BY KATHRYN KELLY
The Minneapolis Park and Recreation Board (MPRB) states that keeping the 18-hole Hiawatha Golf Course dry requires too much pumping of groundwater. But are their stated pumping volumes for dewatering of Hiawatha Golf Course accurate? Documents and data that we received from the MPRB and the DNR bring the stated pumping volumes into question.
We found that pumping volumes from 2015 to 2019 were generally estimates (not actual measured volumes). For 2015, the pumping volume was created from a few days of observed data. From 2016 to May of 2020, most pumping volumes were calculated by multiplying the pumping rate of the pumps in gallons per minute (gpm) by the number of hours the pumps were running. Different documents give different pumping rates for these pumps (530, 900, 944, 1,000, 1,200 and 1,368 gpm). It is unclear which numbers were used. To make it more confusing, an inspection of pumps on the property in 2020 revealed that the pumps were impaired, thus pumping an unknown amount of water. In some cases it would have been less than the rated volume, and in one case water was likely repumped due to backflow from a broken check valve. These issues make the numbers from 2015 to May of 2020 questionable.
In 2019, the Minnesota DNR required the MPRB to get a dewatering permit for pumping groundwater into Lake Hiawatha. This required installation of permanent flow measuring devices on the main pumps, along with creating formal procedures for recording and reporting pumping information to the DNR. It is important to note that the dewatering permit only regulates pumping of groundwater. An MPRB document says that the pumps “pump both groundwater and storm water, so the storm water contribution must be subtracted from the total water pumped.”
Where does this pumped water come from? We know of four sources:
2) Surface storm water runoff.
3) Minneapolis storm water dumped into the golf course pond system.
4) Seepage from Lake Hiawatha.
What has actually been reported to the DNR as pumped groundwater? Water from the above-listed numbers 1 and 4, and sometimes 2 and 3.
The reporting procedure, developed by MPRB’s engineering consultant Barr Engineering, was implemented in June of 2020. It attempts to eliminate numbers 2 and 3 by using acreage that drains into the golf course pond and rainfall at the airport (MSP). Acreage includes the golf course properties, surface runoff and city storm sewer water that is dumped into a golf course pond on the sixth hole. From June 2020 to Dec. 31, 2020, this estimate was subtracted from the total gallons pumped. After that date, this runoff has not been subtracted. This resulted in an estimated over-reporting of pumped water by 43 million gallons in 2021 and 38 million gallons in 2022.
We also question why number 4 (see page from Lake Hiawatha) is not subtracted. This water is just pumped in a circle between the golf course pond and Lake Hiawatha due to two factors: Lake Hiawatha is just yards away from the pond and the lake is at a permanently higher water level than the pond. These factors promote seepage back into the pond. The DNR website states, “Minnesota Statute 103G.265 requires the Department of Natural Resources to manage water resources to ensure an adequate supply to meet long-range seasonal requirements for domestic, agricultural, fish and wildlife, recreational, power, navigation, and quality control purposes. The Water Appropriation Permit Program exists to balance competing management objectives that include both development and protection of Minnesota’s water resources.” Even though some people may consider this to be groundwater, it is a zero-sum game with no water gained or lost in the lake or the golf course, and Barr stated that “the existing pumping is likely to have minimal ecological impact.” Barr found that the lake level has risen since the 1930s, putting it above the level of the pond, and estimated that this seeping lake water constitutes about 30% of the pumped water. Therefore, pumping of this seep-back in a circle is not affecting groundwater and should be subtracted. It is estimated to be 109 million gallons in 2021 and 58 million gallons in 2022.
Subtracting all storm water, surface water and lake water from the total gallons pumped would drastically reduce the pumped volume of groundwater. For 2021 the volume would go from 370 to 218 million gallons of groundwater pumped, and for 2022 the volume would go from 193 to 97 million gallons of groundwater pumped.
2021: 370 – 43 – 109 = 218 million gallons of groundwater pumped
2022: 193 – 38 – 58 = 97 million gallons of groundwater pumped
Another curiosity involves a huge increase in estimated pumping volumes starting in 2017. The two main pumps at Pond E were stated to comprise about 99% of the pumping. Reported pumping on the two main pumps went from 300 million gallons in 2016 to 467 million gallons in 2017 (a 55% increase), yet MPRB documents state that the rainfall went down from 40.40 inches in 2016 to 32.40 inches in 2017 (a 19% decrease). This defies common sense. An MPRB document states that “the data suggests there were some modifications made to the operations of the Pond E pumps in 2017 that more equally runs the two pumps (and potentially increased the total pumping) that continues to present.” MPRB data shows that the left pump increased tremendously from 11 million gallons in 2016 to 252 million gallons in 2017, while the right pump decreased from 289 million gallons to 214 million gallons. We ask why running the two pumps more equally would cause the total pumping volume to increase by over 50 percent when rainfall decreased? Since seep-back from Lake Hiawatha is not tied to rainfall, could this pumping regime be drawing in even more water from Lake Hiawatha that is just pumped back out, thus erroneously elevating the pumping numbers even more?
This assessment indicates that these pumping numbers appear to be very questionable in determining how much groundwater is pumped from the golf course. The MPRB needs to explain why they have submitted pumping numbers to the DNR that don’t follow the procedure. Also, what is the DNR’s role in making sure organizations report accurate and meaningful data?
The MPRB and the DNR need to determine a method that will create meaningful groundwater pumping numbers, and the MPRB needs to admit that their stated pumping numbers have been questionable at best. Plus, the MPRB needs to quit demonizing the golf course over conditions that government agencies have placed on the golf course, such as using the golf course as a storm sewer, or conditions they have refused to correct such as not maintaining the lake at its original level since the lake and property were developed in the 1930s. This lack of proper infrastructure and maintenance is what is really unsustainable for the whole Lake Hiawatha neighborhood.
Note: The golf course pumping has been found to not affect the deeper Prairie du Chien aquifer.