Learn about Misrepresentations of Data Regarding Lake Hiawatha and the Hiawatha Golf Course
August 7, 2017.
The Minneapolis Parks and Recreation Board contracted with Barr Engineering over the past several years to study Lake Hiawatha and the Hiawatha Golf Course regarding water pumpiing issues that affect its future.
We hear information that has been circulated which misrepresents the information that is contained in the February, 2017 report produced by Barr Engineering. This piece attempts to clarify this information.
Text in quotes is taken directly from the Barr Engineering report: February 2017, Stormwater, Surface Water, and Groundwater
Analysis Summary for Hiawatha Golf Course. The full report can be found on the MPRB web-page:
February 2017, Stormwater, Surface Water, and Groundwater
UPDATE: The MPRB has made the Barr Engineering report more difficult to find on their web-site, so you can now get it here: February 2017, Stormwater, Surface Water, and Groundwater Analysis Summary
Existing Pumping of Water
Statements have been made that the pumping of water from Hiawatha Golf Course is detrimental to Lake Hiawatha, and that the volume was a surprise, once it was measured. The Barr Engineering report says that the existing pumping is likely to have minimal ecological impact. And, it is hard to understand how the volumes could have been a surprise when projects have been done which knowingly pumped more water onto the golf course in recent years.
The Barr Report says:
"Through the course of the initial investigations of the groundwater conditions at the Hiawatha Golf Course, we helped quantify the existing pumping rates and inflows to the golf course to understand the magnitude of the pumping. We also determined that the pumping of surface groundwater from the golf course to Lake Hiawatha was not impacting the deep groundwater aquifers in the region, but rather, just recirculating the surface groundwater inflows from the golf course ponds to Lake Hiawatha and back. Although energy intensive, the existing pumping is likely to have minimal ecological impact." p. 47
"on an annual basis, this excessive pumping is due to regional groundwater inflows (~50%), inflow from Lake Hiawatha where lake levels are above the existing golf course pond elevations (~30%), and a storm water diversion project to the golf course from the neighborhood to the west (~20%)." p.47
"In 2011 and 2012, the City of Minneapolis completed a stormwater improvement project. The project diverted stormwater from a 71-acre watershed to the west of the golf course to Pond A in order to provide water quality treatment in Ponds A through F and increase discharge capacity to reduce flooding in the upstream neighborhood. This stormwater runoff along with groundwater inflow to the ponds is pumped to Lake Hiawatha by the existing pumps near Pond E." p. 2
In addition to Barr's documentation, people familiar with this diversion project, including residents that were included in the stormwater improvement project, state that one reason for the diversion project was to save money for the City of Minneapolis. In the past, the stormwater had been combined with sanitary sewer effluent, and then both went to the sewage processing plant. This project separated the stormwater from the sanitary sewer effluent, and diverted the stormwater to the golf course. This saved the city money at the sewage processing plant. Also, the sewage processing plant told the city that the plant may not be able to handle the volume of water that they were receiving.
Insinuations have been made that reduced pumping of water from the golf course is needed to lower phosphorus levels in Lake Hiawatha. The Barr Report indicates that pumping of water from golf course introduces negligible amounts of phosphorus into Lake Hiawatha compared to other sources. Thus, reduced pumping would not significantly impact phosphorus levels in the lake.
The Barr Report says:
"Lake Hiawatha Total Maximum Daily Load (TMDL) has a total annual phosphorus inflow of 6,463 pounds. The annual total phosphorus (TP) being pumped into Lake Hiawatha from Pond E [from the golf course] is calculated at 165 pounds. This is based on pumping 263,000,000 MGY [Million Gallons per Year] at a concentration of 0.076 milligrams/Liter." p. 14
"Based on the estimated seasonal volume pumped from the golf course to Lake Hiawatha using the monitored pumping rate, the estimated volume pumped from the golf course to the lake could range from 0.3% (wet conditions) to 7.6% (dry conditions) of the total seasonal inflow volume. Using the water quality data collected in the golf course ponds and the seasonal volume to the lake, the estimated seasonal phosphorus load from the golf course is only less than 1.0 percent of the total seasonal phosphorus load to Lake Hiawatha." p. 23
Affect of pumping on the Prairie du Chien Group aquifer
Tests were done in February of 2016 to determine if the deep pumping well, installed on the golf course in 1992 for irrigation, was affecting the deep Prairie du Chien aquifer.
