State of the Red River of the North Assessment of the 2003 and 2004 Water Quality Data for the Red River and its Major Minnesota Tributaries

The Red River Flood Damage Reduction/Natural Resource Enhancement Work Group established the Red River Basin Monitoring Advisory Committee to develop a condition monitoring program for the Minnesota portion of the Red River basin. This report presents results and analysis of the first two years of this program. Concentration data as well as total loads of sediment and selected nutrients are reported for the 2003 and 2004 sampling season. This program is primarily designed for estimating pollutant loads, thus it is biased toward periods of high flow. Up to 20 samples were collected per year at six sites along the Red River and at 11 major Minnesota tributaries throughout 2003 and 2004. Field measurements were taken (pH, dissolved oxygen, temperature, conductivity, turbidity, transparency, and stage level) and water samples collected at each site for certified lab analysis of total phosphorus, ortho-phosphorus, nitrate plus nitrite nitrogen, and total suspended solids. In reviewing concentration results, the Grand Marais was the only major tributary that had a median total phosphorus concentration above .3 mg/l. All Red River sites except the upstream site near Brushvale (RR1) were above this threshold. In terms of total suspended solids, six of 11 tributary sites had median concentrations above 100 mg/l, with the Snake and Grand Marais being the highest with 185 and 144 mg/l, respectively. All Red River sites except the upstream site at Brushvale had median TSS values above 100 mg/l, with the four downstream sites all being over 200 mg/l. Discharge rates and loading estimates for 2003 and 2004 were the result of two very different water years. The estimated basin (Minnesota side of basin) mean precipitation in 2004 was 40% greater than the 2003 basin mean precipitation. The peak flow at the Canadian border in 2003 was 14,000 cfs versus a 2004 peak discharge of 45,000 cfs with three other storm events in 2004 reaching flows of 20,000 cfs or more. Sediment loading as total suspended solids in the Red River increased nearly threefold, from nearly 1.1 million tons in 2003 to over 2.9 million tons in 2004 as measured at the Pembina site at the US-Manitoba border. Total phosphorus loads had a similar relationship with the 2003 estimate of 1,359 tons verses 4,062 tons in 2004 at Pembina. The results of this study suggest that the Sand Hill and Wild Rice Rivers delivered the highest yield of phosphorus and sediment to the Red River per acre of watershed. The Grand Marias Creek and Snake River had the highest median total suspended solids and total phosphorus concentrations of the Minnesota tributaries but did not have continuous flow data and hence load and yield estimates. Sources of sediment between Fargo (RR2) and Halstad (RR3) significantly increase the sediment load in the Red River. While the drainage area roughly triples between these two sites, the estimated sediment load (mean of 2003 and 2004) in the Red River is 5.6 times larger at Halstad than at the site north of Fargo. The mean (2003 and 2004) estimated phosphorus load increased by 3.9 times from Fargo to Halstad. Several factors, including significant contributions from the Sheyenne River in North Dakota, channel dynamics, and direct runoff to the Red River are likely causing the increased sediment load. While total sediment loading increases downstream from Halstad to the next Red River sample site at Grand Forks (RR4), the flow weighted mean concentration actually decreases in large part due to the dilution effect of the Red Lake River. The Red Lake River contributes roughly 30% of the Red River flow at Grand Forks but 10% or less of the sediment load during this study period. This dilution effect is also evident when analyzing the influence of the relatively "clean" water contribution from the Ottertail River on the upstream Red River sample site near Brushvale. Both the Ottertail and Red Lake Rivers have a high percentage of their contributing watersheds above the beach ridge areas of the basin. Additional data collection and assessment are required to better establish the range of loading conditions that occur in the basin. Further investigation should focus on establishing annual flow records in the un-gauged watersheds along with continued chemical and physical analysis of the primary sites. Incorporating data from other monitoring partners, especially from established secondary and tertiary sites in contributing sub-watersheds, will yield a more thorough understanding of basin conditions, assist in defining loading hotspots, and lead to the identification of management strategies for pollutant reduction.