Letter to Mayor Hildreth

The following is an email sent to Mayor Hildreth from contracted hydrology consultant, Peter Schreuder:
Mayor Hildreth:
I have reviewed all the information which have been collected by the members of the stakeholders group. It has been very useful. I would like to make a few comments based on my focus on the technical/hydrogeological/water resources aspects.

The SRWMD David Still letter states that” This decrease (in ground water flow) is apparently a result of ground water withdrawals originating in the District , the St. John’s River Water Management District (emphasis added) and the State of Georgia”. The data for the Keystone Heights area indicates that these ground water withdrawals have also increased the vertical gradient between the lakes and the ground water causing them to “leak” more, thus losing more water than was historically the case.

I believe that it is impractical to assume that ground water withdrawals will be curtailed to such an extent that the leakance will be reduced. Thus only three avenues for action remain:
1) reduce the leakance from the lakes by reducing the permeability of the lake bottoms;
2) direct more surface water flow towards the lakes;
or 3) a combination of both.

I believe that the action 2 includes the short term solution which involves the construction of an adjustable weir at the outlet of Lake Lowery (Option 5), an intermediate term solution by withdrawing more surface water from Southwest lake to be pumped to Blue Pond, and a long-term solution by implementing Option 7, the importation of outside water to the Old Mine area.

The data on the renewal of the Dupont mining permit shows that surface water from their northern mine area flows by gravity through an unlined canal towards their southern mine area. This is where NPDES outfall D002 is located. “Negotiating” a larger diversion of that surface water towards Southwest Lake will bring more water to our lakes.

The last possible long-term option would be importing secondarily treated effluent towards the Dupont mining operation in the northern mine part and then let nature clean the water while it is flowing southward to the Old Mine area and to Southwest lake. This naturally cleaned water will be flowing into our Lakes and increasing the ground water recharge thereby increasing ground water levels in the Floridan Aquifer in the SRWMD as well as in the SJRWMD. This would be of great interest and possible benefit to both Water Management Districts and therefore also of great interest to JEA.

Peter

Peter Schreuder, P.G.
www.schreuderwater.us