Engineers and operators have determined that an adequate amount of water has been released from Lake Granby, so we'll get back to filling the reservoir. We've kept the reservoir at lower levels to leave room for the finale of our forecasted runoff and to prevent the need for sudden large releases downstream.
We are going to decrease releases gradually, which limits environmental disruptions. We will cut flows back 200 cfs per day until we reach an outflow of 1,000 cfs, which will be early next week. Then we'll determine whether outflows should be reduced more.
With this reduction in releases, Lake Granby's elevation should begin to rise noticeably in the next week.
2011 RUNOFF UPDATE
Tuesday, June 28, 2011
Sunday, June 26, 2011
Record inflow on North Fork of Colorado River
Yesterday's flow of 995 cfs on the North Fork of the Colorado River broke an all-time record, according to records kept by the USGS since 1953.
The previous record was 976 cfs on June 30, 1957. As it turns out, we've been comparing this year's snowpack to 1957 for some time.
Our models suggest there's still plenty of gas in the tank in terms of snowpack, so record-level flows are likely to continue for another day or two.
The North Fork of the Colorado River discharges into Shadow Mountain Reservoir.
The previous record was 976 cfs on June 30, 1957. As it turns out, we've been comparing this year's snowpack to 1957 for some time.
Our models suggest there's still plenty of gas in the tank in terms of snowpack, so record-level flows are likely to continue for another day or two.
The North Fork of the Colorado River discharges into Shadow Mountain Reservoir.
Wednesday, June 22, 2011
Weekend forecast: Peaking rivers, some records
A cocktail of increased temperatures on top of big snowpack may swell area rivers over the weekend.
The Colorado Basin River Forecast Center recently put out a forecast expecting peaks on all of the high-elevation watersheds in their area this weekend. The center based its forecast on current cool temperatures, which have prevented snowmelt, along with predicted upcoming high temperatures that would kickstart more runoff.
If you had a bird's eye view, the CBRFC's forecast would have you seeing simultaneous peaks in several Upper Colorado basin rivers: the Fraser, Williams Fork, Upper Colorado into Granby, and Blue into Dillion.
The Colorado River at the Cameo gage (between De Beque and Palisade) may have its second peak, possibly higher than the one we saw June 7.
The center is most concerned about Northern Utah, Northwestern Colorado and Southwestern Wyoming. A few streams in Utah and Wyoming, for example, are expected to hit record flows. The forecast also stated that flooding is occurring and will likely continue to occur along rivers where there's still high-elevation snow.
The CBRFC does not forecast Northern Water's East Slope tributaries, but we expect the climate to have similar effects on our snowpack.
The Colorado Basin River Forecast Center recently put out a forecast expecting peaks on all of the high-elevation watersheds in their area this weekend. The center based its forecast on current cool temperatures, which have prevented snowmelt, along with predicted upcoming high temperatures that would kickstart more runoff.
If you had a bird's eye view, the CBRFC's forecast would have you seeing simultaneous peaks in several Upper Colorado basin rivers: the Fraser, Williams Fork, Upper Colorado into Granby, and Blue into Dillion.
The Colorado River at the Cameo gage (between De Beque and Palisade) may have its second peak, possibly higher than the one we saw June 7.
The center is most concerned about Northern Utah, Northwestern Colorado and Southwestern Wyoming. A few streams in Utah and Wyoming, for example, are expected to hit record flows. The forecast also stated that flooding is occurring and will likely continue to occur along rivers where there's still high-elevation snow.
The CBRFC does not forecast Northern Water's East Slope tributaries, but we expect the climate to have similar effects on our snowpack.
Saturday, June 18, 2011
Willow Creek inflow record shattered, with more to come
After 57 years of tracking Willow Creek Reservoir stats, we've now hit an amazing new inflow record.
Some background: in the Western U.S., April through July are considered the snowmelt months, so official streamflow forecasts (and thus runoff records) are based on that four-month period.
Until now, Willow Creek Reservoir's inflow record was in 1986, when the April through July runoff totaled 85,600 acre feet, which is 168 percent of the official average of 50,800 acre feet. That sounded like a lot until yesterday, when we tabulated the inflow since April 1 as 87,100 acre feet. And we still have six weeks to go!
