My advice would be to remove the cattails first with an excavator. You will need a plan and a place to put all the excavated material. Then you can see what soil material you have to work with. It's been dry the last few years, and without rain and runoff the pond will struggle to keep water in it if it is not sealed. What was the purpose of the pond? Is it a storm runoff catchment pond or was it supposed to be a feature of the subdivision?

There is a polymer product on the market that will help seal it if it's not a ground water based pond ( To my knowledge the jury is still out on how well it works with a groundwater pond.) Once the type of soil is determined, and the watershed calculated, it can be determined if there is enough watershed to keep the pond full if it was sealed. Hopefully TJ will chime in.

The Porter County NRCS office was a great place to go to for pond information, unfortunately I haven't worked with them since the head pond guy there retired. I don't know how they are now, but they were 1,000 x better than the NRCS office in Starke County. Give them a shout or stop in there, they should have a list of dirt movers that say they can work on ponds. That should get you started in the right direction, at least with some pricing on what they'd charge.

Porter County NRCS Office
2602 E Chicago St, Valparaiso, IN 46383
(219) 462-7515
Saturday Closed
Sunday Closed
Monday 8AM–4:30PM
Tuesday 8AM–4:30PM
Wednesday 8AM–4:30PM
Thursday 8AM–4:30PM
Friday 8AM–4:30PM

If you want to give me a shout, send me a PM and I'll PM you my number. We are relatively close, near SR 23 and Rt 30.