​With spring runoff underway, West Slope and Rio Grande Basin snowpacks remain well above average, but the Arkansas River Basin continues to record the lowest snowpack in Colorado. According to the latest information from the U.S. Drought Monitor, only Colorado's West Slope river basins remain drought-free with the formerly drought-free Upper Arkansas Basin now experiencing "abnormally dry" conditions.

The three-month outlook from the National Weather Service gives the Arkansas Basin a 33-40% chance of above-normal temperatures for May through July and "even chances" for normal precipitation.

Snowpack
During April, Arkansas Basin snowpack dropped from 92% to 78% of median for snow-water equivalent, the lowest in the state. Two Ark Basin SNOTEL stations – Glen Cove near Pikes Peak and Apishapa near Cuchara – are not reporting any snowpack. Other SNOTEL readings range from 6% at Hayden Pass in the Sangre de Cristo Range to 120% at St. Elmo in western Chaffee County. The Brumley SNOTEL site, near Independence Pass, reports 79% of median, while Fremont Pass reports 82%. Buckskin Joe in the Mosquito Range reads 64%. The Whiskey Creek station west of Trinidad reports 8%.

Reservoir Storage
Pueblo Reservoir water storage dropped to 66.9%, from 221,675 acre-feet to 215,988 at the end of April. Water levels in Turquoise Lake remain low (58,631.5 acre-feet, 45.3% of capacity) in anticipation of Fryingpan-Arkansas Project water imports exceeding 50,000 acre-feet. Twin Lakes Reservoir levels remain virtually unchanged at 100,055 acre-feet (71%). John Martin Reservoir decreased slightly from 38,999 acre-feet at the end of March to 37,202 acre-feet at the end of April. 

River Flows
The Arkansas River flow near Leadville is 77.6 cfs. Downstream, the U.S. Bureau of Reclamation has increased releases from Twin Lakes by 75 cfs to 250 cfs, almost all of which is native Ark Basin water. The flow below Granite is trending upward with a current gauge reading of 492 cfs. The Wellsville gauge, near Salida, reports 588 cfs, well above the target range of 250-450 cfs established by the Voluntary Flow Management Program for April 1 to May 15. 

The flow at Cañon City is currently 502 cfs. Below Pueblo Reservoir, flows are 356 cfs. Near Avondale the river is flowing at 489 cfs, and the gauge at Rocky Ford reads 176 cfs. Current readings below John Martin Reservoir and at Lamar are 127 cfs and 12.5 cfs, respectively.

Calling Water Rights
With irrigation season beginning, Ark Basin calling water rights have increased from nine a month ago to 17. The most senior calling right is the 1863 Hoehne Ditch on the Purgatoire River, followed by two Fourmile Creek water rights, the 1863 Canon Heights Ditch and the 1865 Titsworth Ditch. The other calling water rights are:

• Gonzales Ditch, 1866 priority, Apishapa River.
• Upper Huerfano No. 1, 1869, Huerfano River.
• Coleman Ditch, 1867, Hardscrabble Creek.
• Smith Ditch, 1870, Taylor Creek.
• Cascade Ditch, 1870, Hardscrabble Creek.
• Francisco Daigre, 1871, Cucharas River.
• Cottonwood and Maxwell Ditch, 1874, Cottonwood Creek.
• Spring Ditch, 1876, Middle Tallahassee Creek.
• Missouri Park Ditch, 1882, South Arkansas River.
• Tenassee Ditch, 1882, South Arkansas River.
• Catlin Canal, 1884, Arkansas River mainstem.
• Lamar Canal, 1886, Arkansas River mainstem.
• Welton Ditch, 1889, Huerfano River.
• X-Y Irrigating Ditch, 1889, Arkansas River mainstem.
• Arkansas River Compact (with Kansas), 1949, Arkansas River mainstem.