Our latest forecast anticipated a total of 110,000 acre feet of inflow to Willow Creek by July 31. If it materializes, this would be 216 percent of the official average. And the Colorado Basin River Forecast Center expects even more than we do.
The peak inflow rate (in daily average) this year was 1,652 cfs on June 7. This wasn't quite a record, but anything more than 1,500 cfs is notable for Willow Creek. This date of peak inflow was about two weeks later than usual (about May 24); late peaks often come hand-in-hand with larger-than-normal snowpacks.
This staggering runoff quantity raises questions about what kind of runoff we should expect from neighboring watersheds - especially above Lake Granby. While we don't expect as high an inflow to Granby, our latest forecast anticipates 175 percent of average, which would be another one for the record books.
It's disconcerting to drive past Granby, which is 20 feet below full, and see the surrounding dry sagebrush - if you know how high snowpack is in Rocky Mountain National Park and along the Gore Range.
That snowpack may seem remote and unassuming, but looks are deceiving. Stay tuned.
Some background: in the Western U.S., April through July are considered the snowmelt months, so official streamflow forecasts (and thus runoff records) are based on that four-month period.
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Willow Creek Reservoir |
Our latest forecast anticipated a total of 110,000 acre feet of inflow to Willow Creek by July 31. If it materializes, this would be 216 percent of the official average. And the Colorado Basin River Forecast Center expects even more than we do.
The peak inflow rate (in daily average) this year was 1,652 cfs on June 7. This wasn't quite a record, but anything more than 1,500 cfs is notable for Willow Creek. This date of peak inflow was about two weeks later than usual (about May 24); late peaks often come hand-in-hand with larger-than-normal snowpacks.
This staggering runoff quantity raises questions about what kind of runoff we should expect from neighboring watersheds - especially above Lake Granby. While we don't expect as high an inflow to Granby, our latest forecast anticipates 175 percent of average, which would be another one for the record books.
It's disconcerting to drive past Granby, which is 20 feet below full, and see the surrounding dry sagebrush - if you know how high snowpack is in Rocky Mountain National Park and along the Gore Range.
That snowpack may seem remote and unassuming, but looks are deceiving. Stay tuned.
Wednesday, June 15, 2011
Too soon to say that rivers have peaked
There has been much in the news this week about our rivers being past their peak flows for the season.
Not so fast!
The high elevation portions of our watersheds melted next to nothing during the month of May. They're just now getting started. While temperatures may continue to play nice, there's every chance that a couple of days of warmth could cause surprise surges in streamflow.
Don't believe us? Take a look at the 1957 hydrographs - a year with a giant snowpack (but not as big as this year's) and a cold May. That year, the peak runoff didn't happen until the very end of June. Here's Middle Boulder Creek at Nederland as an example.
Not so fast!
The high elevation portions of our watersheds melted next to nothing during the month of May. They're just now getting started. While temperatures may continue to play nice, there's every chance that a couple of days of warmth could cause surprise surges in streamflow.
Don't believe us? Take a look at the 1957 hydrographs - a year with a giant snowpack (but not as big as this year's) and a cold May. That year, the peak runoff didn't happen until the very end of June. Here's Middle Boulder Creek at Nederland as an example.
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| BODMIDCO - this year (red) vs. 1957 (green) |
Monday, June 13, 2011
Granby releases to increase today
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| Spillway at Lake Granby as seen from below |
The increases in outflows will be evident at the downstream USGS gage.
Note that releases from the outlet valves will continue at approximately 410 cfs. The combined release from the valves and from the spillway will be approximately 500 cfs.
Wednesday, June 8, 2011
Adams Tunnel diversions decreasing
When we expect gigantic runoff, we prefer to keep the Adams Tunnel running full blast, because every acre foot diverted to the East Slope creates room for another acre foot of runoff. With that, we lower the possibility of having to make higher releases out of Lake Granby.
But we have two things working against us. First, East Slope reservoirs are nearly full, and soon we won't have empty space available for Adams Tunnel diversions.
Second, the water rights system limits our options. Northern Water holds decrees for Big Thompson River water, and when those rights come into priority, we are obligated to use that water, not West Slope water, to fill our East Slope reservoirs and make water deliveries.
