15 Shasta Lane, Walnut Creek, CA 94597 Office: 925-946-9090 Cell: 925-899-2578 Email: [email protected]
ELLIS LAKE WATER MANAGEMENT
Proposed Immediate Approach
and
Long-Term Options
August 2024
PURPOSE
The purpose of this study is to determine the best combination of approaches to improve the water quality of Ellis Lake. The objective is to lower nutrient levels in the water, especially phosphorus, to thereby minimize the growth of harmful algae blooms and aquatic weeds, and finally for the lake to sustain a healthy oxygen level to support fish. The desired result is to maintain the lake to be pleasant to look at, clear of algae and weeds, odor free, and healthy for fish.
For context, work for this study began in August 2023. During the study process, the lake has been carefully monitored by Public Works staff, and initial chemical treatments have been conducted. This report covers approaches and explanations of the initial treatments. Thankfully, the outcome thus far is a clean lake.
Four starting approaches for operation of the lake were established leading to this work. They are outlined below.
STARTING APPROACHES TO CONSIDER
Existing Configuration Using the Well Adjacent to the Lake 1) Treat the lake water discharged from the well. Pump only to replace evaporation. 2) Pump enough water to actively circulate water through the lake from south end to north end.
Treat as needed.
Reconnect to the Yuba River
3) Pump low phosphate water from Yuba River. Pump only to replace evaporation. Treat as needed.
4) Pump enough water to actively circulate water through the lake from south end to north end.
Treat as needed.
BACKGROUND
Ellis Lake has been thoroughly studied over the past several years with some pilot activities conducted to clean up the water. The following is a listing of studies completed. 2 In 2014, Vice-Mayor Dale Whitmore prepared a document entitled “Ellis Lake Water Quality Issue.” His work confirms that the problem with summer algae in the lake is long-standing, considering almost 10 years have passed since his report. His primary outcome was to recommend removing Carp from the lake to reduce disturbances of the lake bottom and thereby lowering phosphorus concentrations in the water. He also references the problems of geese and ducks contaminating the lake.
In 2019, EKI completed a study of the lake. The conclusion of that study was to aerate the water, conduct chemical phosphorus removal, and engage a lake quality monitoring program (page 10 of the EKI study). The outcome of the study was installation of three pilot aerators at the South end of the lake.
In 2021, HDR, Inc., working with the Yuba Water Agency, completed the Ellis Lake Management Plan. This 122-page report is scientific, detailed, and thorough. It contains a wealth of helpful information. The recommended alternatives from this work were to install a dedicated pump circulation system in the lake, expand the already installed pilot aeration system, and to conduct fishery management, water monitoring, and chemical treatment.
Following the 2021 Lake Management Plan, some implementation steps were taken. The company “Aquatechnex” applied two treatments of the product Phoslock to sequester phosphorus, followed by one application of a peroxide aquacide to kill algae. Some near-term results were achieved; however, with the continuation of phosphorus injection from the well, the lake returned to a poor state.
In April 2022, the company “FishBio” removed 253 Carp totaling 3,500 pounds, averaging 14 pounds per fish. Additionally, as mentioned above, in 2019 three aerators were also installed. As of the date of this report, the aerators have received needed maintenance after a time of nonoperation, and they are currently working properly. The fountain on the island has also been repaired and is working properly.
Considering the extensive background research already done, and the initial attempts, the present problem is that ongoing implementation of the various recommendations has not continued.
THE CURRENT CONDITION OF THE LAKE
This section summarizes the present condition and operation of Ellis Lake. First and foremost, the lake remains “eutrophic.” This means it is rich in organic and mineral nutrients that support abundant but undesirable plant life, primarily algae and aquatic weeds during summer months. As the algae and weeds cycle and die, the decay depletes the oxygen supply for fish in the lake. This combination is undesirable and unhealthy. Second, no lake management activities had been occurring such as application of herbicides, aquacides, or a binding agent for phosphorus removal.
However, in Fall 2023 during this study, the lake was treated with an aquacide, and injection treatment began at the well head to treat phosphorus in the well water. 3 Interestingly, on an initial visit to the lake on August 16, 2023, the water was green with algae; however, by September 19, 2023, the water had cleared itself of algae, although the weeds were still as bad as before. This is an example of how the lake goes through its own cycles of growth and decay. This was also before the initial treatments mentioned above.
