Excessive Loading of Nutrients and Sediments (BUI #6) Preliminary Workgroup Meeting

Thursday, March 11, 2004
6:30 - 8:30 pm
DeWitt-Seitz 3rd floor conference room

Attending: R.C. Boheim, Nancy Larson, Kay McKenzie, Paul Sandstrom, Jesse Schomberg, Ted Smith

• IJC Criteria: An impairment will be listed when there are persistent water quality problems (e.g. dissolved oxygen depletion of bottom waters, nuisance algal blooms or accumulation, decreased water clarity, etc.) attributed to cultural eutrophication.

Although persistent water quality problems associated with eutrophication are not observed currently in the estuary, the high levels of nutrients and sediments being delivered to Lake Superior is an important concern. Therefore, the RAP will use a modification of the IJC eutrophication criterion to reflect local conditions.

• Adaptation of IJC Criterion to Fit Local Conditions: High nutrient and sediment levels in the St. Louis River estuary lead to excessive loadings to Lake Superior, although these high nutrient levels do not seem to be expressed as eutrophication in the Area of Concern.

• SLR RAP Rational for Listing: Prior to the improvements in wastewater treatment in the late 1970's in this area, water quality and biological investigations characterized the St. Louis estuary as eutrophic. At this time, the Western Lake Superior Sanitary District (WLSSD) treatment plant was built and the Superior wastewater treatment plant was upgraded. Since that time, many indicators of trophic status have shown improvements. For instance, concentrations of total phosphorus, ammonia, and organic nitrogen have decreased in the St. Louis Bay. The loading of phosphorus to the estuary from point sources has been reduced substantially. Further work is needed to ascertain the effects of nonpoint source loadings to the system and to Lake Superior. Despite the reductions in point source loadings, phosphorus concentrations in the estuary remain at levels where eutrophic conditions might be expected. However, algal biomass has been lower than would be expected given these high phosphorus concentrations. Chlorophyll A concentrations measured in the estuary have been similar to levels found in mesotrophic or oligotrophic waters. Several investigators have proposed that reduced light penetration due to turbidity and color may be a limiting factor for algal growth in the estuary. Although persistent water quality problems associated with eutrophication are not observed currently in the estuary, the high levels of nutrients and sediments being delivered to Lake Superior is an important concern. Therefore, the RAP will use a modification of the IJC eutrophication criterion to reflect local conditions.

* The adaptation to the IJC criteria was made with the full approval and support of the IJC.

* Brief summary to date.
- No rationale to remove from list at this time.
- Need to establish a baseline.

* Paul Sandstrom talked with John Kingston, NRRI.
- John has done some research and paleolimnological sampling to determine presettlement loading conditions to the St. Louis River. This data has not been published.

* Paul Sandstrom brought in graphs and tables showing results from water quality studies between 1974 and 1999.
- MPCA Graph: Annual Average Total Phosphorus Concentrations, St. Louis Bay at I-535 Bridge. 1974-1999.
- Total Phosphorus (TP) shows a steady decline from 0.12 mg/L in 1974 to 0.05 mg/L in 1994.

- Table: Brief Summary of Selected Water Quality Studies and Events. Relevant to Assessing Eutrophication in St. Louis Bay and Western Arm of Lake Superior. 1972-1999.
- TP in Bay in 1974 was ~60-90 ppb vs. 1-2 ppb in Lake Superior. (60ppb = ~0.06 mg/L)

- MPCA Study: August 1999 St. Louis Bay Water Quality Sampling Data.
- Average of 0.06 mg/L TP in Bay.
- Near Barker's Island TP = 0.064 mg/L.
- Wisconsin Entry TP = 0.088 mg/L.
- Minnesota Entry TP = 0.059 mg/L.
- Near Hwy 2 Bridge TP = 0.067 mg/L.
- Near I-535 Bridge TP = 0.064 mg/L.

- Erosion and Sedimentation in the Nemadji River Basin. 1998. page 43.
- Most phosphorus in the river is in particulate form. Dissolved orthophosphate (soluble P) concentrations are usually low. Suspended clay particles tend to remove dissolved orthophosphate (Bahnick, 1977). These clay particles are unusual since they absorb P even when they are washed into the water. Most soils release P in this situation. Turbid streams in the red-clay area had lower orthophosphate (dissolved) levels than clear streams except when the water was affected by barnyard runoff (Devore et al., 1980). Although the high total P levels from sediment (which absorbs dissolved P) results in excessive P loading to Lake Superior and the bay, few algae blooms occur due to low dissolved P levels in the lake and cold water temperatures.

* Shouldn't assume that because P is in one particular form that it is locked in that form. Anaerobic conditions could turn particulate form back into dissolved form?

