This question is definitely a valid concern that is often shared with us. There are a variety of factors that come into play when thinking about irrigation. The short answer is that farmers might irrigate while it is raining because only 12% of crop water needs are met by rain. Luckily, both rain and irrigation water are stored in the soil and can be used days later.
Let’s think about the amount of water a crop needs so that it can produce a successful yield. Out of the theoretical total amount of water a crop needs on average throughout the watershed (100%), 59% comes from irrigation and only 12% of the crop’s needs are actually met by rain during the growing season. The remainder comes from a combination of soil moisture obtained from snowmelt during the winter and reduced crop yield when water is not sufficient to meet the theoretical needs.
Any water used on a crop while it is raining is not a waste of water. Both rain and irrigation water are stored in the soil and available to plants days later. If the rain is higher than expected on a given day, less irrigation is needed the following week.
The Drought Planning Management Committee has streamflow targets in place to ensure that there is enough water available in the river for fish habitat during the irrigation season, no matter how much is being diverted (taken out) for irrigation, and these targets were created in partnership with the Henry’s Fork Foundation.
The only reaches of the Henry’s Fork where fish populations are impacted by water supply are:
1. Trout and Kokanee populations upstream of IPR – dependent on the amount of water that stays in the reservoir all summer
2. Trout populations between IP Dam and Riverside – limited by available winter habitat, which depends on outflow from the dam
3. Trout populations downstream of St. Anthony – habitat limited by mid-summer low streamflow and high water temperatures
1. Keep more water in Island Park Reservoir via water conservation
2. Develop managed aquifer recharge strategies that can increase inflow of cool groundwater to streams and reservoirs
3. Increase precision in water management via daily data sharing and collaboration
As it is the afternoon of December 31, I am closing the year with my annual fish-of-the-month blog, this one at the end of my 11th year of catching a fish in my home waters in each month of the year. To spare you the math, that’s 132 consecutive months of catching a wild trout or whitefish (and in some years I’ve fair-caught suckers and shiners, too) within a three-hour drive of my home in
In this blog post, we 1) present our turbidity and suspended sediment data, 2) explain our suspended load calculations, and 3) provide some additional information justifying why we think that a substantial amount of bed load was transported into the Henry’s Fork in addition to the suspended load. Since first observing high turbidity in Thurmon Creek and the Henry’s Fork downstream associated with the Silver Lake drawdown in November 2025, HFF’s Science and Technology team
Written by Doris Squeri Tom and I met on our first day of grad school back in 1982. We were both broke and stressed, and we both loved the outdoors, so I decided that an affordable way to relieve some of that stress might be to learn how to fly-fish. We had learned to fish with our dads when we were very small, but it was bait fishing, and we wanted to try something new.
The Henry’s Fork Drought Management Planning Committee (DMPC) met on Monday, November 24 to set this winter’s outflow and reservoir-fill strategy for Island Park Reservoir—an annual decision with implications for winter trout habitat in Box Canyon and the Ranch. Winter Outflow: What’s Coming on December 1 Beginning December 1, outflow from Island Park Dam will increase, bringing winter streamflow through Box Canyon to ~380 cfs from December through February*. That equates to 76% of Box
