At the end of each year, HFF takes a moment to reflect on all that was accomplished for the Henry’s Fork in the previous 12 months. To keep the tradition going, HFF is taking a look back at the "Top-10" programmatic accomplishments and events worth celebrating from 2018. You can also take a look back at HFF's Top 10 for 2014, 2015, 2016, and 2017.     10. Economic study data collection completed in 2018 9. HFF helps Idaho Fish and Game solve a Henry’s Lake mystery 8. Grand Opening of the HFF Community Campus 7. Precision water management and timely rain flushed 2,000 tons of sediment out of the Henry’s Fork between IP Dam and Pinehaven 6. HFF Launches a new South Fork Initiative 5. Revamped intern program benefitted both HFF and interns 4. HFF was awarded a quarter of a million dollars in grants 3. Bryce (BC) Contor hired as Landowner Outreach Manager for Farms & Fish Program 2. Tale of Two Water Years 1.  Precision water management saved 14,000 acre-feet of water in Island Park Reservoir     10. Economic study data collection completed in 2018 In 2016, HFF, in partnership with Friends of the Teton River, Idaho Fish and Game,

In January of 2015, I started a new run of "fish of the month," a tradition I started years ago with long-time friend Tom Grimes, who is a guide at Henry's Fork Anglers. The idea is to catch a wild trout or whitefish every month of the year in our local waters, the streams and lakes of Montana, Wyoming, and Idaho in the Yellowstone region. My previous record was 55 months, from July 2004 to January 2009. Five academic years spent in California broke that streak, but I'm four years into the current one. How did 2018 turn out? Statistics As a statistician and compulsive record-keeper, I carefully record numbers from each outing. While my stats are laughable compared to those racked up by serious anglers who devote most of their free time to the activity, my stats usually surprise me after the fact, given that I work way too much and devote most of the remaining time to bicycle road racing, driving back and forth to California to visit family, and growing a big vegetable garden. I may not qualify as a serious angler right now, but I have been in the past, fishing well over 100 days per

December precipitaion well below average The month of December turned out to be about average in temperature, as warm weather in the middle of the month was offset by cold periods at the start and end of the month. However, precipitation for the month was only 57% of average. Monthly precipitation was above average in the valley areas, and Ashton led the way at 119% of average. Precipitation was below average at all nine SnoTel sites. By subwatershed, monthly precipitation was 63% of average in Teton, 56% of average in Fall River, and 47% of average in upper Henry’s. As a result, water-year precipitation is only 84% of average, roughly 100% of average in valleys, 90% in Teton, 80% in Fall River and 75% in upper Henry’s. Ashton and Grand Targhee are the only two stations with above-average precipitation, at 115% and 102%, respectively. Watershed-wide precipitation deficit is almost 2 inches for the water year. Snow water equivalent (SWE) follows the same pattern. December SWE accumulation was only 47% of average: 57% of average in Teton, 43% of average in Fall River, and 41% of average in upper Henry’s. Current SWE is 70% of average: roughly 80% in Teton, 70%

Diversion from the Henry's Fork has decreased 30% over the past 40 years, yet consumptive use of water by crops has increased, there is less water in the river during the middle of irrigation season, and use of storage water has increased, all other things being equal. How could this be? In Idaho, administration of irrigation water takes place over the "irrigation year," which runs from November 1 to October 31, lagging the more common October 1 to September 30 "water year" by a month. In most areas of the upper Snake River basin, irrigation water rights can be used from April 1 to October 31. Water for other uses, such as managed aquifer recharge and livestock watering, can occur during the winter. Irrigation year 2018 ended just a little over one month ago, allowing me a little time to summarize data from the 2018 irrigation season. This blog starts out with that summary but quickly moves into a discussion of long-term trends in irrigation practices, and the unintended and counterintuitive consequences of those trends. Data Sources The data reported here come from the Idaho Department of Water Resources (IDWR) water-rights accounting database. These data include all all points of

