Chemistry and Flow Monitoring Results – Wayne County

Data are collected from stream and river locations that facilitate the establishment of relationships between land cover and ecological stream health. The locations are selected based on their use by the Michigan Department of Environment, Great Lakes, and Energy, the HRWC Adopt-A-Stream volunteer stream monitoring program, likelihood of significant sub-watershed phosphorus loading based on modeling, and capturing the range of sub-watershed and upstream conditions.

Annual monitoring occurs during the growing season (April through September) at nine long-term sites throughout the ADW. Long-term sites help determine changing conditions over time. The program also monitors investigative sites. Investigative sites are determined annually based on data from HRWC’s long-term dataset or areas where municipalities or community members have expressed water quality concerns. These investigative sites are generally monitored for a single season and provide additional data to better understand pollutant sources.

In 2023, Chemistry and Flow Monitoring was conducted at ten sites across seven creeksheds located in either the Detroit or Huron River watersheds and at one mainstem Huron River site. Creeksheds include the Detroit River tributaries of Frank & Poet, Brownstown, Blakely, and Ecorse creeks (north and south branch) and the Huron River tributaries of Woods, Silver and Smith creeks. One investigative site, a branch of Blakely Creek called Mizner Drain, was also monitored. For more information about the sites, please see the map below. Orange and purple sites indicate investigative sites, with green markers reflecting long-term sites.

Alliance of Downriver Watersheds Chemistry and Flow Monitoring Sites

Total Phosphorus (TP)

Phosphorus is an essential nutrient for all aquatic plants. It is needed for plant growth and many metabolic reactions in plants and animals. In freshwater systems like the Huron River, phosphorus is typically the growth-limiting factor for aquatic plants. That is, phosphorus controls the pace at which algae and aquatic plants grow and small increases in phosphorus can result in excessive algal growth often termed a bloom. Total phosphorus (TP) is a measure of all forms of phosphorus (inorganic and organic P) present in a water sample and is the primary indicator of eutrophication or excess nutrients in the Lower Huron River and Combined Downriver watersheds. The typical background level of TP for Michigan rivers is 0.03 mg/L or ppm and is the goal for the ADW site in the main-stem of the Huron River . The goal for ADW streams, however, is slightly higher at 0.07 mg/L TP, due to the smaller stream size and the typical concentrations at reference sites within the ecoregion. Further, the goal for the receiving waters of these sites, the Western Lake Erie Basin open waters, is much lower at 0.015 mg/L as established by the Great Lakes Water Quality Agreement Annex 4.

Further, phosphorus is the main parameter of concern in eutrophic lakes and streams for its role in producing harmful algal blooms, especially blue-green algae. Phosphorus enters surface waters from point sources, such as wastewater treatment plants, and nonpoint sources, including fertilizers and animal waste. Excessive concentrations of this element can quickly lead to excessive growth of aquatic plants and algae. Abundant algae, especially harmful blue-green algae, has several adverse effects to the water column: reduced water clarity; unpleasant aesthetics and odor; oxygen depletion that can harm aquatic life and lead to fish kills; and presence of toxins.

Total Suspended Solids (TSS)

Total suspended solids (TSS) include all particles or material mixed in the water that will not pass through a filter. Thus, TSS is often used as a surrogate measure of water clarity or murkiness. Suspended solids may originate from point sources such as sanitary and industrial wastewater, but most tends to originate from nonpoint sources such as soil erosion from construction sites, urban/suburban sites, agriculture and exposed streams or riverbanks. As levels of TSS increase in aquatic systems, water temperature increases and levels of dissolved oxygen decrease. Fish and aquatic insect species are very sensitive to these changes which can lead to a loss of diversity in aquatic life.

While Michigan’s Water Quality Standards do not contain numerical limits for TSS, a narrative standard requires that waters not have any of these physical properties: turbidity, unnatural color, oil films, floating solids, foam, settleable solids, suspended solids, or deposits. Water with a TSS concentration less than 20 mg/L (ppm) is considered clear. Water with levels between 40 and 80 mg/L appear cloudy, and water with concentrations over 150 mg/L usually appear muddy. In streams that have shown impairments to aquatic life due to sedimentation, TSS is used as a surrogate measure for Total Maximum Daily Load (TMDL) regulations, since large amounts of sediment can bury potential habitat for aquatic macroinvertebrates. This is the case for Frank and Poet, Brownstown, Blakely, and Ecorse creeks (North and South branches) TMDLs as well as Smith and Silver creeks 303d listing. Those evaluations set the following targets for TSS:

• Optimum: TSS < 25 mg/L
• Good to Moderate: 25 mg/L < TSS < 80 mg/L
• Less than moderate: 80 mg/L < TSS < 400 mg/L
• Poor: TSS > 400 mg/L

Sediment-phosphorus relationship

Phosphorus tends to bind or stick to particles. Thus, identifying a relationship between TP concentrations and the corresponding TSS measurements can help determine whether the TP originates from sediments or erosive processes. If TP and TSS concentrations show a strong, positive relationship, sedimentation is a potential source of P. If there is not a correlation, P may exist as dissolved forms (e.g., phosphate) and originate from other sources.

