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Ms. Mitchell and Ms. Ris December 14, 2018 Page 6 of 9  “Delayed return flows may also be replaced with depletion credits . . . release[d] to the stream through augmentation stations.” Proposal at 5. It is not clear what the term “depletion credit” means, or how a depletion can also be a credit. Assuming that Applicants are referring to the fully consumable portion of farm headgate deliveries for the water rights included in the pilot project, then the application must show that these credits are available at times and locations needed to replace historical return flows. This method does not appear viable for replacement of return flows owed during the non-irrigation (winter) season.  Delayed return flows may also be replaced with depletion credits that are exchanged to and then released from upstream storage locations. Proposal at 5. This method of return flow replacement is subject to unreliable exchange potential in the Arkansas River. As detailed in Tri-State’s comments regarding the Catlin Pilot Project, use of this method to replace return flows will require extensive terms and conditions to ensure that adequate return flow water is already in storage (or another reliable supply exists) to replace all delayed return flows before fallowing lands each year.  Delayed return flows may also be replaced through “effectuating trades with entities who have downstream replacement obligations.” Proposal at 5. Applicants have not identified any specific trades, and it is not clear how another entity’s downstream obligation would provide water to make up Applicants’ return flow obligations. The legality of trades will depend on the specific statutes and decrees applicable to each trade. For example, Rule 14 Plans are not authorized to replace return flows on water rights changed to municipal uses, and water in a pilot project may not be traded for water in a substitute water supply plan.  Delayed return flows may also be replaced “through the delivery of depletion credits . . . to existing or future recharge facilities.” Proposal at 5. The effectiveness of recharge to replace return flows will require detailed information regarding the siting and lagging factors for all proposed recharge sites. For example, recharge should not be sited where shallow groundwater conditions would interfere with recharge accretion to the alluvial aquifer system. Untested and unidentified recharge sites cannot be considered a firm source of supply for replacing return flows. The Lower Arkansas Valley Water Conservancy District and Tri-State are working to schedule a technical meeting regarding plans to replace historical return flows for the CS -U Pilot Project. Tri-State appreciates the early opportunity to discuss the options above and attempt to identify a return flow plan that is viable and will prevent injury.