In addition to the points already mentioned, I would add a few others:
1. You may be more likely in a flood zone which could affect your homeowners insurance rates
2. You will have more birds in the area. They can make a mess, and have eaten the fish in our backyard pond
3. Aqua Hedionda lagoon allows motorized boating, which will increase the noise level

Overall, I believe property values are higher next to a lagoon, so most people consider lagoon side living as desirable.

Hi Pahl,
A possible downside when living next to a lagoon could be insect control. Some insects are more prevalent by lagoons. Your home will be exposed to more moisture than an inland home. The advantages, however, far outnumber any downsides. The ocean air is invigorating. When considering investment, remember that no developer can create more ocean.

You might also consider the lagoon smell. Inland waterways can have different odors from time to time. I agree with Roberta's comment about road noise; the noise is usually unobstructed and in some areas can be really tough (e.g., north side of Solana Beach, east of I-5).

In Carlsbad, the only possible disadvantage of living next to an ocean lagoon might be freeway noise. Homes around the Agua Hedionda and Batiquitos Lagoons have lovely settings and varying degrees of traffic noise.

Otherwise, the settings are lovely and the views can be breathtaking!