If you do not follow Lees Ferry Anglers on Facebook, you should. We make several posts each week about current conditions at Lees Ferry.
On June 1, the higher summer flows began. As we had hoped, the increased water flows have improved the fishing significantly compared to the previous few months. The higher flows have stirred up the larger food items (scuds and worms) and we are seeing unusually large midge hatches. For most of the spring, the fish were holding in the deeper water and it was tough to get to them. This, coupled with our crappy spring weather, made our fishing slower than normal. Now that the water has risen, the fish are moving back into the shallower water and are much more eager to eat. The fish are in astoundingly great shape and we are catching all sizes of fish from large to small, including a 20-incher on my boat this week that weighed every bit of 4 pounds. The other good news is that we are starting to catch quite a few smaller fish (under 10-inches) which means there are younger generations of trout that are moving out of hiding and into the main channel to feed; these will be the fish that we are catching for the next few years.
The great fishing should continue throughout the summer. The cicadas are starting to sing and we’ll be making regular posts on Facebook regarding their hatches.
The best flies of recent have been scuds, worms and midges. Stop by or call the shop to get the most recent hot fly selection. Wade fishing continues to be highly productive as has been drift fishing from the boat. Weekend flows are lower and as a result the wade fishing is usually better those days.
El Nino came through in the end and provided the Lake Powell drainage with a good snowpack. The lake has risen over 20-feet and we have more to go … I’m hoping that the lake ends up 30 or more feet. The Powell’s current elevation is higher than it has been since 2012. The high inflow will also stir up nutrients that will show up in the river next winter and spring.
The river looks great with abundant algae covering most of the bottom. The algae indicate that there is a good nutrient flow from the water above the dam. These nutrients serve as the foundation for macroinvertebrates that support the food web.
The river is a living creature. Just because you caught fish in a certain spot in years past, don’t think that you are going to experience the same success this year. Fishing is changing daily. It is our goal and desire that everyone have a great trip to the Ferry. Be sure to stop by the shop to see the flies that are currently working. The flies change on a daily basis and every day LFA guides let everyone at the shop know the top producing flies and how to use them. We are anxious to share this knowledge with you – even where to fish!
There is an ongoing aquatic food base study that has taken place over the past couple of years. The purpose of this study is multifaceted and is studying the relationship of flows on food production, taking inventories of and monitoring populations of aquatic insects and invertebrates that live in the river and other very important aspects of the aquatic food base. I believe that this is by far the most important study that has ever been conducted on this river. Previously, hundreds of millions of dollars have been spent studying sediment while ignoring the aquatic food base and resource. Common sense dictates that fish, birds and animals do not live off of dirt or sand. The aquatic food base and habitat are the foundation for all that lives in the Colorado River. One of the long term goals of the food base study is to determine how to enhance the populations and production of aquatic insects in the river which will benefit native fish, trout, and migratory bird populations. This is a study and a goal that we can all embrace!
Quagga mussels have become established in Lake Powell and we are now seeing some in the river below the dam. Their arrival in the river happened sooner than I expected. So far, there has not been a major infestation and there is some thought by experts that they will not become very well established in the river due to the current. Be aware and remember to dry waders and boots before using them in any other body of water. Also, all private boats should drain all water from the boat and live-wells as soon as you exit the river. We all need to do our part to limit the transport of this and all invasive species.
We are hearing positive reports on the walk-in area. I expect the fishing to improve as the summer progresses.
