake though runoff, groundwater, stream inflow, and direct deposit. Phosphate not used up by plants is then deposited. Phosphate can be released from sediment during hypoxic or anoxic conditions, and therefore become more bioavailable for cyanobacteria. Adapted from Søndergaard et al., 1999 and Busman et al., 2009.

Internal phosphate cycle at Lake Temescal A pattern that is increasingly observed in small temperate lakes is that they typically have higher total phosphate in the water column in the summer compared to the winter (Søndergaard et al., 2003). This pattern can be explained by e.g., wastewater inputs not being diluted by rain in small flow inlets, but another plausible explanation suggested by Søndergaard et al. (1998) is that phosphate is being released by sediment during summer months. This latter idea posits that in winter there is a positive retention and in summer a negative retention of phosphate in the sediment.

Søndergaard et al. (1998), notes the negative retention lasts for two months (July-

August typically the warmest months when blooms are noted), and the negative retention can last five months in highly eutrophic lakes. The fluctuations can be attributed to seasonal variation as a result of temperature and biological activity

(Søndergaard et al., 1999). In the winter mineralization and sedimentation are slow, the sediment has a higher P-sorption capacity with oxygen when abundant at low depths.

Winter environments thus promote a positive retention of phosphate. In the summer biological activity and sedimentation rates increase, leading the oxidized surface layer to be diminished (Søndergaard et al., 1999). This results in a negative retention factor in summer and the phosphate being more available in the water column (Søndergaard et al., 1999). The warmer temperatures can also increase the mobility of phosphate found in deeper sediment layers. The internal phosphate cycle demonstrates how even with limited external phosphate inputs, the lake itself internally recycles phosphate.

A key strategy in managing cyanobacteria blooms is limiting phosphate, especially in urban settings where a high amount of impermeable surfaces leads to creeks and lakes being a sink for the excess natural and anthropogenic phosphate.

Increasingly common observations are that reducing the external phosphate load does not lead to a reduction in the cyanobacteria biomass (Lürling et al., 2016; Waajen et al.,

20152016). This is a result of the phosphate cycle within the water body itself, which can retain the historically accumulated phosphate in the sediment and then release that phosphate to the water column. When this occurs, an engineered remediation approach is often used, in which compounds are applied that prevent phosphate from being released from the sediment, and remove phosphate from the water column

(Lürling et al., 2016). These strategies have so far produced acceptable results in managing the cyanobacteria in Lake De Kuil, Netherlands, a freshwater lake (Waajen et al., 20152016). However, they do not fully address the long-term issue, because Lake

Temescal is a sag pond that has a natural additional inflow as a result of the Hayward

Fault.

Local Geology

The Hayward Fault is a right lateral transform fault that extends from San Jose to

Richmond, CA. The last major earthquake on the fault was a 6.8 magnitude in 1868

(Brocher et al. 2008). The Hayward fault has an earthquake interval of 140 50 years, meaning that it is probable that a 6.3 magnitude earthquake will occur in that period

of time (Brocher et al. 2008). The Hayward fault is actively creeping ( 5mm/yr), making visible right lateral deformations in the local natural and anthropogenic landscape.

Fault movement originally resulted in formation of a sag pond at Temescal, but as the surrounding area grew in population the pond became a source of water. A sag pond is a natural phenomenon, caused by fault movement that generates fine grained

‘gouge’, creating a new impermeable layer at the fault boundary. Groundwater no longer is able to flow freely through the aquifer and is forced up and above ground at the boundary. As the population in the area grew the lake was dammed in the 1860s for water supply. Lake Temescal is currently used as a recreational reservoir for the surrounding area (EBRPD, 2015).

Lake Temescal is surrounded by Mesozoic rock of distinct composition, with the

Franciscan Complex to the west and the Great Valley Sequence formation to the east

(Figure 4). It is an approximately 10-acre (4 hectare) lake with two creeks draining into it, Temescal Creek and Caldecott Creek (EPA, 1980). A single concrete spillway regulates the outflow at the northern end. The upper reaches of Temescal creek flow through an unnamed mudstone of Eocene origin, the middle part of the creek is underlain by the late Cretaceous Redwood Canyon Fm, and the lower reaches of the creek flows through rocks of the Franciscan Complex. The upper reaches of Caldecott creek are underlain by an unnamed glauconitic mudstone, while the middle part of the creek flows over rocks of the Great Valley Sequence, and the lower reaches flow in keratophyre (a type of light color sodium containing albite-phyric volcanic) and quartz keratophyre.

The unnamed mudstone of the upper Temescal creek is foraminifer rich mudstone interbedded with mica-bearing, quartz sandstone (Graymer, 2000). The

Redwood Canyon Formation of the middle reaches of Temescal creek a is thick fine-to- course grained biotite, quartz wacke and interbedded with thin mica rich sandstone

(Graymer. 2000). The Franciscan Complex is found in both the lower reaches of

Temescal Creek and all along the west side of the lake. The formation is argillite, greywacke, and small amounts of tuff with lenses of greywacke and meta-greywacke

(Graymer, 2000). The upper reaches of Caldecott creek are underlain by a brown mudstone interbedded with sandy mudstone with glauconite grains and both contain 1 cm or less phosphate nodules (Graymer, 2000). The Great Valley sequence found in the middle reaches of the creek is sandstone, siltstone, shale and small amounts of conglomerate. The rocks exposed along the lower reaches of Caldecott creek and the east side of Lake Temescal are composed of extremely altered intermediate-silicic volcanic and hypabyssal rock; almost all the feldspars are now albite. The Lake

Temescal area is a product of an active fault, and the topography and geology reflect that. The Lake Temescal watershed and lake is an extremely lithologically and tectonically complex area. The area has been rechecked and mapped several times by different parties (Blake, M.C., 2000, Dibblee, T. W., 1980, Jones, D. L., 1994) and each examination has revealed new units not recognized before, demonstrating the intricacy of the area.

Portions of the Lake Temescal Watershed experience more erosion than the solid Great Valley Complex found on the east side of the lake. Examination of the upper

area of Caldecott Creek show the rocks have moderate friability, the rocks can be crushed with fingers. The west side of the lake (Franciscan Formation) also experiences heavy erosion in part from hikers, extremely steep slopes, and the friability of the formation. The paths on the west side are maintained by EBRPD and periodically need to be reinforced as the path degrades into the lake. The relative erodibility of portions of the watershed can be transporting phosphate into the lake.

➤ ➤ N i m

1 af Qha Jsp Tms KJs Ji Tpas fsr Ks Jv Sedimentary rocks (Oligocene and (or) Eocene) and (or) (Oligocene rocks Sedimentary (Holocene) Alluvium (Miocene) rocks Sedimentary (Oligocene)phosphate rocks Sedimentary Toes nodules Tes (Eocene) rocks Sedimentary (Paleocene) rocks Sedimentary (Eocen, mélange Complex Franciscan Late Cretaceous) and (or) Paleocent, rocks sedimentary complex Valley Great (Cretaceous) (Early rocks sedimentary complex Valley Great Late Jurassic) and (or) Cretaceous (Jurassic) rocks volcanic complex Valley Great (Jurassic) rocks plutonic complex Valley Great (Jurassic) serpentinite complex Valley Great Fault Lake Temescal (2000) al. et Graymer from adapted

Figure 4 Geological Map of Lake Temescal and the Lake Temescal Watershed.

Water Quality and Chemistry

Water quality parameters measured in the field such as temperature, dissolved oxygen, conductivity, pH, and turbidity can be useful tools in understanding water dynamics. The pH is important because it affects whether nutrients such as nitrogen, phosphate, and various metals will be dissolved in the water. If the water becomes too acidic or basic, organisms can be stressed or even die. Monitoring an ecosystem’s water quality parameters can give warning if pollutants are entering a system. Conductivity is the ability of a solution to conduct an electrical current (EPA, 2012). Conductivity testing also can show when pollutants are present since elevated temperatures cause higher conductivity, possibly indicating higher amounts of phosphate, nitrogen, and other dissolved solids. Water- rock interaction can also increase conductivity; if rocks are eroded easily then the clay-size particles can cause conductivity to rise.

Photosynthesis can be affected by turbidity, which is the amount of suspended particles.

Turbidity can be affected not only by suspended particles but also by the amount of suspended cyanobacteria. Temperature is an important water quality parameter due to its control on lake stratification and turnover. Warmer temperatures hold less oxygen and biological activity increases. Dissolved oxygen is needed in an aquatic system and in summer as temperatures rise dissolved oxygen decreases.

Individual anion concentrations can also help in comprehending lake dynamics.

High concentrations of Br, Cl, F, NO2, NO3, PO4, SO4 anions can indicate weathering of rock and soil, or wastes from industrial or municipal sewage. Chloride is very mobile

and can easily be eroded from rocks and dissolved into the soil solution or water. The main anthropogenic sources are inorganic fertilizers, sewage effluents, industrial effluents, and irrigation drainage (WHO, 1996). Nitrate is reactive, but does not interact with solids and is very soluble in water. Anthropogenic sources of nitrate include inorganic fertilizers, animal manure, municipal wastewater, and septic tanks (WHO,

2011). Soil decomposing with nitrogen present first produces ammonia, then ammonia undergoes nitrification to nitrite, and finally to nitrate. Any nitrate not consumed by plants is able to freely move into groundwater and surface waters (WHO, 2011).

Anthropogenic sources are from mining, fertilizers, insecticides, and glass and paper production, which can be transported by water (WHO, 2004). The anions give information about the quality, chemistry, and potential sources of water (groundwater, leaky pipes, surface runoff, and precipitation).

Nitrogen and Phosphate Relationship

As noted above, nitrogen and phosphate are important nutrients needed for plant growth and are often limiting nutrients in a natural, undisturbed environment. An important relationship to consider in examining sources of nutrients, is that of total nitrogen to total phosphate. A high wt/wt TN:TP (>15) typically indicates natural sources and an oligotrophic water body, while a very eutrophic lake would typically have a much lower ratio (Downing and McCauley, 1992). Downing and McCauley (1992) determined that the TN:TP is noteworthy when looking into algae blooms, stating high

TP was the greatest influence on ta freshwater bloom. Downing and McCauley (1992)

made the discovery that the TN:TP at low TP was not related to a bloom, but when the ratio was low and TP high (close to sewage 2-4 g/l) a bloom was present or biomass was heavy. The nitrogen and phosphate relationship therefore can be used to further understand nutrient sources.

