if you don't already have one, build a Linked In profile. Just put in information about your education and any jobs you can. This will help people find you. It will also help give you credibility as you go through the next few steps. If you don't have a photo or don't feel like putting a photo up, that's ok for now. Just make sure you have SOMETHING up there. You can talk about what kinds of jobs you're looking for, list relevant classes and internships you've taken and class projects. You can even put some of your grades for some of the relevant courses, if they are good. You can try to add anyone you know who works in this industry/field as a connection. Then do the thing where you tell Linked In to let recruiters find you and that you are looking for a job. After my first job (which I had to go out and find) every single one of my next job opportunities came from a recruiter finding me on Linked In. It might be slower for you since you are in your first job search, but eventually as your career grows, could pay off.
Also, post your resume to sites like Monster and Indeed. There are recruiters working on those sites constantly.
The steps above will help other people find you even while you are doing other things. These are the 1st steps I would recommend.
After that, you have to start getting more aggressive to find the right connections/companies.
Go to your schools' career resource center. Yes, even if it's been a while since you graduated. What you are looking for is any job listings they many have, any companies they have a relationship with, a list of alumnae who are working at companies that hire in your field (even if the alumnae isn't in the right department to hire you). Reach out to them. Ask them for advice. Your talking points would be something like this: I am a graduate of XYZ with an interst in ABC. I found your information through ABC and am hoping you might be able to speak with me/give me some guidance. Then ask them 1 or 2 questions via email (like, what advice would you give). As part of that email or in a follow up, you can ask if you could schedule some time with them to chat. Do not try to get more than 30 minutes of their time. Aim for something like 10-20 minutes. Ultimately you are looking to get them to like you and give you a referral to people they know who may hire you.
Also, go to your professors or even professors in the program that you didn't take. Ask them for advise too. They may have contacts/companies they can refer you to, and you can use the same structure as above to reach out to them (i.e. the email format).
Use all of your resources. Check behind every possible opportunity.
Rajesh recommends the following next steps:
1) Government: Usually civil work (Water-supply, Roads, Highways, etc.) type of work comes under the domain of states, counties, cities and municipalities. So my suggestion would be to look for jobs advertised on a state-government, county, city and/or municipality websites.
2) Private-companies: Usually the above work (from states, counties, cities and municipalities) is also contracted out to private companies. So look for sites like glassdoor, indeed, etc., for any jobs in the civil engineering area.
3) Other options could be looking for job with builders who build-out big housing developments.
4) Regarding Dams related work you may want to look for companies that manage and maintain the existing dams. Lately haven't seen big dams being built these days. But there are Nuclear-Energy plants that may need lots of civil and water related work.