Yesterday our East Slope decree came into priority and operators reduced tunnel diversions by 40 cfs. Today, even more East Slope water became available and tunnel diversions went down an additional 125 cfs.
The amount of East Slope water available to our decree varies from day to day and depends on streamflow and other water users' demands. To keep up to date, you can monitor Adams Tunnel diversions as we move through the warm season.
But we have two things working against us. First, East Slope reservoirs are nearly full, and soon we won't have empty space available for Adams Tunnel diversions.
Second, the water rights system limits our options. Northern Water holds decrees for Big Thompson River water, and when those rights come into priority, we are obligated to use that water, not West Slope water, to fill our East Slope reservoirs and make water deliveries.
Yesterday our East Slope decree came into priority and operators reduced tunnel diversions by 40 cfs. Today, even more East Slope water became available and tunnel diversions went down an additional 125 cfs.
The amount of East Slope water available to our decree varies from day to day and depends on streamflow and other water users' demands. To keep up to date, you can monitor Adams Tunnel diversions as we move through the warm season.
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Willow Creek backing off after three near-record peaks
The past several days have brought three peak events on Willow Creek: 1,748 cfs on May 30 and again on June 3, and 1,761 cfs on June 8.
But it's not over yet. The snowpack at the top of Willow Creek Pass normally peaks in late April, but it's the beginning of June and we still have more snow up there than the average peak, despite the fact it's been melting. The forecast calls for cooler weather, which means snowpack will continue to melt - but at a slower, much more manageable rate. Flows are retreating today and will likely hold steady or decline slightly in the next few days. But keep an eye on the skies and thermometers: We are still vulnerable to additional peaking events if there's a rainstorm or stretch of hot weather.
Our records show that the maximum observed inflow to Willow Creek Reservoir was a daily average of 1,857 cfs on May 24, 1984. In comparison, this year's three peak flow rates occurred for just a few minutes each; our maximum daily average for 2011 so far was yesterday at 1,652 cfs.
So while we don't have a flow rate that's going into the record books, we're still on track to smash the previous record for the total volume of runoff: 85,300 acre feet from April 1 to July 31 in 1957. This year's inflows are already 64,600 acre feet, and we still have seven weeks to go!
As the elevation in Willow Creek Reservoir continues to rise, we will pump water into Lake Granby if necessary to help keep Willow Creek Reservoir outflows at or below 1,300 cfs.
But it's not over yet. The snowpack at the top of Willow Creek Pass normally peaks in late April, but it's the beginning of June and we still have more snow up there than the average peak, despite the fact it's been melting. The forecast calls for cooler weather, which means snowpack will continue to melt - but at a slower, much more manageable rate. Flows are retreating today and will likely hold steady or decline slightly in the next few days. But keep an eye on the skies and thermometers: We are still vulnerable to additional peaking events if there's a rainstorm or stretch of hot weather.
Our records show that the maximum observed inflow to Willow Creek Reservoir was a daily average of 1,857 cfs on May 24, 1984. In comparison, this year's three peak flow rates occurred for just a few minutes each; our maximum daily average for 2011 so far was yesterday at 1,652 cfs.
So while we don't have a flow rate that's going into the record books, we're still on track to smash the previous record for the total volume of runoff: 85,300 acre feet from April 1 to July 31 in 1957. This year's inflows are already 64,600 acre feet, and we still have seven weeks to go!
As the elevation in Willow Creek Reservoir continues to rise, we will pump water into Lake Granby if necessary to help keep Willow Creek Reservoir outflows at or below 1,300 cfs.
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Wednesday, June 1, 2011
Testing may increase Willow Creek releases
Willow Creek releases may be incrementally increased over the next few days for the purpose of testing safe channel capacity below the reservoir.
Northern Water is coordinating closely with area property owners. If you have questions, please contact Noble Underbrink at the Farr Pump Plant at 970-627-3406.
Northern Water is coordinating closely with area property owners. If you have questions, please contact Noble Underbrink at the Farr Pump Plant at 970-627-3406.
Sunday, May 29, 2011
Willow Creek releases will reach 1,200 cfs today
We expect releases from Willow Creek Reservoir to reach 1,200 cfs today. This is our preferred maximum release rate. Once that rate of outflow is reached, we will allow the reservoir to start filling.
