Watershed Symposium 2024

Summary:
Great Salt Lake Stormwater Study: Basin-Wide Analysis of Stormwater Flows, Low-Impact Development and Groundwater Contributions developed a water-balance model to explore the impacts of Low-Impact Development (LID) on the Great Salt Lake watershed.

Full Abstract:
This study , completed in 2023, entitled Great Salt Lake Stormwater Study: Basin-Wide Analysis of Stormwater Flows, Low-Impact Development and Groundwater Contributions developed a water-balance model to explore the impacts of Low-Impact Development (LID) on the Great Salt Lake watershed. LID refers to, “engineered systems, either structural or natural, that use or mimic natural processes to promote infiltration, evapo-transpiration, and/or reuse of storm water as close to its source as possible to protect water quality and aquatic habitat.” LID mimics the undeveloped water flows within a watershed which reduces the volume of runoff and the flows through conveyances thereby improving water quality of stormwater. The team performed an integrated water assessment, including quantification of the influence of low impact development practices associated with post-construction retention stormwater permit requirements on runoff to the Great Salt Lake. The project consisted of a literature review, data compilation, and methodology development and implementation that led to development and application of a SWMM model to estimate how future development with and without LID impacts surface water runoff and groundwater recharge in the context of the Great Salt Lake watershed. SWMM model results were used in MODFLOW groundwater models to elucidate both the surface and groundwater paths to Great Salt Lake. This talk will highlight the potential impacts of LID on the Great Salt Lake watershed including surface water and groundwater systems.

Summary:
Dust blowing from dry lakebeds annually darkens the snowpack of the Great Salt Lake Basin. The darkened snow absorbs more sunlight, resulting in earlier snowmelt. Here, we have used a combination of fieldwork, satellite observations, and modeling to quantify the impact of dust snowmelt, in hopes of improving water supply forecasts in the region.

Full Abstract:
Seasonal snow in the Great Salt Lake Basin (GSLB) provides critical water resources for human infrastructure and local ecosystems alike. The GSLB snowpack has a first order influence on water availability to 2.7 million Utahns and provides the main surface inflows to the Great Salt Lake. Snowmelt rates are primarily controlled by snow albedo, which is impacted by surface darkening from light absorbing particles (LAPs). In the Wasatch Mountains, the primary LAP constituent is dust originating from dry lakebeds across the eastern Great Basin. Dust accelerates snowmelt, adding uncertainty to streamflow forecasts. Despite this, the impact of dust on snowmelt timing is not well known in the GSLB and is not directly accounted for in operational models. Here we present three years of research targeted at quantifying the spatial and temporal distribution of dust on snow and its impacts on snowmelt rates and timing across the GSLB. Our work includes a time series of point-based field observations, analysis of 23 years of satellite remote sensing retrievals, and basin distributed process-based snowmelt modeling. Results reveal that dust impacts snowmelt annually, but with high variability year-to-year, and with no strong temporal trends in the last two decades. The annual impact of dust on snowmelt was quantified over two distinctly different water years (2022 and 2023) by running two model implementations with different albedo representations: 1) A standard time decay relationship representing clean snow albedo evolution, and 2) daily remotely sensed observed snow albedo from MODIS. Differences between model runs, evaluated by melt rates, surface water inputs, and snow depletion timing, reflect the influence of snow darkening on snowmelt across the basin. This approach has allowed us to parse out physical drivers of snowmelt and is the first study to quantify snowmelt acceleration due to dust over the GSLB.

Summary:
In the Western US, irrigation companies play a key role in water conservation, navigating diverse challenges and strategies. Interviews with 18 companies in the Great Salt Lake Basin reveal varied conservation practices and highlight themes like motivations, techniques, and barriers. These insights can support effective water management policies.

Full Abstract:
In the Western US, water conservation efforts are currently top of mind and a rising priority for many individuals and entities. Irrigation companies are an example of an entity whose priorities are focusing on water conservation. Irrigation companies are on-the-ground, day-to-day water managers that are faced with decisions and challenges when it comes to water conservation. There is empirical evidence that emphasizes the importance of multi-scalar, multi-dimensional water conservation efforts. The wide array of efforts and practices related to water conservation are all important when looking at the big picture of conservation. Therefore, viewing a diverse set of conservation efforts to be available to irrigation companies can allow for individuals and entities of all sizes and capacities to participate in conservation efforts in accessible ways. Therefore, the steps and efforts that entities like irrigation companies are able to take toward conservation are critical within the larger picture of water conservation. In the Great Salt Lake Basin, 18 irrigation companies participated in semi-structured interviews where topics around water conservation efforts were discussed. Within the realm of irrigation companies, water conservation efforts look quite different even within the same basin. Examples of some of these efforts include reducing general water usage, work towards making more efficient systems, and participation in water leasing and banking. Conservation themes that arose in the qualitative analysis of the interviews include conservation motivations, conservation decisions, and specific conservation techniques and applications of these irrigation companies. Discussions of the enabling and constraining factors around conservation such as funding and collaborative relationships also arose. These enabling and constraining factors give insights into how to better support the work of these companies at larger policy levels. The themes and findings here are being shared not as a way to dictate what other irrigation companies should be doing, but rather what other irrigation companies could be doing in terms of water conservation. These insights also recognize the work and efforts that these companies are currently participating in and highlight how water conservation is an important component to these irrigation companies. In order to build off these qualitative findings, future efforts of this project will potentially include a paired survey of irrigation companies in the basin to capture more generalizable, quantifiable perspectives. Co-Author: Courtney Flint, Professor, Utah State University, https://courtneyflint.wordpress.com