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Provo River Spring Runoff; a Look at Historical Water Flows and Trout Habitat

Across from Little Lunker on Upper a part of Center Provo with stream at 1600 cfs in 2017.

Everyone appears to be talking concerning the water stream on the Middle Provo this week.

Each Spring we get questions on when the runoff begins on the Center Provo and when the move reduces enough to fish once more.

Is the Center Provo Un-fishable?

First, I have never seen the Center Provo so excessive it couldn’t be fished. There are sections that aren’t protected to wade and a few of the favorite places aren’t straightforward to access (especially exhausting to seek out protected locations to cross), however the fish are in the water and they will eat. So that you simply might not be capable of fish your favourite holes, however you possibly can nonetheless fish.

As instance, right here is a brief video I took of the higher part of the Middle Provo when the circulate was about 1,600 cfs in 2017. The top of the video exhibits our buddy Rod catching a fish. The battery died earlier than he landed it, but you possibly can clearly see the fish bounce out of the water as it was hooked.

The Center Provo is a tail water that comes out of Jordanelle Reservoir, so all the initial stream is controlled at the dam. There’s a minimal established stream (authorized requirement) of 125 cfs to take care of fish populations and minimal water to the riparian zone, however the movement is often maintained about 150 cfs via the winter.

As Spring arrives, the stream must be elevated for a number of causes.

  1. Irrigation demands in Heber Valley
  2. To take care of water ranges in Deer Creek Reservoir, which in flip feeds water in the Decrease Provo River
  3. Take away excess runoff (from snow Melt) from Jordanelle Reservoir

The primary elements that determine the amount of water that needs to be launched in the Spring depends upon how much water is being stored within the mountains as snow, how much water might be absorbed within the soil and how briskly that snow melts.

With the snowpack within the Provo River Watershed over 400% normal, we all knew the movement was going to have to increase at someday.

Timing and Period of Spring Runoff – Middle Provo River

Back to the question of when does the stream improve; How high can it go and when does it return to “fishable” ranges?

However first, let’s define “fishable”. From many people I talked to this week, fishable water movement have to be beneath 700 cfs.

Since Might 25, 2019 (final Tuesday), the circulate jumped above 400 cfs for the primary time since Sept. 1 final fall. We had several guided journeys, all with beginning fly anglers, so would we favor to have less water ? In fact, but why worry about things which might be beyond our management.

Once I checked on Saturday morning, the water was operating about 925 cfs. By the point the info was averaged, the move as 942 cfs for Saturday under the Jordanelle Dam. Our “rookies” managed to dodge two thunderstorms and still catch 14 fish on the first day the move elevated over 900 cfs. And considered one of our students was 15 years previous (I hope photographs will comply with).

I feel that exhibits the river is fishable at 942 cfs and within the video as Rod proved fish could possibly be caught with the move at 1,600 cfs (but I might not advise everyone to aim wading via the water he had to cross).

Water Stream Knowledge for Middle Provo River 1993 – 2019

I needed to look back over the historical move knowledge and see on average, when does the move on the Middle Provo River rise above 400, 600, 800 and 1,000 cfs and how long does the stream stay above these ranges.

The primary table exhibits the variety of days the circulate was above the indicated degree (Cubic Ft per Second – cfs). For instance, in 1993, the river ran at least 400 cfs for 79 days, at least 600 cfs for 58 days, at least 800 cfs for 55 days and it ran 50 days at least 1,000 cfs. Next, look at Table 2 and still using 1993 as example, those 79 days with at least 400 cfs occurred between April 29 and July 28.

The river ran at 600 cfs between Might 4 and July 7; 800 cfs between Might 5 an July 5 and at least 1,000 cfs between Might 13 and July 3. Discover the river jumped to at least 800 cfs on Might 5, so it should have elevated very quickly from less than 600 cfs on Might 4 to at least 800 cfs on Might 5.

Table 1 Spring Runoff – Middle Provo River – Number of Days Flows above 400, 600, 800 and 1,000 cfs.

middle provo river spring runoff 1993-2019

Table 2 Spring Runoff – Middle Provo River – First & Last Day Move above 400, 600, 800 and 1,000 cfs.

middle provo river spring runoff dates 1993-2019

Notice that grey areas within the both tables characterize that flows didn’t attain the required ranges.

In 2007, flows by no means reached 800 cfs, and didn’t go above 600 cfs till Aug. 18.

In 2014, flows by no means received above 400 cfs at all.

It was solely two years in the past (2017), that we had the very best flows since 2011. The truth is, except for 2 days in 2016, we haven’t seen flows over 692 cfs since 2011.

There have been a few years (1993 – 2006) when maximum flows have been never less than 1,100 cfs, so we’ve got seen the drought mirrored in the flows on the Middle Provo up till 2017.

One factor that should stand out for people who look intently at the tables, is there appears to be no common pattern or method that’s being adopted, but we additionally don’t know the timing or the inflows of water from the Upper Provo River into Jordanelle.

We also don’t understand how the irrigation calls for change from one season to the subsequent (though plainly everyone seems to be operating sprinklers all the time, but annually there are extra lawns to water) and we don’t understand how a lot other elements like the poisonous algae (cyanobacteria) in Utah Lake dictates how a lot water is run in the course of the Summer time.

There are different elements we are in all probability not conscious of, so I will attempt to schedule an interview with the individuals in command of releasing the water from Jordanelle Res. and see what we will study.

I might also wish to know if Jordanelle dam has the power to combine in some hotter water into the movement or are they restricted to taking cold water off the underside of the reservoir. These elements have big implications for the fish, the hatches and stream quality.

What does High Spring Circulate mean for Fishing?

When the spring runoff comes, for one factor, it modifications the quantity of one of the best habitat for trout.