Temperatures yesterday were higher than forecasted, and they have been today too. We expect inflows to Willow Creek Reservoir to continue to climb today and in the coming days.
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| Flows below Willow Creek Reservoir |
Temperatures yesterday were higher than forecasted, and they have been today too. We expect inflows to Willow Creek Reservoir to continue to climb today and in the coming days.
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| Flows above/into Willow Creek Reservoir |
Friday, May 27, 2011
NWS predicts hot temperatures next week; could create flood conditions
The National Weather Service is starting to sound the alarm about warm weather next week, which could trigger rapid snowmelt and possible flooding. From today's forecast discussion (issued 3:33 p.m. today by the Denver/Boulder office):
This forecast discussion changes every 12 hours as new forecasts are published.
BY MONDAY...UPPER TROUGH OUT WEST PASSES TO THE NORTH OF THE STATE AND WINDS TURN WESTERLY WHICH WILL START THE BIG WARM UP INITIALLY EAST OF THE MTNS. TUESDAY AND BEYOND...MODELS SHOW STRONG AND STEADY WARMING AS THE HOT UPPER RIDGE OVER TEXAS EXPANDS NORTHWARD OVER THE REGION. COULD SEE TEMPERATURES ON THE PLAINS BY MID TO LATE WEEK IN THE UPR 80S/LOWER 90S...WITH HIGH COUNTRY TEMPERATURES IN THE 70S/LOWER 80S. BUT IT'S THE NIGHT TIME TEMPERATURES IN THE 40S/LOWER 50S IN THE HIGH COUNTRY THAT WILL BE ON MOST CONCERN AS THESE READINGS WILL ACCELERATE THE MELTING OF THE RECORD SNOWPACK... LEADING TO HEAVY RUNOFF AND POTENTIALLY SIGNIFICANT FLOODING ON MANY HIGH COUNTRY STREAMS AND CREEKS.
HYDROLOGY...NO CONVECTION EXPECTED THROUGH THE NEXT 24 HOURS OVER THE FOURMILE CANYON AREA. TEMPERATURES WILL CLIMB ABOVE NORMAL NEXT WEEK WEDNESDAY WITH HIGHS IN THE 50S TO 60S...IN THE MOUNTAINS WITH 70S TO LOWER 80S IN THE MOUNTAIN VALLEYS. THESE ABOVE NORMAL TEMPERATURES WILL PERSIST THROUGH NEXT WEEKEND. OVERNIGHT LOW ARE EXPECTED TO REMAIN ABOVE FREEZING IN THE MOUNTAINS. THIS WILL RESULT IN RAPID SNOW MELT OF THE EXTENSIVE SNOWPACK. LOW LYING AREAS NEAR MOUNTAIN RIVERS AND CREEKS CAN EXPECT FLOODING WITH WIDESPREAD FLOODING POSSIBLE LATE NEXT WEEK AND NEXT WEEKEND.
This forecast discussion changes every 12 hours as new forecasts are published.
Looking ahead to extreme runoff
Even though it's called "forecasting," predicting runoff doesn't come with a crystal ball, in part because we cannot know Mother Nature's next move.
We do know now that we have record-setting snowpack in the high country. But we don't know exactly how that snowpack will translate into streamflow. A sudden heat wave or another soggy spring storm can alter the picture in unexpected ways.
Northern Water has a suite of tools to forecast water supplies. However, most of those tools were designed to predict total streamflow volume, or the total amount of water runoff will add to stored supplies. These models were not explicitly designed to predict or analyze flood flows. Similarly, Northern Water does not own or operate any facilities designed for the sole purpose of flood protection.
However, there are some other good places to look for flood flow information:
This 2011 Runoff Update site originally focused on the unusual runoff expected in Northern Water's West Slope watersheds. As the snow has piled on, we will also use this site to communicate runoff conditions on the East Slope.
Historically, Colorado flood events causing property damage and loss of life were the result of torrential rains and cloudbursts, not snowmelt. But with a record-setting snowpack still in place this week - a time by which most of our snow has normally melted - we can't afford to discount the possibility of damaging floodwaters.
Staying informed is one way to stay safe.
