At least you realize your pond needs rebuilding, that is the first hurdle. There has been a fair amount of discussion about pond construction costs previously. Check them out and use the search feature.

Contractor that rebuilt my pond told me that rebuild costs are about the same as building a new pond, esp it things are deepened. Remember to lower costs you can always down size the pond. Smaller ponds are usually easier and cheaper to manage esp when it comes to buying chemicals.

A really good contractor should be able to work with a well drained and somewhat dried pond bottom if the sludge is not over 4 ft thick. They take dry dirt and mix it with the slop so the bottom materials can be pushed out. Get a contractor that has experience and numerous rebuilds "under his belt".

There several or numerous things that one can do to temporarily prolong the life of an aged pond. Why not post a new question on: How to prolong life of an old pond? or similar title. Try to put it in an appropriate category or heading .

aka Pond Doctor & Dr. Perca Read Pond Boss Magazine -
America's Journal of Pond Management