18 3- O of PO4 as a Source Indicator

As noted above, phosphate is constantly being cycled in an ecosystem. It is very reactive and is not found by itself in nature, making phosphate a viable source tracer.

Unlike many other light elements, phosphate has only one stable isotope. However, phosphate is covalently bonded to oxygen’s three stable isotopes, 16O, 17O, and 18O, in both organic and inorganic forms (Paytan and McLaughlin, 2011). Measuring the amounts of the three stable oxygen isotopes allows phosphate cycling and transformation to be traced through the oxygen isotopes (Paytan and McLaughlin,

2011). Under ambient temperatures and pressure the bond between oxygen and phosphorous does not degrade. This is an important feature because it means inorganic hydrolysis will not affect how oxygen is bound to phosphate, allowing the temperature

3- and water isotope signature of where PO4 formed to be preserved (Paytan and

3- McLaughlin, 2011). The isotope signature is a ratio of heavy to light PO4 molecules. An empirical equation was developed to show the relationship between temperature, oxygen isotopes of water and phosphate (Equation 1). The equation represents equilibrium fractionation between phosphate and water as a function of temperature

(Paytan and McLaughlin, 2011). The temperature used in the equation is the water

temperature. The term delta, , is a ratio and the values are then reported parts per thousand (‰). The isotope standard used in the calculation is SMOW, Vienna Standard

18 Mean Ocean Water. The equation is used to predict a value for OP using measured

18 18 values of T and OW (the O value of H2O), then compared to the results of measured

18 OP.

18 18 T(C) = 111.4 – 4.3( OP - OW)

18 Equation 1 Formula to calculate the expected values of OP

Equation 2 The term can be solved using this equation

Under ambient temperature, pressure, pH and no biological activity, water and phosphate oxygen isotope exchange happens unhurriedly (Paytan and McLaughlin,

2011). The lighter oxygen isotope of phosphate will preferentially partition into the liquid phase, while the heavier phosphate isotopes are found in mineral phase.

However, this fractionation is usually very small (+0.07‰ - +1‰) and is the result of P adsorption and desorption onto/from mineral surfaces (Paytan and McLaughlin, 2011).

In comparison, biological activity causes more extreme fractionation (-30‰- +10‰).

The enzymes involved break the P-O bond and biological organisms then use the

phosphorus in various biological processes. Enzymatic processes and reactions will affect what ratio of oxygen isotopes (heavy or light) are present in phosphate (Paytan and McLaughlin, 2011). Metabolism (which may be intracellular or extracellular), leads to an equilibrium condition between phosphate oxygen and water oxygen isotopes,

18 which precludes using the OP value as a source signature (Paytan and McLaughlin,

2011). When a system is out of equilibrium, as determined from Equation 1, it indicates that a source can potentially be discovered. The possible sources of phosphate can then be determined based on possible oxygen isotopic signatures of natural or anthropogenic

18 phosphate and the observed values of OP in the system of interest.

Source testing done by Young et al. (2009) showed that there is considerable

18 overlap between the observed OP ranges for various phosphate sources such as detergent and vegetation leachate (Figure 5). This overlap may not be as prominent for a local region, as Young et al. (2009) used material from several areas. For example, a vegetation leachate will have a much smaller range for one locale compared to the overall range, thereby minimizing potential overlap between a detergent source and other sources such as vegetation. While the method remains an area of active research,

Young et al (2009) and McLaughlin et al. (2004) have sampled many locations

(freshwater, brackish, and seawater) for 18 O of phosphate, and went so far as to create a database of values to document the isotopic signatures of phosphate in various environments. Elsbury et al. (2009) used the method to determine sources and water equilibrium for Lake Erie. Their data pointed to an unknown source and concluded

more data in the literature are needed. All values from Young et al. (2009) are significantly greater than 0‰, indicating a greater proportion of the heavier isotope

(18O) in these residual materials (left behind during biological/metabolic processes) as compared to the standard (SMOW).

18O of P for Select Substances 25

15 8 of P O

18 Average 10

0 Chemical Dog Feces Goose Feces Soil and Waste Water Detergents Fertilizer Vegatation Treatment (Israel) Plant

18 Figure 5 Select subtances from the Young et al. (2009) study on OP in sources of phosphate from a broad geographic area. The solid circle is the average value from around the world and the lines show the range of high and low values.

Phosphate tracing with Spectroscopy

Another possible way to glean information on phosphate speciation in sediments is through X-ray absorption spectroscopy. For phosphorus, the most common technique

is X-ray absorption near edge structure spectroscopy, or XANES spectroscopy. In X-ray absorption spectroscopy, an X-ray beam is used to probe the electronic structure and local structure (nearest neighbors) of an atom of interest. The technique is element- specific, meaning one can look only at phosphorus, for example, by selecting the energy of the X-ray beam used to probe the sample. Depending on the atom, at some energies there are sharp increases in X-ray absorption, referred to as “X-ray absorption edges.”

X-ray absorption edges are when there is sufficient energy to excite “electrons from low energy bound states in the atoms” (Bunker, 2010). For phosphorus XAS, the X-ray energy typically used for environmental samples is the energy corresponding to the phosphorus K-edge, which is a photon energy of around 2,155 eV. The “K-edge” is the energy at which a phosphorus 1s electron is excited into the 2p energy level.

By probing the behavior of electrons using energetic X-rays, XAS allows the molecular structure around the element of interest (i.e., phosphorus) to be examined. The method can be applied to solids, glass, and liquids allowing its use in many different scientific fields (Bunker, 2010). X-ray absorption spectroscopy measures the X-ray absorption coefficient, which gives insight into “how strongly X-rays are absorbed as a function of X-ray energy E” (Bunker, 2010). The plot of the absorption coefficient versus energy is referred to as the “X-ray absorption spectrum,” and analysis of the spectrum allows for the specific type of phosphorus (e.g., mineral P, organic P, phosphate adsorbed to another mineral, etc.) to be determined. By comparing unknown X-ray absorption spectra to X-ray absorption spectra of known samples (minerals,

compounds, etc.), the specific forms of phosphorus in natural samples can be determined.

Figure 6 X-ray absorption edges shown on a log-log plot. The graph is of Platinum vs. X- ray energy from Bunker 2010

Methods

Samples were gathered over a 14-month period at various sample locations at

Lake Temescal and in the watershed (Figure 7). Sampling events were planned around precipitation events throughout this period with event samples that occurred prior, during and after rain. An initial sampling event was conducted to select viable sites, based on high amounts of nutrients, lake depth, and location of inflows. Water quality parameters including dissolved oxygen (DO), electrical conductivity (EC), temperature,

pH, and oxidation-reduction potential (ORP) were measured using a the YSI Multi-Meter

(YSI Incorporated, Yellow Springs, Ohio, United States). Turbidity was measured several times with an Oakton Instruments T-100 (Oakton Instruments, Vernon Hills, Illinois,

United States). A 20 ml vial was used to collect samples for turbidity measurement. The vial was fully dry, with no air bubbles, in order to ensure accurate measurements.

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Figure 7 Map of Temescal and the watershed with sample locations shown

Thirty mL glass vials with conical caps were used in the collection of samples for the analysis of stable isotopes of water from streams and the lake. In addition, a rain gauge was set up and rainwater samples were collected at regular intervals for stable isotopes analysis. Samples were analyzed on a Los Gatos Research Cavity Ring Down

Isotopic Water Analyzer (Los Gatos Research, San Jose, California, USA) at California

State University East Bay. The instrument uses off-axis integrated cavity output spectroscopy to measure absolute abundances via laser absorption (IAEA, 2009). From

18 2 18 the raw data, ratios of HOD/H2O and H2 O /H2O, the δ H and δ O values were calculated. A set of standards based on SMOW for δ18O, were also run to calibrate the instrument. Typical 1 sigma uncertainty is ±0.3‰ for δ18O and ±1.0‰ for δ2H. The samples were then interpreted by plotting δ2H vs δ18O along with the slope of the meteoric water line (MWL).

A 100ml plastic bottle was used to collect samples for water chemistry. The water chemistry samples were sent to the East Bay Municipal Utility District laboratory and EPA method 300.1 for Ion Chromatography was used (detection limit 0.01 mg/L).

Initially, a 250ml glass bottle were used for radon (222Rn) analysis. Radon samples were measured using the Durridge RAD7 Radon Analyzer. The radon analyzer uses a semiconductor material, also known as a solid state alpha detector, to convert alpha radiation counts into an electric signal (Durridge, 2015). The typical detection limit is approximately 5 pCi/L, while 1 sigma uncertainties are typically 10%. Success has been recorded when the Durridge RAD7 Radon Analyzer is used on site for continuous

sampling event, this was not done for this project, but would be an interesting addition for future research.

A waters staff had previously been installed by the USGS during the late 1970’s for Temescal creek near the entrance to the lake (shown on Figure 6). The staff was used in monitoring creek inflow by checking the height of the creek on the staff. A

Global Water Meter Flow Probe was used to measure the creek flow during several different rain events and seasonal flow. The Global Water Meter Probe measures the velocity of flow via propeller at the bottom of the probe. To improve the accuracy of measurement the creek was divided into 1 foot sections, and at each section the depth was recorded either from the width of the staff, or when the creek was too shallow, using a meter stick. At the middle of each section the velocity was measured by moving the probe in a slow up and down motion. This motion was continued until the average velocity stabilized, or about 40 seconds. The probe calculates minimum, maximum and average velocity, each velocity was recorded and the average velocity was used in the total creek inflow calculation. More measurements were taken during the rainy season, to gather points for the stream rating curve (Figure 8). Microsoft excel was used to calculate the equation of the curve, a linear expression shown on Figure 8 was the best fit curve.

Rating Curve 9 8 7 6 5 y = -3.7912x2 + 7.453x + 4.2168 4 R² = 0.8723 3

Staff Staff Reading (in) 2 1 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Average Velocity ft3/sec

Figure 8 2015-2016 rating curve for Temescal Creek discharging into Lake Temescal. Staff reading values are taken from the height of the stream on the staff. A higher staff reading resulted in a higher flow velocity.

Samples for analysis of 18O of phosphate were collected twice, once in the summer and spring. A peristatic pump was used to collect the samples at various depths in the lake. Samples for both sampling events were taken at the North Dock in two foot increments, as this was the deepest portion of the lake with easy access.