​West Slope river basins are experiencing snowpacks well above average, and the U.S. Bureau of Reclamation is preparing to open the Fryingpan-Arkansas collection system to divert a projected 57,000 acre-feet of water from snowmelt in April. The same snowpack has lifted more than half of Colorado out of drought conditions, but most of the Arkansas River Basin has some level of drought, with "extreme" and "exceptional" drought returning in the lower basin, mainly Baca County (U.S. Drought Monitor). 

Snowpack
Arkansas Basin snowpack sits at 92% of median (a running average of the last 20 years) for snow-water equivalent, the lowest in the state. Readings from Ark Basin SNOTEL stations range from 36% of median at Apishapa near Cuchara to 127% at St. Elmo in western Chaffee County. The Brumley SNOTEL site, near Independence Pass, reports 91% of median, while Fremont Pass reports 94%. Glen Cove, north of Pikes Peak, rebounded from 46% a month ago to 108%. Buckskin Joe in the Mosquito Range reads 62%. In the Sangre de Cristo Range, Hayden Pass sits at 49% of median.

Reservoir Storage
During the past month, Pueblo Reservoir water storage reached 68.6%, increasing from 217,442 acre-feet to 221,675 at the end of March. Water levels in Turquoise Lake (48.6%) and Twin Lakes Reservoir (71.7%) are intentionally low as the Bureau of Reclamation prepares to import West Slope water through the Boustead Tunnel. John Martin Reservoir increased from 35,423 acre-feet at the end of February to 38,999 acre-feet at the end of March, even though the Winter Water Storage Program ended March 14. 

River Flows
The Arkansas River flow at Granite in north Chaffee County is currently 94.4 cfs. The Wellsville gauge, near Salida, reports 242 cfs, down from February. River flows at Cañon City, 225 cfs, and below Pueblo Reservoir, 71.6 cfs, have also dropped since last month. Near Avondale the river is flowing at 254 cfs, also down from a month ago. The gauge at Rocky Ford reads 120 cfs, a tenfold increase since the end of February. Current readings at John Martin Reservoir and Lamar are 0.61 cfs and 6.09 cfs, respectively.

Calling Water Rights
With the Winter Water Storage Program done for the water year, Ark Basin calling water rights increased from seven to nine, and the Welton Ditch adds its authorized diversion to that of the Maria Stevens Reservoir. Once again, the most senior calling right is the 1862 Model Ditch, which diverts Purgatoire River water. Other calling water rights are:

• Canon Heights Ditch, 1865, Fourmile Creek.
• Hamlet Ditch, 1866, Huerfano River.
  
• Coleman Ditch, 1867, Hardscrabble Creek.
• Widderfield Combined, 1868, Apishapa River.
• Dotson Ditch No. 1, 1868, Saint Charles River
• Smith Ditch, 1870, Taylor Creek,
• Catlin Canal, 1884, Arkansas River mainstem.
• Arkansas River Compact (with Kansas), 1949, Arkansas River mainstem.

Snowpack
Arkansas Basin Snowpack Telemetry (SNOTEL) readings for snow-water equivalent range from 28% of median at Apishapa near the Spanish Peaks to 127% at St. Elmo in western Chaffee County. The Brumley SNOTEL site, near Independence Pass, reports 98% of median, while Fremont Pass reports 91%. Glen Cove, north of Pikes Peak, dropped from 108% a month ago to a current reading of 46%. Buckskin Joe in the Mosquito Range reads 64%. In the Sangre de Cristo Range, Hayden Pass reads 42% of median.

Reservoir Storage
During the past month, Pueblo Reservoir went from 64.1% full to 67.3%, with water storage increasing from 207,047 acre-feet to 217,442 at he end of February. Water storage in Turquoise Lake, currently 49.4% full, dropped from 76,014.2 acre-feet to 63,949.2 in February. At Twin Lakes, storage levels increased slightly, from 99,431.4 acre-feet to 100,473 acre-feet, i.e., 71.3% full. John Martin Reservoir, which stores water for the Winter Water Storage Program (WWSP), increased from 30,097 acre-feet of water at the end of January to 35,423 acre-feet at the end of February.