Spin fishing has improved greatly. For most of the spring there was so much algae that it was practically impossible to get a drift without the lure and line being clogged with algae. The higher flows that began June 1 have helped to clear this algae, so conditions have improved greatly
Glen Canyon Dam / Lake Powell
Current Status The unregulated inflow volume to Lake Powell in May was 2,294 thousand acre-feet (kaf) (98 percent of average). The release volume from Glen Canyon Dam in May was 700 kaf. The end of May elevation and storage of Lake Powell were 3,604 ft (96 feet from full pool) and 12.1 maf (50% of full capacity), respectively. The reservoir reached a seasonal low elevation on April 15th near elevation 3591.14 feet. Since that time the reservoir elevation has been increasing and will continue to increase throughout mid-summer as runoff from snowmelt and precipitation enter the reservoir. Current Operations The operating tier for water year 2016 was established in August 2015 as the Upper Elevation Balancing Tier. The April 2016 24-Month Study established that Lake Powell operations will be governed by balancing for the remainder of water year 2016. Under balancing, the contents of Lake Powell and Lake Mead will be balanced by the end of the water year, but not more than 9.0 maf and not less than 8.23 maf shall be released from Lake Powell. Based on the most probable inflow forecast, this June 24-Month Study projects a balancing release of 9.0 maf in water year 2016; the actual release in water year 2016, however, will depend on hydrology in the remainder of water year and will range from 8.23 to 9.0 maf. The projected release from Lake Powell in water year 2016 will be updated each month throughout the remainder of the water year. Reclamation will schedule operations at Glen Canyon Dam to achieve as practicably as possible the appropriate total annual release volume by September 30, 2016.
In June, the release volume will be approximately 800 kaf, with fluctuations anticipated between about 9,000 cfs in the nighttime to about 17,000 cfs in the daytime and consistent with the Glen Canyon Operating Criteria (Federal Register, Volume 62, No. 41, March 3, 1997). The anticipated release volume for July is 950 kaf with daily fluctuations between approximately 11,500 cfs and 19,500 cfs. The expected release for August is 900 kaf with daily fluctuations between approximately 10,000 cfs and 18,000 cfs.
In addition to daily scheduled fluctuations for power generation, the instantaneous releases from Glen Canyon Dam may also fluctuate to provide 40 megawatts (mw) of system regulation. These instantaneous release adjustments stabilize the electrical generation and transmission system and translate to a range of about 1,200 cfs above or below the hourly scheduled release rate. Under system normal conditions, fluctuations for regulation are typically short lived and generally balance out over the hour with minimal or no noticeable impacts on downstream river flow conditions.
Releases from Glen Canyon Dam can also fluctuate beyond scheduled releases when called upon to respond to unscheduled power outages or power system emergencies. Depending on the severity of the system emergency, the response from Glen Canyon Dam can be significant, within the full range of the operating capacity of the power plant for as long as is necessary to maintain balance in the transmission system. Glen Canyon Dam typically maintains 30 mw (approximately 880 cfs) of generation capacity in reserve in order to respond to a system emergency even when generation rates are already high. System emergencies occur fairly
infrequently and typically require small responses from Glen Canyon Dam. However, these responses can have a noticeable impact on the river downstream of Glen Canyon Dam.
Inflow Forecasts and Model Projections The April to July 2016 water supply forecast for unregulated inflow to Lake Powell, issued on June 3, 2016, by the Colorado Basin River Forecast Center, projects that the most probable (median) unregulated inflow volume will be 6.5 maf (91 percent of average based on the period 1981-2010). The forecast increased by 1,000 kaf since last month. There is still uncertainty regarding this year’s water supply and the total inflow to Lake Powell. The spring runoff forecast ranges from a minimum probable of 3.85 maf (54 percent of average) to a maximum probable of 7.65 maf (107 percent of average). There is 10% chance that inflows could be higher than the maximum probable and a 10% chance they could be lower than the minimum probable.
As determined in the August 2015 24-Month Study, and documented in the 2016 Annual Operating Plan, Lake Powell’s operations in water year 2016 will be governed by the Upper Elevation Balancing Tier. Because the April 2016 24-Month Study projected the end of water year elevation at Lake Powell to be above 3,575 feet and the end of water year elevation at Lake Mead to be below elevation 1,075.0 feet, Lake Powell operations shifted to balancing (Section 6.B.4 of the 2007 Interim Guidelines) for the remainder of water year 2016. Under balancing, the contents of Lake Powell and Lake Mead will be balanced by the end of the water year, but not more than 9.0 maf and not less than 8.23 maf shall be released from Lake Powell.
