Tonight the USGS site is showing a drop from about 2,750cfs to about 2,370cfs. However, the Hydromet data is showing pretty steady flows, with the exception of a significant rise in flows around 7am.Here’s the data from Hydromet 6am to 9am this morning (notice the nearly 300cfs jump at 7:30)BHSX |10OCT16| QR | | 06:00 | 2321.53 | | 06:15 | 2321.53 | | 06:30 | 2321.53 | | 06:45 | 2333.59 | | 07:00 | 2345.69 | | 07:15 | 2357.83 | | 07:30 | 2647.63 | | 07:45 | 2560.95 | | 08:00 | 2460.57 | | 08:15 | 2382.82 | | 08:30 | 2345.69 | | 08:45 | 2333.59 | | 09:00 | 2345.69 |
One very reliable source and Bighorn river guide sent this report from Thursday:There was a big jump and it pushed a lot of floating moss to the banks and then dropped so lots of moss beds stuck on the bank and is now noticeably lower than 3 days ago.This is consistent with the stage of the river dropping as mentioned by Dan Jewell in the last post where Dan mentioned the stage dropped a half foot. It should be noted that six inches of stage is a considerable amount of water. Kudos to Reclamation for discovering this anomaly so quickly and taking steps to divert operations to the backup system.
Dan Jewell, Area Manager for Montana Area Office of the Bureau of Reclamation distributed this explanation of recent events yesterday:Those of you who monitor Bighorn River releases via the U. S. Geological Surveys Daily Streamflow Conditions website likely noticed some irregular readings on October 13 14. In keeping with our practice of full disclosure and transparency in Yellowtail operations, I am providing the following information:During a scheduled drawdown of the Yellowtail Afterbay Reservoir on October 13 to accommodate placement of a water intake structure in the afterbay, Reclamation detected inconsistencies between the calculated discharge and river stage relationship. Specifically, the river stage began to drop while the calculated discharge remained constant. After finding no immediate explanation for the anomaly, Reclamation made the decision to switch to river stage control rather than rely further on the calculated discharge methodology provided by the automated control system. In simple terms, Reclamation switched from the new automated control system to the previously-used float control system for operation of the Yellowtail Afterbay. While the river stage was being restored to its previous level (river stage had dropped approximately 0.5 feet during this period), additional anomalies in the calculated discharge were observed. These anomalies (one reading indicated a momentary discharge of approximately 3,800 cubic feet per second) were not substantiated by either gate movement or river stage readings they were however, reported on the U. S. Geological Survey website according to established protocol. Until such time as the issues with the new control system can be identified and remedied, and the reliability of the system restored, Reclamation will operate the Yellowtail Afterbay with the old float control system which operates based on river stage readings. In switching back to the float control system, additional streamflow measurements by manual methods will be necessary to calibrate the float control system. During this period, Reclamation will continue to work closely with the U. S. Geological Survey to obtain sufficient streamflow measurements for use in establishing and helping maintain the fall/winter target flow of 2,370 cubic feet per second in the Bighorn River. If you have any questions or desire additional information, please contact me via reply e-mail, or via telephone at 406-247-7298.Thank you,Dan JewellArea Manager
USGS Graph captured at 7:27pmIf you think this graph is screwy, you should’ve seen the one this morning. It had flows up to 3,800cfs. Assurances have been given by Reclamation that the river releases are being maintained at or near 2,370cfs despite what the graph says. If you were on the river today, and have information to report relating to this matter, please contact us at firstname.lastname@example.org.We anxiously await the official explanation of the cause of these discrepancies, and in the meantime ponder these questions: Do other reservoirs have these problems? What is it with the month of October and the Bighorn?
If you’ve been monitoring the USGS site for Bighorn flows, you’ll notice some strange behaviour. Reclamation had this to report when called:During a scheduled drawdown of the Afterbay to accomodate contractor work in the Afterbay, inconsistencies in the river stage – gate discharge relationship were detected. Until such time as the cause of these discrepancies can be fully identified, we will make releases sufficient to maintain river stage.
Citing storage levels at 93% of average and winter inflow forecasts at 80% of average, Reclamation will drop river releases from the minimum of 2,500cfs to 2,370cfs starting tomorrow.Despite three consecutive above average water years, the Montana Area Office continues to manage the reservoir using a 20 foot window, resulting in minimum or below minimum releases to the river for the majority of the year, followed by record setting releases during spring runoff. If the last three years has taught us anything, river interests should once again expect the reservoir to not be drawn down sufficiently to accommodate spring runoff, and should prepare for higher than normal river releases come May, June and July.