River Flows
The gauge near Leadville is not reporting Arkansas River flow data, which is common during winter months. The gauge at Granite in north Chaffee County reports a flow of 137 cfs. The gauge at Wellsville, near Salida, reports 315 cfs, down slightly from January. River flows at Cañon City, 371 cfs, and below Pueblo Reservoir, 97.8 cfs, have also dropped since last month. River flow near Avondale is 308 cfs, up slightly from a month ago. The gauge at Rocky Ford reads 11.9 cfs, about half of the flow reading from the end of January. Current readings at John Martin Reservoir and Lamar are 0.77 cfs and 9.69 cfs, respectively.

Calling Water Rights
The Arkansas Basin currently has seven calling water rights plus the Maria Stevens Reservoir's authorized diversion on the Cucharas River under its 1887 storage right. The most senior calling right is the 1862 Model Ditch, which began calling for Purgatoire River water Feb. 17. Other calling water rights are:

• Coleman Ditch, 1867, Hardscrabble Creek.
• Fernandez Ditch, 1868, Turkey Creek.
• Upper Huerfano No. 2, 1869, Huerfano River.
• Doris Ditch, 1870, Fourmile Creek.
• Fort Lyon Storage Canal, 1910, Arkansas River mainstem.
• Arkansas River Compact (with Kansas), 1949, Arkansas River mainstem.

January was the coldest month since 1988 in Denver, and the cold temperatures and winter storm pattern produced above-average snowpack for the state, with only the Arkansas and Rio Grande basins recording below-average levels of 81% and 94%, respectively. Almost half of Colorado (45.65%), including the Upper Ark Valley, is no longer under drought conditions, according the latest U.S. Drought Monitor report. Moving east across the Plains, Ark Basin conditions range from abnormally dry in the foothills to extreme drought at the Kansas state line.

Snowpack
Arkansas Basin Snowpack Telemetry (SNOTEL) site readings for snow-water equivalent range from 36% of median at the Apishipa site near the Spanish Peaks to 127% at St. Elmo in western Chaffee County. The Brumley SNOTEL site, near Independence Pass, reports 91% of median, while Fremont Pass reports 94%. Glen Cove, north of Pikes Peak, is at 108%. Buckskin Joe in South Park reads 62%. In the Sangre de Cristo Range, Hayden Pass reads 49% of median.

Reservoir Storage
Pueblo Reservoir is 64.1% full with water storage increasing from 195,933 acre-feet to 207,047 in January. Water storage in Turquoise Lake, currently 58.7% full, dropped almost 8,000 acre-feet to 76,014.2. At Twin Lakes storage levels also decreased in January, from 105,754 acre-feet to 99,431.4 acre-feet, or 70.5% full. John Martin Reservoir, which stores water for the Winter Water Storage Program (WWSP), increased from 23,462 acre-feet of water at the end of December to 30,097 acre-feet at the end of January.

River Flows
In the grips of winter, the flow gauge near Leadville is not reporting Arkansas River flow data. The gauge at Granite in north Chaffee County reports a flow of 162 cfs with ice. The gauge at Wellsville, near Salida, reports 328 cfs, up slightly from December. River flow at  Cañon City is 434 cfs, and the flow below Pueblo Reservoir remains little changed from last month at 113 cfs. River flow near Avondale is 267 cfs, also little changed from a month ago. The gauge at Rocky Ford reads 23.8 cfs, a drop of about 80%. Flow below John Martin Reservoir remains low at 0.46 cfs, and the gauge near Lamar reads 14.7 cfs.