Samples were taken from the surface at West Winterhaven, Parking Lot bridge, and

Caldecott Inlet (see Figure 7 for locations). During summer sampling events, all samples first passed through a 0.45 m filter. The March samples were collected both filtered and unfiltered, to check for a possible effect of particulate P on both concentration and isotopic results. Water samples were frozen and sent to the Water Sciences Laboratory at University of Nebraska-Lincoln for analysis. The samples were analyzed by isotope ratio mass spectrometry. This requires the phosphate to be converted into solid, silver phosphate. This is done very carefully so as not to allow oxygen that is not part of

phosphate to enter the solid. The laboratory used the method 18O in phosphate developed by McLaughlin et al. (2004).

During August of 2015 a boat was obtained so that samples could be taken from the middle of the lake, and again the peristatic pump was used to collect samples at various depths. Water quality, water chemistry, stable isotopes of water, 222Rn samples were collected. 222Rn samples were collected to evaluate if a measurable amount of groundwater could be detected (Lawrence Livermore National Laboratory ran 222Rn analysis on a Quantalus model 1220).

Solid samples to be analyzed using by X-ray absorpotion spectroscopy were collected in June, August and November 2015. An Ekman dredge was used to collect the samples. The samples were then stored in containers at 4C. Half the samples were oven dried and the other half were air dried. This was done to monitor if there were any changes in results based on the drying technique. After drying the samples, they were ground up with a mortar and pestle until they were a uniform powder.

The samples were then then analyzed for bulk P K-edge XANES at Beamline 14-3 at the Stanford Synchrotron Radiation Lightsource (SSRL) at SLAC National Accelerator

Laboratory in Menlo Park, California. A very small quantity of each powdered sample was painted on ultra-low impurity carbon tape (Ted Pella, Inc., Redding, California,

United States) using a synthetic-bristle paintbrush to avoid P contamination. Incident beam energy was selected using a Si(1 1 1) double crystal monochromator in the phi =

90° position, and the beam path was continuously purged with helium. Energy

calibration was achieved by setting the top of the edge peak of the lazulite XANES spectrum to 2153.5 eV.

Multiple spectra were collected, and spectra were averaged using Sam’s

Interface for XAS Package (SIXPACK) (Webb, 2005). Averaged spectra were analyzed using the Athena software package (Ravel, 2005) to perform linear combination fits of the unknown spectra. Some standard spectra, published in Giguet-Covex et al. (2013) were graciously provided by Charline Giguet-Covex, and were used in the linear combination fitting procedure

Results and Discussion

Hydrology and Hydrogeology

The Lake Temescal water level remains nearly constant year round. There is a small amount of inflow at Caldecott Creek. Using the assumption that there is a relatively small Caldecott Creek inflow and that the outflow at the weir is equal to the inflow at Temescal Creek, a simple water budget for the 2015-2016 year was calculated.

The water budget was then used to estimate the groundwater input. Temescal Creek had inflow measured at about 270 acre-ft/yr with little variation in seasonal flow.

Precipitation data collected at station Oakland North (ONO) from the California Data

Exchange Center, shows that from March 16, 2015 – March 15, 2016 the Lake Temescal water surface received 28.64 in. of precipitation (23.87 acre-ft/yr). Evaporation data was gathered from California Lake Evaporation Data and determined to be 44 in. over the lake area (36.52 acre-ft/yr) (Kohler et al., 1959). The groundwater inflow was

determined to be 12.65 acre-ft/yr (0.0175cfs) by difference. Radon samples were collected to identify a possible groundwater inflow location, but the results were mostly below the detection limit (Table 1). The samples collected at various locations and depths in the lake in August and analyzed at LLNL also were also non-detects; i.e., they were below the Quantalus detection limit of 20pCi/L. At times there were measurable radon activities in the watershed streams and even in the lake water, and other times radon activity was very low, but this pattern was not seasonal or depth-dependent. It is possible that the groundwater is being diluted or samples were collected far from the groundwater source, resulting in low values, on many occasions. The Caldecott Inlet sampling location consistently showed relatively high radon activities for surface water, indicating a significant component of groundwater inflow there. Another sample, from

Temescal Creek at the parking area on March 23, 2015, showed high radon activity, likewise indicating a significant component of groundwater inflow. The likelihood that phosphate enters the lake via groundwater inflow is discussed below.

Between 2010 and 2014, California experienced a drought, but late 2015, early

2016 was expected to be an El Nino year, with an above average amount of precipitation. During the year of sampling, Temescal received about 28.42 in. of rain

(Figure 9), while the historical average is 23.99 in. (U.S. Climate Data, 2016). The water budget shows that Lake Temescal receives a significant amount of water from a groundwater source. The primary sources of inflow are from stream flow, with smaller inputs from precipitation and groundwater, while the primary outflows are release at the weir and evaporation.

Rain Accumulated March 205- March 2016 35

Inches 15

0 42079 42179 42279 42379 Date and Time

Figure 9 Precipitation hyetograph plotted from March 2015 to March 2016. Data gathered from Station ONO for the California Data Exchange Center.

Date Site Radon pCi/L 3/5/15 Caldecott Inlet 42.6 Mouth of Temescal Creek 6.3 Woodhaven Western 16 3/23/15 Caldecott Inlet 112 North Dock 48 Parking Lot Bridge 117 6/9/15 N Dock 3ft 10.7 N Dock 6ft 42.6 N Dock 9ft 10.7 N Dock 12ft 5.34 N Dock 15ft 5.34 Caldecott Inlet 64 Table 1 Radon sample results run on the Durridge RAD7 Radon Analyzer. Results reported in pCi/L.

Caldecott Creek is an ephemeral stream that has been heavily modified by construction and channelization. Caldecott Creek is usually dry and receives water from

rain and urban runoff events. The surrounding watershed is very steep, surrounded by homes, numerous culverts (including part of the Caldecott Tunnel). The surrounding freeway drains into Caldecott Inlet (Figure 10). The baseball fields shown on Figure 10 mark the transition from a natural riparian environment to an artificial riparian environment. In the area encompassing the upper natural riparian reaches of the

Caldecott Creek, phosphate nodules can be found in the unnamed glauconitic mudstone

(labeled as Tsm, Miocene and Oligocene origin) (Graymer, 2000), which could erode and be transported into the lake via the creek. Temescal Creek is a perennial stream that most likely has at least a component of natural groundwater inflow in the upperparts of the watershed, and near the mouth, at the entrance to the lake based on continuous flow and high radon data. The natural riparian zone for Temescal creek is present for portions of the creek, observed by the blue in the watershed map (Figure 10). Radon data was too low to confirm, but water quality indicators suggest there is inflow at the upper portion of Temescal Creek at the Pinehaven sample location (Error! Reference source not found.). The temperature had a sharp decrease, the conductivity decreases, and the dissolved oxygen increases compared to the Winterhaven sample location located just downstream of Pinehaven. Both creeks are situated in steep terrain surrounded by densely clustered homes, and many different geological units are mapped in the area.

Figure 10 Watershed map of Lake Temescal. Blue arrow marks the transition of natural riparian stream to the channelized. The brown indicates culverts that flow into Caldecott creek. Caldecott creek receives drainage from homes, both sides of Highway 24, and the Caldecott Tunnel. Temescal creek has a partial natural riparian zone, but is also surrounded by homes and major streets.

As noted above, the geology in the area is complex owing to the close proximity to the Hayward Fault. There is a mixture of sedimentary rocks of the Great Valley

Complex, local metamorphism and volcanic rocks such as the Keratophyre and quartz keratophyre found on the east side of Lake Temescal in the lower portion of the

Caldecott creek. This provides a complex area for groundwater flow, which is already disrupted by the Hayward Fault. Groundwater discharging into Temescal presents another possible transport pathway for phosphate. Phosphate fate and transport in groundwater is still a developing area of research. Early researchers thought that phosphate was mobile only in reducing areas with dissolved iron. Walter et al. (1996),

Leblanc (1984) and Leblanc et al. (1999) reported results from the Cape Cod Wastewater

Treatment Plant, where they had over 10,000 subsurface data points to observe how the contaminants travel in the subsurface. Walter et al. (1996) found phosphate is mobile in both anoxic (no dissolved oxygen) and suboxic (low dissolved oxygen) zones.

The majority of the scientific community’s understanding of phosphate movement in groundwater comes from observation at the Cape Cod Wastewater Treatment Plant. It is now accepted that phosphate is mobile in volcanic aquifers, in soils when they are water saturated, and in reducing environments with or without dissolved iron (Walter et al., 1996; Correll, 1998).

Phosphate transport was also studied via column experiments by Walter et al.

(1997). In a suboxic column, phosphate will initially be sorbed to sediment (on Fe oxides and organic matter) and once these adsorption sites were filled, then phosphate moved

conservatively downgradient (Tamburini et al., 2014; Walter et al., 1996). This

“breakthrough” observed in column experiments and at the Cape Cod site took many years, showing phosphate can be slowly transported in suboxic zones with low amounts of sorption sites. Walter et al. (1996) also did a column experiment on the effects adding oxygenated groundwater into the subsurface. In the suboxic zone, it resulted in the phosphate being desorbed from sediment and made bioavailable again. Phosphate transport was determined to be a slow transportation when compared to water or nitrogen.

Groundwater supplying Lake Temescal with phosphate is a possibility under both anoxic and suboxic conditions. Under both conditions phosphate can be transported by groundwater and if all sorption sites are filled in a suboxic environment then groundwater will move the dissolved phosphate downgradient (in the Temescal watershed Lake Temescal is downgradient). Phosphate could be entering the groundwater from both anthropogenic sources (lawn fertilizer, wastewater, leaky pipes or sewer lines, wildlife feces) and/or the natural lithogenic P nodules. The groundwater may then transport the phosphate into the lake where it can then be used by the cyanobacteria. Additionally, as noted above, the sorbed phosphate (anthropogenic or natural) from the lake sediment can be released into the water column under anoxic conditions. During many sampling events, the bottom of the water column had a strong hydrogen sulfide smell and black sediment, along with very low dissolved oxygen concentrations- all indicators of a strongly reducing, anoxic environment. Groundwater providing Lake Temescal with phosphate is therefore a likely scenario.

Water Quality and Water Chemistry

Lake Temescal’s P levels were consistently high, as was the concentration of total dissolved solids, while the total Nitrogen concentrations varied but were never elevated to a level of concern. Nitrogen is therefore likely the limiting nutrient for bacterial and algal growth in the lake. Lake Temescal water temperature and dissolved oxygen are useful for examining seasonal turnover of the water column and cycling of nutrients.