The phosphorus content of the lake is a key indicator of its health. The phosphorus content of the well and lake water was determined by SePRO labs based on samples taken in September 2023.
These are shown below in parts per billion (ppb) of phosphorus.
Location Phosphorus (ppb)
Well water* 75.2
Lake South 28.1
Lake Middle 39.5
Lake North 40.6
Lake Average** 36.1
* Over 12 monthly samples during 2020 in the Lake Management Plan, the sample range was 56 ppb (October 2020) to 110 ppb (April 2020).
** Similarly, from the Lake Management Plan, the range was 50 ppb (April 2020) to 129 ppb (May 2020).
As shown above, in September 2023, the phosphorus content of the well water is roughly twice the average of the lake. Clearly, phosphorus from the well water is a problem. Based on information from SePRO, the lake remains in a eutrophic state above 25 ppb. The goal, based on information from the biologist at SePRO and consistent with the Lake Management Plan (page 2- 20) is to get into the mesotrophic state, which is below 25 ppb.
Beginning in September 2023, phosphorus sampling, visibility, and temperature measurements have been conducted weekly by Public Works staff. Phosphorus levels were lower during the cold winter months; but then as days lengthened and the lake water warmed through Springtime, phosphorus levels have increased as high as 200 ppb (the upper reading limit on the City’s test device), with the well water tending to be higher than the lake water up to 200 ppb.
Beginning October 31, 2023, wellhead injection was added of the SePRO product “EutroSORB WC” to sequester phosphorus from the well water. Injection continued through January 30, 2024, when the pump was operating but did not show positive results on the lake overall with phosphorous levels remaining high.
In November 2023, Solitude Lake Management did the first of three treatments to successfully kills the surface weeds in the lake. Solitude then returned in May 2024 to treat the lake-bottom sediment to prevent weeds from growing into the summer. In total since November, Solitude has visited the lake approximately 10 times to treat the water body for weeds and algae. The total cost of Solitude’s services as of the date of this report is approximately $66,000. 4 On August 6, 2024, Public Works staff treated the lake overall for phosphorus using 80 gallons of “EutroSORB WC.” This was a more aggressive attempt to lower available phosphorus in the lake.
The results are not available at the time of this report, as the treatment was just completed. The cost of the treatment was approximately $20,000, most of which was for the product itself.
Regarding the physical operation of the well, since the beginning of this work a year ago, the well pump has been failing and the motor has reached its operating life span. Consequently, Public Works solicited quotes to replace the well pump and motor, awarding the work to Durham Pump and Irrigation Company at a cost of approximately $44,000. As of this report writing, the replacement work is scheduled to be done the week of August 12, 2024.
Here are measured statistics associated with the well operation done in conjunction with this report. (Attachments 1, 2, and 3)
1) The existing well pump can raise the height of the lake approximately two inches per day. 2) The rate of evaporation was measured over two days in August. Based on 0.75 inches of loss over two days, the projected monthly total is projected to be about 12 inches. 3) The calculated flow rate of the well pump, after adjusting upward for evaporation, is approximately 1,400 gallons per minute. Some other losses may exist, such as seepage around the lake shore and bottom; therefore, 1,400 gallons should be considered a minimum estimate. 4) Based on 12 months of PG&E information, the operating factor of the well has been 21 percent, or an average of about five hours per day.
PROPOSED IMMEDIATE APPROACH
The proposed immediate approach is to perform water maintenance to the lake in its existing state of operation, which is continuing to keep the lake full using the existing well and install wellhead treatment to inactivate phosphorus in the supply water (Approach 1). In addition, engage one or more lake management companies to support monitoring of the lake and to treat the water when needed. The suggested sequential steps of treatment follow.
Steps of Treatment
1) Obtain a National Pollutant Discharge Elimination System (NPDES) permit through the State Water Board to allow application of aquacides and herbicides to the lake water. This permit was obtained in October 2023.
2) Begin wellhead injection of “EutroSORB WC” to sequester phosphorus entering the lake.
