WATER QUALITY MONITORING PLAN 2021 Wyoming Department of Environmental Quality Water Quality Division Watershed Protection Program Table of Contents Wyoming’s Surface Water Quality Monitoring Strategy ....................................................................... 3 Purpose of the Annual Water Quality Monitoring Plan.......................................................................... 3 Annual Monitoring Objectives – 2021 Field Season .............................................................................. 3 Objective 1 - Complete Bear and Snake Basins Probabilistic Survey ................................................ 3 Objective 2 – Conduct Water Quality Standards Attainment Studies ................................................ 4 Objective 3 – Provide Data Collection Support for Nutrient Criteria Development .......................... 5 Objective 4 - Provide Data Collection Support for TMDLs ............................................................... 5 Objective 5 – Evaluate Potential Harmful Cyanobacteria Blooms ..................................................... 6 Watershed Protection Program Monitoring List for 2021 ...................................................................... 6 Quality Assurance and Quality Control .................................................................................................. 6 Other Watershed Protection Program-Supported Projects for 2021 ....................................................... 7 WDEQ-USGS Statewide Monitoring Network .................................................................................. 7 Figure 1. Monitoring locations included in the 2021 Monitoring Plan ...................................................... 8 Figure 2. Sites included in the WDEQ-USGS statewide cooperative agreement. .................................... 14 Table 1. Base and oversample sites for the Bear/Snake probabilistic survey. ............................................ 9 Table 2. Water quality standards attainment studies. ............................................................................... 12 Table 3. Nutrient-Related Monitoring ...................................................................................................... 12 Table 4. TMDL Program Assistance ........................................................................................................ 12 Table 5. WDEQ/USGS Cooperative Agreement ...................................................................................... 12 2 Wyoming’s Surface Water Quality Monitoring Strategy Wyoming’s Surface Water Quality Monitoring Strategy and Strategy Addendum outlines primary and secondary monitoring objectives for meeting the agency’s surface water quality decision-making needs. Achievement of primary objectives occurs mostly using rotating-basin probabilistic surveys to assess statewide and regional water quality conditions and direct future targeted monitoring for making designated use-support determinations. Achievement of secondary objectives occurs through cooperation between the Watershed Protection Program’s Monitoring (Monitoring), Water Quality Standards (WQS), Non-Point Source (NPS) and Total Maximum Daily Load (TMDL) sub-programs and other entities. Monitoring works cooperatively with WQS to develop and implement study designs to develop new or revised water quality criteria. Evaluation of best management practices used to reduce non-point source pollutants often occurs through collaboration between Monitoring, NPS and TMDL. Likewise, some TMDL study designs and supporting data collection occurs through collaboration between Monitoring and TMDL. Purpose of the Annual Water Quality Monitoring Plan The annual water quality monitoring plan ties the monitoring strategy to specific monitoring projects planned for a given year. The plan serves as an information-sharing tool for the public, government, non-profits and other stakeholders. The plan highlights work of Monitoring and does not contain a complete account of water monitoring occurring within the Watershed Protection Program. Monitoring Objectives – 2021 Field Season 1) Complete Bear and Snake Basins Probabilistic Survey 2) Conduct Water Quality Standards Attainment Studies 3) Provide Data Collection Support for Nutrient Criteria Development 4) Provide Data Collection Support for TMDLs 5) Evaluate Potential Harmful Cyanobacteria Blooms Objective 1 - Complete Bear and Snake Basins Probabilistic Survey (Figure 1; Table 1) Probabilistic rotating basin surveys (PRBS) address the primary objectives of the Wyoming Surface Water Quality Monitoring Strategy (WDEQ 2010, 2021). PRBS involve sampling a randomly selected subsample of a population of interest, similar to a census, in order to make