We do know now that we have record-setting snowpack in the high country. But we don't know exactly how that snowpack will translate into streamflow. A sudden heat wave or another soggy spring storm can alter the picture in unexpected ways.
Northern Water has a suite of tools to forecast water supplies. However, most of those tools were designed to predict total streamflow volume, or the total amount of water runoff will add to stored supplies. These models were not explicitly designed to predict or analyze flood flows. Similarly, Northern Water does not own or operate any facilities designed for the sole purpose of flood protection.
However, there are some other good places to look for flood flow information:
- The National Weather Service maintains models that predict flood flows. Their Advanced Hydrologic Prediction Service provides real-time information and, for a few locations, expected flow forecasts.
- Across the country, designated basin forecast centers provide detailed information about river flows. For areas west of the Continental Divide, the Colorado Basin River Forecast Center has a comprehensive website that details short-term forecasts, water supply forecasts and estimates of peak flow magnitudes and dates.
- For areas east of the Continental Divide, the Missouri River Forecast Center has a website that mostly duplicates the Advanced Hydrologic Prediction Service material. This week, the map on their home page has been lit up with flooding problems across the northern plains.
This 2011 Runoff Update site originally focused on the unusual runoff expected in Northern Water's West Slope watersheds. As the snow has piled on, we will also use this site to communicate runoff conditions on the East Slope.
Historically, Colorado flood events causing property damage and loss of life were the result of torrential rains and cloudbursts, not snowmelt. But with a record-setting snowpack still in place this week - a time by which most of our snow has normally melted - we can't afford to discount the possibility of damaging floodwaters.
Staying informed is one way to stay safe.
Tuesday, May 24, 2011
Cool temps set stage for record-breaking year
So far, May has been much cooler than normal, keeping our deep snowpack chilled in place. The chart housed here shows inflows to Willow Creek Reservoir reached 950 cfs on Thursday but have since fallen off.
Today (May 24) is the average date for peak inflow to Willow Creek Reservoir. The latest weather forecast suggests that it will be at least another week and maybe considerably longer before we see this year's peak inflows. In fact, we're still adding to the snowpack at a time when we should be nearly melted out!
Right now, we're watching temperature trends very closely. Any sort of sustained warmth will trigger rapid snowmelt.
We're starting to run out of superlatives to describe this year's snow season. It'll be one for the record books in nearly all respects, and we'll be talking about it for years to come.
Right now, we're watching temperature trends very closely. Any sort of sustained warmth will trigger rapid snowmelt.
We're starting to run out of superlatives to describe this year's snow season. It'll be one for the record books in nearly all respects, and we'll be talking about it for years to come.
Wednesday, May 18, 2011
Make your own streamflow dashboard page
Would you like to be able to see all of your favorite streamflow gages on one page? Colorado's Division of Water Resources has a Web page that allows you to do just that.
Here are step-by-step instructions for creating your own Northern Water Gage Page.
1. Go to this link and click on the "My Stations" link at the bottom right.
2. Select stations of interest and, one by one, move them from the left side ("Available") box to the right side ("Current Station List") box. Here's a list of stations to get you started. This list will allow you to watch key canyon gages on the East Slope and key collection system flows on the West Slope:
ADATUNCO, ALVA B. ADAMS TUNNEL AT EAST PORTAL NEAR ESTES PARK
BOCOROCO, BOULDER CREEK NEAR ORODELL
SVCLYOCO, SAINT VRAIN CREEK AT LYONS, CO
BTABESCO, BIG THOMPSON RIVER ABOVE LAKE ESTES
BTCANYCO, BIG THOMPSON RIVER AT MOUTH OF CANYON NEAR DRAKE
CLAFTCCO, CACHE LA POUDRE AT CANYON MOUTH NEAR FORT COLLINS
CLANSECO, NORTH FORK CACHE LA POUDRE RIVER BELOW SEAMAN RESERVOIR
COLNGBCO, COLORADO RIVER NEAR GRANBY
COLBAKCO, COLORADO R BELOW BAKER GULCH, NR GRAND LAKE, CO
FRAGRACO, FRASER RIVER AT GRANBY, CO
COLAWICO, COLORADO RIVER AT WINDY GAP, NEAR GRANBY, CO
WILABVCO, WILLOW CREEK ABOVE WILLOW CREEK RESERVOIR
WILWCRCO, WILLOW CREEK BELOW WILLOW CREEK RESERVOIR
3. If you want the list to be in a particular order, use the arrow buttons to sort.
4. After you've populated your Current Station List and sorted it, enter a name in the box at the bottom of the screen (you can keep the name "My Stations" if you like) and click "Save."
