Water Use And The Effect On Lake Cypress Springs

Conclusions from 3 Year Study

LCS Total Water Available (Water Right #04-4560)

     • Adjudicated Water Permit: 11,210 acre-feet/year.

     • Cypress Springs Special Utility District: 3500 acre-feet/year
     • City of Winnsboro: 3000 acre-feet/year
     • City of Mount Vernon: 3000 acre-feet/year
     • Unallowcated water: 2210 acre-feet/year

Contract: Cypress Springs Special Utility District (SUD)

     • Ammended and Restated on August 19, 2008
     • Term: August 19, 2008 to Deccember 31, 2060
     • Maximum Amount of Water Annually: 3500 acre-feet

Contract: City of Winnsboro

     • Ammended and Restated on February 2, 2015
     • Term: February 2, 2015 to Deccember 31, 2035
     • Maximum Amount of Water Annually: 3000 acre-feet

Contract: City of Mount Vernon

     • Executed on April 15, 1996
     • Term: February 2, 2015 to Deccember 31, 2025
     • Maximum Amount of Water Annually: 3000 acre-feet

Do the Franklin County Water District's raw water customer's diversions have a significant impact on the Lake Cypres Springs reservoir level?

What about times when the lake is spilling and flood storage is in use?
• Raw water customer diversions have NO impact on lake level when the reservoir level is above conservation pool and flowing into the Morning Glory spillway!


How much impact to Lake Cypress Springs lake level is there by Franklin County Water District's customer's diversions?
• Raw water customer diversions account for 1.68 feet total impact on lake level when the reservoir level is below conservation pool!


Does the lake “reset” any losses after the lake level reaches conservation pool and starts spilling into the spillway?
• Raw water diversions from customers no longer have any effect on lake level while the lake is overflowing into the spillway.


Do water releases from LCS to the City of Mount Pleasant have a significant impact on lake levels?
• Releases to Mount Pleasant do affect the LCS lake levels but only under drought conditions (as shown below) and more slowly than you'd think.


So how often do the Mount Pleasant releases occur and how did it affect the lake level at LCS
• In the last 3 years only enough water was released to drop the lake level 1 foot!.


* All data and images reimagined from information provided by Carollo Engineers for Franklin County Water District on April 11, 2023.

What about other factors that could have a significant impact on the Lake Cypres Springs reservoir level?

Do private irrigation water pumps have a significant impact on Lake Cypress Springs' level?
• Let's consider...
     • 805 pumps
     • Assume 2 HP at 25 GPM
     • Assume 1 Hr. runtime per day
     • Assume 3-Year timeline
     • 3 Year Total: 0.0034 feet

Do evaporative losses in the reservoir have a significant impact on Lake Cypress Springs' level?
• Evaporation has always had the most impact to any lake's level! In the last 3 years for LCS more than 13 feet has been lost to evaporation!.


So the lake resets don't affect the Lake Cypress Springs' level drop with evaporation?
• If you factor in reset of the lake over the three years due to rain then the total evaporation impact on the lake level looks like this...


* All data and images reimagined from information provided by Carollo Engineers for Franklin County Water District on April 11, 2023.

Conclusions from the 3 Year Study

• Approximated 3 year lake level impact by Cypress Springs Special Utility District was 0.88 feet.
• Approximated 3 year combined lake level impact of all Franklin County Water District customers was 2.75 feet.
• Approximated 3 year lake level impact from Lake Cypress Springs evaporation was 9.55 feet.
• So the approximated lake level impact from Lake Cypress Springs evaporation was ~ 11 times the impact of the Cypress Springs Special Utility District!
• And the approximated lake level impact from Lake Cypress Springs evaporation was ~ 3.5 times the combined impact of all the FCWD customers!

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