The Barr report says:
"It was concluded from the test results that there was no connection between the shallow water table aquifer and the deep Prairie du Chien Group acquifer at the golf course. Therefore, pumping from the lift station is not affecting deep aquifers." p. 17.
Lake Hiawatha Water Level Analysis
Barr compiled a long-term water level record for Lake Hiawatha (1926 to 2017). They also looked at daily average flows in Minnehaha Creek and water levels in Lake Hiawatha, concluding that "There is a strong correlation between creek flows and lake levels." p. 19
A graph in the report shows a lower lake level after dredging in the 1930's. and a slow increase in lake levels through the next decades. After the Grey's Bay dam project in 1979, the lake level peaked and has stayed about the same without peaks and valleys.
Average decade statistics:
|813.4 ft||808.2 ft||810.6 ft||811.0 ft||811.6 ft||811.6 ft||812.8 ft||812.6 ft||812.8 ft|
* after dredging in the 1930's
** after replacing of Gray's Bay Dam
The Barr Report says:
" Increasing water levels in Lake Hiawatha have likely exacerbated the need for additional volume pumped from Hiawatha Golf Course, especially in the past several decades. Water levels in Lake Hiawatha have increased due to a variety of reasons including:
Golf Course Settlement (i.e. the golf course is sinking)
Statements have been made that the golf course is sinking at a rate of 1/4 to 1/2 per year. The Barr Engineering report indicated that they don't have any data to determine if the golf course is sinking. They said, a long-term study over several years would be needed to determine the amount of settling, if any. Also, the majority of settling would most likely have occurred in the 1930's when the dredging and land fill were originally done.
The Barr Report said:
"The historic or current rates of settlement in the golf course are unknown. However, there are several options the MPRB may consider to quantify the historic or current settlement rates in the golf course area. " p. 23
"No geological testing has been performed on the soils in the Hiawatha Golf Course, including the peat. Although the rate of settlement in peat can vary based on the type of peat and loading changes, settlement in peat over time typically [has] the primary consolidation happening over a relatively short period of time and continual creep occurring over the long term."
"Given that the golf course was contructed approximately 90 years ago, the rate of settlement happening today in the golf course is likely very slow. If the settlement rate is on the order of 1/4 to 1/2 inch per year, it may be difficult to measure this amount of settlement during a short monitoring period with any monitoring approach."
Based on tests made at the Lake of the Isles restoration project, Barr said the following: "If the peat in the Hiawatha area is similar to the peat around Lake of the Isles, we would suspect that the primary consolidation in the Hiawatha golf course also happened rapidly after material was placed and after the golf course was constructed. Primary consolidation is complete and the current rate of settlement (secondary consolidation or creep) is very slow." pp.64-65
Protections of Homes From Flooding
The Barr Report said:
"The groundwater monitoring and modeling indicate that pumping in the golf course is protecting the low basements in the adjacent neighborhood from flooding." p. 23
Lake Hiawatha Outlet and Minnehaha Creek Surveys
Statements have been made that removing impediments downstream from Lake Hiawatha would not help lower the water level of Lake Hiawatha. Barr Engineering surveyed Minnehaha Creek downstream from Lake Hiawatha and indicated that removal of weirs and excavation of the creek downstream could, potentially, lower the lake level by 1 foot.
The Barr Report said:
"The lowest channel elevation at the downstream end of the surveyed section of the creek was approximately elevation 809.0 ft NGVD29. Lowering the control for the water levels in Lake Hiawatha to this elevation (1.5 feet lower than the existing control) would require excavation of approximately 2,000 feet of creek channel, replacement/lowering of utility crossings under the creek bed, and the associated permitting for these activities." p. 26
"Based on this survey, we have estimated that the potential lowering of Lake Hiawatha control would result in a water surface of 811.8 ft NGVD29, which is approximately one (1) foot lower than that the Ordinary High Water Level (OHWL) and approximate average water elevation (812,8 ft NGVD29) that we have been using for our groundwater and stormwater evaluations." p. 26
This information was compiled by Kathryn Kelly, August 7. 2017