5. After you save the list, a "Current Conditions" page appears. This is a list of all of your stations with the current values. Bookmark this page!
6. Click on the "Graph(s)" tab to see 10-day graphs for all of your gages.
7. Add or remove gages any time by going to the "Edit List" tab. Remember to save your changes.
Thank you, DWR - this is a great tool!
Here are step-by-step instructions for creating your own Northern Water Gage Page.
1. Go to this link and click on the "My Stations" link at the bottom right.
2. Select stations of interest and, one by one, move them from the left side ("Available") box to the right side ("Current Station List") box. Here's a list of stations to get you started. This list will allow you to watch key canyon gages on the East Slope and key collection system flows on the West Slope:
ADATUNCO, ALVA B. ADAMS TUNNEL AT EAST PORTAL NEAR ESTES PARK
BOCOROCO, BOULDER CREEK NEAR ORODELL
SVCLYOCO, SAINT VRAIN CREEK AT LYONS, CO
BTABESCO, BIG THOMPSON RIVER ABOVE LAKE ESTES
BTCANYCO, BIG THOMPSON RIVER AT MOUTH OF CANYON NEAR DRAKE
CLAFTCCO, CACHE LA POUDRE AT CANYON MOUTH NEAR FORT COLLINS
CLANSECO, NORTH FORK CACHE LA POUDRE RIVER BELOW SEAMAN RESERVOIR
COLNGBCO, COLORADO RIVER NEAR GRANBY
COLBAKCO, COLORADO R BELOW BAKER GULCH, NR GRAND LAKE, CO
FRAGRACO, FRASER RIVER AT GRANBY, CO
COLAWICO, COLORADO RIVER AT WINDY GAP, NEAR GRANBY, CO
WILABVCO, WILLOW CREEK ABOVE WILLOW CREEK RESERVOIR
WILWCRCO, WILLOW CREEK BELOW WILLOW CREEK RESERVOIR
3. If you want the list to be in a particular order, use the arrow buttons to sort.
4. After you've populated your Current Station List and sorted it, enter a name in the box at the bottom of the screen (you can keep the name "My Stations" if you like) and click "Save."
5. After you save the list, a "Current Conditions" page appears. This is a list of all of your stations with the current values. Bookmark this page!
6. Click on the "Graph(s)" tab to see 10-day graphs for all of your gages.
7. Add or remove gages any time by going to the "Edit List" tab. Remember to save your changes.
Thank you, DWR - this is a great tool!
Friday, May 13, 2011
May 1 forecast brings increased runoff expectations
Northern Water released its May streamflow forecast last week. The May 1 snowpack breaks records for the Blue River, Upper Colorado, Willow Creek, Cache la Poudre and Big Thompson basins. And it's not just in our area - many SNOTEL sites across the Western U.S. broke records for snow water equivalent accumulation this year.
The first SNOTEL stations were established 30 years ago; hydrologically speaking, that's not a very long period of record. So although this year's record snowpack is notable, should we consider it exceptional?
We might want to consider it. A much longer-standing record has been smashed too: the Snow Course at Cameron Pass, which has been around since 1936. The chart here shows the May 1 snow water equivalent, which has 17 percent more water than the previous record (1986)!
The first SNOTEL stations were established 30 years ago; hydrologically speaking, that's not a very long period of record. So although this year's record snowpack is notable, should we consider it exceptional?
We might want to consider it. A much longer-standing record has been smashed too: the Snow Course at Cameron Pass, which has been around since 1936. The chart here shows the May 1 snow water equivalent, which has 17 percent more water than the previous record (1986)!However, a record-breaking snowpack doesn't necessarily translate into record-breaking runoff, especially in Northern Water's East Slope watersheds. We need precipitation on top of melting snow to break those records. Still, two of our West Slope basins, the Upper Colorado and Willow Creek, are expected to produce record-breaking runoff this year from snowmelt alone.