The lake is strongly stratified in the early summer, but by late summer it is uniformly mixed and warm throughout the water column (Figure 11). The dissolved oxygen for the June and August sampling events was well stratified (Figure 12). Dissolved oxygen levels were as low as 1% saturation (about .1mg/L), on both dates at deeper depths.

XAS results show that a large proportion of phosphate in sediment is associated with iron oxides (Figure 13). Under reducing conditions the phosphate desorbs from iron oxides, possibly after partial reductive dissolution of the iron minerals, and can be released into the water column.

These low-oxygen conditions create a favorable environment for releasing phosphate into the water column. In June, when the lake was stratified, the re-released phosphate cannot move freely in the water column because the colder bottom waters are denser. However, in the late summer when the dissolved oxygen is still very low and the water is no longer stratified the re-released phosphate can move freely in the water column that now has a uniform density. By November, the lake was stratified, with lower temperature overall and only a near-surface high temperature (Figure 14) and the dissolved oxygen had increased from the summer lows (Figure 15). In January, Lake

Temescal was again fully mixed, and the dissolved oxygen had increased. Dissolved oxygen and temperature are inversely related, i.e., cold water can hold more dissolved oxygen than warmer water. Due to its small size the lake warms up rapidly in the early summer eventually warming the entire water column and takes many months to cool off again. Seasonal cycles of temperature and dissolved oxygen in the lake play a key role in cycling of nutrients, including phosphate.

Temperature vs. Depth

Temperature (C) 15 17 19 21 23 25 0

25 Dpeth below surface (ft) 30

6/9/15 8/13/15

Figure 11 Temperature profile of North Dock in early and late summer 2015. Temperature measured in C and depth below surface measured in feet. In early summer North Dock has a well-defined thermocline and in late summer the profile is almost entirely the same temperature.

DO% and Temp vs Depth for Early and Late Sumer

DO% 0 10 20 30 40 50 60 70 80 90 100 0 5 10 15 20 25 30

Depth below surface (ft) 6/9/15 8/13/15

Figure 12 Dissolved Oxygen profile for early and late summer 2015 at North Dock. Dissolved oxygen is reported at a percent saturation and depth is measured in feet below the surface. Both event showed a decrease in DO with depth.

Figure 13 X-ray absorption spectra showing that phosphate in Lake Temescal sediments are associated with iron oxide minerals. The feature in the spectrum at around 2150 eV (the “bump” just before the main peak) is characteristic of an iron-phosphate association (e.g., iron phosphate minerals, or P adsorbed on iron oxides).

Temperature vs Depth for Fall and Winter

Temperature (C) 6 7 8 9 10 11 12 13 14 15 16 0

10 Depth (ft) 15

11/11/15 1/22/16 3/15/16

Figure 14 Late Fall, Mid and Late Winter temperature profile for the North Dock.

DO % vs Depth for Late Fall, Early Winter, Late Winter

DO % 0 10 20 30 40 50 60 70 80 90 100 0

10 Depth (ft) 15

11/11/15 1/22/16 3/15/16

Figure 15 Late Fall, Mid and Late Winter Dissolved Oxygen Profile for the North Dock.

In addition to dissolved oxygen and temperature, anions and the key nutrients

(phosphate and nitrogen) also experience a seasonal cycle. The tributaries flowing into the lake and the lake, at the north dock sampling site, see an increase in nitrogen during the winter and an increase in phosphate during the summer (Figure 16, Figure 17).

Nitrogen and therefore phosphate demonstrate an inverse relationship to one another

(Figure 18). Fluoride and bromide did not show temporal patterns related to seasonal cycles. The most apparent seasonal cycles were dissolved oxygen (DO), temperature, nitrogen and phosphate.

Phosphate Concentrations 0.8 0.7 0.6 0.5 0.4 0.3 0.2 Phosphate mg/L 0.1 0

N Dock Caldecott Inlet Parking Lot Bridge Woodhaven Western

Figure 16 Phosphate concentration at select surface locations throughout the sampling period.

Total Nitrogen Concentrations 3 2.5 2 1.5 1 0.5 Total Nitrogen mg/L 0

N Dock Caldecott Inlet Parking Lot Bridge Woodhaven Western

Figure 17 Total Nitrogen concentration at select surface locations throughout sampling period.

Total N vs Phosphate 3

2.5

1.5 Total N 1

0.5

0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 Phosphate

Figure 18 Nitrogen and Phosphate display a roughly inverse relationship at Lake Temescal. As total Nitrogen increase the phosphate decreases.

On three occasions depth profiles were measured from North Dock. In August additional samples were taken at the various point in center of the lake (Figure 7).

Results indicate that in winter, when there is more rain, the phosphate is likely diluted, and total nitrogen increases during this time. When all phosphate samples were plotted

against precipitation, it was apparent that rain causes phosphate concentration in the lake to be diluted (Figure 19). Søndergaard et al., (1998) noted that in the colder months nitrogen is high and phosphate is low and nitrogen is low while phosphate is high during the warmer months (Figure 20). Søndergaard et al., (1998) contend that in the winter when sedimentation and biological activity are slow phosphate is able to sorb to sediment, while in the warm periods biological activity increases and sorption decreases. The summer heat also results in more re-mineralization of organic materials, which then releases inorganic phosphate to the water column (Søndergaard et al.,

1999). Dissolved oxygen exerts another control on dissolved phosphate concentrations, low dissolved oxygen results in higher amount of phosphate (Figure 21). At lake

Temescal, low dissolved oxygen and higher temperatures correlate with higher phosphate. Phosphate concentrations at Lake Temescal consistently increase with increasing depth (Figure 22). The late Fall samples show a decrease in phosphate suggesting the cycle switches from the internal cycling of phosphorus within the lake system, to receiving more phosphate from the watershed (Figure 19). The pattern of high phosphate in summer and high nitrogen in winter is prevalent in small shallow lakes (Søndergaard et al., 1999).

Percipitation and Ortho Phosphate at Lake Temescal from 2/27/15 to 3/15/16 2 0

1.8 0.1 1.6 0.2 1.4 1.2 0.3 1 0.4

0.8 0.5 Phophorus mg/L 0.6 Percipitation (in) 0.6 0.4 0.2 0.7 0 0.8 2/27/15 4/18/15 6/7/15 7/27/15 9/15/15 11/4/15 12/24/15 2/12/16 4/2/16 Date

PrecipitationIn C. Inlet Lower Temescal Upper Temescal Lake Surface Lake at depth

Figure 19 Phosphate graphed against precipitation. A rain event leads to phosphate concentrations to decrease.

Temperature vs Phosphate and Total Nitrogen

2.5

1.5

Total N and P mg/L 0.5

0 5 10 15 20 25 30 Temp

Phosphorus Total N Linear ( Phosphorus) Linear (Total N)

Figure 20 Total Nitrogen and phosphate versus temperature. Warmer temperatures have an increase in phosphate and decrease in total nitrogen.

DO vs Phosphate for Lake and Watershed 2 1.8 1.6 1.4 1.2 1 0.8 Phosphate 0.6 0.4 0.2 0 0 20 40 60 80 100 120 140 DO % Watershed Lake

Figure 21 Phosphate plotted against Dissolved Oxygen divided into lake samples and watershed samples. Lower levels of dissolved oxygen resulted in increased levels of phosphate, a pattern also seen when temperatures where high.

Phosphorus vs Depth

Phosphorus mg/L 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0 2 4 6 8 10 12 14 16 Depth below surface (ft) 18

6/9/2015 N. Dock 8/13/2015 N. Dock and Whole Lake 3/15/2016 N. Dock

Figure 22 Phosphate concentrations for four depth profiles at the North Dock and the center portion of lake. Phosphate increases with depth throughout the lake. Light blue swath represents the concentration range for samples taken at the center portion of the lake.

Other anions analyzed by ion chromatography also had relationships between the field parameters and key nutrients, although correlations are weak. Increasing amounts of sulfate did not correlate with the amount of phosphate (Figure 23). The

phosphate vs sulfate relationship does not resemble the Cl- vs sulfate graph, suggesting the phosphate source is different than the Cl- and sulfate sources. Sulfate and Cl- are strongly correlated (Figure 23). Additionally, there is a minor sulfate and Cl- dilution seen in the rainy months compared to the dry times. Seasonal cycling and spatial patterns seen in the anions was minor compared to temperature, dissolved oxygen, nitrogen and phosphate cycling.

Caldecott Inlet 40 3 35 2.5 30 25 2 20 1.5

Cl mg/L Cl 15 1 10 Phosphate mg/L 5 0.5 0 0 50 150 250 350 450 550 Sulfate mg/L

Cl mg/L Phosphorus mg/L Linear (Cl mg/L)

Temescal Creek and Tributaries 45 0.45 40 0.4 35 0.35 30 0.3 25 0.25 20 0.2 Cl mg/L Cl 15 0.15

10 0.1 Phosphate mg/L 5 0.05 0 0 0 50 100 150 200 250 300 350 400 450 Sulfate mg/L

Cl mg/L Phosphorus mg/L Linear (Cl mg/L)

Whole Lake 30 3 25 2.5 20 2 15 1.5

CL mg/L 10 1

5 0.5 Phosphate Nmg/L 0 0 70 90 110 130 150 170 190 210 230 Sulfate mg/L

Cl mg/L Phosphorus mg/L Linear (Cl mg/L)

Figure 23 Water Chemistry and Quality results plotted against Sulfate. 1) At Caldecott inlet there is a minor inverse relationship with Cl and Total N. 2) Cl is seen to increase with Sulfate. 3) Cl strongly increases with sulfate and Total N strong decreases with increasing Sulfate. Between 100-150 mg/L sulfate the relationship between Cl, Total N and sulfate switch.

Nitrogen and Phosphate Relationship

The TN:TP wt/wt relationship at Lake Temescal changes dramatically throughout the data collection period, therefore use of the ratio can give possible source clues

(Figure 24, Error! Reference source not found.). Caldecott Inlet had a consistently high

TN:TP throughout the sampling period (Figure 24). Seasonal cycling was visible in the ratio, i.e., the cooler months had a higher ratio than the warmer months except for an outlier sample from June at Caldecott Inlet. An August lake sample was by far the lowest ratio for all samples; during this time a cyanobacteria bloom was also present at the lake. The results in the summer show very low values, consistent with reported and predicted observations at eutrophic lakes from Downing and McCauley (1992).