inferences about characteristics of the population as a whole. Wyoming uses a customized generalized random tessellation- stratified (GRTS) survey design using the 1:100,000 scale National Hydrographic Dataset Plus (NHD+) as the base sample frame (see http://archive.epa.gov/nheerl/arm/web/html/presents.html; Stevens and Olson, 2004). Fifty primary sites are randomly selected from a target population of perennial, non- headwater (>1st Strahler order) rivers and streams outside of national parks, congressionally-designated wilderness areas and the Wind River Reservation within each of five geographic divisions of the State. The geographic divisions are referred to in this document and WDEQ (2010) as ‘superbasins’ due to their delineation using combinations of 6-digit (3rd level) Hydrologic Unit Codes (HUC) and geographical location. The five superbasins, the associated HUC 6 basins they represent, and the year (or anticipated year), the probabilistic survey was completed are: 3 Bighorn/Yellowstone [Bighorn and Yellowstone Basins] - 2010 Northeast [Belle Fourche, Cheyenne, Little Missouri, Powder and Tongue Basins] - 2011 Green [Great Divide, Green and Little Snake Basins] - 2015 Platte [Niobrara, North Platte and South Platte Basins] - 2016 Bear/Snake [Bear and Snake Basins] - 2021 Site selection is stratified into aggregations of 8-digit (4th level) HUCs, or “HUC8 clusters,” within each superbasin. The additional stratification more equally distributes the 50 primary sites among all HUC 8 clusters and across a superbasin. A population of 100 oversample sites (also stratified by HUC8 cluster) are used as replacements when a primary site cannot be sampled. Oversample sites replace primary sites occurring within the same HUC 8 cluster to maintain representativeness and minimize logistical complexities of sampling. Data from PRBS inform statistical inferences about water quality conditions within each superbasin, including the proportion of the stream target population likely achieving water quality criteria or statistically-derived expected conditions, and the occurrence, extent and relative risk of various pollutants. PRBS data are not used to make determinations of designated use support or resultant categorization decisions in Wyoming’s §305(b)/303(d) Integrated Report. PRBS data identify waters of high quality and those where designated use-support may be limited, thus candidates for future targeted monitoring for determinations of designated use support. Waterbodies are selected for targeted monitoring based on an informal priority ranking derived from findings of the probabilistic rotating basin survey and other factors such as public interest, human health risk, restoration potential, and agency resources. The Bear/Snake is the fifth PRBS implemented by Monitoring. The survey occurs in 2021 followed by data analysis in 2022, and targeted monitoring of priority waterbodies in 2023 and 2024. Refer to the Bear/Snake PRBS sampling and analysis plan for more information. Objective 2 – Conduct Water Quality Standards Attainment Studies (Figure 1; Table 2) Sweetwater River - Class 1 Segment The Sweetwater River from Alkali Creek upstream to its origin became a Class 1 waterbody in 1979. Section 4(a) of Chapter 1 of Wyoming’s Water Quality Rules and Regulations describes Class 1 waters as those surface waters in which no further water quality degradation by point source discharges other than from dams is allowed. Nonpoint sources of pollution shall be controlled through implementation of appropriate best management practices. Pursuant to Section 7 of these regulations, the water quality and physical and biological integrity which existed on the water at the time of designation will be maintained and protected. Despite its Class 1 designation, the Sweetwater River has not been formally assessed. Monitoring will evaluate water quality conditions and standards attainment to enable assessment of designated uses for the Class 1 segment of the Sweetwater River. Select tributaries are included in the evaluation to increase the stream miles assessed and categorized in the Integrated Report. Water quality data collected at various locations with various objectives over the years is not adequate data to determine if water quality has degraded since the designation as Class 1. Monitoring will collect 4 monthly water quality and flow data at three locations on the Class 1 segment for a third year to build a dataset as a baseline for future anti-degradation evaluations. Objective 3 – Provide Data Collection Support for Nutrient Criteria Development (Figure 1; Table 3) Monitoring and WQS will continue collecting nutrient and supporting data on lakes and reservoirs. The focus of 2021 monitoring will be 1) drinking water storage reservoirs