Calling Water Rights
Calling water rights in the Arkansas Basin remain unchanged from the end of December with eight calls for water, and the Maria Stevens Reservoir is authorized to divert water from the Cucharas River under its 1887 storage right. The most senior calling right is the 1862 Chilili Ditch, which began calling for Purgatoire River water Dec. 30, 2022. Otherwise, with the WWSP in effect, calling water rights are limited to:

• Gonzales Ditch, 1866, Apishapa River.
• Coleman Ditch, 1867, Hardscrabble Creek.
• Fernandez Ditch, 1868, Turkey Creek.
• Upper Huerfano No. 2, 1869, Huerfano River.
• Doris Ditch, 1870, Fourmile Creek.
• Fort Lyon Storage Canal, 1910, Arkansas River mainstem.
• Arkansas River Compact (with Kansas), 1949, Arkansas River mainstem.

December brought above-average snowpack to most of Colorado, but Arkansas Basin snowpack remains low at 81% of median. As of Jan. 3, 40% of Colorado was no longer experiencing drought conditions, according the latest U.S. Drought Monitor report. However, severe drought persists across parts of the lower Arkansas Basin with extreme drought continuing in the southeast corner of the basin in Colorado.

Snowpack
Snowpack Telemetry (SNOTEL) sites relevant to the upper Arkansas Basin show snowpack near or above median in most, but the numbers drop off in the southern headwaters of the basin. The Saint Elmo SNOTEL site reports 127% of median for snow-water equivalent (SWE). At Brumley, near Independence Pass, the current reading is 93%, and Glen Cove, north of Pikes Peak, is at 108%. Fremont Pass stands at 94%, but nearby Buckskin Joe in South Park reads 62%. In the Sangre de Cristo Range, Hayden Pass shows 49% of median. Current aerial snow survey data is not yet available in Colorado.

Reservoir Storage
Water storage in Pueblo Reservoir increased from 184,866 acre-feet to 195,933 during December, bringing the largest Fry-Ark Project reservoir to  60.7% full. Water storage in Turquoise Lake , currently 64.9% full, experienced a slight monthly decline of 511 acre-feet to 83,941.2. At Twin Lakes storage levels also decreased in December, from 114,014 acre-feet to 105,754 acre-feet or 75% full. The U.S. Army Corps of Engineers reports water storage in John Martin Reservoir, which is used to store water for the Winter Water Storage Program (WWSP), increased to 23,462 acre-feet at the end of December, up from 15,921 acre-feet at the end of November.

River Flows
Arkansas River flows generally decrease during Colorado's winters, and ice limits the effectiveness of gauges in the upper parts of the basin, like the gauges near Leadville and below Granite, which are not reporting new data. The gauge at Wellsville, near Salida, reports 279 cfs and ice. The gauge at Cañon City reports 322 cfs, and the flow below Pueblo Reservoir has increased to 106 cfs. River flow near Avondale is 280 cfs, almost unchanged from a month ago, while the flow at Rocky Ford has doubled to 141 cfs. Flow has dropped to 0.23 cfs below John Martin Reservoir but has increased to 19.4 cfs near Lamar.

Calling Water Rights
Eight water rights are currently calling for water in the Arkansas Basin. Additionally, the Maria Stevens Reservoir has an authorized diversion in place with an 1887 priority date. The most senior calling right is the 1862 Chilili Ditch, which began calling for Purgatoire River water Dec. 30, 2022. Otherwise, with the WWSP in effect, calling water rights remain unchanged from a month ago:

• Gonzales Ditch, 1866, Apishapa River.
• Coleman Ditch, 1867, Hardscrabble Creek.
• Fernandez Ditch, 1868, Turkey Creek.
• Upper Huerfano No. 2, 1869, Huerfano River.
• Doris Ditch, 1870, Fourmile Creek.
• Fort Lyon Storage Canal, 1910, Arkansas River mainstem.
• Arkansas River Compact (with Kansas), 1949, Arkansas River mainstem.

​Snowpack
In spite of recent snowfall in the upper basin, early season snowpack is trending below average with NRCS Snowpack Telemetry (SNOTEL) data showing basin-wide snowpack at 76% of median for snow-water equivalent (SWE). The highest reading is currently at Saint Elmo, where the SNOTEL station shows SWE at 4.5 inches, 118% of median. More accurate than SNOTEL data, aerial snow survey data is expected to be implemented in Colorado this winter by Airborne Snow Observatories, but that data is not yet available.