Bacteria (E. coli)

Escherichia coli (E. coli) counts measure the presence of bacteria or pathogens that originate in the digestive tracts of warm-blooded animals. Their presence may indicate the presence of sewage, wastewater, or other waste sources. These bacterial counts are not specific enough to directly indicate health risks. Consistently high levels, however, serve as a warning of potential health risks and warrant further investigation to determine the source of bacterial contamination. The State of Michigan water quality standard for total body contact is a monthly average of 130 counts per 100 mL, while a single sampling event for waters protected for total body contact is less than 300 E. coli counts per 100 mL. Michigan also regulates that all waters protected for partial body contact recreation have less than 1000 E. coli counts per 100 mL during a single sampling event. Most reaches in the Lower Huron, Ecorse Creek, and Combined Downriver watersheds are included in the new Michigan statewide E. coli TMDL for impaired waters due to bacterial contamination.

Dissolved Oxygen (DO)

Dissolved oxygen (DO) is a measure of the amount of gaseous oxygen in the water, which enters water through the physical process of aeration or through the biological process of aquatic plant photosynthesis. DO levels drop to very low levels in warm, stagnant water, whereas fast-flowing, cooler water generally has high concentrations of DO. Some forms of pollution can also impact DO levels. For example, excess particles or organic matter as well as nutrients such as phosphorus and nitrogen and resultant algal blooms can reduce DO concentrations.

Most aquatic plants and animals require a certain level of DO for survival. Normal DO values in Michigan waters that support aquatic life range between 5 to 15 mg/L. The statewide minimum water quality standard is 5 mg/L. DO levels below this standard impair aquatic life and hypoxic levels, less than 2 mg/L, harm and even kill most aquatic species. However, concentrations change throughout the day and night due to air and water temperature changes, photosynthesis, respiration, and decomposition.

Conductivity 

Conductivity is a measure of conductible (charged, inorganic) substances dissolved in the water, and is a general measure of water quality. Conductible substances include dissolved inorganic compounds, such as sulfates, nitrates, phosphates, and salts. Conductivity is affected by temperature: the warmer the water, the higher the conductivity. Conductivity in surface waters is affected primarily by the geology of the area through which the water flows.

In Michigan, values for a healthy river or stream habitat range between 100 and 800 µS/cm . Low values are characteristic of oligotrophic (low nutrient) lake waters, while values above 800 µS/cm are characteristic of eutrophic (high nutrient) lake waters where plants are in abundance. There are also several potential sources of minerals and some natural variations that contribute to conductivity, but consistent results above 800 µS/cm would be unexpected from natural sources. Anthropogenic sources can include winter road salts, fertilizers, drinking water softeners, metals, and other pollutants.

pH

pH provides information about the hydrogen (H+) and hydroxide (OH-) ion concentration in the water or the level of acidity or basicity. pH is measured on a logarithmic scale that ranges from 0 to 14, with 7 being neutral. Solutions with a pH less than 7 are considered acidic and solutions above 7 are considered basic. Organisms that live in rivers and streams can survive only in a limited range of pH values. Michigan Water Quality Standards require pH values to be within the range of 6.5 to 9 for all waters of the state. In Michigan surface waters, most pH values range between 7.6 and 8.0. The pH of rivers and streams may fluctuate due to natural events, but inputs due to human activities can also cause abnormal fluctuations in pH.

Temperature

Water temperature dictates which aquatic life will inhabit waterways and controls the gas content of water such as dissolved oxygen or carbon dioxide (as the temperature of water increases, the concentration of dissolved gases decreases). It also influences the rate of both chemical and biological reactions.

Water Velocity/Flow

Measuring water velocity at the long-term monitoring sites, along with collecting water samples that are analyzed for nutrient concentrations, allows for calculating the “load” of a particular nutrient for a specific moment in time. A “load” is a measure of the amount of a substance entering a water body, usually expressed as pounds per year. Concentration, when coupled with stream discharge, can be used to estimate the export rates of various compounds in the water including phosphorus or other nutrients for the subwatershed, and to estimate the loading rates of these compounds to receiving waters.

The procedures used in this monitoring program have been reviewed and approved by the Michigan Department of Environment, Great Lakes, and Energy (EGLE). Complete procedures are documented thoroughly in the program’s Quality Assurance Project Plan (QAPP). The QAPP was originally developed at the beginning of the program in 2012, and revised and approved by EGLE in 2019. The following is a summary of those methods and procedures.

Stream monitoring was conducted twice per month between April and the end of September at the monitoring sites described above. The volunteer monitoring teams visit each site and complete an ArcGIS Survey 123 field datasheet documenting the site location, date and time, team members and current and previous day weather conditions. Volunteers also use the Survey 123 app to record water sample information and the water quality measurement results from the YSI multimeter for water temperature, pH, DO, and conductivity. If volunteers measured stream flow during a field outing, a Survey 123 flow record is created to log of 15 – 20 velocity measurements across the width of the stream or river. Upon completion of the fieldwork, the monitoring team delivers water samples to a partnered laboratory, in 2023 the program partnered with the South Huron Valley Utility Authority, for analysis of TP, TSS, and bacteria.

Sample Collection Methodology

Water samples are completed first at each site to minimize the disturbance of the stream substrate, which could artificially raise the amount of suspended matter in the water column. For all samples, the team member follows the same “grab” sampling protocol in accordance with the method prescribed in the 1994 EGLE field procedures manual for wadable streams.