As of December 10, water-year precipitation is 87% of average, and snow-water-equivalent is only 75% of average. Precipitation deficit since July 1 is over 5 inches. Natural streamflow has been around 95% of average since early October. Outflow from Island Park Dam has averaged 502 cfs since December 1, 143% of average. Water year 2019 has started out the same way 2018 ended, dry and with slightly below-average streamflow. Through December 9, accumulated water-year precipitation is 87% of average, and snow-water-equivalent (SWE) at the watershed's nine SnoTel stations is only 75% of average. So far this winter, precipitation has favored the southern half of the watershed, including the Teton headwater areas and the valleys. Upper Henry's Fork lags the other subwatersheds by quite a bit. In addition to the current water-year precipitaiton deficit of around one inch, the four-inch deficit accumulated during July, August and September puts us over five inches down over the past five months. The winter will have to be much wetter than average to make up the deficit. Graph of accumulated water-year precipitation as a percent of average. Graph of snow-water-equivalent (SWE) across all SnoTel sites in the watershed. Below-average SWE is not the result of

Water-year 2018 ended up close to average, at 102% of average precipitation and 105% of average streamflow. Upper Henry's Fork subwatershed was below average in precipitation and streamflow, vs. above-average values in Fall and Teton rivers. However, Upper Henry's Fork water supply improved from 70% of average in 2016 to 91% in 2017 and 94% in 2018, indicating recovery of deep aquifers from 2013-2016 drought. May and June rain compensated for early snowmelt and resulted in below-average irrigation diversion. Despite very dry conditions and below-average streamflow during July, August and September, Island Park Reservoir ended the water year at 73% full, compared with 43% full on average, thanks to careful and precise water management. This blog is even longer and more detailed than my usual long, detailed blogs, but there was a lot to learn from water-year 2018. This blog is a slightly edited compilation of the four daily water reports I wrote during the first week of the new water year. The four reports appear in four different sections in this blog: Climate Natural flow and diversion Streamflow and water management in lower watershed Streamflow and reservoir management in upper watershed Tables and graphs appear at the end of

Temperatures and rainfall were near average in August. Natural streamflow and diversion were both around 90% of average for the month. As of September 10, Island Park Reservoir is 73% full, compared with 46% full on average. August Weather Near Average August provided a little reprieve in the middle of what has otherwise been a warm, dry summer. Temperatures were warm during the beginning of the month and cool at the end, resulting in a monthly mean about 1 degree F below average. Graph of watershed mean temperature, relative to long-term average. A very deep autumn-like trough of low pressure brought substantial rain and near-freezing temperature to the whole watershed on August 27, adding to lighter showers that fell at scattered locations earlier in the month. The result was near-average precipitation at most stations for the month. Precipitation favored Teton Valley and the Fall River watershed; the upper Henry's Fork and most valley locations recieved below-average precipitation. Ashton was an exception, receiving nearly one inch for the month. Temperatures during the late-August storm were cold enough that snow fell above 7,000 feet and stayed on the ground for a few days at the highest elevations. Water-year precipitation ended the month

The month of July was a little warmer than average but very dry. Natural flow and diversion were both around 90% of average for most of the month. Moisture from May and June rain has kept total diversion for the season about 100,000 ac-ft below average. As of August 3, Island Park Reservoir is still 82% full, compared with an average of 70% full at this time of year. Above-average Temperatures Continue through July Temperature over the month of July was 2 degrees F above average in the Henry’s Fork watershed, continuing the pattern of above-average temperatures. Mean April-June temperature was also 2 degrees above average. Cool nights throughout July offset very warm afternoon highs to keep daily means close to average. As of August 2, Pocatello had set a new record of 30 consecutive days with high temperature at or above 90 degrees. According to the National Weather Service, the current heat wave in southeastern Idaho is record-setting in persistence and duration but not extremes.  Graph above sows temperature relative to average. Note consistently above-average temperature since early July. Spring Rain Keeps Irrigation Demand Low, Despite Dry July After abundant rain in May and June, July was very dry.