PRRIP Governance Committee Meeting and Materials

Home Browse Search

? the anticipated channel maintenance, sandbar formation and other benefits, and EA content remains limited, back-to-back pulse flow releases may not be judged to be the highest priority use of EA water. (4) Other Circumstances: As discussed in the Program Water Management Process document, a request for reregulation and EA bypass may be needed to test the effectiveness of alternative flow routing strategies, particularly during earlier, experimental EA releases. Pulse Flow Implementation A separate Excel worksheet is provided as part of the WI'08 AOP (it is too wide to include a readable copy in this document). The supporting documentation for the worksheet is included in Appendix F (pages 37-41). The worksheet may be used to generally illustrate potential pulse flow release scenarios from the Environmental Account in Lake McConaughy on a daily time-step, assuming known system inflows, river gains, and how gains are anticipated to fluctuate with increases and decreases in river flow. Transit losses (or conveyance factors) for the NPPD and CNPPID canals and the river are also assumed to be known and specified by the user. Two-day travel times are assumed between Lake McConaughy and the North Platte River/South Platte River confluence, and between the confluence/CNPPID diversion and Overton, whether via the Platte River or through the CNPPID system. Therefore, the worksheet is not intended to be a real-time simulation tool, • but may be used to gain insight as to how to sequence EA releases with the Districts operations, given the above assumptions, to produce a pulse flow at the Platte River near Overton gage. An EA pulse flow release in WY08, and the actual peak flow attained at the Overton gage area, will be heavily influenced by local weather, river baseflow conditions, losses, and attenuation in the Platte River paralleling the CNPPID system. Thus, the example scenario should be viewed in that context. Description of EA Operations Utilizing Johnson Lake Reregulation and Intentional EA B??ass at the CNPPID Diversion 1) EA releases are increased at the conservative ramp rate of 300 cfs per day from Lake McConaughy. During an EA pulse flow release, no other releases of CNPPID or NPPD project water are anticipated, due to operation in "conservation mode" to maximize storage in Lake McConaughy. No EA diversions are anticipated due to "conservation mode" operation by NPPD in 2008. Total flow at the North Platte River at North Platte gage should remain at or below the NWS flood-level of 1,980 cfs (stage = 5.7 ft). 2) Prior to the flow rate at the North Platte River gage reaching its maximum, EA water is delivered to Johnson Lake for temporary reregulation. ? 3) EA water is also bypassed at the CNPPID diversion to "wet up" the main Platte River channel. The maximum EA Bypass at the CNPPID diversion occurs when flows are greatest at the North Platte River gage. Water Year 2008 EA AOP 14 October 15, 2007