Downing and McCauley (1992) found that natural sources such as groundwater, typically have higher values (Table 2). Downing and McCauley (1992) also found that a

lake will be highly eutrophic when the ratio is low, and during the extreme lows, cyanobacteria blooms were observed at Lake Temescal. The low ratio values also can give clues as to possible sources, the extreme low values of less than 0.9 which are observed mainly in summer can be indicative of rock erosion/lithogenic P. Many of the values fall below 6, indicating phosphorus enrichment and many different possible sources including sewage, urban runoff, septic tank effluent, gull feces, eutrophic and oligotrophic sediments, and erosion from sedimentary, mafic and, felisic rocks (Downing and McCauley, 1992). While many of these sources are anthropogenic, there are several viable natural sources of low ratio possible at Lake Temescal.

TN:TP for Sample Collection Events 40 35 30 25 20 15 TN:TP TN:TP ratio 10 5 0 Mar. April June Aug. Nov. Dec. BR Dec. AR Jan. BR Jan. AR Mar. Initial Final

N Dock Caldecott Inlet Parking Lot Bridge W. Woodhaven

Figure 24 Select locations for TN:TP changes for data collection period.

Source TN:TP Unfertile Soil Runoff 247.4 Export from Medium Fertile Soil 75 Export from Fertile Soil 33.3 Groundwater 28.5

River Water 18.9 Average Fertilizer 7.9 Mesotrophic Lake Sediment 6.3 Urban Storm water Drainage 5.8 Urban Runoff 4.7 Oligotrophic Lake Sediment 3.3 Septic Tank Effluent 2.7 Eutrophic Lake Sediment 2.5 Gull Feces 0.8 Sedimentary Rocks 0.8 Felsic Rocks <0.1 Mafic Rocks <0.1 Table 2 Downing and McCauley (1992) TN:TP data for various sources natural and anthropogenic origin.

Stable Isotopes of the Water Molecule

Lake Temescal stable Isotope data are plotted along with the global standard meteoric water line are shown in Figure 25. The range in values reflects the range expected for precipitation and runoff in the watershed. Four extremely evaporated samples stand out while several samples show a smaller deviation below the MWL

(Figure 26). The extremely evaporated samples came from the upper Temescal Creek watershed and the Caldecott Inlet in the spring of 2015. Caldecott Inlet is a heavily influenced by the urban development surrounding the area and the high evaporation shows that water is standing or process water is released somewhere upstream of

Temescal. The upper portion of Temescal Creek is a more natural channel than

Caldecott, but there could be an area where the water pools causing such evaporated values. The center of the lake is slightly more evaporated then the lake perimeter and watershed. The lake shoreline constantly has inflow water while the center of the lake does not, allowing for an evaporation trend to form. The results of the stable isotopes

18 18 are the O w values used in calculation of O of P from equation 1. A modest seasonal evaporation trend is visible; the fall and winter samples plot closer to the MWL and the summer samples plot further from the MWL (

Stable Isotopes for Seasons

-10.00

-20.00

-30.00 ‰ 2 H

-40.00

-50.00

-60.00

-70.00

-80.00 -12.00 -10.00 -8.00 -6.00 -4.00 -2.00 0.00 2.00 4.00 18O ‰ Spring June August Fall MWL Winter Spring 2016

Figure 27).

Stable Isotopes for Seasons

-10.00

-20.00

-30.00 ‰ 2 H

-40.00

-50.00

-60.00

-70.00

-80.00 -12.00 -10.00 -8.00 -6.00 -4.00 -2.00 0.00 2.00 4.00 18O ‰ Spring June August Fall MWL Winter Spring 2016

Total Stable Isotopes

-10.00

-20.00

-30.00

-40.00 ‰ 2

H -50.00

-60.00

-70.00

-80.00 -12.00 -10.00 -8.00 -6.00 -4.00 -2.00 0.00 2.00 4.00 18O ‰ Satble Isotopes MWL

Figure 25 Stable Isotope results for all samples. MWL shown to evaluate results. Most samples plot on or near the MWL with four highly evaporated samples.

Stable Isotopes for Locations

-10.00

-20.00

-30.00

-40.00 H ‰ 2 -50.00

-60.00

-70.00

-80.00 -12.00 -10.00 -8.00 -6.00 -4.00 -2.00 0.00 2.00 4.00 18O ‰

Lake Surface Lake at Depth C. Inlet Upper Temescal Creek Lower Temescal Creek ADD/Maintance Rain MWL

Figure 26 Stable Isotopes results separated by location. The four highly evaporated samples come from creeks while lake stations also show some evaporation.

Stable Isotopes for Seasons

-10.00

-20.00

-30.00 ‰ 2 H

-40.00

-50.00

-60.00

-70.00

-80.00 -12.00 -10.00 -8.00 -6.00 -4.00 -2.00 0.00 2.00 4.00 18O ‰ Spring June August Fall MWL Winter Spring 2016

Figure 27 Stable Isotopes broken into seasonal grouping. The late summer values show more of a deviation than winter samples.

Source Indication from 18O of P

Using 18O of P as a source indicator is an innovative method, and Lake Temescal had some expected results and some very unexpected results (Error! Reference source not found.). In the literature most results range from +28 to +8‰, while results from

Lake Temescal ranged from -0.5 to +27.33‰. The expected values were calculated from

Equation 1. As noted above, both filtered and unfiltered samples were collected during the second sampling campaign. Filtered 18O of P samples were lower than the unfiltered 18O of P samples, but only slightly, suggesting that difference was a result of

slightly different sample collection depths. The expected values did not differ by much for the two collections, since the 18O of water did not vary significantly (

Figure 29). However, the actual values varied greatly, both seasonally and with depth

(Figure 28).

Actual 18O of P -2 3 8 13 18 23 28 0 2 4 6 8 10 12 14

Depth Below Surface (ft) 16 18

Actual June Filtered Actual March Unfiltered Actual March Filtered

Figure 28 Actual results for the sampling events plotted against depth.

Expected 18O of P -2 3 8 13 18 23 28 0 2 4 6 8 10 12 14

Depth Below Surface (ft) 16 18

Expected June Expected March

Figure 29 Expected results for the two sampling events plotted against depth.

In June, the 18O of phosphate values differed greatly from the expected values

(Figure 30) while the March values are relatively close to the expected values (Figure

31). March samples plotted closer to the expected values at shallow and mid depths but were greater than predicted values at deep depths. In March processes occurring at the bottom of the lake are leading the 18O of P to be out of equilibrium. This could be a result of a groundwater input or, more likely, is evidence of release of phosphorus from sediment under anoxic conditions. In June, while the results were all out of the expected range, they were most out of equilibrium at the surface. The extreme surface disequilibrium indicates that P has not been taken up by lake biota and that the source signature is preserved. The very isotopically light values may represent an external, likely lithogenic, source entering the lake. The wide range of results from the 18O of P make identifying a single source difficult as the method is developing and a limited number of results are in the reported literature. However, the low 18O of P values observed point to a non-biological, non-organic source, and values of near 0‰ have been reported for igneous rocks (Tamburini et al., 2014).

Actual and Expected 18O of P June -2 3 8 13 18 23 28 0 2 4 6 8 10 12 14

Depth Below Surface (ft) 16 18

Expected June Actual June Filtered

Figure 30 Actual and expected results for June while the actual results are out of equilibrium with the environment then still fluctuate with depth like the expected values.

Actual and Expected 18O of P March -2 3 8 13 18 23 28 0 2 4 6 8 10 12 14

Depth Below Surface (ft) 16 18

Expected March Actual March Unfiltered Actual March Filtered

Figure 31 Actual and expected values for March. The results were closely plotted together at surface locations, but increasing the depth the actual filtered and unfiltered values became more out of equilibrium

Young et al. (2009) created graphs to illustrate how the degree of equilibration of 18O of P is related to temperature, phosphate concentration, 18O of P and the 18O values of the water ( Figure 32- Figure 35). When 18O of P is subtracted from the values measured from 18O of the water it should be zero if the sample is in equilibrium.

Lake Temescal had a few values that plotted close to equilibrium, zero on the y axis

(Figure 32). The March values were much closer to equilibrium then the June values.

Then when the values are again subtracted and plotted against phosphate this time, it is shown that high levels of phosphate lead the 18O of P to be farther away from equilibrium (Figure 33). This finding indicates that excess phosphate is not taken up and fractionated by biota and the phosphate source signature is preserved.

The TN:TP ratio can also be used to interpret the 18O of P values. Graphing these values show that a high TN:TP ratio leads to 18O of P values that is closer to the expected 18O of P value (Figure 34), since P is likely biologically cycled and the isotope ratio reflects the predicted biological fractionation.

Young et al. (2009) reported 18O of P values for various sources of phosphate.

Lake Temescal results, excluding outliers, plot in the range of Young et al. (2009) data of

8- 28 ‰ (Figure 36). While the Lake Temescal results overlap with Young et al. (2009) data it is still difficult to determine an exact source. The results for Lake Temescal overlap many different sources. The large range in results for Lake Temescal also likely indicate either multiple sources or varying states of disequilibrium between oxygen in

3- PO4 and oxygen in ambient water.

When temperatures are low like they were in March the values except for the deep portion plot very close to equilibrium (Figure 35). When the temperature is relatively low and uniform throughout the water column, phosphate is low and TN:TP is

high, phosphate is taken up by biota and the isotope signature reflects an equilibrium condition.

Figure 36 shows that the March average values are in line with some natural phosphate sources (soil and vegetation). The two deepest points of the lake had the highest phosphate concentration and the lowest TN:TP ratio. The March results may indicate multiple sources or multiple states of disequilibrium. The March TN:TP ratio also showed much more variation in comparison to the June results (Error! Reference source not found.).

In the June a change occurs at Lake Temescal leading to low TN:TP values and an increase in phosphate concentrations. At the same time the 18O of P values become isotopically light. The June 18O of P values are farthest from equilibrium at the surface.