Based on the June most probable inflow forecast, the annual release volume from Lake Powell during water year 2016 is projected to be 9.0 maf. Under the minimum probable inflow scenario, the water year release is projected to be 9.0 maf. Under the maximum probable inflow scenario, the release is projected to be 9.0 maf. There is 10% chance that inflows will be lower than the current minimum probable forecast, potentially resulting in lower releases. If inflows are less than the minimum probable forecast, the water year 2016 annual release could be as low as 8.23 maf. If inflows are greater than the current forecasted maximum probable inflow, the annual release will be 9.0 maf. The projected release from Lake Powell in water year 2016 will be updated each month throughout the remainder of the water year.
Based on the current forecast, the June 24-Month Study projects Lake Powell elevation will end water year 2016 near 3,611 ft with approximately 12.82 maf in storage (53% capacity). Projections of elevation and storage still have significant uncertainty at this point in the season, primarily due to uncertainty regarding runoff and the resulting inflow to Lake Powell. Under the minimum probable inflow scenario, updated in April, the projected end of water year elevation and storage are 3585 ft and 10.35 maf (43% capacity), respectively. Under the maximum probable inflow scenario, updated in April, the projected end of water year elevation and storage are 3622 ft and 14.01 maf (58% capacity), respectively. Modeling of projected reservoir operations based on the minimum and maximum scenarios will be updated again in August.
Upper Colorado River Basin Hydrology The Upper Colorado River Basin regularly experiences significant year to year hydrologic variability. During the 16-year period 2000 to 2015, however, the unregulated inflow to Lake Powell, which is a good measure of hydrologic conditions in the Colorado River Basin, was
June 2016 above average in only 3 out of the past 16 years. The period 2000-2015 is the lowest 16-year period since the closure of Glen Canyon Dam in 1963, with an average unregulated inflow of 8.51 maf, or 79% of the 30-year average (1981-2010). (For comparison, the 1981-2010 total water year average is 10.83 maf.) The unregulated inflow during the 2000-2015 period has ranged from a low of 2.64 maf (24 percent of average) in water year 2002 to a high of 15.97 maf (147 percent of average) in water year 2011. The water year 2015 unregulated inflow volume to Lake Powell was 10.174 maf (94 percent of average), which, though still below average, was significantly higher than inflows observed in 2012 and 2013 (45% and 47 percent of average, respectively). Under the current most probable forecast, total water year 2016 unregulated inflows to Lake Powell is projected to be 9.70 maf (90 percent of average), and ranges from a minimum probable inflow of 6.86 maf (63%) and maximum probable inflow of 11.13 maf (103%).
At the beginning of water year 2016, total system storage in the Colorado River Basin was 30.3 maf (51% of 59.6 maf total system capacity). This is nearly the same as the total storage at the beginning of water year 2015 which began at 30.1 maf (50% of capacity). Since the beginning of water year 2000, total Colorado Basin storage has experienced year to year increases and decreases in response to wet and dry hydrology, ranging from a high of 94% of capacity at the beginning of 2000 to a low of 50% of capacity at the beginning of water year 2014. One wet year can significantly increase total system reservoir storage, just as persistent dry years can draw down the system storage. Based on current inflow forecasts, the current projected end of water year 2016 total Colorado Basin reservoir storage is approximately 30.3 maf (51% of capacity). The actual end of water year storage may vary from this projection, primarily due to uncertainty regarding this season’s runoff and resulting reservoir inflow. Based on the April minimum and maximum probable inflow forecasts and modeling the range is approximately 27.6 maf (46%) to 31.4 maf (53%), respectively.
Updated June 9, 2016 Paul Davidson
Bureau of Reclamation