* 20-40 ppb (0.02-0.04 mg/L) P is about what you would expect in relatively undisturbed streams.

* 0.015-0.02 mg/L seems to be the level other AOCs are using.
- 0.02 mg/L seems to be a reasonable target or goal.
- However if presettlement level is significantly lower than 0.02 mg/L, 0.02 mg/L would not be reasonable.

* 1999 MPCA data seems to show we have plateaued or P is going up?
- 0.09 mg/L TP for Wisconsin entry. Lots of clay there so would see more P. Heavy rains could have increased this number as well.
- Trend line won't be straight.
- Point sources are being eliminated.

* John Kingston, NRRI said he would be interested in doing further research to determine presettlement loading to the St. Louis River. However, he would need funding to accomplish this task.
- How much time would this take?
- Perhaps SeaGrant could fund it?

* Even at 0.02 mg/L the loading to Lake Superior is quite high because of the volume of water.
- Lake Superior P concentration is 0.001-0.002 mg/L according to 1974 MPCA study.
- Bay P levels would be 10 times higher than the Lake.
- In older studies, any number under 0.02 mg/L wasn't extremely accurate.

* Why don't we see effects of high loading to Lake Superior?
- High residence time: ~190 years.
- May take a while to go from particulate to production form.

* Don't want a goal to be too low a concentration or it becomes unreachable. Don't want goal to be too high a concentration because Lake Superior is such a valuable resource.

* Goal: Nutrient and sediment levels in the St. Louis River estuary should not lead to excessive loading to Lake Superior.
- Needs to be more specific. Excessive is subject to too much interpretation. Needs to be more precise.

* Shoot for an annual loading amount to Lake Superior?
- Hydraulics more complicated than P.
- If we can estimate the amount of water coming down the St. Louis River and P concentration is 0.02 mg/L we would roughly know the loading to Lake Superior.

* Goal is to limit loading but we can do that by phosphorus concentration. Need to establish a concentration level in stages.

* Goal: Limit the loading to Lake Superior by reducing the input. The marker is the concentration such that the average harbor concentration of phosphorus is below xx number (0.02 mg/L?).
- Paul's work can validate the xx number.
- Other AOCs have 0.02 mg/L (Collingwood Harbour) and 0.015 mg/L (Saginaw River).
- Saginaw River concentration of 0.015 mg/L came from 1978 Water Quality Agreement for Lake Superior. Seems ridiculous to have same concentration in estuary and Lake.
- Collingwood Harbour (Georgian Bay, Canada) concentration of 0.02 mg/L. Also did Secchi disk and dissolved oxygen at saturation. Don't seem to know what they are doing. Did unionized ammonia as well. Maybe ammonia is looking at toxicity? They have a level for sewage load from treatment plant.

* Nutrient and sediment levels in the St. Louis River estuary should limit the loading so average harbor concentrations are below 0.02 mg/L.
- Just need to hit 0.02 mg/L.
- Probably do it by reducing inputs but don't want to limit ourselves to this.
- Add: Nutrient and sediment levels should not impair fishing, boating opportunities, or swimming.

* Is phosphorus the only nutrient that we need to have a concentration listed for it?
- Maybe Lake Superior dynamics would need nitrogen or potassium concentrations?
- Usually phosphorus is the limiting nutrient and everything else is present in excess. Need to ask a few experts if phosphorus is the limiting factor in Lake Superior growth.
- Should be studies on what is the limiting factor of growth in Lake Superior (light, water, etc.)
- Should we use phosphorus as an indicator? Then assume that we are getting lower nitrogen and suspended solids without specifying a concentration number. Is this a valid assumption?
- Substances that promote plant growth are closely tied to phosphorus.

* Sediment and phosphorus are closely tied together.
- Total suspended sediment (TSS) fluctuates a lot. Hard to put boundary on what makes difference. Phosphorus is a prime candidate of suspended sediment.
- Coffee/Newton Creek has a lot of sediment deposited. Hard to measure or make a goal out of this deposited sediment.
- Where and when could you measure sediment load? Would have to be an annual average loading to Lake Superior so mouth of harbor?

* Nemadji and St. Louis River sediment have to be measured separately. Maybe some streams need to be separate.

* Assume lower phosphorus concentration means lower sediment concentrations?
- How much is phosphorus attached to different types of sediment? Sand vs. Clay.
- Other things affect this: aerobic, iron amount, surface area, pH.
- Clay has high surface area and has a negative charge.
- Under anaerobic conditions phosphorus is released which in turn can cause more anaerobic conditions.

* How are sediments and phosphorus used in Lake Superior?
- More data on this would be good.

* Sediment comes down fast moving streams and then settles in estuary, so doesn't load as much as nutrients to Lake Superior.
- Lake Superior will always turn red from suspended red clay even if we reduce nutrient and sediment loading by a factor of ten.