The June values at depth plot within the range of anthropogenic sources and the shallow portion plot with data not previously reported in the literature. In June, an external source of phosphate is affecting the surface of the lake leading to extreme disequilibrium. The graphs help demonstrate the multiple processes that can affect 18O of P values at Lake Temescal.

of p 10 O 18 5

0 14 14.5 15 15.5 16 16.5 17 17.5 18 -5 Expected Expected - -10 of P

O -15 18 -20 Expected 18O of P Actual

Actual- Expected June Actual- Expected March Linear (Actual- Expected June) Linear (Actual- Expected March)

Figure 32 Actual values subtracted from expected values will give the difference from equilibrium. March values plotted closer to predicted, equilibrium than the June values.

of P of 10 O 18

0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 Expected

- -5

of Pof -10 O 18

-15

-20 Actual Phosphate mg/L

June March

Figure 33 Actual values subtracted from expected values plotted against the phosphate concentration. When phosphate concentrations are lower, values are closer to being in equilibrium because P is biologically cycled.

of of P 10 O 18 5

Expected 0 5 10 15 20 25 30 35

- -5

of Pof -10 O 18

-15

-20 Actual TN:TP

June March

Figure 34 Actual values subtracted from expected values plotted against the TN:TP ratio. When the ratio is low, P is in excess, and the isotope ratios indicate disequilibrium conditions.

11.8 11.9 12 12.1 12.2 12.3 12.4 15

of of P 10 O 18

0 0 5 10 15 20 25

Expected -5 -

O -10 18 -15

Actual -20 Temperature

June March Linear (June) Linear (March)

Figure 35 Actual values subtracted from expected values plotted against the water temperature. Note the different temperature ranges for March (top scale, ˚ C) and June (middle scale, ˚ C).

18O of P for Select Substances 30

15 of Pof O

18 Average

-5 Chemical Fertilizer Goose Feces Waste Water June (Israel) Treatment Plant

Figure 36 18O of P for select substances and Lake Temescal results. Except for June lake samples, observed and measured ranges largely overlap. Source data are from Young et al. (2009).

Conclusion

The frequency of problematic cyanobacteria blooms at Lake Temescal is likely increased due to excess phosphorus being rapidly transported to the lake from the surrounding environment. The lake is situated in a densely populated urban setting.

Lake Temescal is highly eutrophic as evidenced by frequent cyanobacteria blooms, high phosphate concentrations and relatively low TN:TP. Several factors are likely contributing to the high phosphate levels seen at Lake Temescal.

A small input into Lake Temescal comes from groundwater. The lake was originally a sag pond, a result of groundwater pooling at the Hayward Fault contact.

Typical freshwater lakes have phosphate concentration on the order of .03 mg/L

(Osmond et al., 1995) while Lake Temescal averaged .449 mg/L over the course of this study. Phosphate concentrations at the lake were consistently high and likely frequently in excess of the biological demand, with a maximum concentration of 1.2mg/L.

The lake averages only about 10ft in depth, shallow enough that in warm months the lake becomes uniform in temperature. In warm months, the lake becomes extremely stratified creating suboxic to anoxic environments at the deeper depths.

These factors allow for phosphate sequestered in the sediment to be re-released and taken up by the cyanobacteria. XAS results show that most phosphate is associated with iron oxides, which under reducing conditions become soluble and provide an environment for phosphate release. Lake stratification plays a key role in the phosphate cycle at Lake Temescal. In the summer the lake is uniform in temperature, but has a strong redox-cline. The lack of a thermocline and the low dissolved oxygen allow phosphate to be released from sediment and travel up the water column. The re- release is also possible in winter when there is a thermocline and a redox-cline, but the thermocline prevents the phosphate to be mobile in the water column due to the higher water density at depth. Lake Temescal is seasonally internally cycling and externally cycling phosphate. An exact source of the excess phosphate is difficult to identify based on the δ18O of phosphate because some of the observed values have not been previously reported in the literature. The present data show that in June, when the

values were out of equilibrium, the lake is likely receiving lithologic phosphate from the surrounding watershed. The June results were most out of equilibrium over the shallow intervals, indicating that excess phosphate was entering the lake via the surface. In

18 3- March, the O of P is close to reflecting an equilibrium between PO4 and water in the lake, excluding the deep interval. The deeper portions of the lake are receiving a source of phosphate that the shallower parts of the lake are not, due to water stratification. The March values are much higher, compared to the June, overlapping reported ranges for both natural and anthropogenic sources of phosphate. The two sampling events show that during different times of year, separate phosphate sources dominate the lake epilimnion. The sources of natural and anthropogenic phosphate can be a result of lake stratification, phosphate movement in the sediment or inflow from the surrounding watershed.

Improvements on the study of Lake Temescal would be made with additional data from water chemistry, water quality, and more temporally and spatially distributed samples for 18O of P. More samples would be beneficial for examining seasonal and rain event changes. Lake Temescal has a complex multi-process system that is continually cycling nutrients.

Reducing the external loading of phosphorus that was observed within the lake

(in June) and throughout the watershed would be beneficial to the lake. As stated earlier reducing the external load does not stop the internal cycling of nutrients.

Extensive dredging would likely help reduce the internal nutrient loading, but could re-

mobilize P sequestered in deeper sediments. Continual use of the engineering controls binding phosphate would still be helpful, especially once the external source is reduced.

Improving Lake Temescal’s bloom dilemma is a long-term problem, because even after phosphate reduction has been conducted, historical deposition, and internal loading of phosphate needs to be addressed.

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Appendix

Table 3 Caldecott Inlet Field Parameters

DO Date Temp C Conductivity DO % pH ORP mg/L 3/5/15 14.48 1507 94.2 9.45 -24 3/23/15 14.85 1029 99.6 10.05 7.2 -30.2 4/7/15 13.85 907 68.6 7.02 -195.3 6/9/15 17.4 1540 9.45 7.09 -5.3 8/13/15 11/3/15 16.5 1204 77 7.33 11/11/15 13.8 1455 94.5 11 -143.2 12/3/15 11.82 327 128.7 13.95 6.98 1/21/16 13.74 1289 53.1 5.48 -48.3 BR 1/22/16 12.61 941 79.5 8.4 9.6 AR 3/15/16 13.74 1289 53.1 5.48 -48.3

Table 4 Maintenance Dock Field Parameters

DO Date Temp Conductivity DO % mg/L pH ORP 3/5/15 12.7 776 109 11.51 -23 3/23/15 18.05 805 148.6 14.02 8.4 -18.5 4/7/15 6/9/15 8/13/15 11/3/15 11/11/15 15.26 991 125.4 12.55 -187.3 12/3/15 1/21/16 BR 1/22/16 AR 11.52 473 73.4 7.99 5.1 3/15/16

Table 5 ADA Dock Field Parameters

DO Date Depth Temp Conductivity DO % mg/L pH ORP

3/5/15 0 12.71 779 93.4 9.83 -23.8 3/23/15 4/7/15

6/9/15 8/13/15 11/3/15 11/11/15 0 13.67 997 70.2 7.24 -169.1 11/11/15 2 13.03 991 55.3 5.76 -168.3 11/11/15 4 12.81 988 46.2 55.3 -175.6 11/11/15 6 12.66 985 43.9 4.62 -177.7 11/11/15 8 12.66 983 45.1 4.75 -196.2 12/3/15 1/21/16 BR 1/22/16 AR

Table 6 Parking Lot Bridge Field Parameters

Date Temp Conductivity DO % DO mg/L pH ORP 3/5/15 10.54 984 88.2 9.8 -28 3/23/15 13.87 823 69.4 7.13 7.8 -42 4/7/15 11.74 424 85.2 9.22 -55.3 6/9/15 8/13/15 11/3/15 11/11/15 10.43 674 107.6 12 -249.4 12/3/15 BR 9.01 600 94.8 11 28 12/3/15 AR 10.56 200 98.7 11.02 7.63 -139.4 1/21/16 BR 11.87 756 91.1 9.82 -45.69 1/22/16 AR 11.56 399 107 11.66 14.3 3/15/16 11.87 756 91.1 9.82 -45.69

Table 7 Detention Pond Field Parameters

Date Temp Conductivity DO % DO mg/L pH ORP 3/5/15 10.18 1000 78 8.71 -30.3 3/23/15 13.46 872 51.5 5.32 7.2 -44.4 4/7/15 6/9/15 8/13/15 11/3/15 14.2 366.9 1.4 0.14 11/11/15 12/3/15 BR 12/3/15 AR 1/21/16 BR 1/22/16 AR 3/15/16

Table 8 North Dock Field Parameters

Conductivit Date Depth Temp DO % DO mg/L pH ORP y 3/5/15 3/23/15 0 16.68 827 92 8.89 8.4 -40.5 10 15.25 818 60.9 6.09 -45.7 15 13.63 796 10.3 1.07 -182.8 4/7/15 6/9/15 0 22.41 837 78.1 6.77 7.96 -116.8 2 22.48 840 74.3 6.72 -120.2 3 22.9 884 7.39 7.96 -56.3 4 22.36 840 71 6.16 -120.6 6 21.51 839 66.2 5.75 8.01 -121 8 20.21 834 9.7 0.83 -120.6 9 22.9 867 1.97 7.71 -41.4 10 18.97 831 3.7 0.35 -204.2 12 18.14 832 2.7 0.26 7.55 -238 14 17.41 835 2.2 0.21 -282.7 15 19.4 884 1.69 7.3 -17.3

16 17.18 841 1.5 0.14 7.31 -311.2 18 17.18 845 1.6 0.15 -302 20 17.1 847 1.5 0.16 -290.6 22 17.08 845 1.4 0.14 -294.1 8/13/15 0 23.9 927 99.3 8.37 -113.6 1 23.96 928 99.6 8.41 -116 2 23.87 928 97.8 8.3 -107.02 4 23.81 930 89.6 7.54 -104.1 6 23.7 931 91.5 7.63 -101.3 8 23.52 932 75.2 6.39 -102.8 10 23.42 933 69 5.84 -102.7 12 23.29 936 43.4 3.6 -105.9 15 22.93 947 4.2 0.36 -306.9 16 22.56 964 2.7 0.23 -324.2 18 22.55 968 2.2 0.18 -293 20 22.49 973 1.7 0.2 -248 22 22.45 976 1.7 0.14 -241 24 22.43 978 1.5 0.13 -238 11/3/15 0 18.4 1018 45.6 4.15 2 17.7 1018 43.1 3.96 4 17.5 36.9 3.47 6 17.4 36.2 3.37 8 17.3 33 3.08 10 17.2 33.4 3.13 11/11/15 0 14.68 1002 81.5 8.22 -201.8 2 13.18 1000 60 6.22 -201.4 4 12.96 1000 57.8 6.09 -201.5 6 12.85 1000 56.8 5.98 -199.7 8 12.77 1000 52.5 5.53 -201.4 10 12.75 999 55.3 5.83 -203.7 12 12.73 999 54 5.71 -204.9 14 12.72 999 55 5.82 -206 16 12.72 999 52.2 5.51 -212.6 12/3/15 1/21/16 0 12.75 419 94.4 9.96 -21.4 2 11.05 420 99.6 10.91 -20.1