EutroSORB contains the natural ingredients bentonite and lanthanum which bind to suspended phosphorus in the water. If needed, engage a lake management company to add additional treatment for phosphorus to the lake water and potentially to the lake sediment. Continue to monitor the lake water for phosphorus to be below 25 ppb. 3) Treat the visible weeds with aquacides and herbicides. Conduct follow-up treatments as needed to keep the lake in satisfactory condition.
5 4) Thereafter, the lake should be monitored for water quality and treated as needed. This will be especially important as warmer temperatures and longer daylight hours return each Spring.
Evaluation of Mechanical Cleanup of the Lake
Mechanical cleanup or harvesting involves a specially built workboat that cuts the lake weeds several feet below the surface of the water and collects them to be transported to the shore for disposal. The primary benefit of mechanical harvesting is immediate visual improvement and the removal of organic matter that will otherwise settle on the bottom of the lake, contributing to further weed growth. The disadvantage to mechanical harvesting is the cost, estimated at a minimum of $37,500, based on 15 days at $2,500 per day for equipment and personnel. Another general disadvantage is the weeds will eventually grow back if they are cut and removed only.
However, the primary reason mechanical harvesting is not a focus of the immediate approach is because it is likely the weeds will die anyway as the lake water cools into winter. Though it would be better to avoid additional dead organic matter in the sediment, this annual cycle has been happening for decades and the sediment can be economically treated with EutroSORB to bind the existing and added phosphorus in the organic matter.
Lake Management Companies
Lake management is a specialized industry with a few service providers in Northern California.
The City engaged the company CleanLakes, Inc. on an initial basis to prepare and submit the NPDES application, now completed. CleanLakes is based in Martinez, California and services Lake Wildwood and Lake of the Pines, both nearby in the Sierra Foothills.
The City further engaged Solitude Lake Management on a limited basis to obtain and test sediment samples. Solitude is a fully integrated, nation-wide lake management company with a division in Northern California, including government clients. Samples were taken on Wednesday, October 4th, which included the opportunity to ask questions of the Solitude biologist and hear ideas about appropriate long-term treatment. As discussed earlier, Solitude has continued to treat the lake, closely managed by Public Works.
As a government entity and in the best interest of the community, staff are researching the best overall approach to engage lake management companies. Based on information as of this report writing, the best approach appears to be for city staff to monitor the lake water condition, but then to pay for professional treatment services only when they are needed. It is possible for Public Works staff to monitor the lake with some training, and also to use high-tech monitoring equipment allowing remote monitoring of water quality. As of the date of this report, Public Works has been closely monitoring lake water conditions.
Regarding ongoing full service from a lake management company, the indication is the monthly budget may be up to $15,000, or $180,000 per year. To the extent Public Works staff can perform lake monitoring and maintenance, this amount would be less; however, this would then be Public Works time not presently assigned. The overall amount is an important reference point when considering longer-term options discussed below.
6 Grant Funding Received from Yuba Water Agency
The Yuba Water Agency had demonstrated significant support to clean up and maintain Ellis Lake.
The Agency is based in Marysville, committed to supporting the community, and water is core to the Agency’s existence. The Agency was primarily responsible for the 2021 Lake Management Plan, and Agency staff have been fully accessible and responsive during this follow-up work. The Agency also has a grant program which the City applied for and received for funding to support maintenance of the Lake. Grants were accepted during September. This was a result of the City Manager submitting a grant request to Yuba Water Agency in the amount of $300,000 to be used during 2024 and 2025.
LONG-TERM OPTIONS: MOVING TOWARD AN INTEGRATED APPROACH As discussed previously, the proposed immediate approach is treatment with a binding agent to sequester phosphorus, and to use appropriate herbicides and aquacides. However, ideally in the long run, use of chemicals would be reduced through creation of a sustainable, healthier lake environment. The items listed below will be evaluated at the same time near-term progress is accomplished. It is notable that all the measures listed below require continuing attention. As a living, thriving body, Ellis Lake requires ongoing attention in the same way the landscape around it needs attention.
1) Maintain operation for the large fountain on the island and consider adding more fountains in the form floating aeration. The fountain is not only a familiar and beautiful sight that people enjoy, but it also serves to oxygenate and circulate water around the island. Oxygen in the water supports aquatic life and serves to clean the water by removing odors. Agitation of the water helps prevent algae from forming and to circulate the oxygen deeper into the lake.
