Up-River Summary. By Terry Gunn
Spring has arrived at Lees Ferry and so have the prolific midge hatches that make the fish happy and the fishing so good. The water flows – 7,000 to 13,000 cfs – are just about perfect for wading; these flows should continue at or near this level until the higher summer flows arrive in July. Keep in mind that the flows on the weekends are almost always lower than the weekdays and in the spring, lower water and midge hatches equals great fishing.
Our guides are currently booking for the spring and we have very limited availability. If you need a guide or a room at Cliff Dweller’s Lodge book it ASAP. Don’t forget that you can book your trip, room and rental boat online at www.leesferry.com. If you don’t see the days that you want, be sure to call the shop because sometimes we can switch things around on our end to make your trip work.
In addition to the good midge hatches, after a three year absence the abundant black fly hatch was back this winter. The black flies really help the trout to put on weight during the winter months when there is otherwise limited food production in the river. If you’ve been to the Ferry in winter or early spring and been surrounded by surface feeding fish and have not been able to get a single fish to eat your fly, you’ve very likely witnessed a black fly hatch. The emerger that the fish eats is almost impossible to replicate with a fly and when trout are keying on black fly emergers, they’ll often eat nothing else.
Recent fishing has been OK; perhaps not quite as good as it was last year at this time, but it is still decent by any measure. To understand where the river stands today, one must first understand where we have been. It has been a very interesting fall, winter and spring. The most notable occurrence was last November and the extreme low flows that occurred before and after the high flow event for the entire month. This was the first time that we have seen flows this low in decades and if we have any say in the matter, it will be the last time. The low flows combined with the warmer than normal river temperatures (58 degrees) resulted in low oxygen levels from the dam releases. This caused a rapid decline in fish condition and we lost some fish. There are areas of the river that were more impacted than others, while some areas saw no decline in fish health or population. We witnessed almost exactly the same thing in 2005. Lake Powell was considerably lower then and the water was even warmer than this year. The good news is that we had a very healthy trout population beforehand and we still have a very good population today. Don’t assume that an area of the river that fished well last year will be the same this year. It is going to take a while for the fish to move back into some areas of the river. Water temperatures returned to normal (48 degrees) in December and the current health of the fish is good and will continue to improve as they feed on the heavy midge hatches this spring.
There has been 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 has 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!
There is currently a 65% chance that there will be an El Nino event in 2015 and through the summer. Strong El Ninos almost always bring big snow packs to the Rockies which could help to fill both Lake Powell and Lake Mead. Current snowpack in the Lake Powell drainage in almost 90% and at this point there will be a decent runoff regardless of how the spring develops. The current lake level is 108 feet below full pool, but it is currently 20 feet higher than it was last year at this time. The good news is that it appears that Lake Powell will rise again this year.
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.
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 the LFA guides let everyone at the shop know the top producing flies and how to use them.
I’m sorry that I do not have an in-depth report on the walk-in section. There have been few people fishing this area. All reports have been that this area has been very slow with few fish being caught. I expect this to change any day now that the spring flows (low water) and as the midge hatches continue to increase with the longer days and warmer weather. I’ll update this walk-in report as soon as we have more information.
Glen Canyon Dam / Lake Powell
Current Status The unregulated inflow volume to Lake Powell in January was 348 thousand acre-feet (kaf) (96% of average). The release volume from Glen Canyon Dam in January was 862 kaf. The end of January elevation and storage of Lake Powell were 3,593.6 feet (106 feet from full pool) and 11.15 million acre-feet (maf) (46% of full capacity), respectively. The reservoir elevation is now declining and is expected to continue to decline until spring 2015.
Current Operations The operating tier for water year 2015 was established in August 2014 as the Upper Elevation Balancing Tier. In the Upper Elevation Balancing Tier the initial water year release volume is 8.23 maf; however, there is the possibility for an April adjustment to equalization or balancing operations to govern for the remainder of the water year. Under the minimum, most, and maximum probable inflow scenarios an April adjustment to balancing releases is projected to occur and Lake Powell is currently projected to release 9.0 maf in water year 2015. The minimum and maximum release projections, last updated in January, will be updated again in April. Reclamation will schedule operations at Glen Canyon Dam to achieve as practicably as possible the appropriate total annual release volume by September 30, 2015.
In February, the release volume will be approximately 600 kaf, with fluctuations anticipated between about 6,500 cfs in the nighttime to about 12,500 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 March and April are 650 kaf and 600 kaf, respectively.