In brief, 1 L in-stream samples are collected in HDPE plastic bottles and capture upstream water from an arm’s length of the volunteer. When stream depth permits, water is taken from the middle of the water column and in the middle of the stream cross-section. The sample bottles are rinsed three times with stream water prior to taking the sample. A separate 100 mL sample is collected without rinses in a sterile 125 mL sample cup for E. coli analysis. All samples receive labels and are stored on ice in a cooler until delivery to the laboratory for analysis. The laboratory analyzes the samples for TP, TSS, and E. coli. E. coli analyses are conducted within 6 hours of collection. If TP samples cannot be analyzed within the method-specified holding period after delivery to the lab, they were treated with preservative.

In-Stream Chemistry Monitoring Methodology

Five water quality chemistry parameters – water temperature, DO, conductivity, total dissolved solids (TDS), and pH – are routinely measured at all sites using a YSI Professional Plus (Pro Plus) multiparameter sensor. For all measurements, the multi-probe instrument was submerged at the appropriate water level at arm’s length distance and upstream from the team member. The results were read from the digital display and recorded in the field survey.

Flow Monitoring Methodology

Water velocity was measured directly in the stream after water samples were collected and water quality testing was completed. Flow was measured at each long-term site by team members across a range of measured water levels. Where stream discharge instrumentation or a water level gage was in place, discharge measurements can be charted against water level to establish a “rating curve.” Once established, the rating curves were used to estimate discharge from water level observations. USGS water-level sensors are located at North Branch Ecorse Creek and in Frank & Poet Creek. The program has also partnered with the University of Michigan Digital Water Lab to install and maintain low-cost water level sensors that record real time water level data. Sensors are installed at Ecorse Creek , Huron River at Metro Parkway, and in Brownstown Creek.

The monitoring sites within the ADW fall within three different sub-watersheds of two river drainage basins: the Detroit River and the Huron River. In this section, water quality trends are assessed in the Lower Huron River watershed, as well as the Ecorse watershed, and the Combined Downriver watershed, which is comprised of 3 individual creeks located in the most downstream section of the Detroit River – Frank and Poet Creek, Brownstown Creek, and Blakely Creek.

Data from the most downstream Huron River site, ADW23 – Huron River at Ford Rd, is evaluated on its own in this section to track water quality over time and diagnose emerging water quality concerns in the main stem of the river. Data collected across the Ecorse Creek watershed and the Combined Downriver watershed are assessed to track changes on the sub-watershed scale. While these creeks drain into the Detroit River, no monitoring occurs on the main stem of the Detroit River, and all monitored tributaries are small in comparison to other inputs to the river. Thus, the results are not representative of the water quality in the Detroit River main stem. Individual tributary results, including tributaries to the Huron River, are explored in the next section, Results by Tributary.

Total Phosphorus

TP concentrations are above the goal levels in the Lower Huron, Ecorse Creek, and the Combined Downriver watersheds (Figure 1 & 2).

TP in the main stem of the Lower Huron is lower than the tributaries that feed into it and shows a decreasing trend over time (Figure 1). Across all monitored years (2016 – 2023), the median concentration in the Huron River at Fort Road is 0.04 mg/L. While this median concentration is above the desired target of 0.03 mg/L for the river, it is slightly lower than the TP concentrations observed upstream in the main stem of the river in Ypsilanti (see Washtenaw County report) and it is about half that of the median concentrations observed in its tributaries . Further, over the period of record, TP concentrations tend to decrease over time. This rate of change is more prominent when analyzing mean concentrations rather than medians (-4.6 µg/L/y, r2= 0.73 vs. -2.9 µg/L/y, r2= 0.34). These finding suggest (1) there is a reduced frequency and magnitude of high TP concentrations over time in the main-stem (Figure 1; black “x”), (2) that TP is both being removed from the system and/or TP concentrations are diluted from upstream to downstream, and (3) the inputs of high TP from point and nonpoint sources in the Lower Huron may be declining. Yet, concentrations remain just above the desired 0.03 mg/L target.

In the Ecorse Creek watershed and the Combined Downriver watershed, however, median TP (0.09 mg/L for both watersheds) over the entire period of record is above typical reference levels and 20 µg/L higher than the target concentration of 0.07mg/L for streams in this ecoregion (Figure 2). TP is variable ranging from between 0 to 1.25 mg/L in Ecorse Creek and 0 to 1.9 mg/L in the Combined Downriver watershed with median values staying relatively constant over time. These findings suggest inputs from unnatural sources are contributing to TP loading such as sediment erosion, fertilizers, or human or animal waste with no clear reductions over time. Although, the Combined Downriver streams had the lowest median TP concentrations in 2023.

