May 28, 2019 2pm
Attendees: John Enloe, Director Natural Resources, Greg Pohll PhD, Principal Hydrogeologist, Andy Gebhardt, Director, Operations and Water Quality, Kris Hemlein, Washoe Resident
We opened the meeting by reviewing previous correspondence from (Lemmon Valley) LV Residents to TMWA, Andy Gebhardt’s responses to their questions on April 23, John’s email to Steve on April 25 stating that two LV extraction wells were shut down due to flooding.
- I explained that I got involved as a citizen with professional experience in hydrogeology and wrote up my questions and requests for information in letter form which we decided to submit to “This Is Reno” for publishing. TMWA was not pleased that I had my letter published in This is Reno, as they felt it was misleading in that it insinuated that the water quality for TMWA’s customers in Lemmon Valley was compromised. “I don’t understand why you couldn’t have just sent the letter directly to us. We would have happily given you all the information you need, without having to make it public. Once this meeting is over, I think you will agree that TMWA’s involvement in the Swan Lake flooding is non-existent. We have explained this to the LV residents over and over again. Tammy Holt Still keeps talking about the 2 million gallons/day coming from the Fish Springs well supply system. That water is being used as supply to our customers, not discharging to Swan Lake. We have tried to explain this to them over and over to no avail.”
- John stated that Andy Gebhardt met with Bob Conrad (This Is Reno editor) to complain about the title of my letter/article and to try to set the record straight – that TMWA is NOT responsible for LV flooding and that our water quality has not been impacted ( TMWA added).
- They presented me with a notebook containing all the information I requested in my letter. We reviewed the contents of the notebook, particularly the extraction wells locations and the pumping information.
- I asked whether they were concerned about contamination due to infiltration of surface water. They have sampled the LV wells frequently and have so far not found any evidence of contamination from surface sources.
- They provided a cross section depicting the depth and extent of the “clay layer” referenced by Dwayne Smith in his LV remediation discussions. The cross section utilizes the well logs from LV7, 8 and 6, Northwest to southeast. The thickness of the clay beneath Swan Lake varies from 50 to nearly 400 feet (TMWA removed).
- We discussed the East and West LV basins, separated by the Airport Fault. TMWA uses the West LV basin for groundwater recharge/storage and a pilot program is underway there evaluating the feasibility of storing additional water underground on Washoe County property north of the airport, but not the East LV basin, where Swan Lake and LV WTP is located. No water injection takes place in the East LV basin, except for a small test well located near the Reno-Sparks treatment plant where an injection test will take place next month at 15 gallons per minute for 2 – 3 months (less than 6 acre-feet in total).
- We discussed the LV Residents’ concern over the 2 million gallons a day extracted from 2 Fish Springs wells to augment water supply. The LV Community suspects that this water is contributing to Swan Lake flooding. In 2019 TMWA only recharged the Silver Lake well, which is in West LV Basin, in the amount of 45 acre-feet, and therefore not contributing to the Swan Lake flooding. Andy Gebhardt provided additional information regarding the amount of recharge taking place via injection at the two Silver Lake wells and reiterated that the Silver Lake wells are in the West LV Basin and not hydrologically connected to the East LV Basin, therefore not contributing to the water balance in that basin.
- We discussed the 40 feet of piezometric loss in the East Basin due to groundwater extraction since the 1970s, as depicted on a hydrograph provided by TMWA. Groundwater is beginning to rebound since the flooding began in 2017 and groundwater pumping was reduced. In 2019 groundwater levels are 20-60 feet below Swan Lake indicating that the aquifer does not discharge to the lake.
- I asked whether the LV Community group has technical/professional assistance to help them understand the issues and the remedial options presented by the City/County engineers. They told me that Mark Walker, UNR professor of Natural Resources has been assisting the LV community.
- TMWA is working with the Western Regional Water Commission and others (Reno, Washoe County, UNR) to evaluate the feasibility of additional groundwater recharge/storage in the Stead area (West LV Basin, at the Washoe County property mentioned previously, north of the Airport) as well as evaluating the feasibility of upgrading the Reno-Stead WTP to A+ water quality standards for injection purposes. Potential implementation of such an option, if feasible, is several years away.
- We discussed options for LV residents in the Hepner Subdivision, still on domestic wells and septic systems. AB 42 provides a financing option for residents to help pay for hooking up to municipal water system. TMWA states that putting these homes on the municipal water system is a prudent strategy if domestic well owners are concerned about their water quality. They did not comment as to whether the Hepner Subdivision septic systems are a possible eventual source of contamination to surface or groundwater in East LV Basin.
Subsequent to the meeting I asked for clarification on several items:
- The thickness of the clay layer that Dwayne Smith references as being “protective of the LV aquifer” is correct in that estimates of 50 – 400 feet of clay underlies the area around Swan Lake playa. Following TMWAs recent evaluation of the hydrogeology in Lemmon Valley, they believe the thickest sections of clay are limited to the area beneath Swan Lake playa. Airborne resistivity mapping done by Washoe County shows lowest resistivity values (which is indicative of fine sediments) beneath the playa, with values increasing laterally, which supports TMWA’s conceptual model. Borehole logs are also consistent with this interpretation.
- The clay horizon does thin as you move away from the playa, and there is a one borehole beyond the western edge of Swan Lake that does not have any fine sediment.
- The clay lens does exist to a depth of approximately 20 ft in the south end of the Hepner Subdivision, but transitions to granodiorite at the north end. This could be a concern as the clay acts as an impermeable barrier to downward infiltration of surface water/fluids and therefore there might be a possibility that leachate from the Hepner Subdivision septic and leach fields could migrate downward into the aquifer.
- I asked TMWA if they have an estimate of the amount of available storage exists in the West LV basin. They stated that they are currently developing a groundwater model for all of Lemmon Valley which will be used to determine the storage potential.
- I asked why East LV basin recharge/storage is not considered feasible/practical. TMWA stated that they do not have an operational reason to recharge groundwater in the East LV basin. In the West LV basin recharge operations have been necessary to improve and maintain groundwater water levels, which benefits both municipal and domestic wells in that area. Also, water levels in Golden Valley (East LV) have been increasing toward land surface which is why Washoe County stopped injecting in 2016 or 2017. Back to Question 4, if there is available storage, why not encourage the active ingress of water by injection as a way to manage overall water storage issues in LV?
In summary, TMWA states that their water management processes are not responsible for the LV flooding, nor does the flooding impact water quality or supply infrastructure in LV. But can they be part of the solution to LV flooding? TMWA has the financial means, technology and infrastructure to be part of the long-term solution.