Fountains, or more practical, floating aerators in the lake are more protected from vandalism because they are not easily accessible. Floating aerators are appropriate for Ellis Lake because the water is shallow so deep aeration is not primarily necessary. Floating aerators are also much less expensive to install and maintain. The only need is a 110VAC power source on the shoreline near the installed locations. However, if boating were to become popular again on the lake, provisions would likely need to be made to separate boats from the fountain or aeration water.
2) Consider adding more subsurface aerators. EKI, in its Memorandum dated January 2019, recommended a total of 25 subsurface aerators. Three were installed as a pilot program. The challenges with the aerators are that the compressors require maintenance, the submerged diffusers can tend to clog, and the aeration process requires electricity to operate the compressors. The Lake Management Plan estimated the cost for operations and maintenance to be $70,000 per year for all 25 aerators. Subsurface aerators are much more expensive the floating aerators.
7 3) Consider additional Carp removal. Depending on the chemical burden to maintain the lake, consider additional Carp removal. As bottom feeders, the carp stir up sediment loaded with phosphorus. Less Carp means less bottom disturbance.
4) Consider pumped circulation. The Lake Management plan recommends aeration and pumped circulation as long-term solutions to keep water in the lake moving for oxygen to be absorbed at the surface and circulated downward. The system involves a 50 hp submersible pump, distribution piping around the bottom of the lake, and approximately seven discharge locations strategically placed to move otherwise stagnant water.
5) Reconnect to the Yuba River. The river pump was installed in 1971 and was operational until 2011, although marginally operating during the later years due to issues with sand and low water levels in the Yuba River. (The well at Ellis Lake was installed in 1979 in conjunction with draining the lake for the Hydrilla Eradication and Clean Lake Project.) This section discusses four primary challenges of reconnection: 1) The existing connection has no value, 2) Permitting challenges are extensive, 3) Reconnection would be expensive, and 4) Reconnection to the river would not solve the problem.
First, unfortunately, there is no remaining value from the old setup that brought Yuba River water to the lake. Here is a list of findings.
a. The city has no water rights and no existing contract to purchase Yuba River water. b. There is no established Point of Diversion with the Water Resources Control Board. c. The existing slant vertical pump apparatus is worn out. d. The existing pump location is bad due to lowered river water level and sand. e. The PG&E electric service has been removed.
f. There is no existing recorded easement across the private property. g. The old pipe through the levy was removed during recent levy rebuilding. h. Moving river water through the storm drain system is no longer recommended and may be prohibited.
Second, before construction can begin to reconnect to the river, the permitting challenges and time required to obtain permits are extensive. Specifically, up to 12 State and Federal environmental permits are required that will take up to 24 months to obtain. This is based on the table on page 4-6 of the Lake Management Plan, which has recently been validated by ECorp through a cursory review of the Lake Management Plan.
Intentionally blank. See next page.
8 Third, the estimated investment cost is significant at a minimum of approximately $3 million as summarized in the table below.
Component Probable
Cost
Comments
Permitting $340,000 Minimum expected cost.
River Pump 674,000 New pump, location, and PG&E service.
Levy Crossing 577,000 Assumes 14-inch pipe, as used before.
Discharge Pipe 1,489,000 3,300 feet type C-905 PVC.
Total Estimated Cost $3,080,000
The permitting cost in the table is from the Lake Management Plan. The costs for a new river pump, levy crossing, and discharge pipe were developed recently by MHM Inc. Interestingly, the MHM costs shown here are less than the $3.9 million comparable amount in the Lake Management Plan (Page C-2, adding $340,000 for permitting). The primary difference is the cost used for the discharge pipe in the Lake Management Plan is much higher. In the Lake Management Plan ductile iron is used instead of Type C-905 PVC. Finally, these estimated costs do not include any expenses for an easement across the private property beside the river.
The details of the MHM work can be found in Attachments 5A, 5B, and 5C.
And finally, although Yuba River water is clear, clean, and phosphorus free, it would provide only marginal operating benefit and yet carries various operating risks, explained below. a. The main benefit of river water is that it is free of phosphorus, but assuming river water is used only to keep the lake full, the lake would likely remain in or near the eutrophic state.