Total Suspended Solids

The branches and creeks that make up the Ecorse Creek watershed, Combined Downriver watershed, and Huron River watershed all have TMDLs to improve the habitat for biota that set limits on sediments as measured as total suspended solids (TSS). Since monitoring began in 2012, Ecorse and the Combined Downriver watersheds have had relatively consistent TSS mean and median values below the “moderate” threshold and the TMDL target of 80 mg/L for the overall period of record (Figure 3) with occasional spikes in TSS following storm events. Some of the highest concentrations were observed in 2021 and 2022 in both watersheds (Figure 3). These high TSS values in recent years indicate that erosion or soil runoff during storm events persist likely due to flashy flow regimes that cause significant erosion of stream banks and possibly bottoms. However, no exceedances were recorded in these watersheds in 2023. Further, 2023 median values were below the “optimum” TSS threshold (< 25 mg/L), suggesting that sediment supply in these streams may be comparable to natural conditions a majority of the time. Even still, mitigation and restoration efforts to reduce flashiness and stabilize stream banks are needed in these watersheds to make progress toward meeting the sediment targets during higher flow conditions.

The Huron River main stem is not impaired for sediments as confirmed by median and mean TSS values below the “optimum” threshold (< 25mg/L) and no exceedances of 80 mg/L throughout the period of record. Some more exceedances, however, have been documented in its tributaries during storm events. Huron River tributary TSS data are assessed further in the next section.

Sediment-phosphorus relationship

Sediment phosphorus relationships vary across sites in these three watersheds, but generally are stronger in the Ecorse and Combined Downriver watersheds than in the Lower Huron River watershed. In the Huron River at Fort Rd there is not a statistical relationship between TP and sediments, suggesting that sediments do not explain the variability in TP and rather the bulk of the TP may be in the dissolved form before entering the Western Basin of Lake Erie. This is of concern since dissolved P tends to be easier to use by algae for growth. Sediment phosphorus relationships in the Ecorse and Combined Downriver watersheds are much more variable with r-squared values (correlations) ranging from 0.04 to 0.88. The North Branch of Ecorse Creek and Frank & Poet Creek have the strongest relationship when all data points between 2012 and 2023 are considered.

Bacteria (E. coli)

E. coli bacteria levels in the main stem of the Huron River regularly meet state standards for recreational partial and full body contact (Figure 4). E. coli values are highly variable in the river, but geomeans and medians for the Huron River at Fort Road are less than the 300 counts/100mL single event, full body contact standard for all monitored years (Figure 4). On rare occasions, generally after storm events, E. coli counts spike above the full body contact standard in the Huron River, but none have ever been measured above the partial body contact limit of 1000 counts/100mL. Unfortunately, both the frequency and magnitude of E. coli spikes in 2023 were the highest recorded, possibly due to extreme weather events . For example, the flash drought conditions in May and June of 2023 were ideal for E. coli growth and heavy rains later in the summer and fall of 2023 led to documented sanitary sewer overflows (SSOs) in the watershed. Correlating the influence of SSOs for this large river site is difficult, however, due to the size of the watershed and the lag time, dilution, and potential transformations of bacteria as it travels to this downstream location. Regardless, these increases in E. coli counts in 2023 are cause for concern since the main stem of the Huron River is highly recreated.

E. coli bacteria levels in the Ecorse and Combined Downriver watersheds, on the other hand, regularly exceed state standards for recreational partial and full body contact. While E. coli values are still highly variable in these two watersheds, geomeans and medians for all monitoring years have exceeded the 300 counts/100mL full body single event contact limit. Additionally, each year several measurements exceed the partial body contact limit of 1000 counts/100mL for a single event. There have been no signs of improvement over time despite some of the lowest E. coli counts recorded in 2023. Overall, more work is needed to address E. coli throughout the ADW, especially in the Ecorse and Combined Downriver watersheds. The public should also be advised of the risks of recreating in these waters.

Conductivity

Due to both the ecoregion of the ADW and natural weathering weathering processes as well as increased inputs, conductivity increases from upstream to downstream in the Huron River. Median conductivity over time at ADW23 is 820 µS/cm which is about 30 µS/cm higher than the median in the Huron River at E. Cross St. in Ypsilanti (see Washtenaw report). The median conductivity at ADW23 is reasonable for the ecoregion of the watershed but falls slightly above the upper conductivity limit for healthy waters (800 µS/cm). ADW23 receives inputs from almost the entire Huron River watershed that drains several known tributaries with extremely high conductivity (i.e. medians > 900 µS/cm; mainly in the middle Huron). Together these high concentrations suggest there are likely unnatural inputs of conductivity to the Lower Huron River that require further investigation and may impact aquatic life, especially macroinvertebrates.

Ecorse creek and the Combined Downriver watersheds have even higher conductivity values than the Huron River with overall medians of 1300 µS/cm and 1047 µS/cm, respectively. Again, the geology in the ecoregion of these creeks contributes to some of these high conductivity concentrations, but extreme highs are likely caused by other factors such as anthropogenic pollution. The landscape that drains into the creeks in these watersheds does not resemble the natural landscapes of this ecoregion, but rather consists of large residential areas with some interspersed commercial and industrial locations. This land use and subsequent channelization of these streams together have altered their flow regimes. Flashy flows with little or no baseflow increases physical weathering and land-based inputs of nutrients and salts during storms contributing to consistently high conductivity that poses a threat to aquatic life.