There was a stream movement research executed for the Middle Provo River in 2004 (click on right here to obtain pdf). The research (partially) modeled totally different movement regimes to foretell how much habitat can be out there for fish.

I borrowed and modified two figures under from that report. The first Figure; Provo River Habitat Niches exhibits eight totally different aquatic habitats based mostly upon water depth and stream stream.

Provo River Habitat Niches

As examples of these habitats, #1 Backwater edge (bottom left of determine) might be any depth as much as about 150 cm (59 inches), but should have water movement lower than zero.1 meters per second (m/s).

#4 the Fast/Shallow habitat is less than 40 cm with water movement higher than m/s.

#5 Average/mid-depth is up to 120 cm deep with water move less than 1.0 m/s.

The adult Brown Trout and Whitefish (and rainbow trout) spend most of their time in niches #5 and Whitefish also use Niche #7.

Confer with the Figure under Provo River Habitat Niches – to see all 8 Habitat Niches

Trout obviously spawn in shallow water and small fry reside in shallow water, but grownup fish spend most of their time in deep water with move less than 1.0 m/s. In truth the report doesn’t give any worth to fast water to adult fish habitat.

Since we all have caught fish in deeper and quicker water, this is a generalization and not an absolute, set in concrete reality. Principally, fish can use quicker segments of water, however are often at the bottom where the velocity is just not so fast. But to simplify the fashions, that is what they got here up with.

Determine – Provo River Habitat Niches

brown trout mountain whitefish habitat niches provo river

So given these definition of fish habitat, how do the amounts of the habitats change because the water move increases?

The amount of habitat is principally outlined within the research as the Weighted Usable Space (WUA), which is defined as the entire area per unit length of river that may be expected to offer usable habitat for a species. In this case, grownup brown trout (which they assume solely makes use of Area of interest #5). To include rainbows (and cutthroats; very few if any remain now), they included a little more of the shallow water habitat.

Appropriate Trout Habitat

In other phrases, how a lot of suitable habitat is accessible for all trout with totally different water flows and that quantity is measured within the variety of sq. ft per linear foot of the river.

The subsequent determine (additionally modified from the 2004 move report), exhibits how the WUA (habitat) should change with elevated stream.

It must be noted that this a part of the research was carried out from measurements taken on the higher part of the Middle Provo, simply downstream of the US-40 bridge.

The report states “Adult trout results show that the large amount (> 20,000 ft2 / 1,000ft) of habitat is available at flows greater between 25-900 cfs”… and this will bee seen within the determine under (word – by regulation, the Middle Provo should never be under 125 cfs – marked on the figure).

Figure – Usable Provo River Trout Habitat vs Water Stream

adult trout habitat vs water flow provo river

In order seen within the Weighted Usable Space determine above, at minimal flows (125 cfs) there’s about 40,000 square ft of grownup trout habitat  for each 1,000 ft of river. That translates to 0.92 acres per every 1,000 ft of river.

Can we extrapolate this for the complete Center Provo? Take this “with a grain of salt”, because the info and the model are all based mostly on one space, but when the Center Provo has 12 miles of river, which would be about 58 acres of prime trout habitat in the whole Center Provo River at 125 cfs.

58 Acres of Appropriate Trout Habitat?

Let’s think about that a minute. That doesn’t sound like very a lot trout habitat for your complete Center Provo River.

If the river is 12 miles long and averaged 40 ft extensive, that may additionally complete 58 acres. The river would have to average virtually 69 ft extensive to complete 100 acres.

So it might look like there must be a lot extra habitat inside the 12 miles of river, however in actuality there’s merely not that many acres of river floor area (or river bottom) in the complete river. To me, that makes it even more superb that our little river can help the excessive fish populations that it does (with no fish being stocked within the Center Provo river since 2003 – rainbows are stocked in Deer Creek Res., and they do run up into the river ).

Will probably be fascinating to see the outcomes of this yr’s fish inhabitants survey and to see how a lot fishing strain the river receives now.

So a excessive proportion of the complete river is sweet habitat for adult trout.

Word – Not that I need to ever see this a lot fishing strain, however… All we actually need at any given time is about 40 foot upstream and 40 ft downstream for each individual to fish. If we fish a seam that is 4 ft broad, that is only 320 square ft. If we more than triple that quantity to 1,000 sq. ft per angler, at 375 cfs, that 45,000 square ft of trout habitat/1,000 ft of river might help 45 anglers.

In response to the models, as move improve from 125 cfs to about 200 cfs, so does the quantity of trout habitat (will increase to 45,000 sq ft/1,000 ft – or 1.03 acres per 1,000 ft or about 65.5 acres for your complete Center Provo.

Because the move will increase to about 375 cfs, the entire quantity of trout habitat returns to about 40,000 sq ft/1,000 ft; the identical as 125 cfs.

At this point, increased move causes a decrease within the complete quantity of trout habitat which decreases to about 28,000 sq ft/1,000 ft at 600 cfs (40.7 complete acres) and to 22,000 sq ft/1,000 ft at 800 cfs (32 complete acres) and then to 19,000 sq ft/1,000 ft at 1,000 cfs (27.6 complete acres).

From that time, there the amount of trout habitat does not decrease very a lot in response to elevated flows even up to 2,000 cfs.

Trout Habitat Decreases when Move Increases above

So yes, as soon as flows are above 600 cfs, the quantity of trout habitat decreases. Meaning fewer locations to fish and since extra individuals are out making an attempt to fish this time of yr, there’s extra crowding.

There are lots of people scrambling round in search of different locations to fish, but the most of the mountain areas aren’t accessible yet and the Strawberry River will in all probability not get well for a number of years.

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