500 m gallon new water supply v. 3.1
TRANSCRIPT
500 Mgallon New Water Supply Presentation (Final) 3/12/2015
Inflatable Dam at the Felton Diversion
Santa Cruz has the rights to take 9.56 Million gallons of water per day from here during the winter, up to 975 Million gallons per year. How much water is available under real conditions? This seminar will explore, step by step, the work first suggested by John Ricker, County Director of Water Resources, in May of 2011. Mr. Ricker demonstrated that there is additional winter water flow in the San Lorenzo which could be used by Santa Cruz and Soquel Creek to increase available water supplies. That work has languished in the shadows for almost 4 years now. The WSAC committee work and budget now approaches 2 Million dollars in consultant costs, and we still hear nothing about this water source.
We will start by looking at the water flows in the San Lorenzo river. Here is a graph from the USGS website showing the daily flows for this winter:
There are two red lines, one at 400 cfs. The other is at 17 cfs. 400 cfs is the upper limit of water turbidity that the water department can handle. 17 cfs is the amount of water that must be supplied for the Steelhead and Salmon during the winter. This is in the tolling agreement The water between the two red lines can be taken from the San Lorenzo by the City of Santa Cruz water department.
Now we will look at the water flows day by day.
The Yellow Triangles are the median water flow for all years . I Picked a conservative estimate of the water flow for each day. The water flows are measured simultaneously, but are recorded every 15 minutes. Reading the USGS graph of the website each afternoon at about 3:30, I learned the flow for the day that went down the San Lorenzo river.
Transfer the Graph to a table. Begin to tabulate water available for storage each day.
Each day, I enter the daily flow rate. Then I deduct the Fish requirement, 17 cfs. That gives a total amount of water that is available for humans. Then I convert the cfs. To Million gallons of water per day. (1 cfs for 24 hours produces 646,272 gallons). From the total water available after the fish get theirs, I subtract the average daily Santa Cruz city usage. In the winter I use the number of 7,000,000 gallons per day. The City of Santa Cruz has permits to take water every day from two sources, the Tait st. intake and the Felton Diversion. The permitted take at Tait st. is 12.2 cfs, which is 7.8 Million gallons per day. The permitted take at the Felton Diversion is 14.8 cfs, which is 9.56 million gallons per day. There is some language in the permit for Felton Diversion which states the permitted take at FD is 20 cfs = 12.925 MGallons per day. Notice that if the water flow in the San Lorenzo is 400 cfs or above, no water is taken because of high turbidity. If the water flow in the San Lorenzo is below 44 cfs, the available water declines below 9.56Mgallons per day.
Doing this every day for a month produces monthly water availability:
The total water available for Harvest during December was 238.17 Million Gallons
Tabulate the Water flows for the Winter of 2014 – 2105
Total Water available for Harvest Winter 2015, to date is 533.19 Mgallons
How do the other recent years look, using the same model?
How much Water does the City of Santa Cruz already have rights to?
The maximum amount that Santa Cruz can take from Felton Diversion is 3000 Acre-‐Ft. = 975,000,000 Gallons
How much Water has the City Harvested from the San Lorenzo River?
This winter 2014-‐ 2015, the Water department has pumped 150 Million gallons to Loch Lomond from The Felton Diversion, as of March 8, 2015.
How much does it cost to pump water up to Loch Lomond from the Felton Diversion? This January, the electric bill for pumping was $35,000. 3 million gallons of water was pumped daily up to the Felton Diversion, or about 90 Million gallons. Using that rate, plus 20% , the cost to pump 500 Million gallons from the Felton Diversion is approximately $230,000. How much does it cost to treat the water to make it ready for drinking? $170 to treat 1Million gallons. So to treat 500 million gallons, would cost $85,000. How much is 500 million gallons worth in revenue to the City during the summer months.? 500 million gallons converts to 668,449 HCF, the standard billing unit for Santa Cruz. At an average price of $8.00, that is $5,347,000 in additional revenue that the customers are happy to pay the city. The cost associated with producing that water is $315,000….This extra water sale generates $5 Million in profit to benefit the city water system. What is the cost of pipeline up East Zayante Rd. , and then up Lompico to the back of the Loch Lomond dam? $16,000,000. This $16,000,000 buys the installation of a 36” pipeline, which can carry 20 million gallons a day. This preliminary estimate should carry a contingency of between $-‐ 4 million to $+ 8 Million. Thus the range of expected cost is $ 12 to $24 Million.
How Much Water has the Loch Lomond held on April 1, each year?
I notice that Loch Lomond fills most years without any pumping of water up from the Felton Diversion? Why do we need more water, and what do we do with it? There are 2 parts to the answer:
1. The City needs to replace the North Coast stream sources. The following table shows recent declines in N. Coast supply:
Supply (Mgal) Avg. 2003-‐12 2012 2013 2014 N. Coast streams 1,129 710 ? 503 2. The Pipeline running up E. Zayante rd. is very close to 3 quarries and is in the heart of the Santa Margarita aquifer.
On top of the Santa Margarita aquifer, which has been depleted between 10,000 and 15,000 Acre feet, (3 to 4.5 billion gallons. )
The proposed pipeline route passes 3 Quarries which could be converted to
additional storage, silt sedimentation ponds or aquifer recharge ponds into the Santa Margarita aquifer.