This means the lake would likely need regular maintenance anyway. This is supported by language in the Lake Management plan on page 3-5, restated below, underline added:
In 1979, the Ellis Lake Hydrilla Eradication and Clean Lake Project was implemented by the City. In addition to removing invasive hydrilla from the lake, the project also upgraded the existing stormwater system via the construction of a storm water interceptor system that was designed to capture and reroute the majority of storm water runoff prior to it entering the lake. The short period of time between the Yuba River Pump Diversion Project (1970) and the Clean Lake Project suggests that the bringing Yuba River water to the lake did not resolve the issues, water quality or otherwise, that were the driver for the Pump Diversion Project.
This conclusion is logical because replacing evaporative losses through the summer amounts to about one foot of lake level each month. Considering an average depth of six feet, this is one-sixth of the lakes volume, or just 17 percent. Replacing just 17 percent of the lake’s volume each month with phosphate-free water is unlikely to offset other factors hurting water quality, primarily phosphorus from other sources such as heavy storm runoff, and phosphorus contained in the lake-bottom sediment. The lake is also a large, shallow, 9 and stagnant body that becomes as warm as 80 degrees Fahrenheit in summer months, fostering the growth of weeds and algae.
b. Yuba River water has a wholesale market value between $60 and $500 per acre-foot, whereas well water is free, at least before the cost of phosphorous treatment. However, for the purpose of this analysis, a lower value of $10 per acre-foot is used assuming Yuba Water Agency may provide discounted water to the City. Using river water, the operating cost to replace one foot of evaporation based on the $10 per acre-foot of water, including pumping cost, is calculated at approximately $840 per month (Attachment 4). Using well water to keep the lake full, including treatment, the operating cost is estimated at $5,000 per month (Attachment 3). Therefore, under wet winter conditions with plentiful water, some operating savings would be achieved using river water; however, in drought years, if river water were at $500 per acre-foot, the cost would jump to almost $16,000 per month. (Attachment 4).
c. The long lead time and large capital investment required to reconnect to the river requires that future risks be considered. As California’s water supplies become increasingly stressed, changing regulations may prohibit nonessential use of Yuba River water for delivery to Ellis Lake.
d. As detailed above, water supply from the Yuba River based on $10 per acre-foot water is less cost than pumping well water. Based on the nameplate data from the old river setup, the 40 hp pump would move 4,000 gallons per minute or 5.76 MG per day. Whereas the 50 hp well pump at the lake produces a calculated rate of 1.99 MG per day. In fact, the much greater flow rate of 4,000 gallons per minute from the river would fill the entire lake in just 11 days. (Attachment 4)
ALTERNATIVE APPROACH NOT FEASIBLE
Nine Turnovers: Well Pumping. Nine turnovers per year using well water would push lake water over the weir boards into Jack Slough. This would result in providing clear water to the lake. The cost to run the pump to accomplish nine turnovers and replenish evaporation, based on current PG&E rates would be approximately $144,000 per year. Doing so would require treatment of additional phosphorus into the lake at an estimated cost of $376,000 per year. It would also strain the well and potentially strain the aquafer supplying the well. Further, it would take an estimated 35 days to turnover the water at the current flow rate from the well. And finally, water movement across the length of the lake would not be uniform because of the wide surface area of the lake.
Considering the cost for lake management activities to be up to $180,000 per year, a better solution is to treat the existing lake water and add wellhead treatment for phosphorus, saving the cost and strain of the well (Attachment 3 and comparison table below). 10 COMPARISON TABLE
The table below provides an economic comparison of the four different approaches to maintain Ellis Lake. The comparison table is simplified:
• It does not consider the time-value of capital invested in reconstruction of the connection to the Yuba River,
• Nor does it consider inflationary operating cost increases into the future, • And finally, it does not consider financial risks associated with the different approaches, which are noted below the table.
However, the table does accurately compare the near-term costs of the different approaches.
Considering that the assumptions incorporated are generous toward river water, such as wholesale water at $10 per acre-foot, the comparison costs shown for river water should be considered absolute minimums and will likely be higher.