Morning spike in Willow Creek releases
Operators tested the outlet works at Willow Creek Reservoir this morning. They initially released 900 cfs and then went up to 1,200 cfs for a brief period. This was a test to check operations for the releases we anticipate making. It was successful, and we're back to passing inflows.
The graph here shows the spike in flow that occurred this morning.
The graph here shows the spike in flow that occurred this morning.
Monday, May 9, 2011
Warm weather triggers increased snowmelt
Warm weekend temperatures increased the inflow to Willow Creek Reservoir. Right now we are holding the reservoir's elevation steady at around 8,092 feet and passing inflows right through. The highest release so far this year was 782 cfs at 9:45 this morning.
Releases from Lake Granby are holding steady at about 400 cfs. Below the dam at Lake Granby there are small side tributaries that add to the flow of the river, so flows can be higher by the time they reach the "Y Gage" (listed as "Colorado River near Granby, CO" on the USGS website). Saturday evening was a good example: the flows were at 600 cfs, so the tributaries likely contributed about 200 cfs. The flow has not been as high since then.
Releases from Lake Granby are holding steady at about 400 cfs. Below the dam at Lake Granby there are small side tributaries that add to the flow of the river, so flows can be higher by the time they reach the "Y Gage" (listed as "Colorado River near Granby, CO" on the USGS website). Saturday evening was a good example: the flows were at 600 cfs, so the tributaries likely contributed about 200 cfs. The flow has not been as high since then.
The schematic shown with this post shows the various stream gages below Willow Creek Reservoir and Lake Granby. The releases from Granby and Willow Creek reservoirs, along with the flow of the Fraser River, all add to the Colorado River's flow as measured below Windy Gap Reservoir. Today, that flow went above 2,000 cfs for the first time this year. The flows are affected by Denver Water's diversions; they aren't diverting much Fraser River water right now because it has been so cold.
Wednesday, April 27, 2011
Granby releases increase Friday
Beginning at 8 a.m. Friday, outflow from Lake Granby will increase by 50 cfs every two hours until outflow reaches 430 cfs in the late afternoon.
The flow of 430 cfs will be maintained indefinitely. It is the maximum that operators can release out of the valves that sit toward the bottom of Granby. If more water needs to be released, it will come down the spillway at the top of the reservoir, but only after the reservoir rises to the spillway's elevation.
The Colorado Basin River Forecast Center is predicting inflow to Lake Granby to be the largest on record. Northern Water's models agree.
The flow of 430 cfs will be maintained indefinitely. It is the maximum that operators can release out of the valves that sit toward the bottom of Granby. If more water needs to be released, it will come down the spillway at the top of the reservoir, but only after the reservoir rises to the spillway's elevation.
The Colorado Basin River Forecast Center is predicting inflow to Lake Granby to be the largest on record. Northern Water's models agree.
Sunday, April 10, 2011
News coverage: April 13 meeting, water year
The Sky-Hi Daily News ran an article about government agencies' preparation for the 2011 runoff season. Check out the article to learn more about what's going on the Grand County area.
The article mentions our April 13 meeting in Granby, which we highly encourage you to attend if you're interested in the forecast and related project operations. It's at 6 p.m. at the Granby Library, 55 Zero Street.
The article mentions our April 13 meeting in Granby, which we highly encourage you to attend if you're interested in the forecast and related project operations. It's at 6 p.m. at the Granby Library, 55 Zero Street.
Thursday, April 7, 2011
Releases from Willow Creek Reservoir going up
Inflows to Willow Creek Reservoir are on the rise, which means runoff is underway. Reservoir operators determined that we need more empty space in the reservoir to capture and dampen the peaking flows.
To do this, operators started increasing releases out of Willow Creek Reservoir today, and by later this afternoon they will be at 230 cfs. They will continue increasing releases tomorrow until they reach a rate of 330 cfs.
Plans are to lower the reservoir, which is at 8,117 feet in elevation now, to 8,092 feet.
To do this, operators started increasing releases out of Willow Creek Reservoir today, and by later this afternoon they will be at 230 cfs. They will continue increasing releases tomorrow until they reach a rate of 330 cfs.
Plans are to lower the reservoir, which is at 8,117 feet in elevation now, to 8,092 feet.
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