Dissolved Oxygen (DO)

Dissolved oxygen in the Lower Huron typically meets state standards. There have only been 3 years – 2019, 2022, and 2023 – across the period of record when DO in the Lower Huron has fallen below the impaired threshold for aquatic life of 5 mg/L. In 2019 and 2022, low DO was only recorded once in the Huron River at Fort Rd, suggesting that aquatic life may have been able to seek refuge elsewhere during the short-term low DO event. In 2023, however, low DO was recorded in May, June, and July during a time when southeast Michigan was experiencing flash-drought conditions. These instances were not sequential and likely caused intermittent periods of stress on aquatic life as they were forced to relocate for short periods of time to survive. Low DO in a flowing river is concerning and may need to be further investigated to determine extent. Since the occurrence of these extreme weather events are only expected to increase with climate change, parts of the Lower Huron River may become more vulnerable to DO impairments in the future.

DO concentrations in the Ecorse Creek and Combined Downriver watersheds varies among creeks. Over time in both watersheds, DO values tend to follow a normal seasonal trend of high DO in the spring and fall with low DO (slightly below saturation; < 8 mg/L) in the summer with values sometimes falling below the 5 mg/L aquatic life threshold. Ecorse Creek experiences low DO at least once a season in the northern branch of the creek and occasional low DO in the south branch. In the Combined Downriver watershed, Frank & Poet and Blakely Creek experience occasional low DO in the summer months, while Brownstown Creek consistently experiences low DO near hypoxic levels (2 mg/L). Like the Huron River, some records of low DO in these two watersheds are associated with periods of hot and dry conditions. Others are the result of flashy flow regimes that cause creeks, especially Brownstown Creek, to become stagnant. Restoration efforts in these watersheds to address flashy flow regimes is needed especially as flows are further disrupted by climate change.

pH

The Lower Huron, Ecorse, and Combined Downriver watersheds all have stable pH values between the acceptable range of 6.5 to 9 throughout the period of record. Though the pH range varies between individual creeks, most values fall between 7.6 and 8 pH units.

Temperature

The monitoring season occurs during the spring and summer months when water temperatures increase. Temperatures in the Lower Huron River are cold in early April (i.e. between 5 – 14°C) and warm into the summer months (generally between 20 – 27°C). In the summer months, native fish species will seek cooler water or die off when water temperatures exceed 29°C (85°F). There have been no recorded values above this high temperature threshold in the Lower Huron at Fort Road. Only a few records of high temperatures in the Huron River have been recorded upriver and were localized events in shallow sections of the river with significant sun exposure (see Washtenaw report).

Ecorse and the Combined Downriver watersheds also follow typical seasonal trends with cold water temperatures in early April (i.e. between 4 and 16°C) and warm temperatures in the summer months (between 19 – 28°C). All the creeks tend to have similar temperature ranges that are supportive of aquatic life. This is likely due to the riparian zone tree canopy that often shades the sampling locations of these creeks.

Macroinvertebrates, Aquatic Quality and Diversity

All macroinvertebrate data collected over time in the ADW can be explored on HRWC’s Aquatic Critters Benthic Macroinvertebrates Dashboard. The ADW 2023 Biomonitoring Report provides detailed information on the 2023 data and findings. Overall, additional work is needed to restore the benthic macroinvertebrate community in the Downriver area and better address the various TMDL’s for biota in the Ecorse and Combined Downriver watersheds.

Flow

Visit the Digital Water Lab Water Level and Flow webpage to explore flow records from the University of Michigan’s node network. Additional flow data in the ADW is also available through the USGS: Ecorse Creek North Branch gage and Frank & Poet gage.

In this section, water quality parameter trends are assessed at each of the eight long-term tributary sites: Woods, Silver, Smith, N. Ecorse, S. Ecorse, Frank & Poet, Blakely, and Brownstown creeks. Water quality trends are examined for trends related to land cover and use and drainage size as well as to identify potential hot spots of pollutants. Woods Creek subwatershed has the least amount of impervious surface and drains a mix of land uses including 42% natural land, 35% agricultural, and 19% residential and commercial land. Silver and Smith creeks, like Woods Creek, drain mixed land use area, but with less agricultural land and more residential and commercial areas. The five other monitored creeks that drain into the Detroit River – N. Ecorse, S. Ecorse, Frank & Poet, Blakely, and Brownstown creeks – have large amounts of impervious surface coverage and drain highly urban and suburban residential and commercial/industrial areas. Woods Creek is the smallest sub-watershed in this section of the Huron River watershed and Brownstown Creek is the smallest sub-watershed to the Detroit River.

Overall, the sites with urban drainages in the Ecorse Creek and Combined Downriver watersheds tend to have greater water quality concerns than those draining more mixed-use land in the Huron River watershed . Urbanized sites tend to be hot spots for nutrients, sediments, E. coli, and conductivity pollution based on evaluations of concentrations. While mixed use sites, especially Silver Creek, are still large contributors of phosphorus, bacteria, and sediments.

Total Phosphorus (TP)

The program assesses TP concentrations in all creeks within the ADW against a standard of 0.07 mg/L, which is the long-term 75th percentile concentration at Woods Creek, ADW06, which is defined as the “reference site” for the area. That standard is also consistent with regional analysis conducted by the U.S. EPA in 2001. Tributaries are assigned a grade based on the percentage of data collected over the last five years that fell below the target threshold according to the following scale:

• A = 80-100%
• B = 60-80%
• C = 40-60%
• D = 20-40%
• F = 0-20%

The table below lists current grades for each tributary from data collected between 2019 and 2023.