Replenishment
Only
Turn Over Nine
Times Per Year
Replenishment
Only
Turn Over Nine
Times Per Year
Investment Costs
Capital improvement $46,200 $46,200 $2,660,000 $2,660,000 Permitting $0 $0 $340,000 $340,000
Easement $0 $0 Unknown Unknown
Total Investment Cost $46,200 $46,200 $3,000,000 $3,000,000 Annualized over 20 years $2,310 $2,310 $150,000 $150,000 Annual Operating Costs
Pumping electricity $23,000 $144,000 $6,400 $35,200
Pump maintenance $16,000 $26,000 $16,000 $26,000
Wholesale water $0 $0 $3,700 $20,300
Phosphorus control $40,000 $250,000 $0 $0
Herbicides/Algaecides $50,000 $16,667 $50,000 $16,667
Lake Mgmt. Company Labor $30,000 $10,000 $30,000 $10,000 Permit renewals $3,300 $3,300 $5,000 $5,000
Annual Operating Cost $162,300 $449,967 $111,100 $113,167 $164,610 $452,277 $261,100 $263,167
Compare to Well
Replenishment Only 0 $287,667 $96,490 $98,557
Ellis Lake Management Operating Comparisons
Well Water River Water
Annualized Investment +
Operating
11 Comparison Table Notes, Assumptions, and Risks
Annual Operating Costs for Well Water are updated as of 8/24 for the treatment categories based on actual costs over the previous year.
Capital improvement for well water is new pump and motor 8/24 at $44,000, plus well injection at $2,200.
Average 24-hour cost to operate 50 hp well pump is $384 (summer) as of Sept 2023 Easement costs across private property are unknown and not included Annualized investment cost does not include the time-value of money invested Availability of river water subject to 1) drought conditions, 2) fish flow requirements, and 3) future regulatory restrictions
River water is valued at $10 per AF based on the potential to received discounted water from the Yuba Water Agency; however, the minimum market value is understood to be $60 per AF Assumes river pumping achieves 9 CFS at 40 hp, as before.
Assumes treatment needs are 1/3rd when water is turned over nine times Phosphorous control includes wellhead and lake
Excessive operation of lake well may damage or otherwise strain well Assumes phosphorous treatment for all well water, including nine turnovers Permit renewals are for NPDES. The increased amount for river water is an estimate.
CONCLUSION
Over the past 10 years, Ellis Lake has been thoroughly studied. Similar ideas to improve water quality were provided in each of the studies completed. Some attempts have been made to improve water quality, such as Carp removal, isolated chemical treatment, and limited aeration. However, to achieve a clean lake, focused attention is first needed to restore the lake, followed by ongoing lake management that is critical to long-term success. Anticipated costs are within reason considering the importance of Ellis Lake in the community, estimated at a maximum of $15,000 per month. This is reasonable especially when compared to the large preliminary investments needed for longer-term approaches such as pumped circulation or accessing river water, up to $3 million initially. As time progresses, other solutions should be considered to reduce chemicals needed to thereby move toward a more naturally balanced lake environment. 12 RESOURCES USED
1) Ellis Lake Water Quality Report, by Dale Whitmore, dated December 2014. (37 pages) 2) Ellis Lake Technical Memorandum, dated January 7, 2019, prepared by EKI Environment and Water, Inc. (44 pages)
3) Ellis Lake Management Plan (Administrative Draft), dated April 26, 2021, supported by the Yuba Water Agency and completed by HDR Engineering. (122 pages) 4) Ellis Lake Carp Removal, Spring 2022
5) Jeff Mathews, Senior Project Manager, Yuba Water Agency (Involved with creation of 2021 Ellis Lake Management Plan)
6) John Mallen, City Engineer, MHM, Inc. (Involved with 2021 Lake Management Plan and long history with management of Ellis Lake)
7) David Thomas, Senior Aquatic Biologist/ Project Manager. ECorp Consulting, Inc. 13 ATTACHMENT 1
Ellis Lake Fill and Evaporation Rate Data (Measured August 2023) The lake surface area used for calculations is 30.7 acres, and the average depth used is six feet.