4 10.85 428 96.3 10.64 -20.5 6 10.85 514 91.9 10.15 -20.1 8 10.66 527 89.5 9.95 -18.9 10 9.76 562 85.9 9.72 -19.2 12 8.61 658 55.7 6.47 -22.2 14 8.26 670 38 4.43 -23.3 16 8.24 672 30.3 3.55 -22.9 1/22/16 0 11.35 453 116.7 12.7 6 3/15/16 0 12.34 455 80.5 8.61 7.46 25 1 12.04 456 80.9 8.24 20.5 2 11.93 457 82 8.84 18.5 3 11.9 457 83.5 9.01 14.2 4 11.84 458 84.3 9.1 12.7 5 11.88 460 84.5 9.12 12.3 6 11.88 461 84.5 9.11 12 7 11.9 488 83 8.95 11.7 8 11.93 542 74.8 8.05 11.1 9 11.97 573 71 7.64 11 10 11.96 586 61.5 6 11 11 11.91 613 53 5 10.9 12 11.91 632 465 5.02 11.4 13 11.94 653 38 4.07 12.1 14 11.95 681 26.5 2.85 12.9 15 11.96 691 17.2 1.84 13.6 16 11.96 699 13.8 1.47 7.33 14 17 11.96 701 12.2 1.32 13.8 18 11.96 702 10.6 1.14 -60

Table 9 Woodhaven West Field Parameters

Date Temp C Conductivity DO % DO mg/L pH ORP 3/5/15 9.95 1273 79.3 8.89 -23.5 3/23/15 4/7/15 10.97 1190 87.7 9.38 -207.2 6/9/15 15.7 1257 9.19 8.02 -58.5 8/13/15

11/3/15 11/11/15 9.94 1132 89.7 10.2 -186.2 12/3/15 8.07 42 114 13.48 25.4 1/21/16 BR 1/22/16 AR 10.9 540 132 14.7 -102.2 3/15/16

Table 10 Woodhaven East Field Parameters

Date Temp Conductivity DO % DO mg/L pH ORP 3/5/15 10.63 981 76.1 8.44 -27 3/23/15 4/7/15 11.79 801 92.5 9.87 -197.6 6/9/15 16.3 970.7 9.3 8.03 -59.1 8/13/15 11/3/15 11/11/15 13.28 461 80.1 8.35 -189.8 12/3/15 1/21/16 BR 1/22/16 AR 11.07 372 103 13.36 -64.4 3/15/16

Table 11 Pinehaven Field Parameters

DO Date Temp Conductivity DO % mg/L pH ORP 3/5/15 3/23/15 4/7/15 6/9/15 8/13/15 11/3/15 11/11/15 9.86 11 91.3 10.32 -221.2 12/3/15 1/21/16 BR 1/22/16 AR 11.35 453 116.7 12.7 6 3/15/16

Table 12 Lake Stations Field Parameters

DO Date Temp Conductivity DO % mg/L pH ORP Station 4 1ft 25.04 928 112.2 9.28 -77.6 Station 4 8ft 23.89 931 108 8.9 -77.9 Station 4 12ft 23.72 934 76 6.05 -78.2 Station 4 13ft 23.34 937 52 4.49 -78.2 Station 5 1ft 24.93 925 117 9.7 -97.1 Station 5 8ft 23.99 929 88.2 7.99 -94.2 Station 5 12ft 23.35 941 43 3.52 -94.3 Station 5 14ft 23.27 940 24.7 2.19 -96.7 Station 5 16ft 23.2 900 15.5 1.35 -169.7 Station 6 1ft 25.32 926 119.7 9.84 -79.5 Station 6 4ft 25.19 926 125.3 10.29 -79.5 Station 6 6ft 25.19 926 128.8 10.64 -79.2 Station 7 1ft 25.53 925 120.5 9.84 -82 Station 7 6ft 25.31 926 125.5 10.29 -85.7 Station 7 12ft 23.56 941 50.6 4.43 -86.4 Station 7 14ft 23.29 928 8.3 0.74 -127.5 Station 8 9ft 23.74 945 16 1.32 -95.4 Station 9 8ft 23.56 885 26.2 2.2 -87 Station 10 13ft 23.35 909 229 1.94 -126 Station 11 12ft 23.64 934 49.4 4.76 -88.8 Station 12 15ft 23.71 909 9 0.73 -80.2

Table 13 Caldecott Inlet water chemistry

Date Cl- mg/L Nitrate Nitrite Bromide Sulfate 3/5/15 25 0.38 0.058 0.29 510 3/23/15 4/7/15 18 0.94 0.25 0.17 260 6/9/15 25 0.28 0.0005 0.41 420 8/13/15 11/3/15 11/11/15 36 0.52 0.14 0.39 400 12/3/15 8.7 0.68 0.18 0 77 1/21/16 BR 21 1.8 0 0.17 500 1/22/16 AR 16 1.2 0.24 0.12 340 3/15/16 19 1.3 0.046 0.1 390

Table 14 Maintenance Dock water chemistry

Date Cl- mg/L Nitrate Nitrite Bromide Sulfate 3/5/15 3/23/15 4/7/15 6/9/15 8/13/15 11/3/15 11/11/15 24 0.12 0.14 0.21 210 12/3/15 1/21/16 BR 1/22/16 AR 14 1.5 0.25 0.088 120 3/15/16

Table 15 ADA Dock water chemistry

Date Cl- mg/L Nitrate Nitrite Bromide Sulfate 3/5/15 3/23/15 4/7/15 6/9/15 8/13/15

11/3/15 11/11/15 23 0.16 0.14 0.21 210 12/3/15 1/21/16 BR 1/22/16 AR 3/15/16

Table 16 Parking Lot Bridge water chemistry

Date Cl- mg/L Nitrate Nitrite Bromide Sulfate 3/5/15 3/23/15 4/7/15 12 1.4 0.25 0.07 87 6/9/15 8/13/15 11/3/15 11/11/15 19 0.38 0.14 0.052 160 12/3/15 19 0.39 0.043 0.059 140 1/21/16 BR 24 2.2 0.24 0.1 200 1/22/16 AR 13 1.1 0.23 0.071 89 3/15/16 39 2 0.049 0 180

Table 17 North Dock water chemistry

Date Depth Cl- mg/L Nitrate Nitrite Bromide Sulfate 3/5/15 3/23/15 0 10 15 4/7/15 6/9/15 0 20 0.0071 0.0005 0.14 210 2 3 20 0.045 0.0005 0.14 190 4 6 20 0.045 0.0005 0.14 190 8 9 20 0.045 0.0005 0.14 190 10 12 20 0.045 0.0005 0.14 180

14 15 20 0.045 0.0005 0.15 120 16 19 0.045 0.001 0.17 120 18 20 22 8/13/15 0 23 0.018 0.01 0.18 230 1 2 4 6 22 0.16 0.01 0.16 230 8 10 22 0.018 0.01 0.18 230 12 22 0.018 0.01 0.18 220 15 16 18 20 22 24 11/3/15 0 2 4 6 8 10 11/11/15 2 24 0.16 0.14 0.2 210 4 6 8 10 12 14 16 1/21/16 0 13 1.7 0.25 0 95 2 4 6

8 10 12 14 16 1/22/16 0 13 1.7 0.24 0.079 110 3/15/16 0 14 1.5 0.058 0.048 110 1 2 3 14 1.6 0.055 0.047 110 4 5 6 7 8 9 15 1.1 0.057 0.06 170 10 11 12 15 1 0.059 0.063 170 13 14 15 16 16 0.32 0.065 0.092 180 17 18

Table 18 Winterhaven West water chemistry

Date Cl- mg/L Nitrate Nitrite Bromide Sulfate 3/5/15 30 0.52 0.24 0.11 400 3/23/15 25 1.2 0.24 0.094 380 4/7/15 27 0.26 0.0005 0.069 340 6/9/15 8/13/15 11/3/15 11/11/15 27 0.11 0 0 320 12/3/15 27 0.062 0 0.042 310 1/21/16 BR 15 1 0.23 0.071 150 1/22/16 AR

3/15/16

Table 19 Winterhaven East water chemistry

Date Cl- mg/L Nitrate Nitrite Bromide Sulfate 3/5/15 3/23/15 4/7/15 6/9/15 22 0.46 0.0076 0.074 220 8/13/15 11/3/15 11/11/15 12/3/15 1/21/16 BR 1/22/16 AR

Table 20 Lake Station water chemistry

Station Cl- mg/L Nitrate Nitrite Bromide Sulfate Station 1 1ft 22 0.12 0.18 0.16 220 Station 1 8ft 22 0.095 0.15 0.16 220 Station 1 12ft 22 0.096 0.15 0.16 220 Station 2 1ft 22 0.095 0.15 0.17 220 Station 2 8ft 22 0.097 0.15 0.16 220 Station 2 15ft 22 0.093 0.14 0.17 210 Station 3 1ft 22 0.094 0.15 0.17 229 Station 3 12ft 22 0.094 0.15 0.17 220 Station 4 1ft 22 0.018 0.01 0.17 220 Station 4 8ft 22 0.018 0.01 0.17 220 Station 4 12ft 22 0.018 0.15 0.17 220 Station 5 1ft 22 0.018 0.01 0.18 220 Station 5 8ft 22 0.094 0.15 0.17 220 Station 5 12ft 22 0.095 0.15 0.17 220 Station 6 1ft 22 0.018 0.15 0.17 220 Station 6 6ft 22 0.095 0.15 0.17 220 Station 7 1ft 22 0.018 0.01 0.17 230 Station 7 6ft 22 0.018 0.01 0.17 220 Station 7 12ft 22 0.018 0.01 0.17 220

Station 8 9ft 22 0.018 0.01 0.17 230 Station 9 8ft 22 0.018 0.01 0.18 230

Table 21 18O of phosphate samples. Actual is the reported lab values and expected is the values calculated from equation 1