Total Phosphorus Grades by Long-Term Site

*Huron River (Rockwood) is assessed based on the standard 0.03 mg/L since it is a large river that drains more than one ecoregion

Individual river and tributary site data help decipher potential sources of phosphorus in the Lower Huron sub-watershed and Ecorse and Combined Downriver watersheds. Individual tributary results are not representative of conditions throughout each of the three watersheds, but rather represent the conditions within the respective tributary and sub-watershed. Figure 6 shows TP concentrations for each long-term tributary site over the entire period of record (2012-2023). TP concentrations are variable within a single site and among sites, but most creeks have average and median values above the 0.07 mg/L target. Despite a significant declining trend in the main stem of the Lower Huron River, Smith Creek is the only tributary in the ADW with a significant declining TP trend.

Woods Creek has had the lowest TP concentrations over the period of record, with a mean concentration of 0.026 mg/L in 2023 (median = 0.025 mg/L). This site serves as the reference site for TP concentrations since it drains primarily natural lands representative of a “natural” stream in this ecoregion. Even still, it only earned a B grade over the last five years. Smith Creek, another tributary of the Lower Huron River also received a B grade with annual median TP equal to or less than the 0.07 mg/L target over the last 5 years. In 2023, the mean TP concentration at Smith Creek was the lowest recorded at approximately 20 µg/L below the target (mean = 0.053 mg/L, median = 0.055 mg/L). The other monitored tributary of the Huron River, Silver Creek , received a C score with annual mean TP exceeding the target value 4 of the last 5 years. In 2023, Silver Creek had its lowest recorded annual mean TP concentration of 0.059 mg/L (median = 0.05 mg/L). While low concentrations were observed at Silver Creek in 2023, only data at Smith Creek shows a significant declining trend in TP over time (slope = -3.3 µg/L/yr, r2 = 0.342, p-value < 0.05). This decreasing trend in TP at Smith Creek along with decreasing trends in TP upstream in the Middle Huron sub-watershed are likely contributing to the similarly decreasing TP concentrations in the main stem of the Lower Huron. It is not clear if there is a cause for these decreasing trends.

TP in the three creeks within the Combined Downriver watershed tends to be higher than the creeks draining into the Lower Huron River. Both Frank & Poet and Brownstown creeks received C scores. Concentrations have varied over the years at these sites. Frank & Poet recorded a rare maximum TP value above 0.5 mg /L. Both creeks did have their lowest recorded annual median values in 2023 with 0.057 mg/L at Frank & Poet Creek and 0.035 mg/L at Brownstown Creek. Blakely Creek, however, has higher recorded TP than Frank & Poet and Brownstown creeks throughout the monitoring record. Median TP values for three of the last five years were above 0.1 mg/L at Blakely Creek. However, again TP concentrations in 2023 at Blakely Creek differed from longer term values and were the lowest recorded year in that site’s record with an average of 0.071 mg/L (median = 0.061 mg/L). Brownstown Creek is the only creek in the Combined Downriver watershed that shows some sign of declining TP concentrations over the last four years, but the trend is not significant over the entire period of record. Additional data will determine if this trend is a real sign of improvement.

The south and north branches of Ecorse Creek have the highest TP concentrations observed in the ADW. Both sites tend to have yearly median concentrations about 10 to 30 µg/L above the target concentration. Unlike the other ADW sites, median and average concentrations were not low in 2023 with an average of 0.12 mg/L in the north branch and 0.16 mg/L in the south branch.

The high concentrations in both the Ecorse and Combined Downriver creeks are likely reflective of the highly urban, suburban, and commercial and industrial land these creeks drain. Fertilized lawns, eroded sediments, and pet waste are large contributors of TP to creeks especially with a lack of natural areas to trap and treat runoff. Additionally, as mentioned in the subwatershed section of this report, as urbanized creeks, these creeks are heavily channelized. This combined with the large amounts of impervious surfaces leads to flashy flows that erode stream banks and input large amounts of TP from the phosphorus rich sediments found this ecoregion. Restoration and mitigation strategies, such as broad-based green stormwater infrastructure and regional detention, need to be implemented to help reduce TP inputs to these creeks. They drain into the larger Detroit River — a major source of TP to the western Lake Erie Basin, which has been plagued by harmful algal blooms since the 1970s.

Total Suspended Solids (TSS)

TSS concentrations in the ADW tributaries are assessed against a stormwater standard of 80 mg/L. With this standard, the stream should not exceed the threshold during high precipitation events (or ever). Since storm samples are rare, grade ranges are narrow. Tributaries are assigned a TSS grade based on the percentage of data collected over the last five years that fell below the target threshold according to the following scale:

• A = 99-100%
• B = 96-99%
• C = 92-96%
• D = 85-92%
• F = 0-85%

The table below lists current grades for each tributary stream through data collected through 2023.

Total Suspended Sediment Grades by Long-Term Site

Most TSS concentrations are below the state standard of 80 mg/L, but storms can generate turbid runoff with values above this threshold (Figure 7; outliers above red line marked with “x”). Over the past five years, storm erosion has been minimal in the tributaries of the Lower Huron River with Woods, Silver, and Smith Creek all receiving B grades. None of these tributaries have had any TSS values above the 80 mg/L target for the last 3 years. They each received B grades due to one occurrence of high TSS after different storm events in either 2019 or 2020. Otherwise, they all have had median TSS values in the optimum range (< 25 mg/L) over the entire period of record.