Calculation of Full Lake Volume:
30.7 acres x 0.325851 million gallons (MG) per AF x 6 feet = 60 MG Calculation of Evaporative Loss Per Day:
0.75 inchs per 2 days / 2 = 0.375 inchs per day
0.375 inches per day x 31 days per month = 12 inches per month (rounded) 1 foot x 30.7 acres x 0.325851 MG per AF = 10 MG per month (summer, rounded) or
1 acre-foot per month
or
10 MG / 31 days = 0.3226 MG per Day
Calculation of Pump Flow Rate:
Net Water Inflow = Gain + Evaporation
Gain = 2/12 feet per day x 30.7 acres x 0.325851 MG per AF = 1.6673 MG per day Net Water Inflow = 1.6673 + 0.3226 = 1.9899 MG per day
Calculated Pump Flow
1.9899 MG per day x 1,000,000 gal per MG / 24 hour / 60 mins = 1,382 gal per minute Calculation of Amount of Time to Fill Lake From Empty
60,000,000 gal / 1,382 gal per min / 60 min per hr / 24 hrs per day = 30 days Plus evaporation, add on foot of lake level, or 1/6th of the six foot depth 60,000,000 gal / 6 feet / 1,382 gal per min / 60 min per hr / 24 hrs per day = 5 days Therefore, the total is approximately 35 days to fill the lake from the well pump After the lake was filled and water stopped flowing over the weir board, the rate of evaporation and other losses was measure with the pump off. The measured rate of decline 0.75 inches over a 48 hour period, as measured during peak summer heat conditions (but with minor wind).
The measured fill rate was 2 inches of elevation gain per day over a six-day period raising the lake 12 inches to the top of the weir boards.
14 ATTACHMENT 2A
Ellis Lake Well Water Pump PG&E Service Agreement 1418428704 Start Stop kWh Cost Peak kW Avg.
$/kWh
8/25/20 9/23/20 11,691 $2,802.85 45.56 $0.24
9/24/20 10/25/20 9,760 $2,370.00 45.48 $0.24
10/26/20 11/23/20 9,683 $2,267.51 44.75 $0.23
11/24/20 12/23/20 10,660 $2,479.66 44.98 $0.23
12/24/20 1/25/21 11,247 $2,649.42 44.83 $0.24
1/26/21 2/24/21 10,594 $2,506.34 44.81 $0.24
2/25/21 3/25/21 10,093 $2,469.30 44.92 $0.24
3/26/21 4/26/21 10,797 $2,584.42 44.73 $0.24
4/27/21 5/25/21 10,024 $2,399.27 44.77 $0.24
5/26/21 6/24/21 10,255 $2,559.07 45.20 $0.25
6/25/21 7/26/21 10,224 $2,577.17 44.52 $0.25
7/27/21 8/25/21 9,746 $2,483.36 44.34 $0.25
8/26/21 9/26/21 7,035 $1,794.82 43.24 $0.26
9/27/21 10/25/21 7,968 $1,940.59 42.41 $0.24
10/26/21 11/23/21 6,977 $1,692.39 45.13 $0.24
11/24/21 12/23/21 9,374 $2,275.93 44.63 $0.24
12/24/21 1/24/22 7,213 $1,883.26 43.54 $0.26
1/25/22 2/23/22 9,662 $2,524.50 43.77 $0.26
2/24/22 3/24/22 7,868 $2,249.12 44.58 $0.29
3/25/22 4/25/22 12,808 $3,717.46 44.47 $0.29
4/26/22 5/24/22 9,189 $2,668.00 43.76 $0.29
5/25/22 6/23/22 10,024 $3,023.53 44.58 $0.30
6/24/22 7/25/22 10,065 $3,081.26 44.42 $0.31
7/26/22 8/24/22 8,352 $2,562.31 44.34 $0.31
8/25/22 9/25/22 9,752 $3,132.17 44.03 $0.32
9/26/22 10/24/22 3,778 $1,081.79 43.49 $0.29
10/25/22 11/22/22 8,648 $2,345.64 44.88 $0.27
11/23/22 12/22/22 4,904 $1,346.34 43.95 $0.27
12/23/22 1/24/23 2,299 $701.56 43.45 $0.31
1/25/23 2/23/23 11,433 $3,281.65 43.65 $0.29
2/24/23 3/26/23 8,954 $2,616.43 42.75 $0.29
3/27/23 4/25/23 3,582 $1,082.12 42.68 $0.30
4/26/23 5/24/23 5,795 $1,732.44 42.85 $0.30
5/25/23 6/25/23 6,060 $1,952.25 42.84 $0.32
6/26/23 7/25/23 5,749 $1,974.33 42.60 $0.34
15 ATTACHMENT 2B
PG&E Charges for Ellis Lake Pump During June and July 2023 16 ATTACHMENT 3
Calculations of Cost to Operate Ellis Lake Well Pump
From PG&E data, the 50 hp well pump draws a constant 43 kW.
