Dam Operations

River Report

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February 17, 2017

Fishing Report

Upriver Report
5

Walk-In Report
3

Spin Report
7


1 = Go Elsewhere

10 = Get Here Now!

Crowd Report

Upriver Crowd

1 Weekday

2 Weekend

Walk-In Crowd

1 Weekday

2 Weekend



1 = Sleep late and fish wherever

10 = Very crowded, get up early

Up-River Summary

Spring is not only in the air – it has arrived!

Sunlight began to enter the canyon and areas of the river that were dark for the past few months.  They are now bathed in sunlight.  Many of the fish are deep into the spawn.  This looks like one of those years where the fish are spawning in deep water and not using the shallows. There are advantages and disadvantages to a deep spawn … the good news is that the survival rate of the eggs and fry is very good.  In shallow water the redds (trout nests) are often dewatered due to fluctuating flows. One of the downsides to a deep spawn from an angling standpoint, it makes it difficult to get down to the fish with a fly.

Recent spin fishing has been the really great! It is easy to get down to the deeper fish using spinning gear with a fly. If you know where the fish are concentrated, spin fishing is as good or better as anytime the last few seasons.

The fish are looking very healthy and their condition is outstanding. In addition, the overall average size of the trout is larger than we have seen in a couple of years. Trout numbers have also increased compared to the past two years and we are looking forward to a great season at the Ferry.

Most all of the fish are either spawning or holding in the deeper water. Change may on the horizon; in the next couple of weeks our prolific midge hatches will begin and the fish will start feeding on the midge pupae.  Perhaps this will make the fish move into the shallow riffles.

Our best success has been drifting from the boat and using a 12- to 14-foot leader with a strike indicator near the fly line.  Couple that with a BB spilt shot (or larger) 18-inches above a size #14 ginger scud with a size #18 bead-head zebra midge underneath. Also, streamers like a bead-head olive woolly bugger have been working well. Our favorite line for streamer fishing is a Teeny 200; a dream to cast and gets the fly where it needs to be.

Current snowpack is 157% of normal!  If there is no radical change in the next couple months, this means Lake Powell will rise significantly this summer.  It is early, but estimates call for the lake level to raise 40 t0 50-feet above the current mark. This also means that we may see higher releases from the dam later this spring.

Just because you caught fish in a certain spot in years past, don’t think that you are going to experience the same success in the same spot 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. They 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; we are anxious to share this knowledge with you, even where to fish.

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 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.

 

 

 

 

Walk-In Summary

Some good reports from the walk-in area, while other reports are that the fishing is slow. There has not been any real consistency to the fishing. Perhaps, as the weather warms and the midge hatches increase, we will see more fish move into the shallow water to feed on the pupae.

Spin Fishing Summary.

Spin fishing continues to be productive. Many of the fish are in the deeper water and it is much easier to get down to them with spinning gear than fly gear. If you know where the fish are concentrated, you will have great fishing!

Dam Operations

(Last Updated: February 16, 2017)

Current Status

The unregulated inflow to Lake Powell in January was 359 kaf (99% of average).  The release volume from Glen Canyon Dam in January was 880 kaf.  The end of January elevation and storage of Lake Powell were 3,596 feet (104 feet from full pool) and 11.4 maf (47% of full capacity), respectively.  The reservoir is declining and will continue to decline until spring runoff begins to enter the reservoir. The current snowpack above Lake Powell is 157% of median.

To view the most current reservoir elevation, content, inflow and release, click on: Lake Powell Data.
To view the most current reservoir elevation projections, click on: Lake Powell Elevation Projections.
To view the 2017 progession of snowpack above Lake Powell, click on Lake Powell Snow Chart.
To view the current inflow forecast relative to past inflows, click on Lake Powell Inflow Forecast

Current Operations

The operating tier for water year 2017, established in August 2016, is the Upper Elevation Balancing Tier, with an initial water year release volume of 8.23 maf and the potential for an April 2017 adjustment to equalization or balancing releases.  Based on the current forecast, an April adjustment to balancing releases is projected to occur and Lake Powell is currently projected to release 9.0 maf in water year 2017.  This projection will be updated each month throughout the water year.

In February 2017, the release volume will be approximately 715 thousand acre-feet (kaf), with fluctuations anticipated between approximately 9,000 cfs and 15,000 cfs and consistent with the Glen Canyon Operating Criteria (Federal Register, Volume 62, No. 41, March 3, 1997).  The anticipated release volume for March is approximately 720 kaf with daily fluctuations between approximately 8,000 cfs and 14,000 cfs.  The expected release for April is 645 kaf with daily fluctuations between approximately 8,000 cfs and 14,000 cfs.

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 up to 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 currently maintains 27 MW (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 2017 water supply forecast for unregulated inflow to Lake Powell, issued on February 2, 2017, by the Colorado Basin River Forecast Center, projects that the most probable (median) unregulated inflow volume will be 9.6 maf (134% of average based on the period 1981-2010).  The projected water year 2017 inflow is 13.2 maf (122%).  At this early point in the season, there is still significant uncertainty regarding this year’s water supply.  The April-July forecast ranges from a minimum probable of 6.6 maf (92%) to a maximum probable of 13.5 maf (189%).  There is a 10% chance that inflows could be higher than the current maximum probable forecast and a 10% chance that inflows could be lower than the minimum probable forecast.

Based on the current forecast, the February 24-Month Study projects Lake Powell elevation will end water year 2017 near 3,640 feet with approximately 16.0 maf in storage (66% capacity).  Note that projections of elevation and storage for water year 2017 have significant uncertainty at this point in the season.  Projections of elevation and storage using the minimum and maximum probable inflow forecast, updated in January, are 3,586 feet (10.4 maf, 43% capacity) and 3,640 feet (16.0 maf, 66% capacity), respectively.  Under these scenarios, there is a 10 percent chance that inflows will be higher, resulting in higher elevation and storage, and 10 percent chance that inflows will be lower, potentially in lower elevation and storage.  The annual release volume from Lake Powell during water year 2017 is projected to be 9.0 maf under the minimum, most, and maximum probable inflow scenarios.  There is a chance that inflows could be higher or lower, potentially resulting in releases greater than 9.0 maf or as low as 8.23 maf in water year 2017.  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 17-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 above average in only 3 out of the past 17 years.  The period 2000-2016 is the lowest 17-year period since the closure of Glen Canyon Dam in 1963, with an average unregulated inflow of 8.57 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 2000-2016 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.  In water year 2016 unregulated inflow volume to Lake Powell was 9.62 maf (89% 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, the total water year 2017 unregulated inflow to Lake Powell is projected to be 13.5 maf (189% of average).

At the beginning of water year 2017, total system storage in the Colorado River Basin was 30.2 maf (50% of 59.6 maf total system capacity).  This is nearly the same as the total storage at the beginning of water years 2015 and 2016 which began at 30.1 maf and 30.3 maf, respectively, both of which were 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 2005.  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 total Colorado Basin reservoir storage for water year 2017 is approximately 29.8 maf (50% of total system capacity). The actual end of water year 2017 system storage may vary from this projection, primarily due to uncertainty regarding the season’s snowpack and resulting runoff and reservoir inflow.  Based on the January minimum and maximum probable inflow forecasts and modeling, the range of end of water year 2017 total system capacity is approximately 27.3 maf (46%) to 33.5 maf (56%), respectively.

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