Mary if I had to guess I would say you have a muskrat that is coming to your pond or is in your pond. I would also guess that there could be other holes in the pond some could be 6" in diameter.
Mike

i'm not real good at ponds yet, but maybe if you lower the water and cover the area with silicone 1.. 100% silicone. maybe that would hold it untill you could get some repair tape. i hope you can figure out something.

Thank you Mike and Loriques, I'm not sure how to repair this as it's in a fold, but I am keeping the water level below the 13 inch long tear in the liner that looks like a giant pair of pinking shears cut into it. It's an EPDM liner and looking on the internet--Firestone sells repair "tape", so guess I'll try that, but underwater--will it hold?

Thanks again for your help, and I wish I knew how this happened, but my guess is a raccoon clawing his way out of the pond. M

Mary,

Here is a thread discussing patching two pieces of liner together to expand the pond. I would think the same technique would work for patching a long tear as you have.
Anne

Here is a link that might be useful: Cliff and JoAnn's Dog Leg Addition

Silicone is not going to help you with a tear like that. Only a patch designed for EPDM will work. If you go on the Firestone specialty products website you will find instructions on every type of seaming and liner work.

It's hard to say what ate through your liner. Let's hope it was not a muskrat. They like to make several entrances to their dens about a foot below the water line dumping the dirt inside the pond.
To keep the Raccoons out I installed a fido type fence from TTS easy and cheap to install. I used bamboo stakes instead of the supplied plastic ones. Looks great and keeps the Herons out also.

Awww....so sorry for about your leak. I would buy: liner, dish brush or scrubby pad, double sided seaming tape, acetone, a roller, and aquarium silicone.

First cut out the bad liner and clean very well with acetone the edges of the liner you will be replacing. You may need to use a dish brush or scrubby pad to help remove the algae. Buy the 100% strength acetone if you can and make sure the liner is clean and dry before you attempt repair. Make sure you have a piece of plywood or a similiar hard surface to put behind the liner you need to repair.

Cut out the old liner, clean the edges, put a board behind the liner. Window pane the new liner with the double sided liner seaming tape. Once you have that in place you need to very firmly attach the new liner to the old liner with the seaming tape. Use a roller and make sure the tape is warm and pliable. This takes some elbow grease to get it right. After that apply the silicone around the edges. WAIT 24 HOURS for the silicone to cure before adding water to the pond.

I hope this makes sense and hope your repair goes well.

Regards,
Lisa

Hello, and THANK YOU ALL for all the help. Pashta, thanks for the Cliff and JoAnn link--what great pictures and all the detail on how they added the dog-leg. And thank you frogman4 I have some extra EPDM liner left from the initial laying of the liner, and I appreciate your mentioning that using silicone wouldn't work--as believe me I have no idea. I also appreciate the fido type fence idea as I do get raccoons almost every night, but this is the first time I've had any damage.
goodkarma, your explanation is wonderful--so clear and step by step How to do it! Youve made me feel that I can tackle it and it will work. -I really appreciate your expert advice--Thanks to all of you for your help--I feel like I have friends who care--my best to each of you! marycontrary

The problem with silicone is that it will peel away from whatever it is applied to.It works well with layered materials that are sandwiched between something rigid. Any flexing or intrusion of material like sand or dirt will cause it to fail.