Actual Actual 18O of Expected 18O of phosphate Date Location Depth Results 18O of phosphate Results phosphate Results Filtered Unfiltered 6/9/15 N. Dock 0 15.16832783 3.23 - N. Dock 3 15.05544421 1.94 - N. Dock 6 15.15536593 4.1 - N. Dock 9 14.59165821 -0.41 - N. Dock 12 16.59304117 12.57 - N. Dock 15 16.07282979 9.1 - N. Dock 16 16.41612039 12.3 - C. Inlet - 14.87383148 11.05 - W. - 15.12647669 -0.5 - Woodhaven 3/15/16 N. Dock 0 17.2572093 16.41 17.07 N. Dock 3 17.76143701 16 16.57 N. Dock 6 17.51675176 17.3 17.54 N. Dock 9 17.5182618 18.29 18.44 N. Dock 12 17.47985465 17.56 18.55 N. Dock 15 16.40009796 19.76 24.88 N. Dock 16 16.43010462 26.88 27.33 C. Inlet - 16.79007283 - UD Parking Lot - 16.8298689 - UD Bridge

Table 22 Caldecott Inlet stable isotopes

Date H (‰) 8O (‰) 3/5/15 -55.89 3.13 3/23/15 -35.29 -5.63 4/7/15 -69.36 2.47 - 6/9/15 47.25841278 -6.986633632 8/13/15

11/3/15 11/11/15 -51.99 -7.77 12/3/15 -29.27 -5.11 1/21/16 BR -44.28 -6.75 1/22/16 AR -37.03 -5.91 3/15/16 -41.75 -5.92

Table 23 Maintenance Dock stable isotopes

Date H (‰) 8O (‰)

3/5/15 3/23/15 4/7/15 6/9/15 8/13/15 11/3/15 11/11/15 -38.48 -5.03 12/3/15 1/21/16 BR 1/22/16 AR -52.75 -7.28 3/15/16

Table 24 ADA Dock stable isotopes

Date H (‰) 8O (‰)

3/5/15 3/23/15 4/7/15 6/9/15 8/13/15 11/3/15 11/11/15 -45.33 -5.88 12/3/15 1/21/16 BR

1/22/16 AR 3/15/16

Table 25 Parking Lot Bridge stable isotopes

Date H (‰) 8O (‰)

3/5/15 3/23/15 4/7/15 -73.01 -10.42 6/9/15 8/13/15 11/3/15 11/11/15 -59.28 -8.29 12/3/15 BR -24.98 -5.42 12/3/15 AR 1/21/16 BR -48.85 -7.03 1/22/16 AR -35.74 -5.32 3/15/16 -42.99 -6.32

Table 26 Detention Pond stable isotopes

Date H (‰) 8O (‰) 3/5/15 3/23/15 4/7/15 6/9/15 8/13/15 11/3/15 11/11/15 -41.40 -5.83 12/3/15 BR 12/3/15 AR 1/21/16 BR 1/22/16 AR

3/15/16

Table 27 North Dock stable isotopes

Date Depth H (‰) 8O (‰)

3/5/15 3/23/15 0 -48.95 -6.78

4/7/15 6/9/15 0 -43.2677564 -5.527021005

2 3 -41.93261163 -5.525951141

4 6 -43.49873798 -5.749285231

8 9 -41.45045245 -5.989737144

10 12 -40.15264489 -5.095330919

14 15 -42.24785281 -5.322519046 16 -41.22184656 -5.495507513

22 8/13/15 0 -36.21486476 -4.701191295

6 8 -36.14268257 -4.787815595

10 12 -35.934628 -4.628354046 15 -40.18052883 -4.581999069

24 11/3/15 0

10 11/11/15 0 -42.95 -4.83

12/3/15 1/21/16 0 -55.63 -7.40

16 1/22/16 0 -53.52 -7.46 3/15/16 0 -40.95 -5.78

2 3 -37.26 -5.38

5 6 -38.10 -5.63

8 9 -39.39 -5.60

11 12 -41.51 -5.66

14 15 -45.11 -6.73 16 -42.72 -6.70

Table 28 Winterhaven West stable isotopes

Date H (‰) 8O (‰) 3/5/15 -53.52 0.88 3/23/15 4/7/15 -56.27 1.99 6/9/15 -45.33028 -7.129337261 8/13/15 11/3/15 11/11/15 -55.84 -7.31 12/3/15 1/21/16 BR 1/22/16 AR -33.78 -5.10 3/15/16

Table 29 Winterhaven East stable isotopes

Date H (‰) 8O (‰) 3/5/15 3/23/15 4/7/15 6/9/15 -43.11589936 -6.490234338 8/13/15 11/3/15 11/11/15 12/3/15 1/21/16 BR 1/22/16 AR -32.25 -5.35 3/15/16

Table 30 Pinehaven stable isotopes

Date H (‰) 8O (‰)

3/5/15 3/23/15 4/7/15 6/9/15 8/13/15 11/3/15 11/11/15 -47.74 -7.07 12/3/15 1/21/16 BR 1/22/16 AR -47.17 -6.57 3/15/16

Table 31 Lake Station stable isotopes

Date H (‰) 8O (‰) Station 1 1ft -36.85108588 -4.346377949 Station 1 8ft -35.06413063 -4.158079263 Station 1 12ft -34.55985901 -4.211967374 Station 1 14ft Station 1 20ft Station 2 1ft -34.14427252 -3.846395385 Station 2 6ft Station 2 8ft -39.10929438 -4.162908922 Station 2 12ft Station 2 14ft Station 2 15ft -36.69021189 -4.671556048 Station 3 1ft Station 3 8ft Station 3 12ft Station 3 14ft Station 3 16ft Station 3 18ft Station 4 1ft Station 4 8ft Station 4 12ft Station 4 13ft

Station 5 1ft Station 5 8ft -67.74 -8.68 Station 5 12ft Station 5 14ft Station 5 16ft Station 6 1ft Station 6 4ft Station 6 6ft Station 7 1ft Station 7 6ft Station 7 12ft -38.12389699 -4.321083519 Station 7 14ft Station 8 9ft Station 9 8ft -36.48683216 -4.43811301 Station 10 13ft Station 11 12ft Station 12 15ft

Table 32 Flow meter (ft2/sec) and staff reading (inches)results

Section Section Section Section Section Section Average Staff 1 Flow 2 Flow 3 Flow 4 Flow 5 Flow 6 Flow Flow Reading 0.14 0.16 0.14 0.17 0.20 0.05 0.14 5.4 0.51 0.57 0.81 1.17 1.28 0.94 0.88 7.6 0 0.1 0.16 0.21 0.07 0.05 0.10 5 0 0.92 0.72 0.85 0.61 0.73 0.64 8 0.11 0.34 0.14 0.20 0.18 0.16 0.19 9 0.05 0.25 0.21 0.51 0.20 0.39 0.27 5.3

Table 33 TN:TP ratios for Lake Temescal

Date Site TN:TP 3/5/15 Caldecott Inlet 17.52 3/5/15 Mouth of Temescal Creek 1.689655172 3/5/15 Woodhaven Western 5.846153846 4/7/15 Parking Lot Bridge (1st Bridge) 8.25 4/7/15 Caldecott Inlet 3.5 4/7/15 Woodhaven Western 9.6

6/9/15 N Dock 0ft 0.025333333 6/9/15 N Dock 3ft 0.151666667 6/9/15 N Dock 6ft 0.151666667 6/9/15 N Dock 9ft 0.122972973 6/9/15 N Dock 12ft 0.059090909 6/9/15 N Dock 15ft 0.026764706 6/9/15 N Dock 16ft 0.025555556 6/9/15 C. Inlet 35.50632911 6/9/15 Woodhaven Eastern 5.918987342 6/9/15 Woodhaven Western 1.628125 8/13/15 N Dock 0ft 0.049122807 8/13/15 N Dock 6ft 0.288135593 8/13/15 N Dock 12ft 0.044444444 8/13/15 N Dock 16ft 0.025454545 8/13/15 Station 1 1ft 0.517241379 8/13/15 Station 1 8ft 0.415254237 8/13/15 Station 1 12ft 0.336986301 8/13/15 Station 2 1ft 0.4375 8/13/15 Station 2 8ft 0.404918033 8/13/15 Station 2 15ft 0.194166667 8/13/15 Station 3 1ft 0.428070175 8/13/15 Station 3 12ft 0.406666667 8/13/15 Station 4 1ft 0.049122807 8/13/15 Station 4 8ft 0.046666667 8/13/15 Station 4 12ft 0.284745763 8/13/15 Station 5 1ft 0.048275862 8/13/15 Station 5 8ft 0.375384615 8/13/15 Station 5 12ft 0.35 8/13/15 Station 6 1ft 0.294736842 8/13/15 Station 6 6ft 0.4375 8/13/15 Station 7 1ft 0.05 8/13/15 Station 7 6ft 0.04516129 8/13/15 Station 7 12ft 0.048275862 8/13/15 Station 8 9ft 0.041791045 8/13/15 Station 9 8ft 0.04 11/11/15 C. Inlet 6.6 11/11/15 ADD Dock 0ft 0.428571429 11/11/15 Maintenance Dock 0.530612245

100

11/11/15 N Dock Surface 0.422535211 11/11/15 Detention Pond 3.789473684 11/11/15 Parking Lot Bridge 3.466666667 11/11/15 Pinehaven 0 11/11/15 Woodhaven West 0.5 12/3/15 Parking Lot (prior to rain) 1.11025641 12/3/15 W. Winterhaven (light rain) 0.364705882 12/3/15 Parking lot after rain 5.44 12/3/15 C. Inlet 5.375 1/21/16 Before Rain N Dock Surface 9.285714286 1/21/16 Before Rain Parking Lot 0 1/21/16 Before Rain W. Winterhaven 0 1/22/16 After Rain Pinehaven 6.833333333 1/22/16 After Rain N Dock Surface 6.454545455 1/22/16 After Rain Parking Lot 9.7 1/22/16 After Rain C. Inlet 6.65 1/22/16 After Rain Maintenance Dock 0 3/15/16 N Dock 0ft 8.75 3/15/16 N Dock 3ft 12.98333333 3/15/16 N Dock 9ft 12.73076923 3/15/16 N Dock 12ft 7.23125 3/15/16 N Dock 15ft 5.883333333 3/15/16 N Dock 16ft 0.740384615 3/15/16 C. Inlet 28.04166667 3/15/16 Parking Lot 28.06849315