Water Availability
The Governor's Water Availability Task Force report for November summarizes data for Water Year 2022, noting it was "the sixth warmest and 35th driest on record going back to 1896" with February being the coldest month of the year. Colorado experienced a "wet July" and benefited from "monsoonal moisture in the central and southern parts of the state."

As Water Year 2023 begins, "Colorado has some of the best antecedent soil moisture in years," the report states, "but on the eastern side of the Divide, (soil) conditions are a lot drier than normal. Precipitation is near normal at 95% of median. ... La Niña looks likely to continue through early winter and possibly beyond. On average, the Northern Rockies are wetter during La Niña and with colder temperatures that can result in good snowpack conditions. Drier conditions may impact the southern part of the state."

Winter Water Storage Program

The Winter Water Storage Program (WWSP) in the Arkansas River Basin runs from Nov. 15 to March 14 every year. The program was devised during the early planning stages of the Fryingpan-Arkansas Project and stores water that would otherwise be diverted by irrigators downstream from Pueblo Reservoir during the winter months. This stored water is then released during the following irrigation season.

The WWSP has been refined to arrive at "an equitable means of apportioning the stored water among the WWSP participants and avoiding injury to non-participants." Negotiations ultimately produced a consensus among participants and objectors, producing an initial decree approved by Water Court Judge Tracey in 1987. In 1990, Tracey entered an order making the decree final.  

The participants in the WWSP primarily store their WWSP water in Pueblo Reservoir but also use Henry, Meredith, Holbrook, Dye, Adobe, Horse Creek, Great Plains and John Martin reservoirs. When space is limited, priority for storage of WWSP water in Pueblo Reservoir goes to entities that don't have access to off-channel reservoir storage. When active, the WWSP affects reservoir storage, river flows and calling water rights in the Arkansas Basin.

Reservoir Storage
Water storage in Pueblo Reservoir increased during November, from 177, 342 acre-feet to 184,866 acre-feet or 57.2% full. Water storage in Turquoise Lake fell from 85,368.5 acre-feet a month ago to 84,452.2 acre-feet or 65.3% full. At Twin Lakes storage levels also decreased in November, from 120,899 acre-feet to 114,014 acre-feet or 80.9% full. The U.S. Army Corps of Engineers reports water storage in John Martin Reservoir increased from 11,442 acre-feet to 15,921 acre-feet in November.

River Flows
With Fyingpan Arkansas project water releases currently suspended and the WWSP in effect, Arkansas River flows have generally decreased in Colorado. The Leadville gauge hasn't reported any new data for the past week, and the gauge at Granite currently reads 119 cfs. River flow at Wellsville is 315 cfs, and at Cañon City, 380 cfs. The flow below Pueblo Reservoir has dropped 69.9 cfs, a reflection of the WWSP. The gauge near Avondale currently reads 289 cfs, while the flow at Rocky Ford has dropped to 68.8 cfs. Flow below John Martin Reservoir has dropped to 1.16 cfs but has increased to 16.3 cfs near Lamar.

Calling Water Rights
With the WWSP in effect, only eight water rights are currently calling for water in the Arkansas Basin. The most senior calling right is the Lewellyn McCormick right with an 1864 priority date on the Purgatoire River. The 1866 Gonzales Ditch right on the Apishapa River is next in priority, followed by the 1867 Coleman Ditch right on Hardscrabble Creek.

​The Fernandez Ditch (1868 priority) has a call on Turkey Creek, the Upper Huerfano No. 2 (1869) has a call on the Huerfano River, and the Doris Ditch (1870) has a call on Fourmile Creek. On the Arkansas River mainstem, the 1910 Fort Lyon Storage Canal right has a call, and as always, the Arkansas River Compact has a call at the Kansas state line to ensure that Colorado sends water to Kansas.