2020-2040 Water Resource Plan - Q&As

A: Yes, multiple models were used and applied in this Water Resource Plan. 

Regarding the impact of drought and climate change:  TMWA evaluated a range of scenarios that included historic droughts (including the worst droughts on record), climate change models, and future greenhouse gas emission projections.  Precision Water Resources Engineering was also retained by TMWA to provide third-party verification regarding how climate factors may impact future conditions of the Truckee River system.

Regarding the impact of population growth on water demand:  To estimate future water demand in the Truckee Meadows, the following data sources were used: Washoe County population, historical water services in TMWA’s service area, and historical water use data. TMWA’s population projection used in this report is based on a logistical growth curve, assuming that current trends and conditions continue.

With these conditions and projections, multiple drought and climate scenarios were simulated to the year 2098 to evaluate the resiliency and sustainability of TMWA’s water resources.  Using this information, the results show that TMWA’s water supply is extremely resilient at least 50 years into the future, even under extreme climate change scenarios where more severe droughts are projected to occur.

Of related note:  New residential development served by TMWA is required to dedicate water rights to not only meet a project’s estimated water demand, but also includes an additional 11% safety factor of additional water rights which are dedicated to TMWA for drought storage.

To explore this topic more:  Details about models used and outcomes of all simulations are provided in Chapter 3 of the draft plan.

For more information see the Draft 2020-204 Water Resource Plan, pgs. 34-40.

A: TMWA’s plans consider a 20-year horizon to be consistent with the Truckee Meadows Regional Planning Agency’s Regional Plan, which considers land use and growth projections over a 20-year time frame.  Furthermore, 20 years is a reasonable timeframe to plan, design and construct capital improvements and solutions, many of which can take years to implement.  TMWA uses the Water Resource Plan in conjunction with its Water Facility Plan, which addresses necessary infrastructure improvements over a 20-year timeframe as well.  Both the Water Facility Plan and the Water Resource Plan are updated every 5 years. TMWA’s Funding Plans are updated annually.

With every update, the Water Resource Plan accounts for change that could impact TMWA’s approach to resource management (e.g. population shifts, availability of convertible water rights, changes in available sources of supply, regulatory issues, etc).

For more information see the Draft 2020-204 Water Resource Plan (Plan Goals and Objectives & Scope), pg. 10.

A: No. Truckee River reservoir storage capacity is not likely to increase, although the Truckee River Operating Agreement allows TMWA to greatly expand the amount of upstream water stored during prolonged drought periods.  Additionally, TMWA continues to pursue other innovative ways to increase and diversify its water resources.  In Chapter 5 of the draft Water Resource Plan (see PDF), future water resource projects are identified, which include adding additional groundwater capacity, aquifer storage and recovery projects, utilizing creek resources in more efficient ways, investigating new reclaimed water treatment technologies, and other options.

For More Information See:

A: Recharging treated surface water into aquifers, which typically occurs during winter months when customer demands are low, has water quality requirements that are permitted and monitored by the Nevada Department of Environmental Protection.  In adherence to these requirements, water recharged into aquifers cannot negatively impact groundwater quality.  In some areas with higher levels of naturally occurring minerals, such as Arsenic, groundwater quality is improved through TMWA’s aquifer storage and recovery program.

For More Information see the Draft 2020-2040 Water Resource Plan (ASR), pgs. 21-22

A: The water conveyed in irrigation ditches continues to play a role in aquifer recharge, specifically in southwest Reno and Spanish Springs.  The irrigation ditches are managed and operated by private irrigation companies.  Exceptions to this are the hydroelectric ditches and flumes supplying TMWA’s three run of the river hydroelectric plants (see Chapter 6) and the Highland Ditch, which supplies the Chalk Bluff Water Treatment Plant.  Decisions about the future of these ditches would be under the purview of the individual irrigation companies and the local government jurisdictions where the ditches are located.  TMWA has no authority on decisions made regarding the private irrigation ditches in the Truckee Meadows.

Currently, TMWA has no plans to take over any additional irrigation ditches in the region.

A: TMWA has three hydroelectric plants on the Truckee River that are over 100 years old but remain important to our energy portfolio. From a lost-revenue perspective, the Washoe Hydroelectric Plant is the lowest grossing energy producer of TMWA’s three plants.  Replacement construction costs are estimated to be around $3 million to repair the Washoe flume, which had been budgeted in TMWA’s Capital Improvement Plan and now is set at a higher priority.  We anticipate approximately $500,000 in lost hydrogeneration revenue before the flume is fully operational again.

Meanwhile, the Verdi and Fleish Hydroelectric Power Plants are fully operational and continue to help offset TMWA’s power costs.  Last year, the two plants generated $2.3 million in revenue.  Also, a new hydroelectric facility at the Chalk Bluff Water Treatment Plant has been recently approved by the TMWA Board of Directors. The new hydroelectric facility will not require new dams or diversions on the Truckee River.

For More Information see the Draft 2020-2040 Water Resource Plan (ASR), pg. 78

A: The Truckee River Fund, established by TMWA in 2005, has been very active in funding forest management and bank stabilization efforts, particularly on the California side of the watershed where the river is more susceptible to landslides during thunderstorm events.  When these events happen, advanced water quality monitoring systems can identify upstream mudflows, and if substantial, TMWA can opt to shut off treatment-plant intake channels to allow the impacted water to flow by.

For More Information see the Draft 2020-2040 Water Resource Plan (Truckee River Fund & Wildfires), pg. 74

A: Data used in this Water Resource Plan was based on the most current customer demand, after the removal of flat-rate billing and reflects a customer base that is 99% metered.

We believe community conservation of 10% is very realistic:  When TMWA requested 10% conservation during the 2015 drought year, our customers conserved 15-18%.  Based on this outcome, we believe achieving 10% water conservation from our customers is reasonable.  Additionally, since 2015, we are observing that more customers are using highly efficient, drip-style irrigation. Also, most new development lots are smaller with bigger buildings, further reducing water demand for landscaping needs.

For More Information see the Draft 2020-2040 Water Resource Plan (Increased Conservation During Drought), pg. 54

A: While commercial usage is down due to office and other business closures, commercial billing only accounts for approximately 10% of TMWA’s total revenue. For our residential customers, usage is up due to a dry spring and the fact that the pandemic has many people spending more time at home.  TMWA fiscal year projected revenues are within 0.5% of what had been estimated before the pandemic.  Of note:  Customers who have not been able to pay their bill due to the economic shutdown have continued to receive service.  TMWA will work with customers who need to delay their bill payments during this health crisis.

Return to Public Input Page for TMWA’s Draft 2020-2040 Water Resource Plan