* Different type of measuring criteria for Duluth streams.
- Is there controllable sediment loading to streams that isn't linked to phosphorus? Yes, sand.
- Forestry activities, streambank reduction hydrology, overuse of road sand, construction sites all contribute to sand in the streams.
- A lot of sediment comes from streambed rather than watershed.

* Have high phosphorus concentration in estuary but don't have eutrophication symptoms, so our AOC modified the IJC criteria. IJC approved.

* Phosphorus alone is probably enough to specify then.

* Is sedimentation going to be considered in the wildlife habitat BUI?
- Habitat Committee should consider this.
- Habitat Committee should also look at road salt.
- There are a couple of snow management areas. They mostly control garbage and runoff but don't affect salt.
- Salt doesn't seem to affect the river as a nutrient, so doesn't need to be addressed in this BUI.

* Goal: Nutrient and sediment levels in the St. Louis River estuary should be limited so the annual average harbor concentrations are below 0.02 mg/L total phosphorus. Nutrient and sediment levels should not impair fishing, boating opportunities, or swimming.

* Milestones should be significant points towards development of a goal.
- Milestones should measure what you accomplish not how you get there.
- Measuring a percentage decrease, etc. not that you conducted 3 studies.
- Milestones are steps we will reach as we work towards our goal.
- Lots of things we can do to reduce sediment and nutrients. DonÕt want to say these are things we have to do to reach these goals or are the only things we can do to reach these goals.
- How do we measure progress towards our goal?
- Not list of things we did. List of effect of things we did.
- Doesn't have to be that way. Some milestones are actions.

* So many acres planted in trees below goal of having 40% open subwatersheds.
- Rural subwatersheds that are over 40% open due to past agricultural activity.
- Urban issues: water runoff from blacktop, etc. very different.

* Milestones from previous meetings.
- Completion of urban erosion project to reduce phosphorus and sediment in tributary.

* Need to identify non-point sources and point sources.
- Agricultural reduction and soil loss.
- Feed lots.

* Need to say not just do a study but do a study that will reduce phosphorus and sediment loadings.
- EPA will use milestones to measure our progress.
- We will use them to encourage ourselves that we are getting to our goal.

* Do we need milestones for each of the different source categories?
- urban, rural, forestry, etc.

* Milestone use in Binational Program.
- Mercury reduction has an overall goal of 100% reduction of all sources in Basin by 2020.
- Milestone is 60% reduction by 2000 and 80% by 2010.
- This allows them to say: in order to achieve 60% reduction, we need to do x, y, z. Use it to support proposals. Not doing this project because we like it, but to get get to x, y, or z.

* Our milestones will be used by the AOC.
- Something we do that will bring us towards our goal.
- Not everything has been identified, but we do know some sources.

* Why do we need milestones?
- Should be able to ask yourself at any point, "Is anything being done?" If answer is yes, then you can say we are making progress.
- Can be used as a plan to get us toward our goal.
- Can be used to emphasize that 2020 isn't that far away.

* Possibilities:
- Reduce peak runoff in rural watersheds by 20% by x date.
- Maintain no more than 40% open subwatersheds by 15 years from now.
- Reduce nutrients and sediments from urban watersheds by x% by x year.

* Include line: Such activities include but are not limited to:
- Don't want to say we can't do anything outside of this list.

* Would want to touch on all sources that we know of.
- Objective = Measuring
- Objective = Tools

* Total phosphorus (TP) concentration of 0.02 mg/L.
- All source categories are controlled.

* TP concentration of 0.04 mg/L.
- Reduce urban sediments by x% by 2010, y% by 2015.
- List tools to reduce.
- Reduce rural sediments by x% by 2010, y% by 2015.
- List tools to reduce.

* TP concentration of 0.06 mg/L.
- Reduce peak flow of tributary.
- List tools to reduce (the tasks). BMPs, zoning, etc.

* Nemadji data is there, Duluth streams turbidity reduction per stream rather than whole AOC.

* 2020 being the target year to delist was discussed at an earlier SLRCAC executive committee meeting (July 12, 2000 EC Meeting).
- Delisting goal should match the delisting date.
- 2020 doesn't seem reasonable.
- Sometimes you need a date goal to start working towards it.
- But we have milestones that are dated so perhaps don't need a final date.
- Don't want to put a date on goal to fail.
- Might reach at 2025 instead of 2020.
- Sometimes it is good to have a date so have a failure point.

* 0.02 mg/L is still open to getting more data.
- 0.02 mg/L is restoration goal for estuary. Maybe the delisting target could be less?
- 0.02 mg/L seems to be a reasonable goal for both restoration and delisting.
- Need something to keep working towards after delisting.
- Don't want to stop getting funds because we "reached our goal."