Calculation based on PG&E B6 Rate schedule as of August 2023.
Peak Hours: 6 pm to 9 pm
43 kW x $0.60 per kWh = $25.80 per hour
Off Peak Hours: All other times
43 kW x $0.34 per kWh = $14.62 per hour
($25.80 - $14.62) per hours x 3 hours = $33.54
The cost to run the pump 24 hours straight:
(21 x $14.62) + (3 x $25.80) = $384 per 24 hr period.
Cost per MG pumped
$384 per day / 1.99 MG per day = $193 per MG pumped
If the pump were to operate continuously, the monthly kWhs and cost would be:
43 kW x 24 hrs per day x 30.4 days per month = 31,373 kWhs $384 per day x 30.4 days = $11,674 per month
Cost to keep the lake full replacing one foot of water
30.7 acres x 1 ft x 0.325851 MG per AF x $193 per MG = $1,931 per month Estimated cost of wellhead phosphorus treatment $3,000 per month Wellhead pump plus phosphorus treatment $5,000 per month (rounded) Wellhead pumping per year, electricity only $23,000 per year (rounded) Cost to turn water over nine times per year
Evaporative loss (from above) $23,000
$/day Days to fill Turnovers
Turnover 384 35 9 $120,960
Total $144,000 (rounded)
6,660 kWh / 31,373 kWh x 100% = 21% or 0.21 x 24 x 30.7 = 153 hrs per month Therefore, the added cost to let the pump run during peak hours is about $34 per day.
Also, for the past 12 months, the average kWh usage has been 6,600 kWh. From this, the capacity factor of the pump can be calculated to be 21% based on:
17 ATTACHMENT 4
Calculations of Operation of River Pump
The old river pump was 40hp and was rated at 9 cubic feet per second (CFS design conditions) 9 CFS x 7.48 gal per CF x 60 sec per min = 4,039 gal per min or
4,000 gal per min x 60 min per hr = 240,000 gal per hr (continuous operation) or
240,000 gal per hr x 24 hr per day x 1 MG per 1,000,000 gal = 5.76 MG per day 40 hp / 50 hp x $384 per day = $307 per day
Alternatively, in terms of dollars per MG pumped:
$307 per day / 5.76 MG per day = $53.30 per MG
The cost to replenish one foot of evaporation:
Pumping 30.7 acres x 1 ft x 0.325851 MG per AF x $53.30 per MG $533 per month Water Value 30.7 acres x 1 ft x $10.00 per AF $307 per month Total $840 per month
Pumping $6,400 per year (rounded)
Water Value $3,700 per year (rounded)
Total $10,100
Premium if water at $500 per AF
30.7 acres x 1 ft x ($500 - $60) $15,043
Cost at $500 per AF $15,883
River pump benefit vs well to keep the lake full: ($1,931 + $3,000) per Mo - $840 per Mo = $4,091 per Mo The cost to turn the lake over nine times per year, including evaporation:
Evaporative loss, pumping (from above) $6,400 per year (rounded) Nine turnovers, pumping
9 x 30.7 acres x 6 ft x 0.325851 MG per AF x $53.30 per MG $28,800 per year (rounded) Total pumping $35,200
Evaporative loss, water value (from above) $3,700 per year (rounded) Nine turnovers, water value
9 x 30.7 acres x 6 ft x 10 per AF $16,600 per year (rounded) Total water value $20,300 per year (rounded)
Time required to fill the lake, ignoring evaporation:
60 MG / 5.76 MG per day = 11 days (rounded up)
This calculation is done based on discounted wholesale water at $10 per acre-foot.
The estimated operating cost of the pump based on the current B-6 PG&E rate (same as well pump).
This is a simplified approach done by extrapolating down from the cost to operate the 50 hp well pump at the lake.
18 ATTACHMENT 5A
19 ATTACHMENT 5B
20 ATTACHMENT 5C