In addition to daily scheduled fluctuations for power generation, the instantaneous releases from Glen Canyon Dam may also fluctuate to provide 40 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 27MW (approximately 800 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 2015 water supply forecast for unregulated inflow to Lake Powell, issued on February 3, 2015, by the Colorado Basin River Forecast Center, projects that the most probable (median) unregulated inflow volume will be 5.2 maf (73% of average based on the period 19812010). The forecast decreased by 1.3 maf over the past month. At this early point in the season,
there is still significant uncertainty regarding this year’s water supply. The forecast ranges from a minimum probable of 3.4 maf (47% of average) to a maximum probable of 8.35 maf (117% 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 2014 24-Month Study, and documented in the 2015 Annual Operating Plan, Lake Powell’s operations in water year 2015 will be governed by the Upper Elevation Balancing Tier. In this tier, the initial water year release volume is 8.23 maf, however, there is the potential for an April adjustment to equalization or balancing releases in April 2015. If the April 2015 24-Month Study projects Lake Powell’s September 30, 2015, elevation to be greater than 3,649 feet, the Equalization Tier would govern Lake Powell’s operations for the remainder of water year 2015 and releases could be approximately 10.8 maf or greater. Based on analysis of a range of forecasted inflow scenarios, the current probability of realizing an inflow volume that would trigger equalization in 2015 is approximately 5 percent. If the April 2015 24Month Study projects Lake Powell’s September 30, 2015, elevation to be between 3,575 feet and 3,649 feet, and Lake Mead’s elevation to be less than 1,075 feet, Lake Powell’s annual release volume would be increased to balance the contents of Lake Mead and Lake Powell up to 9.0 maf. Based on analysis of a range of forecasted inflow scenarios, the current probability of realizing an inflow volume that would trigger balancing releases of up to 9.0 maf in 2015 is approximately 90 percent. The February 2015 24-Month Study projects that an April adjustment to balancing releases is likely to occur and Lake Powell is currently projected to release 9.0 maf in water year 2015.
Based on the current forecast, the February 24-Month Study projects Lake Powell elevation will end water year 2015 near 3,597 feet with approximately 11.47 maf in storage (47% capacity). Note that projections of elevation and storage have significant uncertainty at this early point in the season, primarily due to uncertainty regarding this season’s final snowpack and the resulting inflow to Lake Powell. Under the minimum probable inflow scenario, last updated in January, the projected end of water year elevation and storage are 3589 feet and 10.73 maf (44% capacity), respectively. Under the maximum probable inflow scenario, last updated in January, the projected end of water year elevation and storage are 3639 feet and 15.94 maf (66% capacity), respectively. The annual release volume from Lake Powell during water year 2015 is projected to be 9.0 maf under all three inflow scenarios. However, there is a 10% chance that inflows will be higher, potentially resulting in higher releases; and 10% chance that inflows will be lower, potentially resulting in lower releases. If inflows are less than the current forecasted minimum probable inflow, the water year 2015 annual release could be as low as 8.23 maf. If inflows are greater than the current forecasted maximum probable inflow, the annual release could be 10.8 maf or greater. Modeling of projected reservoir operations based on the minimum and maximum scenarios will be updated again in April.
Upper Colorado River Basin Hydrology The Upper Colorado River Basin regularly experiences significant year to year hydrologic variability. During the 15-year period 2000 to 2014, however, the unregulated inflow to Lake Powell, which is a good measure of hydrologic conditions in the Colorado River Basin, was above average in only 3 out of the past 15 years. The period 2000-2014 is the lowest 15-year period since the closure of Glen Canyon Dam in 1963, with an average unregulated inflow of 8.39 maf, or 78% 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 2000-2014 period has ranged from a low of 2.64 maf (24% of average) in water year 2002 to a high of 15.97 maf (147% of average) in water year 2011. The water year 2014 unregulated inflow volume to Lake Powell was 10.381 maf (96% of average), which, though still below average, was significantly higher than inflows observed in 2012 and 2013 (45% and 47% of average, respectively). Under the current most probable forecast, total water year 2015 unregulated inflows to Lake Powell is projected to be 10.08 maf (93% of average).
At the beginning of water year 2015, total system storage in the Colorado River Basin was 30.0 maf (50% of 59.6 maf total system capacity). This is nearly the same as the total storage at the beginning of water year 2014 which began at 29.9 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 2015 total Colorado Basin reservoir storage is approximately 28.7 maf (48% of capacity). The actual end of water year storage may vary from this projection, primarily due to uncertainty regarding next season’s snowpack and resulting runoff. Based on January minimum and maximum probable inflow forecasts and modeling the range is approximately 27.5 maf (46%) to 33.6 maf (56%), respectively.
Updated February 13, 2015 Katrina Grantz