Simple Optimization Method to Determine Best Management Practices to Reduce Phosphorus Loading in Echo Reservoir, Utah

Abstract

This study develops and applies a simple linear optimization program to identify cost effective Best Management Practices (BMPs) to reduce phosphorus loading to Echo Reservoir, Utah. The optimization program tests the feasibility of proposed Total Maximum Daily Load (TMDL) allocations based on potential BMP options and provides information regarding the spatial redistribution of loads among sub-watersheds. The current version of the TMDL for Echo reservoir allocates phosphorus loads to existing non-point phosphorus sources in different sub-watersheds to meet a specified total load. Optimization results show that it is feasible to implement BMPs for non-point sources in each sub-watershed to meet reduction targets at a cost of $1.0 million. However, relaxing these targets can achieve the overall target at lower cost. The optimization program and results provide a simple tool to test the feasibility of proposed TMDL allocations based on potential BMP options and can also recommend spatial redistributions of loads among sub-watersheds to lower costs.

Blended near‐optimal alternative generation, visualization, and interaction for water resources decision making

“…Throughout the U.S., excess nutrients like phosphorus and nitrogen impair water bodies and managers must select and locate nutrient removal practices to meet water quality standards. Researchers have developed both simple and complex optimization programs to recommend practices [ Alminagorta et al ., ; Hsieh and Yang , ; Maringanti et al ., ]. This near‐optimal application first overviews an existing single‐objective linear program for Echo Reservoir [ Alminagorta et al ., ] then compares the prior‐published optimal solution, near‐optimal alternatives generated by several MGA methods, and by the new tools with the goal to demonstrate several key features of the new tools.…”

“…Researchers have developed both simple and complex optimization programs to recommend practices [ Alminagorta et al ., ; Hsieh and Yang , ; Maringanti et al ., ]. This near‐optimal application first overviews an existing single‐objective linear program for Echo Reservoir [ Alminagorta et al ., ] then compares the prior‐published optimal solution, near‐optimal alternatives generated by several MGA methods, and by the new tools with the goal to demonstrate several key features of the new tools. All alternatives were generated on a Windows 2.7 GHz machine with 8 GB RAM; the number of alternatives for the MGA‐Serial and Simultaneous methods were set to make runtimes commensurate with the new tools.…”

“…The linear program formulation is identical to Alminagorta et al . [] except that here all decision variables are expressed (scaled) in phosphorus mass removed (Appendix ).…”

“…For all but one practice (stabilize stream banks in Chalk Creek), MGA‐HSJ generated between one and four unique nonzero values. Also, MGA‐HSJ terminated much earlier after alternatives 4 and 5 had the same 13 nonzero variables on a model version with different scaled land area and stream bank length decision variables [ Alminagorta et al ., ]. Five MGA‐Simultaneous trials each generated 10 alternatives in 100–500 s all at the 110% removal cost threshold. These alternatives implemented up to six phosphorus removal practices in each subwatershed.…”

Prioritizing Irrigation‐System Upgrades to Maximize Improvements to Agricultural Drain‐Network Water Quality: A Graph‐Theoretic Approach

“…Many approaches have been published to address the problem of prioritizing BMPs to improve water quality in watersheds. For example, Alminagorta et al (2013) and Orlando (2017) proposed linear programming approaches to prioritize BMPs to reduce agricultural water pollution. Both are valuable approaches, but are conducted at a sub-watershed level, and do not allow for the prioritization of specific fields/projects.…”