High TSS concentrations are documented in the creeks that make up the Combined Downriver watersheds, but again annual medians over the entire period of record fall within the optimum range (<25 mg/L). Frank & Poet and Blakely creeks, both of which have a TMDL for biota with a TSS limit of 80mg/L to protect habitat, have each had at least two occurrences of TSS above this limit in the last 5 years. In 2021 and 2023, however, neither site had TSS values that reached above the 80 mg/L target even though there were notable storms that brought record rain fall. This is likely due to the two-week cadence of sampling not capturing TSS data immediately following those storm events in June of 2021 and August of 2023. Unlike Frank & Poet and Blakely creeks, Brownstown Creek has not had any TSS exceedances in the last seven years and received an A score. This again is likely due to sampling bias because this stream has an extremely flashy flow regime with little to no baseflow. Unless samples are collected during a rain event, it is difficult to capture TSS along the rising or falling limb of the hydrographic curve.

Like two of the creeks in the Combined Downriver watershed, the two branches of Ecorse Creek also have TMDLs for biota with TSS targets included. The south branch has had at least one occurrence of TSS above 80 mg/L in 3 of the last 5 years and the north branch has had at least one occurrence of TSS above the limit in 4 of the last 5 years. The north branch had a maximum TSS value of 446 mg/L August of 2021 several days after a rain event with 3 to 5 inches of rain. Both branches of Ecorse Creek also experience flashy flows, both due to the high percentage of impervious surfaces they drain and channelization, which makes them more prone to murky waters after storm events.

Additional mitigation and restoration efforts are needed to reduce erosion and sedimentation in both branches of Ecorse Creek, Frank & Poet Creek, and Blakely Creek to meet the TSS limits outlined in their TMDLs for biota. An emphasis on slowing stormwater runoff and reducing flashy flows during storm events is essential not only for reducing TSS concentrations, but also to mitigate many of the other water quality concerns in these creeks (e.g. low DO, high TP, and lack of macroinvertebrate populations and diversity).

Bacteria (E. Coli)

Bacteria levels in ADW tributaries are assessed against the state’s single sample standard of 300 E. coli counts per 100 mL for full body contact. Tributaries are assigned a bacterial grade based on the percentage of data collected over the last five years that fell below the 300 E. coli counts per 100 mL target threshold according to the following scale:

• A = 97-100%
• B = 90-97%
• C = 75-90%
• D = 50-75%
• F = 0-50%

The table below lists current grades for each tributary stream through data collected through 2023.

Bacteria Grades by Long-Term Site

Aging infrastructure, which includes combined sewer and stormwater systems, illicit connections, impervious surfaces, makes streams in the ADW susceptible to high bacteria levels. While no streams in the ADW received grades above a C, tributaries of the Lower Huron River received the best on average, with a C at Woods Creek, an F at Silver Creek, and a D at Smith Creek. Woods Creek drains a large percentage of natural area relative to other ADW monitoring sites, but it also drains 35% agricultural and 16% residential land that can contribute bacteria from livestock, pet waste, or illicit connections. Even with fewer potential inputs, Woods Creek has not met the full body contact limit a handful of times in 3 of the last 5 years. Woods Creek, however, has only exceeded the partial body contact limit (> 1000 MPN/100 mL) once over the last five years. As impervious surfaces cover a greater area in Silver and Smith creeks, bacteria levels are higher. Values exceed the full body contact limit in these creeks almost 50% of the time with maximum values exceeding the single event partial body contact limit (> 1000 mg/L) almost every year.

Bacteria levels worsen in the tributaries of the Detroit River. All five monitoring locations drain primarily urban and suburban areas of mixed residential, commercial, and industrial uses. Median and geomean values at all three long-term monitoring sites in the Combined Downriver watershed generally are equal to or greater than the 300 counts/100 mL full body contact single event standard. All three sites have also had one to two years with geomeans that exceed the partial body contact single event limit of 1000 counts/100 mL. In Brownstown Creek, two yearly geomeans exceeded 2000 counts/100 mL. The two branches of the Ecorse creek are worse still, with yearly geomeans often exceeding the partial body contact single event limit. Both branches had at least one yearly geomean above 2000 counts/100 mL. Both branches also had the highest recorded geomeans in 2019 and one of their lowest recorded geomeans in 2023. None of the tributaries in the Combined Downriver watershed show signs of improvement in bacterial levels over time.

Overall, significant work is needed to address E. coli and other pathogens in the ADW tributaries, especially in Ecorse Creek and the Combined Downriver creeks, and the public should be advised of the risks of recreating in these creeks. Full body contact activities are ill-advised, and recreationalists should use caution and disinfect after contact with tributaries due to many streams exceeding the partial body contact standard in the last five years.

Conductivity

Conductivity values at most sites in the ADW are periodically elevated above the target threshold of 800 µS/cm during the sampling season. The urban sites in the ADW, especially the branches of Ecorse Creek, generally have the highest readings. Conductivity is naturally high in this ecoregion, but values above 800 µS/cm suggest potential human sources of contamination. As with other contaminants evaluated in this report, the tributaries of the Lower Huron tend to have lower conductivity values than the tributaries of the Detroit River. Woods Creek has never exceeded the target value, while at least 25% of all conductivity data each year in Silver and Smith creeks tends to exceed the standard. Blakely Creek similarly only tends to have about 25% of yearly data exceed the standard. Frank & Poet and Brownstown creeks on the other hand consistently have yearly median values above 900 µS/cm. Both branches of Ecorse Creek also have yearly medians generally greater than 900 µS/cm with maximums that have reached above 2000 µS/cm many years. The highest values are often observed during periods of low baseflow associated with hot and dry atmospheric conditions, such as the flash drought between May and July 2023.

Additional work is needed to track sources contributing to high conductivity. Due to multiple large highways within the Downriver area, one potential source is road salt contamination that can build up over time in groundwater. Salinity has been estimated in these creeks using 2023 data and standard translations from conductivity as part of the program’s participation in the Lake Erie Volunteer Science Network. Estimates suggest high salinity occurs in Ecorse, Frank & Poet, and Brownstown creeks. The north branch of Ecorse Creek may be experiencing high salinity frequently, suggesting ecosystem degradation, while Frank & Poet and Brownstown creeks have fewer, non-consecutive occurrences that may allow for aquatic life to seek refuge during these periods of high salinity. Again, these conclusions are based on estimates and should be validated by direct measures of salinity, chloride, or sulfate.

Dissolved Oxygen (DO)

Dissolved oxygen concentrations regularly meet state standards in all tributaries in the ADW during the spring months, but DO tends to decrease in the summer with occasional low DO (< 5 mg/L) observed at most sites. Woods Creek is the only long-term monitoring site in the program that has not had any occurrences of low DO below the aquatic life standard. All other long-term sites have had occurrences of low DO with some concentrations falling near or below hypoxic levels (< 2 mg/L). Silver Creek had minimum DO values below the hypoxic threshold three of the last 5 years. Brownstown Creek experienced consistently low DO with more than 50% of all DO records falling below the aquatic life standard. Brownstown Creek has notoriously stagnant flow that prevents the waters from being replenished with oxygen. Most other sites only experience one to two occurrences of low DO a monitoring season. These low measurements are often associated with hot and dry conditions that contribute to stagnant water such as the flash-drought conditions recorded in Southeast Michigan between late May and early July of 2023.

pH

Tributary pH records differ slightly across sites, but tend to be stable over time at individual sites. There have been no recorded pH values at the eight creek monitoring locations that have fallen outside the state water quality standards of 6.5 to 9.0.

Temperature

The monitoring season occurs during the spring and summer months when water temperatures increase as air temperatures increase. Temperatures in the tributaries range between 4 – 16°C in early April and warm to between 20 – 29°C in the summer months. Most of the tributary sites are shaded by riparian buffers that help protect their often-shallow waters from overheating. There has only been one occurrence of high water temperatures in Woods Creek back in 2014. Frank & Poet Creek and Blakely Creek also had water temperatures that neared 28 to 29°C in 2012. Otherwise, water temperatures have been normal and supportive of aquatic life throughout the Lower Huron tributaries and Ecorse and Combined Downriver creeks through 2023.

Flow

Analysis to come!

Macroinvertebrates, Aquatic Quality and Diversity 

A detailed summary of the macroinvertebrate analyses and findings are available in the 2023 Biomonitoring report. The findings further corroborate the conclusions outlined in each of the chemistry analyses above. For example, Woods Creek has the greatest macroinvertebrate abundance and diversity consistent with this creek having the best water quality with low TP, low bacterial counts, low conductivity, and DO concentrations that generally support aquatic life. Macroinvertebrate abundance and diversity tends to decrease the more impervious surfaces the other Downriver tributaries drain resulting in high, poor water quality ratings and low EPT and sensitive species counts. Explore the macroinvertebrate data further on HRWC’s Benthic Macroinvertebrate Dashboard.

Funding Partners & Governments

The Wayne County/Downriver Chemistry and Flow Monitoring Program is a project of the Alliance of Downriver Watersheds. The ADW is a voluntary watershed-based group of 23 public agencies working together since 2007 to cooperatively manage the rivers, lakes and streams within the watershed. Member governments include:

Allen Park
Belleville
Dearborn Heights
Ecorse
Flat Rock
Gibraltar
Grosse Ile Township
Inkster
Lincoln Park
Melvindale
Riverview
Rockwood
Romulus
Southgate
Sumpter Township
Taylor
Trenton
Van Buren Township
Wayne County
Westland
Woodhaven
Woodhaven-Brownstown School District
Wyandotte

Partners and Volunteers

The strength and breadth of the ADW Chemistry and Flow Monitoring Program is made possible by the generous time and effort provided by the over 40 annual volunteers. The ADW and the Huron River Watershed Council would like to sincerely thank the volunteers and leaders for their dedication to the program.

The ADW would also like to thank the South Huron Valley Utility Authority in Brownstown Township for providing water sample processing and analysis.

For additional information on the Chemistry and Flow Monitoring Program and results, please contact Kelly McCabe at [email protected].

To become a volunteer in the program, please visit hrwc.org/chemflow.